U.S. patent application number 10/453783 was filed with the patent office on 2004-12-02 for nanoelectromechanical transistors and switch systems.
Invention is credited to Harlan, John C., Mullen, Jeffrey D., Pinkerton, Joseph F..
Application Number | 20040238907 10/453783 |
Document ID | / |
Family ID | 33452131 |
Filed Date | 2004-12-02 |
United States Patent
Application |
20040238907 |
Kind Code |
A1 |
Pinkerton, Joseph F. ; et
al. |
December 2, 2004 |
Nanoelectromechanical transistors and switch systems
Abstract
Nanoelectromechanical switch systems (NEMSS) are provided that
utilize the mechanical manipulation of nanotubes. Such NEMSS may
realize the functionality of, for example, automatic switches,
adjustable diodes, amplifiers, inverters, variable resistors, pulse
position modulators (PPMs), and transistors. In one embodiment, a
nanotube is anchored at one end to a base member and coupled to a
voltage source that creates an electric charge at the tip of the
nanotube's free-moving-end This free-moving end may be electrically
controlled by applying an additional electric charge, having the
same (repelling) or opposite (attracting) polarity as the nanotube,
to a nearby charge member layer. A contact layer is located in the
proximity of the free-moving end such that when a particular
electric charge is provided to the nanotube (or charge member
layer), the nanotube electrically couples with the contact
layer.
Inventors: |
Pinkerton, Joseph F.;
(Austin, TX) ; Harlan, John C.; (Leander, TX)
; Mullen, Jeffrey D.; (Scarsdale, NY) |
Correspondence
Address: |
FISH & NEAVE
1251 AVENUE OF THE AMERICAS
50TH FLOOR
NEW YORK
NY
10020-1105
US
|
Family ID: |
33452131 |
Appl. No.: |
10/453783 |
Filed: |
June 2, 2003 |
Current U.S.
Class: |
257/419 ;
257/415; 257/424; 438/53 |
Current CPC
Class: |
G11C 23/00 20130101;
B81B 3/0021 20130101; G11C 2213/16 20130101; H01H 1/027 20130101;
H01H 1/0094 20130101; B82Y 10/00 20130101; B82Y 30/00 20130101;
Y10S 977/732 20130101; G11C 13/025 20130101; B81B 2201/014
20130101 |
Class at
Publication: |
257/419 ;
257/415; 438/053; 257/424 |
International
Class: |
H01L 029/82; H01L
021/00 |
Claims
What is claimed is:
1. A nanoelectromechanical system comprising: a base member; a
mounting assembly attached to said base member; a first electrical
contact; a nanometer-scale beam fixed to said mounting assembly,
wherein a first portion of said beam is free-to-move, said beam has
a first charge, and said first free-moving portion being able to
electrically couple with said first electrical contact at a contact
rate; and a charge member, having a second charge, located in the
proximity of said first free-moving portion such that said second
charge interacts with said first charge to affect said contact
rate.
2. The nanoelectromechanical system of claim 1, wherein said
nanometer-scale beam is a nanotube.
3. The nanoelectromechanical system of claim 1, wherein said first
free-moving portion and said fixed portion are located at opposite
ends of said nanometer-scale beam.
4. The nanoelectromechanical system of claim 1, wherein said first
charge is provided by a first voltage source.
5. The nanoelectromechanical system of claim 1, wherein said second
charge is provided by a second voltage source.
6. The nanoelectromechanical system of claim 1 further comprising:
a source of thermal energy, wherein said thermal energy affects
said contact rate.
7. The nanoelectromechanical system of claim 1 further comprising:
sense circuitry for determining said contact rate.
8. The nanoelectromechanical system of claim 1 further comprising:
control circuitry coupled to said charge member for providing
voltage signals to said charge member.
9. The nanoelectromechanical system of claim 1 further comprising:
control circuitry coupled to said nanometer-scale beam for
providing voltage signals to said nanometer-scale beam.
10. The nanoelectromechanical system of claim 1 further comprising:
a second electrical contact coupled to said beam, wherein current
flows between said first and second electrical contacts when said
nanometer-scale beam electrically couples said first electrical
contact.
11. The nanoelectromechanical system of claim 1 wherein said first
electrical contact is located between said charge member and said
nanometer-scale beam.
12. The nanoelectromechanical system of claim 11 wherein said
contact rate is greater when said first and second charges have
opposite polarities then when said first and second contacts have
the same polarity.
13. The nanoelectromechanical system of claim 11 wherein said first
and second charges are of opposite polarities and increasing the
intensity of said first charge increases said contact rate.
14. The nanoelectromechanical system of claim 11 wherein said first
and second charges have the same polarity and increasing the
intensity of said first charge decreases said contact rate.
15. The nanoelectromechanical system of claim 1 wherein said
nanometer-scale beam is located between said first electrical
contact and said charge member.
16. The nanoelectromechanical system of claim 15 wherein said
contact rate is greater when said first and second charges are of
the same polarity then when said first and second charges have
opposite polarities.
17. The nanoelectromechanical system of claim 1 further comprising:
an isolation layer located between said charge member and said
first electrical contact.
18. The nanoelectromechanical system of claim 1 further comprising:
a second charge member located on substantially the opposite side
of said nanometer-scale beam as said charge member, wherein said
second charge member has a third charge that affects said contact
rate.
19. The nanoelectromechanical system of claim 18 further
comprising: a third electrical contact, wherein said third
electrical contact is located between said second charge member and
said nanometer-scale beam and said first electrical contact is
located between said charge member and said nanometer-scale
beam.
20. The nanoelectromechanical system of claim 19, wherein said
first and third electrical contacts are electrically coupled
together.
21. The nanoelectromechanical system of claim 1, wherein said
nanometer-scale beam is fixed to said mounting assembly at both
ends and said first free-moving portion is located between said
both ends.
22. The nanoelectromechanical system of claim 1, further
comprising: a second electrical contact coupled to said beam; and a
resistor coupled to said second electrical contact.
23. The nanoelectromechanical system of claim 1, wherein said
second charge is provided by an AC voltage source.
24. The nanoelectromechanical system of claim 1, wherein said
second charge is provided by a DC voltage source.
25. A nanoelectromechanical system comprising: a base member; a
nanometer-scale beam fixed at one end to said base member, said
beam having a first charge and having a portion that is
free-to-move; a charge member layer having a second charge; a first
electrical contact located within the proximity of said beam such
that interactions between said first and second charges determines
if said free-moving portion electrically couples to said first
electrical contact; and sense circuitry for sensing said electrical
coupling.
26. The nanoelectromechanical system of claim 25, wherein said
sense circuitry is coupled to said first electrical contact.
27. The nanoelectromechanical system of claim 26, wherein said
electrical coupling is a galvanic coupling.
28. The nanoelectromechanical system of claim 25 further
comprising: control circuitry coupled to said beam for providing
electrical signals to said beam.
29. The nanoelectromechanical system of claim 28, wherein said
control circuitry is operable to adjust the polarity and magnitude
of said electrical signals.
30. The nanoelectromechanical system of claim 25 further
comprising: control circuitry coupled to said charge member layer
for providing electrical signals to said charge member layer.
31. The nanoelectromechanical system of claim 30 wherein said
control circuitry is operable to adjust the polarity and magnitude
of said electrical signals.
32. The nanoelectromechanical system of claim 25 wherein said beam
is a nanotube.
33. The nanoelectromechanical system of claim 25 further
comprising: a magnetic field, wherein said magnetic field creates a
temporary bond between said first electrical contact and said
free-moving portion when current is flowing through said beam.
34. The nanoelectromechanical system of claim 33, wherein said
temporary bond is broken by decreasing the intensity of said second
charge.
35. The nanoelectromechanical system of claim 33, wherein said
temporary bond is broken by changing the polarity of said second
charge.
36. The nanoelectromechanical system of claim 33, wherein said
temporary bond is broken by changing the temperature around said
beam.
37. The nanoelectromechanical system of claim 33 further
comprising: a light source, wherein said temporary bond is broken
by changing the intensity of light impinging said beam.
38. The nanoelectromechanical system of claim 33, wherein said
temporary bond is broken by changing the intensity of said first
charge.
39. The nanoelectromechanical system of claim 33, wherein said
temporary bond is broken by changing the polarity of said first
charge.
40. The nanoelectromechanical system of claim 33, wherein said
temporary bond is broken by changing the intensity of said magnetic
field.
41. The nanoelectromechanical system of claim 25, wherein said
first electrical contact is located, at least in part, between said
free-moving portion and said charge member.
42. The nanoelectromechanical system of claim 41, wherein said
electrical coupling occurs when said first and second charges have
opposite polarities.
43. The nanoelectromechanical system of claim 25, wherein said
free-moving portion is located, at least in part, between said
first electrical contact and said charge member.
44. The nanoelectromechanical system of claim 43, wherein said
electrical coupling occurs when said first and second charges have
the same type of polarity.
45. A nanoelectromechanical transistor comprising: a first
electrically conductive contact layer; a second electrically
conductive contact layer; a nanotube having a first and a second
end, wherein said first end is fixed to said first contact layer
and said second end is free-to-move with respect to said first
contact; and a charge member layer, wherein said second end of said
nanotube electrically couples to said second contact layer when an
appropriate charge is applied to said charge member layer to
physically move said second end.
46. The nanoelectromechanical transistor of claim 45, wherein said
charge attracts said second end to said charge member layer.
47. The nanoelectromechanical transistor of claim 45, wherein said
charge repels said second end away from said charge member
layer.
48. The nanoelectromechanical transistor of claim 45, wherein a
portion of said first end of said nanotube is fixed to said first
contact layer by a retaining layer.
49. The nanoelectromechanical transistor of claim 45, wherein an
non-conducting isolation layer separates said charge member layer,
at least in part, from said second contact layer.
50. The nanoelectromechanical transistor of claim 45 further
comprising: a magnetic field, wherein said magnetic field creates a
Lorentz force on said nanotube when said second end is electrically
coupled to said second contact layer and is conducting a current
that bonds said second contact layer and said second end
together.
51. The nanoelectromechanical transistor of claim 45, wherein said
nanotube has a first charge.
52. The nanoelectromechanical transistor of claim 45 further
comprising: a resistive layer; and a third contact layer separated
from said first contact layer by said resistive layer.
53. A nanoelectromechanical transistor comprising: a first
electrically conductive contact layer; a second electrically
conductive contact layer; a nanotube having a first end and a
second end, wherein said first end is fixed to said first contact
layer and said second end is free-to-move; and a charge member
layer, wherein said second end electrically couples with said
second contact layer at a contact rate.
54. The nanoelectromechanical transistor of claim 53, wherein said
contact rate increases as the voltage applied to said charge member
layer increases.
55. The nanoelectromechanical transistor of claim 53, wherein
thermal vibrations affect said contact rate such that said contact
rate increases as temperature increases.
56. The nanoelectromechanical transistor of claim 53, wherein said
contact rate is non-zero when a zero-voltage is applied to said
second contact member.
57. The nanoelectromechanical transistor of claim 53, wherein said
contact rate is representative of an analog signal applied to said
charge member layer and said contact rate is utilized as a digital
signal at said first contact layer that is representative of said
analog signal.
58. The nanoelectromechanical transistor of claim 53, wherein said
contact rate is representative of an analog signal applied to said
charge member layer and said contact rate is utilized as a digital
signal at said second contact layer that is representative of said
analog signal.
59. The nanoelectromechanical transistor of claim 53 further
comprising: a light source that is focused on said nanotube,
wherein the intensity of said light affects said contact rate.
60. A nanoelectromechanical transistor comprising: a first contact
layer; a nanotube having a first portion that is fixed to said
first contact layer and a second portion that is free-to-move; a
second contact layer placed in the proximity of said second end of
said nanotube such that said second portion is operable to bend and
physically contact said second contact layer; and a light source
focused, at least in part, on said nanotube.
61. The nanoelectromechanical transistor of claim 60, wherein said
second portion of said nanotube electrically couples with said
second contact layer when the intensity of said light source
surpasses a threshold intensity.
62. The nanoelectromechanical transistor of claim 60, wherein said
light source is a laser.
63. The nanoelectromechanical transistor of claim 60, wherein said
light source is a light emitting diode.
64. The nanoelectromechanical transistor of claim 60, wherein said
light source is sunlight.
65. A method for making a nanoelectromechanical assembly
comprising: laying a first conductive layer on a substrate; forming
an isolation layer above said conductive layer; laying a second
conductive layer above a first portion of said isolation layer;
placing a first end of a nanotube on said second conductive layer,
wherein the opposite end of said nanotube is free-to-move; and
laying a third conductive layer in the proximity of said
free-to-move end of said nanotube such that if said free-to-move
end was bent a certain amount said free-to-move end would contact
said third conductive layer.
66. The method of claim 65 wherein said third conductive layer is
placed above a second portion of said isolation layer and beneath
said opposite end of said nanotube.
67. The method of claim 65 wherein said certain amount is the
height difference between said second conductive layer and said
third conductive layer.
68. The method of claim 65 wherein said forming of said second and
third conductive layers further comprises: forming a general
conductive layer on said isolation layer; and etching away a
portion of said general conductive layer to create said forming of
said second and third conductive layers.
69. The method of claim 65 further comprising forming a
non-conductive layer above said first end of said nanotube and at
least a portion of said second conductive layer.
70. The method of claim 65 wherein said placing said first end of
said nanotube on said second conductive layer further comprises:
forming a support layer adjacent to said second conductive layer
and placing said free-to-move portion on said support layer; and
removing said support layer after said first end of said nanotube
has been anchored to said second conductive layer.
71. A method for making a nanoelectromechanical assembly, said
method comprising: laying a first conductive layer on a substrate;
forming an isolation layer above said conductive layer; laying a
second conductive layer above a first portion of said isolation
layer; growing a nanotube on said second conductive layer, wherein
a first end of said nanotube is self-attached to said second
conductive layer and the opposite end of said nanotube is
free-to-move when said growing is complete; and laying a third
conductive layer in the proximity of said free-to-move end of said
nanotube such that if said free-to-move end was bent a certain
amount said free-to-move end would contact said third conductive
layer.
72. The method of claim 71 wherein said third conductive layer is
placed above a second portion of said isolation layer and beneath
said opposite end of said nanotube.
73. The method of claim 71 wherein said certain amount is the
height difference between said second conductive layer and said
third conductive layer.
74. The method of claim 71 further comprising forming a
non-conductive layer above said first end of said nanotube and at
least a portion of said second conductive layer.
75. The method of claim 71 wherein said forming of said second and
third conductive layers further comprises: forming a general
conductive layer on said isolation layer; and etching away a
portion of said general conductive layer to create said forming of
said second and third conductive layers.
76. A method for making a nanoelectromechanical assembly
comprising: laying a first conductive layer on a substrate; forming
an isolation layer above said conductive layer; laying a second
conductive layer above a first portion of said isolation layer;
growing a nanotube on the side of said second conductive layer,
wherein a first end of said nanotube is self-attached to the side
of said second conductive layer, and a second end of said nanotube
is free-to-move; and laying a third conductive layer in the
proximity of said free-to-move end of said nanotube such that if
said free-to-move end was bent a certain amount said free-to-move
end would contact said third conductive layer, wherein the
longitudinal axis of said nanotube is parallel with said third
conductive layer.
77. A nanoelectromechanical system comprising: a base member; and a
plurality of nanoelectromechanical transistors, each of said
nanoelectromechanical transistors comprising: a first electrically
conductive layer; a nanometer-scale mechanically flexible and
electrically conductive beam able to electrically couples to said
first conductive layer as a result of a displacement of said beam
by an electric field; and a second electrically conductive layer
that is coupled to said beam.
78. The nanoelectromechanical system of claim 77 wherein said
nanometer-scale beam is a carbon nanotube.
79. The nanoelectromechanical system of claim 77 wherein said
nanometer-scale beam is a nano-wire.
80. The nanoelectromechanical system of claim 77 further comprising
sense circuitry coupled to said first conductive layer for
determining the rate that said beam electrically contacts said
first conductive layer for a period of time.
81. The nanoelectromechanical system of claim 77 further comprising
control circuitry coupled to said second conductive layer for
providing electrical signals to said second conductive layer.
82. A method for operating a nanoelectromechanical transistor
comprising: applying a first charge on a nanometer-scale beam that
is fixed to a mounting assembly, said nanometer-scale beam having a
first portion that is free to move; applying a second charge to a
conductive charge member layer, that is placed in the proximity of
said first free-moving portion such said first and second charges
interact with each other; and sensing electrical coupling between
said first free-moving portion and said conductive charge member
layer that occurs, at least in part, based on said interaction of
said first and second charges.
83. The method of claim 82 wherein said nanometer-scale beam is
provided as a nanotube.
84. The method of claim 82 wherein said nanometer-scale beam is
provided with a second free-moving portion and said fixed portion
is located between said first and second free-moving portions.
85. The method of claim 82 further comprising sensing the rate of
contact between said first free-moving portion and said first
conductive layer.
86. The method of claim 82 further comprising: providing a second
conductive layer in the proximity of said free-moving portion; and
sensing said first charge on said second conductive layer.
87. The method of claim 82 further comprising: providing said first
charge in a polarity opposite that of the polarity of said second
charge.
88. The method of claim 82 further comprising: providing said first
charge in the polarity as the polarity of said second charge.
89. The method of claim 82 further comprising: adjusting the
intensity of said first charge resulting in an increased rate of
contact between said nanometer-scale beam and said first conductive
layer.
90. The method of claim 82 further comprising: adjusting the
intensity of said second charge resulting in an increased rate of
contact between said nanometer-scale beam and said first conductive
layer.
91. The method of claim 82 further comprising: adjusting the rate
of contact between said nanometer-scale beam and said first
conductive layer by providing light on said nanometer-scale
beam.
92. A nanoelectromechanical system comprising: a base member; a
first electrical contact; a second electrical contact; a first
nanometer-scale beam fixed to said base member, wherein said first
beam has a first portion that is free-to-move and said first beam
is coupled to said first electrical contact; and a second
nanometer-scale beam fixed to said base, wherein said second beam
is provided in the proximity of said first nanometer-scale beam,
said second beam has a second portion that is free-to-move, and
said second beam is electrically coupled to said second electrical
contact.
93. The system of claim 92 wherein second beam is fixed at both
ends and said second free-moving portion is located between said
both ends.
94. The system of claim 92 wherein said first nanometer-scale beam
is a nanotube and said second nanometer-scale beam is a
nanotube.
95. The system of claim 92 further comprising: a charge member
located in the proximity of said first free-moving portion, wherein
said first nanometer-scale beam has first charge, said charge
member has a second charge, and said first and second charges
interact to affect the distance between said first free-moving
portion and said charge member.
96. The system of claim 92 further comprising: a charge member
located in the proximity of said first free-moving portion, wherein
said first nanometer-scale beam has first charge, said charge
member has a second charge, and said first and second charges
interact to affect the distance between said first free-moving
portion and said second free-moving portion.
97. The system of claim 92 further comprising: a charge containment
layer located in the proximity of said first free-moving portion,
wherein said first nanometer-scale beam has first charge, said
charge containment layer has a second charge, and said first and
second charges interact to affect the motion of said first
free-moving portion.
98. The system of claim 92, wherein said second free-moving portion
is substantially perpendicular to said first free-moving
portion.
99. A nanoelectromechanical system comprising: a base member; a
mounting assembly attached to said base member; a first
nanometer-scale beam fixed to said base member, wherein said first
beam has a first portion that is free-to-move; a second
nanometer-scale beam fixed to said base member, wherein said second
beam has a second portion that is free-to-move; and a first
electrical contact coupled to said second nanometer-scale beam and
placed in the proximity of said first free-moving portion.
100. A nanoelectromechanical system comprising: a base member; a
mounting assembly attached to said base member; a first
nanometer-scale beam fixed to said base member, wherein said first
beam has a first portion that is free-to-move; a second
nanometer-scale beam fixed to said base member, wherein said second
beam has a second portion that is free-to-move; and a first
electrical contact placed in the proximity of both said first
free-moving portion and said second free-moving portion.
101. A nanoelectromechanical system comprising: a base member; a
first conductive mounting assembly attached to said base member; a
second mounting assembly attached to said base member; a first
nanometer-scale beam having a first end, a second end, and a first
portion that is free-to-move, wherein said first end is coupled to
said first conductive mounting assembly, and said second end is
coupled to said second mounting assembly; and a sense contact
placed in the proximity of said first free-moving portion.
102. The nanoelectromechanical system of claim 101, wherein said
second mounting assembly is non-conductive.
103. The nanoelectromechanical system of claim 101 further
comprising: a charge member layer placed in the proximity of said
first free-moving portion, wherein said charge member layer is
provided a first charge, said first beam is provided a second
charge, and said first and second charges electrically
interact.
104. The nanoelectromechanical system of claim 103, wherein said
first beam is a nanotube.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to nanoelectromechanical (NEM)
switch systems and transistors. In particular, the present
invention relates to NEMSS that can be utilized as traditional
electrical components such as, for example, transistors,
amplifiers, adjustable diodes, inverters, memory cells, pulse
position modulators (PPMs), variable resistors, and switching
systems.
[0002] As designs for metal-oxide semiconductor field effect
transistors (MOSFETs) become more compact and approach the minimum
theoretical sizing limitations for a MOSFET, the need for
technologies that can produce smaller transistor structures becomes
apparent. It is therefore desirable to fabricate a transistor that
can be sized smaller than a transistor fabricated at the minimum
theoretical size of a MOSFET. By decreasing a transistor's size,
the number of transistors that may be placed on an integrated
circuit increases. As a result, circuit complexity increases, speed
increases, and the circuit's operating power decreases.
[0003] Microelectromechanical systems (MEMS) and NEMSS that are
structured around nanotubes have been developed. Such systems are
described, for example, in commonly assigned copending U.S. patent
application Ser. No. 09/885,367 to Pinkerton that was filed on Jun.
20, 2001. Looking at FIG. 11 of this application, a novel power
generator that utilizes a nanotube immersed in a working fluid to
generate electrical power from the kinetic and thermal
characteristics of a working substance is illustrated. As shown by
the application, nanotubes can be fabricated at extremely small
sizes (e.g., 1 nanometer) and their characteristics (e.g.,
elasticity and conductivity) may be utilized in many different
ways. It is therefore desirable to realize nanotube-based
transistors that can be fabricated to have sizing limitations
roughly equivalent to the size of a single nanotube.
[0004] Sizing limitations are not the only limitations that affect
the performance characteristics and utility of a traditional
MOSFET. For example, traditional MOSFETs have minimum turn-ON
voltages (e.g., 0.7 volts). Thus, miniscule voltage signals (e.g.,
0.00001 volts) cannot be utilized to turn on conventional MOSFETs.
Numerous applications exist in which there is a need for
transistors with small turn-ON voltages. For example, applications
in which faint signals, such as thermal or electromagnetic noise
signals, need to be recognized would benefit from transistors with
extremely low turn-ON. It is therefore desirable to realize a
transistor structure with a very low turn-ON voltage.
[0005] Additionally, traditional MOSFETs exhibit linear output
characteristics. More particularly, traditional MOSFETs may be
configured to provide an output (e.g., emitter current) that is
continuous and has a linear gain dependent upon an input (e.g.,
base current). Applications exist in which the need for devices
that can convert continuous signals to digital signals is present
such as in pulse position modulation. However, traditional pulse
position modulators are currently bulky because they require
circuits that contain multiple instances of traditional MOSFET
transistors. It is therefore desirable to fabricate a single NEM
transistor that can function as a pulse position modulator.
SUMMARY OF THE INVENTION
[0006] It is an object of the present invention to fabricate NEMSS
which are based upon the manipulation of electrically conductive
and mechanically flexible nanometer-scale beams such as, for
example, nanotubes or nano-wires. These NEMSS can employed as, for
example, transistors, amplifiers, variable resistors, adjustable
diodes, inverters, memory cells, PPMs, and automatic switches.
[0007] In one embodiment of the present invention, a carbon
nanotube is anchored at one end to an electrical contact. The
opposite end of this nanotube, however, is unattached and free to
move. By inflicting an electric field on the nanotube when it
carries an electric charge, the position and oscillation of the
free-moving end of the nanotube can be controlled (e.g., by either
repelling or attracting the nanotube).
[0008] Manipulating the location of the free-moving end of such a
nanotube can be utilized to realize many electrical components. For
example, a transistor may be realized by configuring the nanotube
such that when an appropriate electric field is applied to the
nanotube (e.g., a minimum base or gate threshold voltage), the free
moving end of the nanotube couples to an electrical contact (e.g.,
an emitter or drain terminal). Thus, if the anchored end of the
nanotube is also coupled to an electrical contact (e.g., collector
or source terminal) current may flow through the nanotube when the
threshold voltage is met.
[0009] Appropriate magnetic fields may also be applied to a
partially anchored nanotube of the present invention. In doing so,
the free-moving end of the nanotube may be held in contact, as a
result of the magnetic field, with an electrical contact (e.g.,
emitter or drain contact) when current is flowing through the
nanotube. The basic structure of a NEM transistor of the present
invention can also be configured, utilized, or adjusted to provide
the functionality of, for example, amplifiers, adjustable diodes,
inverters, memory cells, PPMs, and automatic switches.
[0010] Additionally, a nanotube-based NEM transistor of the present
invention has a very low minimum turn-ON voltage. Thus, miniscule
voltage signals such as, for example, Johnson noise signals, may be
sensed and manipulated. By adjusting, for example, the charge,
length, width, temperature, and elevation of a nanotube, a minimum
turn-ON voltage may by included in a particular embodiment of the
present invention.
[0011] Nanotube-based NEM transistors of the present invention can
also function as pulse position modulators. More particularly, if a
strong magnetic field is not applied to a NEM transistor of the
present invention then the free-moving end of the nanotube will
couple to an emitter terminal at a rate dependent upon the
intensity of the electric field created by the base terminal in
combination with the charge density of the nanotube. As the
intensity of the electric field created by the base terminal
increases, so does the number of contacts per unit of time that
will occur between the nanotube and the emitter contact. Thus, a
PPM can be realized such that any analog signal applied to the base
terminal of a NEM transistor of the present invention is converted
to a digital signal, representative of the original signal applied
to the base terminal, at the collector terminal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The above and other objects and advantages of the present
invention will be apparent upon consideration of the following
detailed description, taken in conjunction with accompanying
drawings, in which like reference characters refer to like parts
throughout, and in which:
[0013] FIG. 1 is a circuit schematic of a nanometer-scale
transistor constructed in accordance with the principles of the
present invention;
[0014] FIG. 2 is another circuit schematic of a nanometer-scale
transistor constructed in accordance with the principles of the
present invention;
[0015] FIG. 3 is a perspective view of one embodiment of a
nanometer-scale transistor of FIG. 1;
[0016] FIG. 4 is another perspective view of one embodiment of a
nanometer-scale transistor of FIG. 1;
[0017] FIG. 5 is yet another perspective view of one embodiment of
a nanometer-scale transistor of FIG. 1;
[0018] FIG. 6 is a perspective view of a nanometer-scale dual-gate
transistor constructed in accordance with the principles of the
present invention;
[0019] FIG. 7 is a circuit schematic of a nanometer-scale inverter
constructed in accordance with the principles of the present
invention;
[0020] FIG. 8 is a perspective view of one embodiment of a
nanometer-scale inverter of FIG. 7; and
[0021] FIGS. 9A-9F are sectional views of process steps used in the
fabrication of a nanometer-scale electrical-mechanical system
constructed in accordance with the principles of the present
invention;
[0022] FIG. 10 is a perspective view of one embodiment of a
nanometer-scale transistor of FIG. 1; and
[0023] FIG. 11 is a perspective view of one embodiment of a
nanometer-scale transistor of FIG. 1.
DETAILED DESCRIPTION OF THE DRAWINGS
[0024] Turning first to FIG. 1, NEM system 100 is illustrated.
System 100 is defined by charge member layer 122 along with
contacts 141, and 142. Generally, nanometer-scale beam 111 couples
contact 141 to contact 142 dependent upon the signals supplied by
charge member 122. More particularly, nanometer-scale beam 111 may
mechanically bend and electrically couple to contact 142 at a rate
dependent upon the voltages applied to contacts 141 and 121.
[0025] System 100 may be, for example, a transistor such that
charge member 122 is the base terminal, contact 141 is the
collector terminal, and contact 142 is the emitter terminal of the
transistor. Additionally, the functionality of contact 142 as an
emitter terminal may easily be interchanged with the functionality
of contact 141 as a collector terminal. In this manner, contact 141
may be an emitter terminal of NEM system 100 while contact 142 may
be a collector terminal of NEM system 100. Furthermore, the terms
collector, emitter, and base terminals do not limit the
functionality of a NEM transistor constructed in accordance with
the principles of the present invention to model only the
functionality of a bi-polar junction transistor (BJT). The
collector, emitter and base terminals of NEM system 100 can also be
utilized as source, drain, and gate terminals. Such terms are
commonly used to model the functionality of a MOSFET. However, the
terminals of a NEM transistor constructed in accordance with the
principles of the present invention are not limited to a
functionality appreciated by a BJT or MOSFET. In this manner,
functionality not included in a BJT or MOSFET may be realized and
employed by a NEM transistor constructed in accordance with the
principles of the present invention. Such alternative
functionality, and any modifications needed to realize such
functionality, will become apparent by the detailed description
that follows.
[0026] Particularly, nanometer-scale beam 111 preferably has either
a positive or negative charge such that the signals supplied by
charge member 122 either repels nanometer-scale beam 111 to
position 112 or attracts nanometer-scale beam 111 to position 113.
In those instances when nanometer-scale beam 111 is attracted to
position 113 by attracting signals from charge member 122,
nanometer-scale beam 111 electrically couples to contact 142.
[0027] In one preferred embodiment, nanometer-scale beam 111 is a
positively charged nanotube that couples to contact 142 when the
negative charge intensity of charge member 122 increases as a
result of an increase in voltage to charge member 122. In such an
embodiment, charge member 122 is a negatively charged dielectric
located beneath contact 142 where a higher voltage supplied to
charge member 122 results in a higher negative charge density. A
more detailed description of a nanotube-based transistor is
provided below with the description of transistor 300 of FIG.
3.
[0028] Persons skilled in the art will appreciate that
nanometer-scale beam 111 may be a structure other than a carbon
nanotube. In this manner, nanometer-scale beam 111 may be embodied
by any nanometer-scale member that is mechanically flexible and
electrically conductive. For example, nanometer-scale beam 111 may
also be a nanometer-scale wire.
[0029] The amount of charge on charge member 122 may be controlled
by, for example, an AC or DC voltage supply source 121.
Additionally, contact 141 may be coupled to source voltage 131 such
that a voltage is applied to nanometer-scale beam 111 and a current
flows across nanometer-scale beam 111 when nanometer-scale beam 111
closes (e.g., electrically couples with contact 142). To complete
the circuit of NEMS system 100, resistor 132 is optionally included
and separates contact 142 from source voltage 131.
[0030] Persons skilled in the art will appreciate that in preferred
embodiments of NEM system 100, voltage source 121 creates an
electric field at charge member 122 that mechanically manipulates
nanometer-scale beam 111. The polarity and intensity of this
electric field, along with the charge profile and polarity of
nanometer-scale beam 111 can be adjusted to manipulate the
functionality of NEMS system 100.
[0031] When no static charge is placed on base charge member 122
(e.g., there is no electric field near nanometer-scale beam 111),
nanometer-scale beam 111 will preferably still vibrate at a
mechanical frequency that is in the MHz range within positions 112
and 113 due to thermal vibrations. Occasionally, these vibrations
will allow nanometer-scale beam 111 to touch contact 142 (e.g.,
once per hour). As introduced above, if a negative static charge is
placed on charge member 122 and nanometer-scale beam 111, for
example, gains a positive charge by voltage source 131,
nanometer-scale beam 111 may connect to emitter contact 142 more
frequently (e.g., once per millisecond).
[0032] However, if the voltage at contact 141 is positive then
nanometer-scale beam 111 will take on a positive charge. If voltage
121 is also a positive voltage then nanotube 111 will rarely come
into contact with contact 142 (e.g., once per year). In one
embodiment, the signal applied to contact 142 may be averaged over
a period of time such that an operational transistor is
realized.
[0033] Depending on the application, it may be beneficial to hold
nanometer-scale beam 111 in electrical contact with contact 142
such that the signal at contact 142 does not lose strength (e.g.,
the signal is not averaged). Thus, NEMS system 100 may be placed in
a magnetic field such as magnetic field (B) 171. Magnetic field 171
can be utilized to create a Lorentz force around nanometer-scale
beam 111 such that nanometer-scale beam 111 will stay electrically
coupled to contact 142 as long as current flows through
nanometer-scale beam 111.
[0034] Persons skilled in the art will appreciate that voltage
source 131 may be a thermally-induced voltage. For example, voltage
source 131 may be the Johnson noise of resistor 132. Inductor 133
may also be included in NEMS system 100 and configured to be in a
series connection with resistor 132. As a result, if current
flowing through inductor 133 changes then inductor 133 may "fight"
the current change by providing a back electromotive field voltage.
In this manner, inductor 133 may be utilized to smooth out current
pulses provided when nanometer-scale beam 111 electrically couples
contact 142.
[0035] Additionally, multiple instances of NEMS system 100 may be
placed in an array such as a common-base array constructed in a
parallel configuration. An example of such an array is included in
array 400 of FIG. 4. This array's output signal stability and
strength increases as more nanotubes are included in the array
because the number of contacts between a single nanometer-scale
beam and contact 142 increases.
[0036] Persons skilled in the art will appreciate that temperature
and thermal vibrations may be utilized in NEMS system 100. For
example, if nanometer-scale beam 111 is a carbon nanotube (CNT)
then the free-moving end of nanometer-scale beam 111 may oscillate
at different frequencies depending upon its temperature. In this
manner, NEMS system 100 may actually be controlled by a temperature
in conjunction with an electric field. Similarly, NEMS system 100
may be utilized as a temperature sensing device by measuring the
number of times that nanometer-scale beam 111 contacts emitter
contact 142 per period of time. If only temperature was
manipulating nanometer-scale beam 111, a large number of contacts
per period preferably indicates that nanometer-scale beam 111 was
subjected to a high temperature during that period. Thermal
vibrations can also be utilized to allow NEMS system 100 to have a
zero voltage minimum turn-ON voltage. For example, if zero voltage
is present at voltage source 121 then nanometer-scale beam 111 will
still occasionally electrically couple with contact 142 due to the
thermal vibrations of NEMS system 100.
[0037] Similar to utilizing thermal characteristics of NEMS system
100, optical devices may also be advantageously employed. For
example, charge member 122 and voltage source 121 may be replaced
by a lens and/or a light source. By focusing or introducing light
onto nanometer-scale beam 111 that bends nanometer-scale beam 111,
the rate of contacts between nanometer-scale beam 111 and contact
142 may be altered. Once again, introducing magnetic field 171 to
such a transistor allows nanometer-scale beam 111 to maintain
contact with contact 142 while current is flowing through
nanometer-scale beam ill. Thus, the contact rate of nanometer-scale
beam 111 may be manipulated by a variety of means. As shown above,
light and temperature are two conditions that may be utilized to
control and manipulate the contact rate of nanometer-scale beam 111
with contact 142. Similarly, other conditions such as magnetic and
electric fields may be applied to nanometer-scale beam 111 to
affect this contact rate. Moreover, NEM system 100 may be employed
as, for example, a temperature, light, magnetic field, or electric
field sensor by determining the contact rate and associating it to
a particular condition intensity. To isolate a particular condition
(e.g., light) from another condition (e.g., temperature),
additional sensors may be utilized to correct for the sensing of
the unwanted condition.
[0038] Persons skilled in the art will appreciate that magnetic
field 171 is not the only technique that can be employed to
maintain contact between nanometer-scale beam 111 and contact 142.
For example, Van Der Wall forces may be utilized in NEMS system 100
to create a temporary bond between nanometer-scale beam 111 and
contact 142.
[0039] Temporary bonds that are created between nanometer-scale
beam 111 and contact 142 may be broken by procedures other than
stopping current flow through nanometer-scale beam 111. For
example, a voltage of the same polarity as the charge of
nanometer-scale beam 111 may be applied to charge member 122 to
overcome any Lorentz forces created by magnetic field 171.
Furthermore, magnetic field 171 may simply be turned off or
adjusted. Preferably, the electric field originally applied near
nanometer-scale beam 111, via charge member 122, that caused
nanometer-scale beam 111 to electrically couple with contact 142
may simply be turned off (e.g., given a zero voltage) such that the
natural spring force of nanometer-scale beam 111 (or the thermal
vibrations of nanotube 111) overcomes the Lorentz force caused by
magnetic field 171. If nanometer-scale beam 111 is employed as a
nanotube then this nanotube could be filled with different
materials in order to manipulate the properties of the nanotube.
For example, carbon nanotubes will have a lowered electrical
resistance when filled with alkali metals such as, for example,
sodium, lithium, or potassium.
[0040] FIG. 2 shows NEMS system 200 that includes nanometer-scale
beam 211. Preferably, nanometer-scale beam 211 is both mechanically
flexible and electrically conductive. Persons skilled in the art
will appreciate that NEMS system 200 can be implemented on the
micro-meter scale and, as a result, be configured as a
microelectromechanical (MEM) system.
[0041] Nanometer-scale beam 211 may be, for example, a nanotube,
nanometer-scale tube, group of bonded molecules, nano-wire, or an
electrically conductive filament. As shown, nanometer-scale beam
211 is anchored at anchor point 215. Thus, anchor point 215
provides stability to one end of nanometer-scale beam 211 such that
nanometer-scale beam 211 can flex between positions 212 and
213.
[0042] Preferably, mechanical stress is placed on nanometer-scale
beam 211 as follows. Voltage source 220 is electrically coupled to
nanotube 211 and can be, for example, either an AC or DC voltage
signal. In this manner, electric charge 214 is applied to
nanometer-scale beam 211 that is proportional to voltage source
220. Electrostatic forces can then introduce mechanical stress in
nanometer-scale beam 211 and cause nanometer-scale beam 211 to
flex. More particularly, if electric charge 231 is placed within
the proximity of nanometer-scale beam 211 and electric charge 231
has the same polarity as electric charge 214 then nanometer-scale
beam will preferably repel from electric charge 231. Similarly, if
electric charge 231 is placed within the proximity of
nanometer-scale beam 211 and electric charge 231 has a polarity
that is opposite to the polarity of electric charge 214 then
electrostatic forces will attract nanotube 211 to electric charge
231.
[0043] Electric charge 231 may be provided by voltage source 230
which may be, for example, an AC or DC voltage signal. Electrical
contacts 243 and 242 may be placed within the region that
nanometer-scale beam 211 can displace to. In this manner, voltage
source 230 and voltage source 220 may influence the rate at which
nanometer scale beam 211 electrically couples to electrical
contacts 243 and 242.
[0044] Voltage source 230 (or voltage source 220) can also
manipulate the frequency at which nanometer scale beam 211 contacts
an electrical contact (e.g., electrical contacts 243 and/or 242).
Output signals 253 and 252 may be obtained from contacts 243 and
242 respectively.
[0045] Light source 271 may be employed in NEMS system 200 to
affect the contact rate between nanometer-scale beam 211 and an
electrical contact (e.g., electrical contacts 243 and/or 242). As a
result, NEMS system 200 may provide a system that converts light
signals into electrical signals. Additionally, the contact rate
between nanometer-scale beam 211 and an electrical contact will
increase as the temperature of nanometer-scale beam 211 increases.
In this manner, light source 271 may work in conjunction with a
heat source. Even a low grade heat source (e.g., body heat) may be
sufficient to provide a significant amount of heat to
nanometer-scale beam 211. Thus, thermal motion of nanometer-scale
beam 211 provides natural commutation events for a switch. The
mechanical frequency of nanometer-scale beam 211 may be configured
to be analogous to the switching frequency of a conventional
switching circuit. Changing the intensity of the light/heat source,
electric charge profile 214, mechanical attributes of
nanometer-scale beam 211, or electric charge 231 will preferably
change the switching characteristics.
[0046] Persons skilled in the art will appreciate that if a light
source is included in NEMS system 200 then voltage source 230 does
not have to be included in NEMS system 200. For example, voltage
source 230 may be removed and replaced by light source 271. Input
signals may then be applied as light signals. Depending on these
signals, nanometer-scale beam 211 will switch differently with an
electrical contact (e.g., electrical contacts 243 and/or 242). In
this manner, output signals (e.g., output signals 253 and 252) of
such an embodiment are representative of the input signals from
light source 271. If voltage source 220 is large enough, then these
output signals are not only electrical representations of the light
signal but are also amplified signals.
[0047] Persons skilled in the art will also appreciate that voltage
source 220 may be a relatively HIGH DC voltage source (e.g.,
approximately 1-5 volts) and voltage source 230 may be a relatively
LOW input voltage signal (e.g. 1-5 microvolts). Conversely, voltage
source 220 may be a relatively LOW input voltage signal while
voltage source 230 is a relatively HIGH DC voltage source. In this
manner, a weak input signal may be amplified such that an amplified
signal is produced at, for example, electrical contacts 243 and
242.
[0048] Persons skilled in the art will appreciate that multiple
instances of the NEMS system 200 may be arrayed together. For
example, a billion such systems may be arrayed, in parallel, within
a square centimeter. If each nanometer-scale beam is 1000 ohms then
the minimum ON resistance (ignoring the resistance between the
nanometer-scale beam and contacts 242 and/or 243) would be roughly
1 micro-ohm. Thus, the resistive losses when conducting 1000
amperes of current would be a single watt (a conventional
state-of-the-art insulated gate bipolar transistor would dissipate
at least hundreds of watts when conducting 1000 amperes of
current). As a result, the above array could be employed in high
power applications. Turning on half of such switches would double
the resistance while turning ON a quarter of the switches would
increase the resistance by a factor of four (and so on). Thus, the
array could be implemented as a variable resistor that is nearly
perfectly linear and adjustable in, as introduced above, a billion
steps. The speed of such an array would also beneficially be able
to turn ON and OFF in mere fractions of a micro-second.
[0049] FIG. 3 shows NEM transistor 300 that is constructed to
include nanotube 311 as a switching mechanism. Transistor 300 is
similar to NEMS system 100 of FIG. 1 such that the general
functionality of the components of NEMS system 100 of FIG. 1 are
generally modeled by the components of transistor 300. For example,
nanometer-scale beam 100 of FIG. 1 is embodied in transistor 300 as
nanotube 311. Base charge member 122 of FIG. 1 is embodied in
transistor 300 as charge member layer 322. Furthermore, emitter
contact 142 and collector contact 141 of FIG. 1 are embodied in
transistor 300 as emitter contact layer 342 and collector contact
layer 341, respectively.
[0050] Nanotube 311 may be said to be in a closed position (e.g.,
position 313) when nanotube 311 electrically couples collector
contact layer 341 to emitter contact layer 342. Persons skilled in
the art will appreciate that nanotube 311 may have electrical
interactions with emitter contact layer 342 even when nanotube 311
is close to, but not physically touching, emitter contact layer
342. Nanotube 311 may be said to be in an open position when
nanotube 311 does not electrically couple collector contact layer
341 to emitter contact layer 342 (e.g., position 312).
[0051] Preferably, nanotube 311 is in a closed position when the
negative charge at charge member 322 is high enough to attract the
positively charged nanotube 311 toward charge member layer 322 to a
point where collector contact layer 341 electrically couples to
emitter terminal 342. Persons skilled in the art will appreciate
that the charge of nanotube 311 is affected by the voltage of
collector contact layer 341 to an extent where changing the voltage
applied to collector contact layer 341 causes nanotube 311 to
electrically couple with emitter contact layer 342. Thus, both the
values of the voltages applied to charge member layer 322 and
collector contact layer 341 need to be considered when designing
transistor 300 to meet specific switching characteristics.
Isolation layer 352 is provided such that the voltage on charge
member 322 does not leak into emitter contact layer 342.
[0052] Persons skilled in the art will appreciate that the voltage
applied to charge member layer 322 (the base or gate terminal of
transistor 300) does not have to be a DC voltage. In this manner,
an AC voltage source may be utilized to supply voltage to charge
member layer 322 and control the operation of transistor 300.
[0053] Additionally, one end of nanotube 311 may be attached to
collector contact layer 341 by nanotube retainer member 361.
Variably, nanotube 311 may be grown onto collector contact layer
341 as shown in optional configuration 381 in which nanotube 383 is
selectively grown onto conductive layer 382. In optional
configuration 381, nanotube 383 is preferably self-attached to
conductive layer 382.
[0054] Persons skilled in the art will appreciate that NEM
transistor 300 may be manipulated by external magnetic field (B)
371. Introducing a magnetic field upon transistor 300 may cause,
for example, nanotube 311 to remain in a closed position when
current is flowing from collector contact 341 to emitter contact
342. Persons skilled in the art will appreciate that motion of
nanotube 311 in the presence of magnetic field 371 induces an
electric field along the length of nanotube 311. This electric
field affects current flow through nanotube 311 when nanotube 311
is in motion. In this manner, magnetic field (B) 371 introduces a
gain factor to transistor 300.
[0055] Persons skilled in the art will appreciate that in creating
a temporary bond between nanotube 311 and emitter contact layer 342
by magnetic field 371 that NEM transistor 300 performs more like a
traditional MOSFET. Without magnetic field 371, or a different
bonding instrument, nanotube 311 will generally contact emitter
contact layer 342 intermittently and at a rate dependent upon the
intensity of the electric field created by charge member layer 322,
the temperature of nanotube 311, and other factors of transistor
300. As mentioned, this contact rate, or contact frequency, can be
utilized to realize the functionality of a PPM and an
analog-to-digital converter. Persons skilled in the art will
appreciate that by including a bonding instrument to transistor 311
(e.g., magnetic field 371 created by a magnetic field generator),
transistor 300 may be utilized as a traditional MOSFET in that if a
continuous electric field is supplied by charge member layer 322, a
continuous output will preferably be supplied at emitter contact
layer 342.
[0056] Persons skilled in the art will appreciate that the Lorentz
forces about nanotube 311, when current is flowing through nanotube
311, may be strong enough to keep nanotube 311 in position 313 even
after an appropriate attracting voltage source is removed from
terminal 321. As mentioned above, nanotube 311 may be made to "pop
off" (e.g., return substantially to a resting location) of emitter
contact layer 342. Reiterating, such procedures could involve, for
example, reversing the polarity of the electric field created by
charge member layer 322 or removing/reducing magnetic field 371
from transistor 300. However, designs can be fabricated to
configure nanotube 311 such that nanotube 311 naturally "pops off"
emitter contact layer 342. For example, nanotube 311 may be placed
a particular distance above emitter contact layer 342 such that
when an appropriate attracting electric field is removed from
emitter contact layer 322, the elasticity and spring constant of
nanotube 311 naturally overcomes the Lorentz forces created by
magnetic field 371. Additionally, emitter contact layer 342 may
actually be the collector of transistor 300 while collector
terminal 341 has the functionality of an emitter terminal.
[0057] Transistor 300 may utilize system or device characteristics
to boost weak signals. As per one example, the voltage applied to
charge member layer 322 may be adjusted so that a known number of
contacts occur between nanotube 311 and emitter terminal 342 when
no signal is present at collector terminal 341 except for the
Johnson noise of the circuit. A weak signal may then be
superimposed on this thermal voltage that will produce a measurable
increase in the number of contacts per unit of time between
nanotube 311 and emitter terminal 342. The Johnson noise of the
circuit may then be averaged out of the signal, leaving only the
weak signal. Particularly, an array of nanotube 311 amplifiers
configured in parallel with a common base would average out the
Johnson noise of the signal. As a result, weak signals can be
detected and transistor 300 may be employed as an amplifier.
[0058] Stated another way, a weak signal can be applied to charge
member layer 322. A relatively HIGH voltage source (e.g., 3 volts)
may be applied to collector contact layer 341 such that when
nanotube 311 couples to emitter contact layer 342 in response to
weak signals applied to charge member layer 322, the voltage of
collector terminal 341 will be applied to emitter terminal 342. If
emitter contact layer 342 is the output signal of the amplification
operation of transistor 300, than the amplification gain would be
approximately equal to V.sub.341/V.sub.322 when nanotube 311 is in
a closed position. The voltage values at emitter contact layer 341
may than be averaged together over a period of time so that
different input signals applied to charge member 322 may be
distinguished by the number of times a closed circuit is formed
(because a higher voltage at charge member layer 322 will result in
more closed circuit instances over a set period of time). Persons
skilled in the art will appreciate that, in the above amplification
method, the linearity between the number of closed circuit contacts
and the magnitude of the input signal applied to charge member
layer 322 is important if the amplified signals at emitter contact
layer 342 are to be representative of the input signals.
Alternatively, a charge may be placed on charge member layer 322
and weak signals may be detected at collector contact layer 341.
Persons skilled in the art will appreciate that nanotubes may be
employed as contact layers (for example in place of contact layer
342) of NEM transistor 300 in order to improve the wear
characteristics of NEM transistor 300.
[0059] Additionally, the greater the number of closed circuits that
occur in NEM transistor 300 over a set period of time, the larger
the average voltage of emitter contact layer 342 will be for a set
voltage at collector contact layer 341. Thus, the average voltage
of emitter contact layer 342 over a period of time can be utilized
to be representative of the weak input signals applied to charge
member layer 322. The maximum amplified output voltage of such a
design would be roughly equivalent to the voltage applied to
collector contact layer 341. Alternatively, the number of contacts
(e.g. the rate or frequency of contacts) can be measured and
utilized to determine the input signals applied to charge member
layer 322.
[0060] Transistor 300 may also be employed as an adjustable diode.
In this embodiment, magnetic field (B) 371 is required. If voltage
source 331 is a voltage signal with an alternating polarity and the
voltage supplied to charge member layer 322 is held constant,
transistor 300 will only allow current to flow when nanotube 311 is
at a certain polarity. Once current is flowing in a certain
direction through nanotube 311, magnetic field 371 will create a
Lorentz force that holds the current conducting nanotube 311 in a
closed position (e.g., nanotube 311 will be coupled to emitter
contact layer 342). Now, when the polarity of the current through
nanotube 311 reverses, magnetic field 371, in conjunction with
reversed current of nanotube 311, will cause nanotube 311 to be in
an open position (e.g. nanotube 311 will not be electrically
coupled to emitter terminal 342). As a result, a diode
functionality is realized. More specifically, a half-wave rectifier
is realized in transistor 300. Persons skilled in the art will
appreciate that the half-wave rectifier functionality of transistor
300 may be utilized to create a full-wave rectifier as well as
various other diode circuits.
[0061] When transistor 300 is employed as a diode, the forward
voltage drop of the diode may be lower than a conventional diode.
This is because the forward voltage drop of a diode constructed
from transistor 300 is approximately equal to the contact
resistance between nanotube 311 and emitter contact layer 342 and
the resistance of nanotube 311. A diode constructed from transistor
300 also has an extremely high efficiency because the diode is
either in an ON or OFF state. Persons skilled in the art will
appreciate that the forward voltage drop of transistor 300 can be
reduced by placing multiple instances of transistors 300 in a
parallel configuration. A diode realized by transistor 300 may be
an adjustable diode in that the polarity of the diode may be
changed by reversing the polarity of charge member layer 322 and
magnetic field 371. Furthermore, the minimum required voltage of
source voltage 331 may be adjusted by changing base voltage 321 to
control the flow of current through nanotube 311. Similarly,
magnetic field 371 may be adjusted.
[0062] As discussed above, the contact frequency of nanotube 311
with emitter contact layer 342 may be, for example, any thermally
induced contact frequency modulated by the magnitude of the charge
density on charge member 322 and nanotube 311. Yet, this contact
frequency may be modulated by different means and mechanisms. For
example, the contact frequency may be modulated optically. For
example, light from a light emitting diode (LED), laser, or the sun
may be focused on nanotube 311. By adjusting the light intensity
impinging nanotube 311, current through nanotube 311 will increase,
or decrease, for a given voltage applied to collector contact layer
341 because the light bends nanotube 311 toward, or away from,
emitter contact 342. If the source of light is directed at nanotube
311 at a certain angle, current through nanotube 311 will increase
because the amount of times that nanotube 311 couples to emitter
terminal 341 will increase as light intensity incident to nanotube
311 increases.
[0063] Persons skilled in the art will appreciate that if charge
member layer 322 remains negatively charged and the voltage of
collector contact layer 341 produces a negative charge on nanotube
311 than nanotube 311 preferably will never, or at least rarely,
contact emitter terminal 342. In this manner, if the charges
between nanotube 311 and charge member layer 322 are the same
(e.g., both are negative or positive) than nanotube 311 will repel
from charge member layer 322. If the polarities of the charge
profiles of nanotube 311 and charge member layer 322 are opposite
then nanotube 311 will preferably be attracted to charge member
layer 322. Thus, nanotube 311 may either have a negative or
positive charge and still achieve the operation of a
transistor.
[0064] Persons skilled in the art will appreciate that the contact
layers of transistor 300 are preferably fabricated from a
conductive material such as a metal layer. To minimize wear,
however, these contact layers may also include, for example,
stationary nanotubes. Persons skilled in the art will also
appreciate that the isolation layers of transistor 300 are
preferably fabricated from a non-conductive material such as an
oxide layer.
[0065] Base 393 may be included in transistor 393 in order to
provide a structure on which the rest of the components of
transistor 300 may be, for example, grown, laid, sputtered, etched,
or placed. Base 393 may be, for example, a layer of silicon.
Generally, a mounting assembly fixes a portion of nanotube 311 to
base 393. This mounting assembly may include multiple components of
transistor 300 as well as components not shown in transistor 300.
For example, the mounting assembly may include contact layer 341
and isolation layer 352. Alternatively, isolation layer 352 may
extend from base 393 and form the mounting assembly or contact
layer 341 may fix nanotube 311 directly to base 393. Thus, the
mounting assembly can take on numerous forms while still retaining
the principle of fixing a portion of nanotube 311 such that the
fixed portion only moves with respect to movement of base 393.
[0066] Sense circuitry 391 may be provided to sense electrical
signals at contact 342. Sense circuitry 391 may, for example,
determine the rate of contact between nanotube 311 and contact 342.
Control circuitry 392 may be provided to provide electrical signals
to charge member layer 322 or contact 341. For example, control
circuitry 392 may selectively provide voltage source 331 to contact
341 and voltage source 321 to charge member layer 322. Control
circuitry 392 may also control the polarity and intensity of any
provided signals. Persons skilled in the art will appreciate that
control circuitry 392 and sense circuitry 391 may be coupled to
other components of transistor 300. For example, sense circuitry
391 may be coupled to contact 341 to sense electrical signals at
contact 341 while control circuitry 392 may be coupled to contact
342 to provide electrical signals to contact 342. Such a
configuration may used, for example, when light is used to change
the contact rate between nanotube 311 and contact 342. When light
is used to change the contact rate, charge member layer 322 is not
needed. Moreover, charge member layer 322 may not be needed in a
diode implementation. For example, if a large enough charge was
applied to contact 342 then an oppositely charged nanotube 311 may
electrically couple to contact 342 without the electrostatic forces
supplied by charge member layer 322. In this diode embodiment, the
turn-ON voltage would be roughly equivalent to the voltage needed
to electrically couple nanotube 311 with contact 342.
[0067] FIG. 4 depicts transistor array 400 that includes two
transistors, transistors 401 and 402, constructed in a series
configuration. In realizing the series configuration, emitter
contact layer 446 of transistor 402 is coupled to collector contact
layer 441 of the transistor 401.
[0068] Persons skilled in the art will appreciate that the base
terminals of transistors 401 and 402 are defined by separate charge
member layers 422 and 426, respectively. Charge members 422 and 426
are isolated from each other by isolation layers 452. Thus,
transistors 401 and 402 can be controlled separately. Nanotubes 411
and 415 are preferably attached to collector contact layers 441 and
445, respectively.
[0069] A signal applied to transistor array 400 will only pass from
collector contact layer 445 of transistor 402 to emitter contact
layer 442 if the charge on charge member layers 422 and 426 are
both of the appropriate magnitude and type to attract nanotubes 411
and 415 to emitter contact layers 442 and 446, respectively. In
this manner, transistors constructed in accordance with the
principles of the present invention may employed as logic
components. For example, transistor array 400 may be viewed as a
logical AND gate in that both charge members 422 and 426 have to
close transistors 401 and 402, respectively, if a signal is to pass
from collector terminal 445 to emitter terminal 442.
[0070] Magnetic field 471 may be included in transistor array 400
to create Lorentz forces on transistors 401 and 402 that are in a
closed position (e.g., nanotubes 411 and 415 are electrically
coupled to emitter contact layers 442 and 446, respectively). As
described above, the Lorentz force created by magnetic field 471
will preferably keep transistors 401 and 402 closed as long as
current of one polarity is flowing through nanotubes 411 and 415,
respectively. Persons skilled in the art will appreciate that
magnetic field 471 may be two independent magnetic fields. In such
an embodiment, a separate magnetic field may be utilized in
transistors 401 and 402.
[0071] Turning now to FIG. 5, transistor array 500 is shown that
includes three transistors constructed in a parallel configuration.
More particularly, the transistors defined by nanotubes 511-513 are
coupled at one end to common collector contact layer 541. The
free-moving ends of nanotubes 511-513 may, depending on the state
of the transistors of transistor array 500, couple to common
emitter contact layer 542. Thus, the transistors of transistor
array 500 share the same collector terminal (e.g., collector
contact layer 541) and emitter terminal (e.g., emitter contact
layer 542). The transistors of transistor array 500 also share a
common base terminal at charge member layer 526 that is isolated by
isolation layer 552.
[0072] As a result of the configuration of the transistors of
transistor array 500, persons skilled in the art will appreciate
that transistor array 500 may be employed as a single transistor.
Furthermore, adding additional nanotubes to transistor array 500 in
a common-base parallel configuration increases the stability of the
single transistor modeled by transistor array 500. In other words,
adding nanotubes to transistor array 500 increases the frequency at
which at least one of the nanotubes of transistor array 500 creates
an electrical connection between common collector contact layer 541
and common emitter contact layer 542 for any given voltage applied
to common charge member layer 526. In addition to increasing
transistor stability, transistor array 500 has other advantages.
For example, minute differences in the signals supplied to charge
member layer 526 result in a more distinguished output signal at
common emitter contact layer 542. When transistor array 500 is
employed as an amplifier, this attribute provides better
linearity.
[0073] Each nanotube of transistor array 500 may have a significant
internal resistance (e.g., 1,000-10,000 ohms). However, if
nanotubes 511-513 electrically contact emitter contact layer 542 at
the same time then the internal resistance that will be seen in
these three parallel nanotubes will be approximately equivalent to
1/3 of the resistance of an individual nanotube 511-513. One
embodiment of array 500 may contain thousands of, or even billions
of, nanotubes in a parallel configuration. Thus, the minimum ON
resistance of such an array can be very low while keeping the
linearity of the array very high. In this manner, transistor array
500 is similar to a linear transistor in that transistor array 500
may be utilized as a variable resistor.
[0074] Persons skilled in the art will also appreciate that
isolation layer 552 may be fabricated such that each of nanotubes
511-513 has a separate charge member 526. As a result, an
independent-base parallel configuration is realized that may be
useful in many applications. For example, transistor arrays 500 in
an independent-base parallel configuration, depending on how charge
members 526 and nanotubes 511-513 are charged, may be employed as
an "OR" logic circuit. In this manner, transistors in an
independent-base series configuration (e.g. transistor array 300 of
FIG. 3), depending on how charge members 526 and nanotubes 511-513
are charged, may be used as an "AND" logic circuit.
[0075] FIG. 6 depicts NEM assembly 600 that utilizes two charge
members, charge member layers 601 and 606, to control and position
nanotube 611. Charge member layers 601 and 606 can be utilized in
many ways to give NEM assembly 600 many different
functionalities.
[0076] In one embodiment, for example, charge member layers 601 and
606 may be positioned on opposite sides of nanotube 611.
Furthermore, charge member layers 601 may also impose, at all
times, an opposite charge on nanotube 611. As a result of this
embodiment, the stability of NEM assembly 600 increases when it is
employed as a transistor. This is because as one of the charge
members is "repelling" nanotube 611, the opposite charge member
layer is "attracting" nanotube 611. As a result, the frequency of
nanotube 611 contacts increases. Furthermore, if emitter contacts
603 and 604 are coupled together, the number of contacts per unit
of time increases (even if, for example, charge member layer 601 is
removed from transistor 600). One application where an increase in
the number of contacts would be useful would be in amplification
such that weak signals could be more easily distinguished from each
other.
[0077] As per another embodiment, charge member layers 601 and 606
are similarly placed on opposite sides of nanotube 611. However, in
this embodiment, only one of charge member layers 601 and 606 is
charged at any given time. As a result, this embodiment can be
utilized as a transistor to provide the same logic as two
transistors constructed to have a common collector contact layer
(e.g., layer 607) with separate emitter contact layers (e.g.,
layers 603 and 604). Isolation layers 602 and 605 may also be
included in NEM assembly 600. Persons skilled in the art will
appreciate that this embodiment can easily be reconstructed to have
a common emitter layer with separate collector layers such that
emitter contact layer 603 would be coupled to emitter contact layer
604 and a small isolation region would split collector contact
layer 607 into two portions about nanotube 607.
[0078] Persons skilled in the art will appreciate that additional
charge members may be included in NEM assembly 600 in order to
increase control of nanotube 611. For example, if charge member
layer 601 is considered to be above nanotube 611 and charge member
layer 606 is considered to be below nanotube 611, charge member
layers may also be placed behind and in front of nanotube 611.
Surrounding nanotube 611 with additional charge member layers
allows the position of nanotube 611 to be controlled in a three
dimensional environment. Applications such as NEM and MEM robotic
components (e.g., propulsion and motor components), sensors, and
switches may all benefit from such an embodiment. Furthermore,
additional electrical contacts may be placed about this three
dimensional environment, thus providing nanotube 611 with complex
switching capabilities. As in all embodiments of the present
invention, one or more magnetic fields 671 may be utilized to
control and manipulate NEM assembly 600.
[0079] The principles of the present invention may be utilized to
construct memory components (e.g., memory latches) from
nanotube-based inverters. An example of a nanotube-based inverter
is inverter 700 of FIG. 7.
[0080] In inverter 700, a system HIGH supply (e.g., 3 volts)
voltage is provided to contact 741 while a system LOW (e.g., ground
799) supply voltage is provided at contact 742. Generally, inverter
700 has an output signal at output contact 751. This output signal
is an inverted signal of the input voltage applied at input contact
721. Thus, if a system HIGH supply voltage is applied to input
contact 721 then a system LOW supply voltage is applied to output
contact 751. Similarly, if a system LOW supply voltage is applied
to input contact 721 then a system HIGH supply voltage is applied
to output contact 751. By creating an inverter, the basic building
block of not only memory components, but also logic circuits are
realized.
[0081] Inverter 700 operates as follows when a HIGH signal is
provided by input voltage source 721. Nanometer-scale beam 711
preferably has a charge of a particular polarity respective to the
polarity of the voltage supplied at node 741. For example,
nanometer-scale beam 711 may have a positive charge. Thus, when a
HIGH negative charge is applied to charge member 722 by input
voltage source 721, charge member 722 attracts nanometer-scale beam
711 into a position where nanometer-scale beam 711 couples LOW
contact 742 (e.g., position 713). Contact 742 is preferably coupled
to ground 799. Therefore, a ground signal (e.g., a LOW signal) will
be applied to output contact 751 when HIGH voltages are applied to
input contact 721. Persons skilled in the art will appreciate that
the voltage difference across resistor 732 is equivalent to
V.sub.741-V.sub.799 when nanotube 711 is electrically coupled to
contact 742 (ignoring the internal resistance of nanometer-scale
beam 711).
[0082] Inverter 700 operates as follows when a LOW signal (e.g.,
zero volts) is provided by input voltage source 721. Charge member
722 does not attract nanometer-scale beam 711 into a position where
nanometer-scale beam 711 couples LOW contact 742 (e.g., position
713) because the LOW signal applied to charge member 722 does not
attract nanotube 711 to contact 742. As a result, there is no
voltage difference across resistor 732 and the voltage applied to
HIGH voltage contact 741 will be applied to output contact 751.
Persons skilled in the art will appreciate that a HIGH charge, or
any charge, of the same type as the charge of nanotube 711 will
also preferably provide a HIGH output at output node 751 because
nanotube 711 will be repelled from contact 742. For the same
reasons that magnetic field 371 of FIG. 3 is included in transistor
300 of FIG. 3, magnetic field 771 may also be included in inverter
700.
[0083] FIG. 8 illustrates inverter 800 that includes nanotube 811
as a nanometer-scale beam. The operation of inverter 800 is similar
to the operation of inverter 700 of FIG. 7. From a structural
perspective, nanotube 811 is coupled to output contact layer 843.
Output contact layer 843 is separated by voltage source contact
layer 841 by resistive layer 832. Contact layer 842 is isolated
from charge member layer 822 by isolation layer 852. Generally,
contact layer 842 is electrically coupled to nanotube 811 when the
voltage supplied to charge member layer 822 attracts nanotube 811
into position 813.
[0084] Inverter 800 is preferably configured such that contact
layer 842 is coupled to a LOW voltage signal (e.g., ground) and
power contact layer 841 is coupled to a HIGH voltage signal (e.g.,
3 volts). In doing so, inverter 700 will have an output voltage at
output contact layer 843 approximately equivalent to ground when
the input voltage applied to charge member 822 is HIGH, thus
attracting nanotube 811 into position 813. When the input voltage
applied to charge member layer 822 is LOW (e.g., ground) or such
that nanotube 811 is repelled to position 812, the output voltage
applied to output contact 843 will be approximately the HIGH
voltage signal applied to power contact layer 841. For the same
reasons that magnetic field 371 of FIG. 3 is included in transistor
300 of FIG. 3, magnetic field 871 may also be included in inverter
800.
[0085] FIGS. 9A-9H are sectional views of process steps used to
fabricate a nanometer-scale electrical-mechanical system. More
particularly, FIGS. 9A-9H show one embodiment of a fabrication
process for creating transistor 300 of FIG. 3.
[0086] Turning first to FIG. 9A, step 951 is shown in which
conducting layer 902 is placed on base layer 901. Conducting layer
902 may be, for example, a metal layer such as an aluminum, tin,
copper, or tungsten or a dielectric layer such as a polysilicon.
Base layer 901 may be, for example, a semiconductor. Conducting
layer 902 may be placed on base layer 901 by, for example,
selective disposition, sputter deposition, plasma vapor deposition,
or a chemical vapor deposition (CVD). Non-conductive layer 903 may
then be placed on top of conductive layer 902. Non-conductive layer
903 may be, for example, an oxide layer or silicon-dioxide. In
constructing a transistor in accordance with the principles of the
present invention, conductive layer 902 would preferably be a
charge member layer while non-conductive layer 903 would preferably
be an isolation layer between a charge member layer and emitter
contact layer.
[0087] In FIG. 9B conductive layer 904 is placed on non-conductive
layer 903 in step 952. Persons skilled in the art will appreciate
that conductive layers fabricated in accordance with the principles
of the present invention, including conductive layer 903, may be
fabricated and laid on a base member by the same method as
conductive layer 902. In constructing a transistor in accordance
with the principles of the present invention, conductive layer 904
would preferably be an emitter contact layer.
[0088] Depending on the application, it may be necessary to shape
conductive layer 904. Step 953 of FIG. 9C illustrates initial
shaping steps. More particularly, photoresist layer 905 may be
deposited on top of conductive layer 904. Light may then be
introduced on photoresist layer 905 via mask 911. Mask 911 may be
constructed such that light 912 will only pass through specific
portions of mask 911 and, as a result, etch respective portions of
photoresist 905. As a result of step 953, the structure shown in
step 954 of FIG. 9D will be fabricated. Step 954 introduces etching
process 921 to conductive layer 904 in the portions not covered by
photoresist 905. As a result, conductive layer 904 is shaped as
shown in step 955 of FIG. 9E. Remaining photoresist 905 may then be
washed or etched away in step 955.
[0089] Step 956 of FIG. 9E includes conductive layer 906. In
constructing a transistor in accordance with the principles of the
present invention, conductive layer 906 may be utilized as a charge
member layer. Conductive layer 906 may be formed and shaped with a
process similar to the one used on conductive layer 904. Conductive
layer 906 may also be formed and shaped with conductive layer 904
during steps 953-955 of FIGS. 9C-9E.
[0090] Nanotube 930 may then be placed on conductive layer 906 as
illustrated in step 957 of FIG. 9G. In constructing a transistor in
accordance with the principles of the present invention, nanotube
930 may be utilized as a beam that electrically couples conductive
layer 906 to conductive layer 904 when the appropriate signals are
applied to conductive layer 902 and nanotube 930.
[0091] Nanotube 930 may be placed on conductive layer 906 by many
different means. For example, a support layer may be provided in
area 931. Nanotube 930 may then be formed partially on top of
support layer 931 and partially on top of conductive layer 906. The
portion of nanotube 930 above conductive layer 906 may then be
attached by a non-conductive layer (e.g., layer 907 of FIG. 9H).
Persons skilled in the art will appreciate that layer 907 may also
be a conductive layer. After support layer 931 is removed, nanotube
930 is free to move except for the portion of nanotube 930 anchored
to conductive layer 906.
[0092] As per another example, Nanotube 930 may be grown outward
from conductive layer 906 as shown by growth arrow 957. Persons
skilled in the art will appreciate that during growth, the portion
of nanotube 930 located over conductive layer 906 does not have to
be anchored by another layer (e.g., layer 907 of FIG. 9H). Instead,
nanotube 930 may self-attach to conductive layer 906. In other
embodiments, nanotube 930 may be held in place by electro-magnetic
fields while it forms.
[0093] As per yet another example, Nanotube 930 may be formed
outside of step 957, independent from the formation of the
nanometer-scale electrical-mechanical system on base 901, and then
placed on conductive layer 906. Nanotube 930 may be placed on
conductive layer 906 by, for example, electro-magnetic fields. For
additional support during nanotube 957 placement, support layer 906
may also be utilized.
[0094] Step 958 of FIG. 9H preferably forms non-conductive layer
907 on top of nanotube 930 and conductive layer 906. As mentioned
above, layer 907 may be-used to anchor a particular portion of
nanotube 930 to conductive layer 906. In constructing a transistor
in accordance with the principles of the present invention, the
attached end of nanotube 930 is preferably placed partially over
conductive layer 906. As a result, non-conducting layer 907 also
forms a bond with end portion 933 of nanotube 930. Persons skilled
in the art will appreciate that non-conductive layer 933 is not
necessary. For example, nanotube 930 may anchored in conductive
layer 906. In this embodiment, non-conductive layer 907 is a
portion of conductive layer 906.
[0095] FIG. 10 shows NEMS system 1000 constructed in accordance
with the principles of the present invention. NEMS system 1000 is
similar to transistor 300 of FIG. 3 except that nanotube 1011 is
anchored at both ends; the free-moving portion of nanotube 1011 is
the middle portion of nanotube 1011. In anchoring both ends of
nanotube 1011, the stress on any one portion of nanotube 1011 is
reduced when compared to nanotube 300 of FIG. 3. Persons skilled in
the art, however, will appreciate that nanotube 1011 may be more
difficult to bend then a nanotube only anchored at one end.
[0096] NEMS system 1000 preferably operates as follows. Nanotube
1011 has a charge of a particular type. When an opposite charge is
placed on base member layer 1022, nanotube 1011 is attracted to
base member 1022. When the opposite charge on base member layer
1022 is large enough, nanotube 1011 will be manipulated into
position 1013 and create an electrical connection between emitter
contact layer 1042 and collector contact layer 1041. Nanotube 1011
is anchored at one end by collector contact layer 1041 and retainer
1061. At the opposite end, nanotube 1011 is anchored by
non-conductive layer 1063 and retainer 1062. Persons skilled in the
art will appreciate that non-conductive layer 1063 or retainer 1062
may be a conductive layer and, as a result, realize additional
functionality that may be useful in some applications. NEMS system
1000 may be utilized as other electrical components. For example,
NEMS system 1000 may be utilized as a memory cell.
[0097] Furthermore, persons skilled in the art will appreciate that
nanotube 1011 may be extended beyond retainer 1061 and 1062.
Additional charge members and emitter contacts may then be placed
underneath these extended areas such that additional functionality
may be realized from a single nanotube.
[0098] FIG. 11 shows nanoelectromechanical system 1100 that
includes suspended nanotube 1115 as an electrical contact. More
particularly, system 1100 is similar to system 300 of FIG. 3 but
includes suspended nanotube 1115 as an electrical contact in order
to reduce wear to system 1100 that is created by physical impacts
from nanotube 1111. In system 300 of FIG. 3, the sense contact is a
conductive layer. An impacting nanotube may wear down this
conductive layer. Furthermore, if the conductive layer is provided
as a non-suspended nanotube then, although the two nanotubes will
not wear, energy from the impacting nanotube may be transferred to
the other components of system 1100. Thus, any impacting energy
may, as a result, wear down the base, other components coupled to
the base, or other components coupled to the non-suspended
nanotube.
[0099] Similar to system 300 of FIG. 3, charges applied to layer
1141 and charge member 1122 may cause nanotube 1111 to move from
resting location 1113 (or location 1112) to a position that either
physically touches or electrically couples with a sense contact
(e.g., nanotube 1115). When physical contacts occur in system 1100,
however, nanotube 1115 will bend and, as a result, release energy
that may otherwise, if not controlled, create wear in system
1100.
[0100] Nanotube 1115 is preferably suspended from mounts 1191 and
1192. Either mount 1191, mount 1192, or both mounts may be
conductive and coupled to sense contact 1142. Nanotube 1115 may
also be fixed to mounts 1191 and 1192, at both ends, by a
restraining member similar to restraining members 1162 and 1161.
Persons skilled in the art will appreciate that charge member layer
1122 may also be a charge containment layer that is operable to
store a charge. Thus, system 1100 may be used as a memory cell.
Such a charge containment layer may, like charge member layer 1122,
be isolated from sense contact 1142 by non-conductive layer 1152.
Persons skilled in the art will also appreciate that nanotube 1115
is not limited to employment as a nanotube but, more generally, any
nanometer-scale beam that is mechanically flexible, electrically
conductive, and exhibits good (e.g., LOW) wear characteristics.
Persons skilled in the art will appreciate that nanotube 1115 does
not have to be fixed to base 1193 at both ends. Instead, nanotube
1115 may be, for example, fixed to base 1193 at only one end.
[0101] Persons skilled in the art will appreciate that two
components do not have to be connected or coupled together in order
for these two components to electrically interact with each other.
Thus, persons skilled in the art will appreciate that two
components are electrically coupled together, at least for the sake
of the present application, when one component electrically affects
the other component. Electrical coupling may include, for example,
physical connection or coupling between two components such that
one component electrically affects the other, capacitive coupling,
electromagnetic coupling, free charge flow between two conductors
separated by a gap (e.g., vacuum tubes), and inductive
coupling.
[0102] Additional advantageous nanometer-scale electromechanical
assemblies are described in commonly assigned copending U.S. patent
application No. ______ to Pinkerton et. al, (Attorney Docket No.
AMB/004), entitled "Nanoelectromechanical Memory Cells and Data
Storage Devices," commonly assigned copending U.S. patent
application No. ______ to Pinkerton et. al (Attorney Docket No.
AMB/002), entitled "Electromechanical Assemblies Using
Molecular-Scale Electrically Conductive and Mechanically Flexible
Beams and Methods For Application of Same," and commonly assigned
copending U.S. patent application No. ______ to Pinkerton et. al
(Attorney Docket No. AMB/005), entitled "Energy Conversion Systems
Utilizing Parallel Array of Automatic Switches and Generators,"
which are all hereby incorporated by reference in their entirely
and filed on the same day herewith.
[0103] From the foregoing description, persons skilled in the art
will recognize that this invention provides nanometer-scale
electromechanical assemblies and systems that may be used as
transistors, amplifiers, memory cells, automatic switches, diodes,
variable resistors, magnetic field sensors, temperature sensors,
electric field sensors, and logic components. In addition, persons
skilled in the art will appreciate that the various configurations
described herein may be combined without departing from the present
invention. For example, a magnetic field may be included in the
nanometer-scale assembly of FIG. 10. It will also be recognized
that the invention may take many forms other than those disclosed
in this specification. Accordingly, it is emphasized that the
invention is not limited to the disclosed methods, systems and
apparatuses, but is intended to include variations to and
modifications therefrom which are within the spirit of the
following claims.
* * * * *