U.S. patent application number 09/792905 was filed with the patent office on 2001-11-29 for method for making a diode device.
Invention is credited to Berishvili, Zauri, Koptonashvili, Larisa, Skhiladze, Givi, Tavkhelidze, Avto.
Application Number | 20010046749 09/792905 |
Document ID | / |
Family ID | 26880534 |
Filed Date | 2001-11-29 |
United States Patent
Application |
20010046749 |
Kind Code |
A1 |
Tavkhelidze, Avto ; et
al. |
November 29, 2001 |
Method for making a diode device
Abstract
A method for manufacturing a pair of electrodes comprises
fabricating a first electrode with a substantially flat surface and
placing a sacrificial layer over a surface of the first electrode,
wherein the sacrificial layer comprises a first material. A second
material is placed over the sacrificial layer, wherein the second
material comprises a material that is suitable for use as a second
electrode. The sacrificial layer is removed with an etchant,
wherein the etchant chemically reacts with the first material, and
further wherein a region between the first electrode and the second
electrode comprises a gap that is a distance of 50 nanometers or
less, preferably 5 nanometers or less. Alternatively, the
sacrificial layer is removed by cooling the sandwich with liquid
nitrogen, or alternatively still, the sacrificial layer is removed
by heating the sacrificial layer, thereby evaporating the
sacrificial layer.
Inventors: |
Tavkhelidze, Avto; (Tbilisi,
GE) ; Koptonashvili, Larisa; (Tbilisi, GE) ;
Berishvili, Zauri; (Tibilisi, GE) ; Skhiladze,
Givi; (Tbilisi, GE) |
Correspondence
Address: |
Borealis Technical Limited
23545 NW Skyline Blvd
North Plains
OR
97133-9204
US
|
Family ID: |
26880534 |
Appl. No.: |
09/792905 |
Filed: |
February 23, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60184852 |
Feb 25, 2000 |
|
|
|
Current U.S.
Class: |
438/380 ;
257/E45.001 |
Current CPC
Class: |
F25B 2321/003 20130101;
H01L 37/00 20130101; H01J 45/00 20130101 |
Class at
Publication: |
438/380 |
International
Class: |
H01L 021/20; H01L
021/28; H01L 021/44 |
Claims
We claim:
1. A method for manufacturing a pair of electrodes, said method
comprising the steps of: a) fabricating a first electrode having a
substantially flat surface; b) placing a sacrificial layer over a
surface of said first electrode, wherein said sacrificial layer
comprises a first material; c) placing a second material over said
sacrificial layer, wherein said second material comprises a
material that is suitable for use as a second electrode, wherein
said second material has a thermal expansion coefficient that is
different to the thermal expansion coefficient of said first
electrode, whereby a composite is formed; and d) cooling said
composite whereby thermal stress in said sacrificial layer causes
it to disintegrate.
2. The method of claim 1, wherein said cold environment comprises a
temperature of -50.degree. C. or less.
3. The method of claim 1, wherein said cooling step comprises
contacting said composite with liquid nitrogen.
4. The method of claim 3, wherein said cooling step creates a gap
between said first electrode and said second electrode.
5. The method of claim 3, further comprising the steps of: a)
attaching said first electrode and said second electrode to an
actuator; and b) using said actuator to maintain a region between
said first and second electrodes, wherein topographical features on
the surface of said first electrode are maintained in spatial
orientation with a matching topographical feature on said second
electrode.
6. The method of claim 1, wherein said sacrificial layer comprises
Si, Ti, or Mo.
7. The method of claim 1, wherein said first electrode comprises a
third material and wherein said second material has a thermal
expansion coefficient that is different from a thermal expansion
coefficient of said third material.
8. The method of claim 7, wherein said thermal expansion
coefficients of said second and third materials are different by a
factor of 3 or greater.
9. The method of claim 7, wherein said cold environment causes
mechanical tension between said first electrodes and said second
electrode.
10. The method of claim 9, further comprising destroying said
sacrificial layer with said mechanical tension.
11. A method for manufacturing a pair of electrodes, said method
comprising the steps of: a) fabricating a first electrode having a
substantially flat surface; b) placing a sacrificial layer over a
surface of said first electrode, wherein said sacrificial layer
comprises a sublimative material; c) placing a material that is
suitable for use as a second electrode over said sacrificial layer;
and d) heating said sacrificial layer, wherein said step of heating
evaporates said sacrificial layer.
12. The method of claim 11, wherein said sublimative material is
cadmium.
13. The method of claim 11, wherein after said heating step, said
first electrode and said second electrode are separated by 50
nanometers or less.
14. The method of claim 11, wherein after said heating step, said
first electrode and said second electrode are separated by 100
angstroms or less.
15. The method of claim 11, wherein after said heating step, said
first electrode and said second electrode are separated by 50
angstroms or less.
16. The method of claim 11, wherein said step of heating creates a
gap between said first electrode and said second electrode.
17. The method of claim 11, wherein said step of heating is applied
to said sacrificial layer, said first electrode and said second
electrode.
18. The method of claim 11 further comprising the steps of: a)
attaching said first electrode and said second electrode to an
actuator; and b) using said actuator to maintain a region between
said first and second electrodes, wherein topographical features on
the surface of said first electrode are maintained in spatial
orientation with a matching topographical feature on said second
electrode.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to a method for making
diode devices and more specifically to an improved method of making
diode devices.
BACKGROUND OF THE INVENTION
[0002] The present invention is related to diode devices, in
particular to methods for making diode devices and particularly for
making a pair of electrodes that may be used in a diode device. The
term diode devices encompass, for example, thermionic converters
and generators, photoelectric converters and generators, and vacuum
diode heat pumps. It is also related to thermotunnel
converters.
[0003] WO99/13562 discloses a method for making pairs of electrodes
whose surfaces replicate each other. This approach uses solvents
and reactive solutions, and involves heating and evaporating metal
surfaces. The present invention offers a novel means for providing
similarly paired electrodes by a more rapid, more economical and
more environment-friendly than existing approaches.
SUMMARY OF THE INVENTION
[0004] From the foregoing, it may be appreciated that a need has
arisen for an improved method of making a diode device that is
faster, cheaper, easier, and more efficient. In accordance with one
embodiment of the present invention, a method for manufacturing a
pair of electrodes comprises the steps of: fabricating a first
electrode with a substantially flat surface; placing a sacrificial
layer over a surface of said first electrode, wherein said
sacrificial layer comprises a first material; placing a second
material over said sacrificial layer, wherein said second material
comprises a material that is suitable for use as a second
electrode; and placing said sacrificial layer in a cold environment
wherein said cold environment cools said sacrificial layer.
[0005] In accordance with another embodiment of the present
invention, a method for manufacturing a pair of electrodes
comprises the steps of: fabricating a first electrode with a
substantially flat surface; placing a sacrificial layer over a
surface of said first electrode, wherein said sacrificial layer
comprises a sublimative material; placing a material that is
suitable for use as a second electrode over said sacrificial layer;
and heating said sacrificial layer, wherein said step of heating
evaporates said sacrificial layer.
[0006] It is a technical advantage of the present invention to make
diode devices faster, cheaper, easier, and more efficient.
[0007] Another technical advantage of the present invention is that
it produces a reliable, small separation between an anode and a
cathode, and this spacing is maintained and stabilized with
piezo-electric actuators. Another technical advantage of the
present invention is that it may make this separation in a diode
device.
[0008] Other technical advantages of the present invention will be
readily apparent to one skilled in the art from the following
figures, descriptions, and claims.
BRIEF DESCRIPTION OF THE DRAWING
[0009] For a more complete understanding of the present invention
and the technical advantages thereof, reference is now made to the
following description taken in conjunction with the accompanying
drawings, in which:
[0010] FIG. 1 is a diagrammatic representation of one embodiment of
the electrode configuration of the present invention;
[0011] FIG. 2 is a diagrammatic representation of one embodiment of
the electrode configuration of the present invention;
[0012] FIG. 3 is a diagrammatic representation of one embodiment of
a diode device embodying the present invention;
[0013] FIG. 4 is a diagrammatic representation of one embodiment of
a device illustrating how heat transfer is facilitated; and
[0014] FIG. 5 is a schematic representation of the method of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The embodiments of the present invention and its technical
advantages are best understood by referring to FIGS. 1-5. While in
this description of the present invention the actuating element is
often described as being connected to the collector electrode, in
the present invention the actuating elements may be applied to
either the emitter electrode or the collector electrode. Further,
the present invention may be used in a number of devices, as stated
herein, including, for example, (i) a device which uses a thermal
gradient of any kind to generate electrical power or energy output
using thermionics, thermotunneling, or other methods as described
herein; (ii) a device which uses electrical power or energy to pump
heat, thereby creating, maintaining, or degrading a thermal
gradient using thermionics, thermotunneling, or other methods as
described herein; and (iii) as any diode which employs a gap
between the anode and the cathode, or the collector and emitter,
and which causes or allows electrons to be transported between the
two electrons, across or through the gap (with or without a vacuum
in the gap). Alternatively, the device of the present invention may
be integrated into or used for any ordinary diode applications.
[0016] Further, when surface features of two facing surfaces of
electrodes are described as "matching," it means that where one
surface has an indentation, the other surface has a protrusion and
vice versa. Thus when "matched," the two surfaces are substantially
equidistant from each other throughout their operating range.
[0017] Referring now to FIG. 1, two electrodes 1 and 5 are
separated by a region 10 between an emitter and a collector and
housed in a housing 15. Electrode 1 is mechanically connected to a
piezo-electric actuator 20. An electric field is applied to the
piezo-electric actuator via connecting wires 40 which causes the
actuator to expand or contract longitudinally, thereby altering the
distance of region 10, which is between electrodes 1 and 5.
Electrodes 1 and 5 are connected to a capacitance controller 29
which generates a reference electrical signal for closed loop
feedback electronics 28. Closed loop feedback electronics 28
applies electrical signals to actuator 20, which in turns maintains
a constant distance between electrode 1 and 5. Emitter 5 may also
be referred to as the "hot side" and collector 1 may also be
referred to as the "cold side." Thus, the emitter may be the side
where heat is applied, if electrical power is to be generated from
the heat. When functioning as a heat pump, the collector may be the
side that provides cooling, if refrigeration is to be generated
from electrical power applied from the power supply. Piezo-electric
actuator 20 may be on either the collector or the emitter, however,
it is preferable to have piezo electric actuator 20 on the cold
side as the higher temperatures on the hot side may interfere with
proper operation of piezo electric actuator 20.
[0018] Referring now to FIG. 2, two electrodes 1 and 5 are
separated by a region 10 and housed in a housing 15. Electrode 1 is
attached to a number of piezo-electric actuators 20 at intervals.
An electric field is applied to the piezo-electric actuators via
connecting wires 40 which causes the actuators to expand or
contract longitudinally, thereby altering the longitudinal distance
of region 10 between electrodes 1 and 5. Electrodes 1 and 5 are
connected to capacitance controller 29. The longitudinal distance
of region 10 between electrodes 1 and 5 is controlled by applying
an electric field to piezo-electric actuators 20. The capacitance
between emitter 5 and collector 1 is measured and controlling
circuitry 29 adjusts the field applied to piezo-electric actuators
20 to hold the capacitance, and consequently the region 10 between
the electrodes, at a predetermined fixed value. Alternatively the
controller may be set to maximize the capacitance and thereby
minimize region 10 between the electrodes. The diagram shown in
FIG. 2 may be used as a thermionic device and/or as a tunneling
device, and may be used to function as a device to create
electrical power or energy output or as a device to pump heat.
Capacitance controller 29 may be composed of multiple elements, and
each piezo actuator 20 may receive its own distinct signal,
independent from the control of surrounding elements.
[0019] If it is used as a thermionic device, then electrodes 1 and
5 are made from, or are coated with, a thermionically emissive
material having a work function consistent with the copious
emission of electrons at the temperature of thermal interfaces 30
and 35. The specific work functions may be determined by
calculation.
[0020] When functioning as a heat pump, electrons emitted from
emitter 5 move across an evacuated space 10 to a collector 1, where
they release their kinetic energy as thermal energy which is
conducted away from collector 1 through housing 15 to thermal
interface 30, which is, in this case, hotter than thermal interface
35, which the electron emission serves to cool.
[0021] When functioning as a device to generate electrical power or
energy output, region 10 may be evacuated. Electrons emitted from
emitter 5 move across the evacuated space of region 10 to collector
1, where they release their kinetic energy as thermal energy which
is conducted away from collector 1 through housing 15 to thermal
interface 30, and a current is generated for electrical load 27.
The feedback loop from the capacitance controller to the piezo
elements allows for the device to adjust for varying conditions,
including vibration, shock, and thermal expansion.
[0022] When functioning as a tunneling device of the present
invention, as one side of the device becomes hot and its components
expand, the distance between the electrodes may be maintained at a
fixed distance with the feedback loop between capacitance
controller 29 and piezo elements 20. Provided that the surface of
emitter 5 and collector 1 are made sufficiently smooth (or, as
discussed below, matching one another), emitter 5 may be moved into
such close proximity to collector 1 that quantum tunneling between
the electrodes occurs. Further, region 10 may or may not be
evacuated.
[0023] Alternatively, atoms, such as cesium vapor, or alternatively
an inert gas, may be in region 10. When the gap distance between
the electrodes is on the order of tens of angstroms, thermal
conduction through a gas is considerably lessened. In the tunneling
embodiments disclosed in this application, this advantage is noted,
especially for applications where thermal conduction is a concern,
such as a device to generate electrical power or energy output and
heat pumps. Hence, the region 10 is in some embodiments filled with
an inert gas or cesium vapor.
[0024] Referring now to FIG. 3, which shows a thermal interface 35,
electrical connectors 40, and electrical load/power supply 27 for a
photoelectric generator embodiment of the device shown in FIG. 2.
For the sake of clarity, in FIG. 3, capacitance controller 29 and
additional connecting wires 40 shown in FIG. 2 have been omitted. A
light beam 70 passes through housing 15 and is absorbed by emitter
5. Emitter 5 is made from, or is coated with, a photoelectrically
emissive material having a work function consistent with the
copious emission of electrons at the wavelengths of light beam 70.
In FIG. 3, region 10 is evacuated. Electrons emitted from emitter 5
move across the evacuated space of region 10 to a collector 1,
where they release their kinetic energy as thermal energy which is
conducted away from collector 1 and housing 15 to thermal interface
35. The electrons return to emitter 5 by means of external circuit
40 thereby powering electrical load/power supply 27. The spacing of
region 10 between electrodes 1 and 5 is controlled as described
above (see FIG. 2). Thus, as the device becomes hot and its
components expand, the distance between the electrodes may be
maintained at a fixed distance. Provided that the surface of
emitter 5 and collector 1 are made sufficiently smooth, collector 1
may be moved into such close proximity to emitter 5 that quantum
tunneling between the electrodes occurs. Under these conditions, it
is not necessary that region 10 should be evacuated, and the device
operates as a tunneling device used to generate electrical power or
energy output. It should be noted that a photoelectric device used
to generate electrical power or energy output may use a temperature
differential, by collecting some of the solar energy in heat form.
In this embodiment, the device would function as the device used to
generate electrical power or energy output, as in FIG. 2, with the
heat energy provided as solar energy.
[0025] The device in FIG. 3 may alternatively be primarily
photoelectric, where direct photon-electron contact results in the
electron either topping the work-function barrier and emitting
thermionically, or, in the tunneling version, the incident photon
may cause the electron to tunnel. The device may also be a
combination of the above, providing any combination of thermionic
emission caused by solar heat, thermionic emission caused by direct
photoelectric effects, thermotunneling from solar heat, or
tunneling emission caused by direct photoelectric effects.
[0026] Referring now to FIG. 4, a preferred embodiment for
facilitating heat transfer between a thermal interface 30 and an
electrode 1 is shown. Corrugated tubes 80, preferably fabricated
from stainless steel, are shown as forming part of the structure
between electrode 1 and thermal interface 30. These tubes may be
positioned with many variations, and act to allow for the movement
of the positioning elements 20 and of the electrode 1 while
maintaining support, containment, or the like for the device, by
being able to be stretched and/or compressed longitudinally. In
some embodiments, corrugated tubes 80 may form the walls of a
depository of a metal powder 82, preferably silver powder with a
grain size of between 3 and 5 microns. More metal powder 82 would
be used to receive heat transferred to the collector electrode 1,
but the surroundings of the metal powder would be made smaller as
the positioning elements 20 cause the electrode to move upwards.
Hence, an expandable depository made from corrugated tubing 80 is
preferably used. Corrugated tubes 80 may also enclose the entire
device, to allow for movement, as well as individual piezo
actuators 20.
[0027] On a device having electrodes with an area on the order of
1.times.1 cm.sup.2, surface irregularities are likely to be such
that electrode spacing may be no closer than 0.1 to 1.0 .mu.m.
However for smaller electrodes, with an area on the order of
0.05.times.0.05 cm.sup.2, surface irregularities will be
sufficiently small to allow the electrodes to be moved to a
separation of approximately 5 nanometers or less, which is
sufficiently close for quantum tunneling to occur. Moreover, it is
preferable for large (with an area on the order of 1.times.1
cm.sup.2) electrodes to be brought into close proximity to more
easily facilitate electron tunneling.
[0028] The diode devices described in the present invention may be
produced using various methods. For example, one such approach is
illustrated in FIG. 5, which in schematic form describes a method
for producing pairs of electrodes having substantially smooth
surfaces in which any topographical features in one are matched in
the other. The method involves a first step 100 in which a polished
monocrystal of material 102 is provided. This forms one of the pair
of electrodes. Material 102 may also be polished tungsten, or other
materials. In a step 110 a thin layer of a second material 112,
preferably Si, Ti, or Mo, is deposited onto the surface of the
material 102. This layer is sufficiently thin so that the shape of
the polished surface 102 is repeated with high accuracy. A thin
layer of a third material is deposited on layer 112 in a step 120,
and in a step 130 it is thickened using electrochemical growth to
form second electrode 132. This forms the second electrode. In a
step 140 the composite formed in steps 100 to 130 is cooled.
Preferably, the cold environment is less than -25.degree. C.
(248.degree. K) or is less than -50.degree. C. (223.degree. K).
More preferably, the cold environment is less than -100.degree. C.
(173.degree. K) or less than -150.degree. C. (123.degree. K). Most
preferably, liquid nitrogen is used to establish the cold
environment. Preferably, sandwich 150 may be immersed in liquid
nitrogen, or liquid nitrogen vapor may be applied to sandwich 150.
Materials used to make electrodes 102 and 132 are chosen so that
they have different coefficients of linear thermal expansion. Thus
when composite 150 is cooled, the two electrodes 102 and 132 of
reduce differently in linear dimensions. This causes controlled
mechanical tension between electrodes 102 and 132. The thickness
and hardness of both electrodes 102 and 132, however, is higher
than the thickness and hardness of sacrificial layer 112. As
result, sacrificial layer 112 disintegrates and turns to powder
while being cooled by the liquid nitrogen, making electrodes 102
and 132 separable. The resulting powder from sacrificial layer 112
may be removed using a suitable a suitable solvent or reactive
solution. Thus, by using liquid nitrogen to cool sandwich 150, the
sandwich 150 is opened using forces which arise due to the
different thermal expansion of the electrodes. Accordingly, the
cold environment may be any environment with conditions that are
cold enough to cool sandwich 150 such that tension between
electrodes 102 and 132 destroys sacrificial layer 112.
[0029] In an alternative embodiment (not shown in FIG. 5),
electrode 102 additionally comprises a third material, which has a
different coefficient of thermal expansion to the second material
112. Preferably the coefficients of expansion differ by a factor of
3 or more.
[0030] After the sacrificial layer 112 has been reduced to powder,
first electrode 102 and second electrode 132 are somewhat separated
to allow the removal of the remnants of sacrificial layer 112.
First and second electrodes 102 and 132 are then returned back to a
close proximity by piezoelectric actuators, such that they are no
more than approximately 5-10 nanometers apart. Preferably, the two
electrodes will be separated less than or equal to approximately
100 angstroms. More preferably, the two electrodes will be
separated less than or equal to approximately 50 angstroms.
[0031] In another embodiment, a sublimative material (for example
Cd (Cadmium), Zn, NA, K, or the like) may be used as the
sacrificial layer in the present invention. These materials begin
to evaporate before the melting temperature is reached.
Considerable vapor pressure is developed inside the sandwich.
Pressure opens the sandwich even before the melting point of
Cadmium is reached. For example, with Cadmium, the vapor pressure
at 150.degree. C. is enough to open the sandwich. This allows a
lower temperature to be used to open the sandwich. Thus, to remove
the sacrificial layer when a sublimative material is used as the
sacrificial layer, the sacrificial layer is heated. By heating the
sacrificial layer, when it is comprised of a sublimative material,
the sacrificial layer evaporates (or is boiled off) leaving the
sandwich with a gap between the electrodes. The gap may be as
described above, for example less than 50 nanometers, less than 100
angstroms, or less than 50 angstroms in distance.
[0032] Any of the above methods may be used to fabricate the diode
devices described herein. Thus, for example, the actuators,
preferably piezo actuators, may be introduced to keep region 10 at
a desired distance. The actuators are preferably added after step
140. Alternatively still, region 10 may be evacuated or may have an
inert gas, such as He or Ar, or a vapor of cesium, introduced into
region 10.
[0033] When considering a device of the present invention wherein
the two electrodes are close enough to one another to allow for
electron tunneling to occur, thermal expansion should be
considered. If thermal expansion is not taken into account, then
the two electrodes could touch, causing the device to not optimally
function. If the cold side of the device has a thermal expansion
coefficient larger than that of the hot side, then the risk of
touching is minimized. A preferred embodiment for this selection
process, depending on the design temperature ranges of the device,
is that the cold side should have a thermal expansion coefficient
which is more than that of the hot side. Specific embodiments
include the use of Silver or Aluminum on the cold side and Mo or Si
on the hot side. The thermal expansion coefficient of aluminum is
approximately 6 times that of Mo or Si and when either of these
materials are used for the electrodes, when combined with the
electrode matching invention shown in FIG. 5, they should tolerate
a difference in temperature between the two sides. For example, if
the hot side is heated by 500.degree. C. and the cold side is
heated by 80.degree. C., ideal matching of the surfaces will occur.
Ti could also be used on the hot side, but aluminum's thermal
expansion coefficient is approximately 3 times that of Ti as
opposed to 6 times that of Mo or Si.
[0034] Included in this invention is a method for constructing
electrodes with matching topologies, the use of thermotunneling to
produce a cooling effect, the use of solar energy as the motive
energy for the devices of the present invention, the use of small,
and angstrom-scale gaps for insulation.
[0035] Although the above specification contains many
specificities, these should not be construed as limiting the scope
of the invention but as merely providing illustrations of some of
the presently preferred embodiments of this invention. For example,
the piezo-electric, electrostrictive or magnetostrictive actuators
could be used to position either or both electrodes. Such actuators
do not need to be active once the device has been manufactured. For
small temperature variations, it is conceivable that the
capacitance loop and power supply for the actuators themselves will
not be necessary, and the electrodes may be locked into place in
the manufacturing or packaging process. Thus in operation the
actuators should not be necessary, as the gap would not be
compromised with smaller temperature fluctuations.
[0036] In the above specification, capacitance is used to measure
the distance between the electrodes. Other methods may be used,
including measuring the tunneling current and optical
interferometry. The generated current produced by a thermionic,
thermotunneling or photoelectric device may also be measured to
assess the separation of the electrodes. Other properties which may
be measured include heat, for example the temperature of one or
both of the electrodes may be used to initiate programmed actuation
of the piezo-electric, electrostrictive or magnetostrictive
elements. The position of the electrodes may also be set according
to the length of time the device has been in operation. Thus it may
be envisaged that the electrodes are set at a certain distance when
the device is first turned on, and then the positioning of the
electrodes is adjusted after certain predetermined time
intervals.
[0037] In addition, if the inter-converters are constructed using
micro-machining techniques, the controlling circuitry for the
separation of the electrodes may be deposited on the surface of the
wafer next to the piezo-electric, electrostrictive or
magnetostrictive actuators.
[0038] The devices of the present invention may be constructed as
MicroElectroMechanicalSystems (MEMS) devices using micro-machining
of an appropriate substrate. Integrated circuit techniques and very
large scale integration techniques for forming electrode surfaces
on an appropriate substrate may also be used to fabricate the
devices. Other approaches useful in the construction of these
devices include vapor deposition, fluid deposition, electrolytic
deposition, printing, silk screen printing, airbrushing, and
solution plating.
[0039] Substrates which may be used in the construction of these
devices include silicon, silica, glass, metals, and quartz.
[0040] Additionally, the active control elements may be pulsed,
which generates AC power output when the device is used as a power
generator. The pulsing speeds of piezo elements are well within the
requirements necessary for standard alternating current
outputs.
[0041] Moreover, the electrodes made according to the present
invention may be used in diode devices, vacuum diode devices, heat
pumps, any other devices that are based on tunneling effects, and
the like.
[0042] While this invention has been described with reference to
numerous embodiments, it is to be understood that this description
is not intended to be construed in a limiting sense. Various
modifications and combinations of the illustrative embodiments will
be apparent to persons skilled in the art upon reference to this
description. It is to be further understood, therefore, that
numerous changes in the details of the embodiments of the present
invention and additional embodiments of the present invention will
be apparent to, and may be made by, persons of ordinary skill in
the art having reference to this description. It is contemplated
that all such changes and additional embodiments are within the
spirit and true scope of the invention as claimed below.
[0043] All publications and patent applications mentioned in this
specification are indicative of the level of skill of those skilled
in the art to which this invention pertains. All publications and
patent applications are herein incorporated by reference to the
same extent as if each individual publication or patent application
was specifically and individually indicated to be incorporated by
reference.
* * * * *