U.S. patent application number 14/449885 was filed with the patent office on 2016-07-21 for system and method for using pre-equilibrium ballistic charge carrier refraction.
This patent application is currently assigned to Neokismet, LLC. The applicant listed for this patent is Neokismet, LLC. Invention is credited to Jawahar M. Gidwani, Anthony C. Zuppero.
Application Number | 20160211435 14/449885 |
Document ID | / |
Family ID | 55180915 |
Filed Date | 2016-07-21 |
United States Patent
Application |
20160211435 |
Kind Code |
A9 |
Zuppero; Anthony C. ; et
al. |
July 21, 2016 |
System and Method for Using Pre-Equilibrium Ballistic Charge
Carrier Refraction
Abstract
A method and system for using a method of pre-equilibrium
ballistic charge carrier refraction comprises fabricating one or
more solid-state electric generators. The solid-state electric
generators include one or more of a chemically energized
solid-state electric generator and a thermionic solid-state
electric generator. A first material having a first charge carrier
effective mass is used in a solid-state junction. A second material
having a second charge carrier effective mass greater than the
first charge carrier effective mass is used in the solid-state
junction. A charge carrier effective mass ratio between the second
effective mass and the first effective mass is greater than or
equal to two.
Inventors: |
Zuppero; Anthony C.;
(Pollock Pines, CA) ; Gidwani; Jawahar M.; (San
Francisco, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Neokismet, LLC |
San Francisco |
CA |
US |
|
|
Assignee: |
Neokismet, LLC
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20160035955 A1 |
February 4, 2016 |
|
|
Family ID: |
55180915 |
Appl. No.: |
14/449885 |
Filed: |
August 1, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13397618 |
Feb 15, 2012 |
8829325 |
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14449885 |
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12650841 |
Dec 31, 2009 |
8378207 |
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13397618 |
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11762864 |
Jun 14, 2007 |
7663053 |
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12650841 |
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60883748 |
Jan 5, 2007 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 35/30 20130101;
H01J 45/00 20130101; H01L 29/872 20130101; H01L 29/24 20130101;
H01L 35/34 20130101 |
International
Class: |
H01L 35/30 20060101
H01L035/30; H01L 35/34 20060101 H01L035/34 |
Claims
1. An apparatus, comprising: one or more solid-state electric
generators, the solid-state electric generators including at least
one chemically energized solid-state electric generators; wherein
the one or more solid-state electric generators include, a first
region of a solid-state junction, the first region including a
first material having a first charge carrier effective mass; a
second material of the solid-state junction, the second material
having a second charge carrier effective mass greater than the
first charge carrier effective mass, wherein a charge carrier
effective mass ratio between the second charge carrier effective
mass and the first charge carrier effective mass is greater than or
equal to two; and a heat sink that removes heat from the one or
more solid state electric generators, the heat sink having a heat
sink temperature higher than an ambient temperature; wherein the
one or more solid-state electric generators use an interaction of
chemically energized reactants to energize a charge carrier in the
first material, to have an effective carrier temperature higher
than a second material temperature of the second material; wherein
the first material permits ballistic transport of the charge
carrier through the first material and into the second
material.
2. The apparatus of claim 1, wherein the second charge carrier
effective mass of the second material is greater than 2.
3. The apparatus of claim 1, wherein the at least one chemically
energized solid-state electric generators include an electrical
potential barrier that retards transport of the charge carrier from
the first material to the second material.
4. The apparatus of claim 1, wherein the one or more solid-state
electric generators are formed from one or more additional
materials, the additional materials including a ZT thermoelectric
material having a figure of merit greater than 0.05.
5. The apparatus of claim 1, wherein the second material is chosen
from a materials group including additional materials having a
carrier effective mass greater than two, and the additional
materials including, rutile TiO2, anatase TiO2, porous anatase
TiO2, SrTiO3, BaTiO3, Sr.sub.13 x-Ba_y-TiO_z, boron carbide, LiNiO,
and LaSrVO3, and certain organic semiconductors, such as PTCDA, or
3,4,9,10-perylenetetracarboxylicacid-dianhydride.
6. The apparatus of claim 1, wherein the at least one chemically
energized solid-state electric generators include vibrationally
excited molecular reaction products that are generated by chemical
reactions, the vibrationally excited molecular reaction products
interacting with a conductor of the first region to cause the
effective carrier temperature to be higher than the second material
temperature.
7. The apparatus of claim 1, further comprising chemically
energized highly vibrationally excited molecular reaction products
initialized by chemical association reactions.
8. The apparatus of claim 1, wherein the heat sink is directly
connected to the second material.
9. The apparatus of claim 1, wherein the heat sink is connected to
the second material.
10. A method comprising: providing one or more solid-state electric
generators including, generating a first region of a solid-state
junction including a first material having a first charge carrier
effective mass; generating a second material of the solid-state
junction, the second material having a second charge carrier
effective mass greater than the first charge carrier effective
mass, wherein a charge carrier effective mass ratio between the
second charge carrier effective mass and the first charge carrier
effective mass is greater than or equal to two; providing a heat
sink that removes heat from said one or more solid-state electric
generators, the heat sink having a heat sink temperature higher
than an ambient temperature; the first material permits ballistic
transport of a charge carrier through the first material into the
second material; and retarding transport of a charge carrier from
the first material to the second material with an electrical
potential barrier that permits the charge carrier to traverse into
the second material.
11. The method of claim 10, wherein the one or more solid-state
electric generators are formed from one or more additional
materials, the additional materials including a ZT thermoelectric
material having a figure of merit greater than 0.05.
12. The method of claim 10, wherein during the connecting a heat
sink step to the second material, directly connecting a heat sink
to the second material.
13. The method of claim 10, wherein the heat sink is connected to
the second material.
Description
RELATED APPLICATIONS
[0001] This application is a Continuation of U.S. patent
application Ser. No. 13/397,618 filed Feb. 15, 2012, now U.S. Pat.
No. 8,829,325; which is a Continuation of U.S. patent application
Ser. No. 12/650,841, filed Dec. 31, 2009, now U.S. Pat. No.
8,378,207; which is a Divisional of U.S. patent application Ser.
No. 11/762,864, filed on Jun. 14, 2007, now U.S. Pat. No.
7,663,053, which claims the benefit of U.S. Provisional Patent
Application No. 60/883,748, filed on Jan. 5, 2007.
FIELD
[0002] The field of the invention relates generally to energy
conversion systems and more particularly relates to a method and
system for using pre-equilibrium ballistic charge carrier
refraction.
BACKGROUND
[0003] The use of solid state junctions to convert ballistic charge
carrier motion directly into electricity has recently been
demonstrated in several novel methods and approaches. As shown in
cross section in FIG. 1-A, in each case a charge carrier, most
often an electron, is energized on or near a conducting surface 10A
by an energizer 12A, such as chemical reactions with or without
using conducting catalysts, using photovoltaic energizing
materials, or using heat combined with a thermal gradient. In each
case the charge carrier ballistically moves from a conductor 10A
into a semiconductor or dielectric 11A. The conductor 10A is so
thin that the electron effectively travels through it
ballistically, without loosing energy or colliding with another
electron or atom. The result is a voltage 14A across positive
terminal 17A and negative terminal 16A. In FIG. 1-A, the dielectric
junction 15A is a semiconductor junction specifically chosen to
create an electrical potential voltage barrier which tends to
impede the electron ballistic motion, shown as 11B in FIG. 1-B.
FIG. 1-B shows the electrical potential in the device as a function
of distance along the device. As shown in FIG. 2-A, electrons 21A
at the conductor surface 22A have an energy greater than the top of
the potential voltage barrier. These electrons 21A cross over the
voltage barrier and lose energy to heat 24A before they settle down
to the semiconductor conduction band 25A, which separates the
charge across the conductor-dielectric junction. Electrons
traveling against a potential voltage barrier convert some of the
ballistic electron kinetic energy into electrical potential energy
27A. The rest of the ballistic electron kinetic energy becomes heat
24A. The voltage 27A developed is the difference between the Fermi
level of the conductor on one side 28A and the Fermi level of the
dielectric conductor electrode on the other side 26A. A voltage, V
(Volts), is developed when the charges separate.
[0004] In a prior art, when energetic chemicals adsorbed on a thin
conductor surface, electrons with energies greater than a voltage
barrier of about 0.5 eV were detected in sensors similar to those
represented by FIGS. 1-A, 1-B and 2-A. However, the energy
distribution decreased exponentially beyond .about.0.1 eV,
rendering the effect not useful for energy conversion and
generation. Further, in those sensors the effective electron mass
of the metal conductor 10A, of order 1 m_e, is much greater than
the effective electron mass in the semiconductor 11A, typically
silicon, of order 1/3 m_e. This results in most of the generated
electrons being reflected away from the semiconductor/metal
interface 15A, and therefore not collected. The relevance or
utility of the role of electron effective mass has not been
disclosed or expanded. The scheme also required the cryogenic
cooling of the diode to reduce thermal noise. The efficiency of
this scheme is so low that current can only be measured in the
short circuit mode. The system can only be used as a chemical
sensor and is not a useful electric generator.
[0005] In a prior system, association reactions on or near a
conducting catalyst surface energized and initialized highly
vibrational excited molecules. The energy of the vibrationally
excited molecules was transferred to the electrons in the
conductor. The electron energy was apparently in excess of a 1.2
volt barrier 11B. When a wide bandgap oxide semiconductor,
TiO.sub.2 was used, useful short circuit currents at temperatures
well exceeding the boiling point of water, (up to 473 Kelvin) are
observed. Useful open circuit forward voltage was observed under
conditions of almost zero temperature gradient at room temperature.
The forward voltage was similar to that observed in a
photovoltaicaly energized system using the same oxide
semiconductor.
[0006] It would be highly advantageous to use a fabrication method
resulting in predictable high output voltages and currents, and to
be able to choose materials other than TiO2, to operate such a
converter at an elevated temperature and to generate electricity in
devices of this type using thermal gradients.
[0007] The field of solid state thermionics uses thermal gradients
to energize charge carriers and uses semiconductor bandgap
engineering to provide voltage barriers across semiconductor
junctions. In such devices, charge carriers must travel
ballistically through the dielectric 11A. No charge carrier
ballistic travel is required in the material 10A. Moreover, it is
acknowledged that charge carriers travel in all directions from
material 10A towards the dielectric 11A. The effects of a step
increase in the carrier effective mass during ballistic transport
has not been used to enhance conversion efficiency and lower
fabrication costs.
[0008] All known related converter concepts suffered an
inefficiency directly related to the unspecified and therefore
uncontrolled relative charge carrier effective masses of junction
materials used. Nowhere does the field claim nor profess to claim
any method or knowledge of tailoring or controlling carrier
effective masses to enhance energy conversion efficiency.
SUMMARY
[0009] A method and system for using pre-equilibrium ballistic
charge carrier refraction are disclosed. According to one
embodiment, a device comprises one or more solid-state electric
generators. The solid-state electric generators include one or more
from the group including a chemically energized solid-state
electric generator and a thermionic solid-state electric generator.
A first material having a first charge carrier effective mass is
used in a solid-state junction of a solid-state electric generator.
A second material having a second charge carrier effective mass
greater than the first charge carrier effective mass forms the
solid-state junction. A charge carrier effective mass ratio of the
second effective mass divided by the first effective mass is
greater than or equal to two.
[0010] The above and other preferred features, including various
novel details of implementation and combination of elements, will
now be more particularly described with reference to the
accompanying drawings and pointed out in the claims. It will be
understood that the particular methods and systems described herein
are shown by way of illustration only and not as limitations. As
will be understood by those skilled in the art, the principles and
features described herein may be employed in various and numerous
embodiments without departing from the scope of the teachings
herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The accompanying drawings, which are included as part of the
present specification, illustrate the presently preferred
embodiment and together with the general description given above
and the detailed description of the preferred embodiment given
below serve to explain and teach the principles of the present
teachings.
[0012] FIG. 1-A illustrates a prior art solid-state electric
generator.
[0013] FIG. 1-B illustrates a prior art graph of potential versus
distance and indicating the effect of a voltage barrier in a
solid-state junction.
[0014] FIG. 1-C illustrates a graph of potential versus distance in
an exemplary solid-state electric generator having a Schottky
barrier.
[0015] FIG. 1-D illustrates a graph of potential versus distance in
an exemplary solid-state electric generator having a p-n junction
potential barrier.
[0016] FIG. 1-E illustrates a graph of potential versus distance in
an exemplary solid-state electric generator having a
conductor-dielectric-conductor nanocapacitor potential barrier.
[0017] FIG. 2A illustrates a prior art graph of potential versus
distance, indicating the effect of heat in an energy conversion
process.
[0018] FIG. 2-B illustrates a graph of potential versus distance in
an exemplary solid-state electric generator where electrons
experience energy loss to heat.
[0019] FIG. 2-C illustrates a graph of potential versus distance in
a solid-state electric generator where heat re-energizes electrons
to leak back across the junction.
[0020] FIG. 2-D illustrates a graph of potential versus distance in
an exemplary solid-state electric generator with a heat sink.
[0021] FIG. 3-A illustrates an exemplary diagram of potential
versus distance in a region where a pre-equilibrium ballistic
charge carrier moves from a region of low charge carrier effective
mass into a region of high charge carrier effective mass.
[0022] FIG. 3-B illustrates an exemplary diagram of a single
pre-equilibrium ballistic charge carrier refracted into a
concentrated angle of travel across a junction
[0023] FIG. 3-C illustrates an exemplary diagram of multiple
pre-equilibrium ballistic charge carriers refracted into a
concentrated angle of travel.
[0024] FIG. 3-D illustrates an exemplary diagram of multiple charge
carriers reflected back towards the junction.
[0025] FIG. 4-A illustrates an energy converting nano-layer
electrode capacitor.
[0026] FIG. 4-B illustrates an exemplary solid state electric
generator using diode pre-equilibrium energy converter with
pre-equilibrium ballistic refraction and heat rejection.
[0027] FIG. 5 illustrates an exemplary solid-state, in-series,
chemically energized pre-equilibrium electric generator, according
to one embodiment of the present invention.
[0028] FIG. 6 illustrates exemplary electrically and thermally
stacked thermal gradient converters using pre-equilibrium energy
converters with ballistic refraction.
[0029] FIG. 7 illustrates an exemplary cross section of a pillar
structure on which pre-equilibrium ballistic refraction converters
are attached.
[0030] FIG. 8-A illustrates an exemplary cross sections of a
generalized pillar structure on which ballistic refraction
converter assemblies are affixed.
[0031] FIG. 8-B illustrates another exemplary cross sections of a
generalized pillar structure that includes multiple long thin
forms, on which ballistic refraction converter assemblies are
affixed.
[0032] FIG. 8-C illustrates another exemplary cross sections of a
generalized pillar structure that includes multiple forms such as
corrugations, channels, pores and holes on which ballistic
refraction converter assemblies are affixed.
[0033] FIG. 9 illustrates an exemplary cross section showing
reactant and coolant flow from coldest (inside of structure) to
hottest (outside of structure) on which pre-equilibrium ballistic
refraction converter assemblies are affixed.
[0034] FIG. 10-A illustrates an exemplary cross section showing
inert spacers formed along with ballistic refraction converter
assemblies on a supporting substrate.
[0035] FIG. 10-B illustrates an exemplary cross section detail of a
spacer and ballistic refraction converter assemblies on a
supporting substrate.
[0036] FIG. 11 illustrates an exemplary cross section showing
stacking of substrates containing ballistic refraction converter
assemblies and showing reactant, cooling and exhaust flows in the
spaces between stacked elements.
[0037] FIG. 12 illustrates an exemplary cross section showing
pre-equilibrium ballistic refraction converter assemblies connected
electrically in series across the surface of a supporting
structure.
[0038] FIG. 13 illustrates an exemplary cross section showing a
substrate with reactant and coolants flowing through a supporting
structure and around ballistic refraction converter assemblies on
the structure.
[0039] FIG. 14 illustrates an exemplary cross section of clusters
electrically connected predominantly by tunneling and physically
separated on an energy converter.
[0040] FIG. 15 illustrates an exemplary addition of materials
useful to manage thermal conductivity issues into a low charge
carrier effective mass region.
[0041] FIG. 16-A illustrates an exemplary device with minimal or no
barrier in the first material and an increasing charge carrier
effective mass.
[0042] FIG. 16-B illustrates an exemplary device with minimal or no
barrier in the first material and the middle material having the
lowest charge carrier effective mass.
[0043] FIG. 16-C illustrates an exemplary device with a barrier in
the first material and an increasing charge carrier effective
mass.
[0044] FIG. 16-D illustrates an exemplary device with potential
barriers against charge transport in both directions, and a minimum
charge carrier effective mass in the middle material.
[0045] FIG. 17 illustrates an exemplary cross section of catalytic
accelerators on pillars, thermally isolated nanoscopically and near
active surface of ballistic refraction converter assemblies on a
support structure.
[0046] FIG. 18 illustrates an exemplary surface containing
ballistic refraction converters and spacers being rolled,
permitting reactant and coolant flow through the roll.
DETAILED DESCRIPTION
[0047] Methods, devices and systems for using pre-equilibrium
ballistic charge carrier refraction are disclosed. According to one
embodiment, a method comprises fabricating one or more solid-state
electric generators. The solid-state electric generators include
one or more chosen from the group including a chemically energized
solid-state electric generator and a thermionic solid-state
electric generator. A solid state electric generator energizes a
pre-equilibrium energy distribution of charge carriers in a first
material having a first charge carrier effective mass and forming a
solid-state junction with a second material. The second material
has a second charge carrier effective mass greater than the first
charge carrier effective mass. A charge carrier effective mass
ratio of the second effective mass divided by the first effective
mass is greater than or equal to two.
[0048] In the following description, for purposes of explanation,
specific nomenclature is set forth to provide a thorough
understanding of the various inventive concepts disclosed herein.
However, it will be apparent to one skilled in the art that these
specific details are not required in order to practice the various
inventive concepts disclosed herein. The present methods, devices
and systems improve the energy conversion efficiency of junctions
used in solid-state devices to generate electricity. An energy
source creates an unbalanced, pre-equilibrium energy distribution
of charge carriers, e.g. electrons, on one side of a junction. When
a net excess of charge carriers travel ballistically and surmount
an electrical potential barrier upon crossing from one side of a
junction to the other, some of the charge carrier kinetic energy
associated with motion is directly converted into an electrical
potential energy. Charge separation occurs and the regions form a
capacitor. In the absence of tunneling, only the velocity component
close to the normal to the potential barrier contributes to
surmounting the barrier.
[0049] The result is the conversion of some pre-equilibrium
distribution of energy into the useful form of an electrically
charged capacitor. A key element of the embodiments, the efficiency
of this process is improved when the directions of the charge
carriers are refracted to travel substantially normal to the
electrical potential by providing a material with an abrupt
increase in the carrier effective mass across the junction.
Carriers ballistically traveling backwards, from high to low charge
carrier effective mass regions may experience total internal
reflection if they approach the junction from any angle greater
than a relatively small critical angle. Backward flow tends to
drain the separated charges.
[0050] Energizing methods which cause a higher effective charge
carrier temperature in a material with low charge carrier effective
mass compared to the temperature of the high charge carrier
effective mass region define a non-isothermal charge carrier
distribution, and include transient, pre-equilibrium distributions
of charge carriers. Energizing methods include using chemical
reactions, using photovoltaic methods, using propagating and/or
evanescent electromagnetic radiation, using electric coulomb
coupling, using heat flow and associated thermal gradients, using
solar energizers, using heat sources such as geothermal, friction,
and nuclear heat sources, using nuclear energizing, using in-situ
ionizing radiation, using radioactive waste radiation, using flame
heaters and catalytic heaters, using piezo-electric energizing and
initializing highly vibrationally excited reaction products using
energetic chemical reactions.
[0051] According to one embodiment, the present system improves
energy conversion efficiency by adding a charge carrier effective
mass element. The element includes a nanoscopic ballistic carrier
refraction effect inherent in ballistic charge transport from a
region of lower charge carrier effective mass into a region of
higher charge carrier effective mass.
[0052] The ratio of the charge carrier effective masses
(m_e_high/m_e_low) determines the degree to which the ballistic
charge carrier gets refracted towards the potential barrier. This
ballistic refraction maximizes the charge carrier velocity
component towards and directly against the potential barrier and
minimizes the other charge carrier velocity components transverse
to the barrier. Minimizing the other components minimizes energy
losses. Ballistic transport is assured when the lower charge
carrier effective mass region is thin enough to be transparent to
charge carrier motion. The lower charge carrier effective mass
region forms a nano-layer electrode of the capacitor. The junction
of the low and high charge carrier effective mass regions forms a
capacitor, which stores electrical potential energy as separated
charges. The material with higher carrier effective mass is the
dielectric of the capacitor.
[0053] According to another embodiment, heat transport across the
junction is minimized. Ballistic refraction and a junction
electrical potential barrier reflect heat-carrying charge carriers
away from the junction. In the low charge carrier effective mass
region, carriers with energy less than the barrier potential are
reflected back into the hotter region from whence they came. In the
high charge carrier effective mass side, carriers approaching the
junction with angles greater than the relatively small critical
angle (relative to the surface normal) are reflected and can not
travel backwards to the low charge carrier effective mass side.
[0054] Additional embodiments connect nanoscopic thermal gradient
converters thermally in parallel and/or in series and connect them
electrically in parallel and/or in series. The connected converters
are further connected in parallel and/or in series. The thermal
connections can be physically distinct from the electrical
connections. The energy and heat sources include those with unique,
spatially non-uniform temperature profiles, temporally sporadic and
non-constant energy bursts, and various regions may present
non-uniform heat flow rates.
[0055] According to one embodiment, a secondary energy conversion
process is used to extract electrical work by operating a solid
state thermionic/thermoelectric heat engine between a higher
temperature, such as reject heat from a primary energy conversion
process, and the colder temperature heat sink of the ambient
surroundings. Efficiency is enhanced by using pre-equilibrium
ballistic charge carrier (e.g. electron) refraction (PEBCCR). Heat
engine device components utilizing PEBCCR are nanoscopic thermal
gradient converters (NTGC). Stacking nanoscopic thermal gradient
converters in series thermally and electrically provides an
efficient way to implement a heat engine.
[0056] According to one embodiment, a system has successive
converter units one on top of the other, each converter unit having
(a) conductor electrode, (b) low charge carrier effective mass
region (also referred to as a nano-layer electrode or
nano-electrode), (c) high charge carrier effective mass region
(also referred to as the dielectric) and (d) conductor electrode.
One preferred embodiment of this nano-electrode capacitor system
forms element (b) from conductors such as metals that have
relatively long carrier mean free paths, such as Cu, Ag, Au, Al;
forms material (c) using oxidized Ti metal to create n-type
TiO.sub.2; and forms material (a) and (d) from unoxidized Ti.
Another embodiment includes a heavily doped n-Si layer between the
conductor electrode (a) and the nano-layer electrode (b). Another
embodiment forms the element (b) using a heavily doped
semiconductor such as n-Si or SiGe alloy. The electrical barrier of
this junction is formed by the band offsets, which are
approximately 0.1 eV. This favors operation at the maximum power
density. Another embodiment includes a heavily doped n-Si layer
between the high charge carrier effective mass region (c) and the
conductor electrode (d).
[0057] According to one embodiment, the thickness of the region of
lower charge carrier effective mass is formed so thin that the
carriers effectively travel predominantly ballistically. The lower
charge carrier effective mass region is formed with one or more
materials with a lower thermal conductivity relative to electrical
conductivity over nanoscopic dimensions. Materials with a
favorable, enhanced, or high ZT thermoelectric figure of merit,
values of ZT greater than approximately 0.05, are generally
considered to be at least favorable. The region including the
lowest charge carrier effective mass material with the other
materials is referred to generally as low charge carrier effective
mass region.
[0058] The methods and systems may be used as a cooler or
refrigerator upon application of a potential across the junction.
The addition of PEBCCR increases both the cooling efficiency and
the cooling rate. The methods and systems may be also be used to
alter reaction rates.
[0059] One embodiment uses three-dimensional constructs and methods
for tailoring heat transfer, cooling and power density and for
increasing the active area per volume (volumetric) to enhance the
performance made possible by ballistic carrier refraction.
[0060] According to one embodiment, using pre-equilibrium ballistic
charge carrier refraction enhances energy conversion efficiency in
solid state electric generators. The embodiment includes a
ballistic charge carrier transport from a region of lower charge
carrier effective mass into a region of higher charge carrier
effective mass. A ratio of high to low charge carrier effective
mass in excess of approximately 2 provides desirable performance
enhancement. An absolute high effective carrier mass in excess of
approximately 2 will generally provide acceptable performance
enhancement. The junction region materials are chosen such that a
surmountable electrical potential is formed for charge carriers
traveling from the low charge carrier effective mass side to the
high charge carrier effective mass side. Any pre-equilibrium
effective temperature gradient of charge carriers across the
junction enables the energy conversion.
[0061] Several configurations utilizing PEBCCR include devices
energized by the products of chemical reactions, surface chemical
reactions, interactions with highly vibrationally excited
molecules, thermal gradients, all forms of electromagnetic coupling
such as propagating and/or evanescent radiation, in-situ energizing
by nuclear radiation, or other methods.
Pre-Equilibrium Ballistic Charge Carrier Refraction Process
(PEBCCRP)
[0062] One embodiment of the present teachings uses a combination
of a step increase in the charge carrier (electron or hole)
effective mass at a material junction and an electrical potential
barrier at the junction which tends to retard the charge carrier
from traveling into the junction, as shown generally in FIGS. 3-A
thru 3-D. The step increase in the charge carrier effective masses
refracts the direction of ballistic travel towards the normal to
the surface junction. Velocity components transverse to the normal
are therefore diminished. In the solid state, these effects occur
in the nanoscopic regime where transport is ballistic and the
dimensions are less than the charge carrier mean free path,
typically .about.1-50 nm and preferably >.about.1 nm. Thickness
dimensions greater than 1 nm can be acceptable. Thicknesses greater
than 4 nm are desirable. This is referred to as the pre-equilibrium
ballistic charge carrier refraction process (PEBCCRP). Devices or
device components based on PEBCCRP that convert thermal gradients
to electrical potential are referred to as nanoscopic thermal
gradient converters (NTGC).
[0063] For example, as in FIG. 3-B, an electron crossing from a
region of low to a region of high electron effective mass changes
direction towards the normal to the region of higher electron
effective mass. This is equivalent to the Snell's law effect on
light when traveling from a region of low index of refraction (air)
to a region of high index of refraction (water or glass), and the
governing equations are the same.
[0064] One embodiment provides ballistic carrier refraction.
Electrons generally move in all directions in a material. Electrons
in the low electron effective mass material approaching the
interface ballistically from any approaching direction all find
themselves traveling nearly entirely forward with a restricted
range of angles into the region of higher electron effective mass,
as shown in FIG. 3-C. Electrons in the high electron effective mass
material ballistically moving backwards into the region of lower
electron effective mass are reflected and can not move back unless
they approach with angles restricted inside the critical angle, as
shown in FIG. 3-D.
Recursive Pre-Equilibrium Ballistic Charge Carrier Refraction
(R-PEBCCR)
[0065] One embodiment provides a method to recursively connect
PEBCCRP and/or nanoscopic thermal gradient converter (NTGC) units
where one end of the recursive system is the hottest and the other
end of the recursive system is the coldest and attached to a heat
sink. Connecting PEBCCRP and/or nanoscopic thermal gradient
converter (NTGC) units allows conversion of the heat flow at a
higher temperature of a previous PECCRP unit in the recursive
system to an electrical potential.
Charge Carrier Effective Mass Discontinuity for Chemically
Energized Pre-Equilibrium Electric Generators.
[0066] To enhance the energy conversion efficiency of chemically
energized pre-equilibrium electric generators, one embodiment of
the teachings uses the carrier effective mass discontinuity
principle in choosing the material for the junction of lower charge
carrier effective mass region with dielectric and electrical
potential barrier higher charge carrier effective mass region. The
conductor material is chosen such that its charge carrier effective
mass is as low as possible compared to the dielectric material
whose charge carrier effective mass is as high as material choices
permit.
Thermal or Heat Rectifier
[0067] One embodiment provides a form of thermal isolation and the
resemblance to heat rectification. Almost all of the thermal
conductivity in most conductors is associated with (charge carrier)
electron flow, not with phonon or lattice vibrations. The ballistic
charge carrier refraction permits charge carriers approaching from
the low charge carrier effective mass side material to transport
electrical energy, and hence heat, directly into the high charge
carrier effective mass side material. The total internal reflection
in the high charge carrier effective mass side material greatly
reduces electrical energy flow backwards, and therefore also
minimizes heat energy flow backwards. Consistent with the Second
Law of Thermodynamics, this is analogous to the total internal
reflection of binocular prisms and certain reflective coatings used
for thermal insulation.
Heat Sink and Energy Losses
[0068] One embodiment converts a fraction of the ballistic charge
carrier motion into electrical potential energy. Energy conversion
from ballistic charge carrier motion into electrical potential
occurs when charges are separated after surmounting an electrical
potential barrier. The potential barrier can be formed in any one
of many ways, for example, a Schottky barrier, FIG. 1-C, a p-n
junction FIG. 1-D and a conductor--dielectric--conductor
nanocapacitor FIG. 1-E.
[0069] A forward biased diode provides one of the simplest methods
to implement this energy converting nano-layer electrode capacitor.
FIG. 1-C depicts a forward biased Schottky diode whose positive
terminal, a conductor, is the nano-layer electrode and whose
junction capacitance forms the capacitor. FIG. 1-D depicts a
forward biased p-n junction diode. A nano-layer electrode forms one
side of the capacitor, the p-type semiconductor forms the
dielectric of the capacitor, and the n-type semiconductor forms the
other conductor of the capacitor. FIG. 1-E depicts a
conductor-dielectric-conductor capacitor, where the nano-layer
electrode forms one side of the capacitor and an insulator forms
the dielectric of the capacitor. The devices can all be generally
described as energy converting nano-layer electrode capacitors.
[0070] In all these energy-converter nano-layer electrode
capacitors, minimizing conduction across the capacitor in the
forward bias direction increases the efficiency of energy
conversion. In contrast, a good diode maximizes conduction in the
forward bias direction.
[0071] One conduction property of a diode is characterized by the
property referred to as an "ideality factor", "n". The ideality
factor of 1.0 describes a theoretically optimized diode, and values
greater than 1 are less ideal. The smallest n close to unity is
best for a diode. Ideality factors of 1.5 and greater generally
reduce forward conduction and are not generally regarded as "good"
for a diode. A good capacitor requires the exact opposite of the
diode and requires such minimizing of conduction in the forward
bias direction.
[0072] One way to minimize conduction of a forward biased diode
used as an energy-converter nano-layer electrode capacitor is to
tailor the diode ideality property to be large to minimize the
forward current. Minimizing forward current is achieved by favoring
diodes with ideality factors, n, greater than unity. Calculations
show that diodes with ideality as low as 1.2 can enable a 50
Celsius increase in reaction temperature, which can result in an
order of magnitude increase in reaction rates. Diodes with ideality
>2 can enable more than 150 Celsius increase in reaction
temperature.
[0073] Tailoring diodes to have relatively high
generation--recombination (R-G) currents tends to result in
ideality factors approaching n=2. Forming diodes with a large state
density due to metal interdiffusion and dangling bonds is a way to
increase ideality. Forming diodes with high defect density results
in diodes with n>2. Diodes with significant Poole-Frenkel
tunneling transport and trap-assisted tunneling transport both
increases n. Good diodes are not good capacitors, and vice versa.
We emphasize the objective is to achieve the highest "fill factor"
for the energy conversion.
[0074] Thermionic models of Schottky diodes use "effective
Richardson constant" as a multiplying factor for the diode forward
current. Minimizing the effective Richardson constant is also a way
to minimize diode forward conduction. The methods of our invention
include the methods to maximize ideality and choosing
semiconductors known to have relatively small effective Richardson
constants, e.g. less than approximately 10
amp/cm.sup.2-Kelvin.sup.2. For example, TiO.sub.2 has a Richardson
constant less than 0.05 amp/cm.sup.2-Kelvin.sup.2Kelvin.sup.2.
Using ballistic refraction in diode junctions can be an effective
method to reduce effective Richardson constants.
[0075] To tailor solid state junctions, bandgap engineering,
degenerative doping, doping gradients and composition gradients are
effective in optimizing the charge separation property of the
junction. Potential barriers may be tailored to enhance tunneling
and resonant tunneling through the junction by narrowing and
shaping the junction. Shaping includes forming periodic or almost
periodic electrical potential barriers using quantum well
superlattice structures. Barriers may be tailored to enhance
carrier diffusion in the direction of charge separation by
deliberately tailoring a sloping junction potential.
[0076] Embodiments remove reject heat in various ways, e.g. 3 D
constructions. Embodiments stack and connect planar devices to
maximize power density.
Pre-Equilibrium Ballistic Refraction Energy Converter
[0077] Referring to FIGS. 4-A and 4-B, one embodiment uses
chemically energized, pre-equilibrium hot carriers as the first
source of energy and converts the energy using pre-equilibrium
ballistic charge carrier refraction process coupled with a heat
sink. Another embodiment adds one or more stacked nanoscopic
thermal gradient converters to convert reject heat from the
chemically energized conversion step to electrical potential.
[0078] Referring to FIGS. 4-A and 4-B, chemical reactants in a
region bounded in part by a surface 401 containing a catalyst may
react in the vicinity of the surface, may contact, adsorb,
dissociate, recombine, or form reaction intermediates on, near or
in the vicinity of the surface 401. Reactions typically form highly
vibrationally excited intermediates and products. Highly
vibrationally excited products have been recently shown to transfer
a major fraction of their vibrational energy directly to an
electron in the first conductor encountered.
[0079] One embodiment initializes highly vibrationally excited
products directly on or near a conductor to energize a
pre-equilibrium ballistic refraction energy converter conceptually
shown in FIGS. 4-A-4-B and FIG. 5, 505-508. In one embodiment, the
catalyst conductor 505 is part of the device and promotes
association reactions directly on or near the catalyst conductor.
As a result, highly vibrationally molecules are initialized
directly on or near the conductor 505. Approximately one electron
per association reaction is energized with energy sufficient to
surmount 0.5-1.2 eV barriers in various conductor-dielectric
junctions. The energy distribution of the ballistically transported
electrons in the conductor during the compressed phase of vibration
is peaked about the higher energies. Adsorbtion reactions are
similar to molecular association reactions and result in similar
energy transfer, but with an exponentially decreasing distribution.
Charge transfer associated with precursor mediated adsorbtions are
associated with charged intermediates, such as peroxo and superoxo
adsorbates, which have short residence times on the surface and in
some cases also energize and emit energetic electrons. Highly
vibrationally energized gas specie transfer vibrational kinetic
energy to energize electrons in the surface conductors 505.
[0080] The dielectric and electric potential barrier material 403
in this device is chosen to have a large charge carrier effective
mass, such as semiconductor TiO.sub.2, compared to the conductor.
TiO.sub.2 is one of at least several semiconductors known to have
charge carrier effective mass greater than 2. The charge carrier
effective mass of TiO.sub.2 has been measured under various
conditions to be in the range 5-200 m_e, with probable values
.about.25 m_e. Therefore, nearly all the carriers energized in the
nano-electrode conductor 402 are refracted to have a direction
nearly normal to the Schottky barrier formed by the conductor 402
and the highest charge carrier effective mass material, e.g.
TiO.sub.2 dielectric semiconductor 403. Electric potential is
observed between negative electrode 406 and positive electrode 407.
Both conductor and electrode materials include materials chosen
from the group including at least a conductor such as a metal, a
conducting oxide, and degeneratively and heavily doped
semiconductors such as heavily doped silicon, and semiconductors,
materials with a high ZT figure of merit. Heat generated by the
reactions and by the Schottky junction energy converter is rejected
into a colder temperature heat sink 405.
[0081] The lower temperature heat sink may comprise the reactants
400 themselves, because the reactants in this device are generally
not hot when supplied to the system.
[0082] One embodiment includes using dielectric or semiconductor
403 other than TiO.sub.2 with higher than unity carrier effective
mass, including but not limited to, for example, rutile TiO2,
anatase TiO2, porous anatase TiO2, SrTiO3, BaTiO3, Sr_x-Ba_y-TiO_z,
LiNiO, and LaSrVO.sub.3, and certain organic semiconductors, such
as PTCDA, or 3,4,9,10-perylenetetracarboxylicacid-dianhydride. The
subscripts x,y and z denote concentrations, per usual conventions.
One advantage of SrTiO.sub.3 is that Schottky barriers on it may be
unpinned, providing a relatively larger barrier compared to that of
TiO.sub.2.
[0083] One embodiment includes providing a direct heat sink 405 to
the dielectric 403. Such heat sinks can include but are not limited
to heat pipes, capillary systems with fluid flow, evaporative
cooling including but not limited to using reactants themselves,
heat conductive materials and convective flow methods, and a
nanoscopic thermal gradient converter.
Nanoscopic Thermal Gradient Converter (NTGC)
[0084] One embodiment is a device based on the pre-equilibrium
ballistic charge carrier refraction process: a nanoscopic thermal
gradient converter. In one embodiment, shown in FIG. 5, elements
501-503 are a Surface Nanoscopic Thermal Gradient Converter
(SNTGC), while element 703 of FIG. 7 is a Volumetric Nanoscopic
Thermal Gradient Converter (VNTGC). The junction providing an
electrical retarding potential between the materials may include at
least a conductor-dielectric, dielectric-dielectric, or a
dielectric-conductor-dielectric junction. Insulators and semimetals
are considered subsets of dielectrics and metals here. Elements
501-503 of FIG. 5 show an example schematic layout of
conductor-semiconductor junction in a nanoscopic thermal gradient
converter.
[0085] The term "semiconductor junction" includes semiconductor
junctions, junctions including quantum wells formed of metal and/or
semiconductor, insulator materials with a large bandgap and low
doped and amorphous materials, semimetal, insulator, amorphous
material, polycrystalline material. The term "metal" includes
heavily doped semiconductors, metal, semimetal, heavily doped
semiconductor, electrical conductor. In all the cases related to
pre-equilibrium charge carrier ballistic refraction energy
conversion processes, the guiding principal is that the junction
presents both a retarding and surmountable and/or tunneling
potential to the approaching ballistic charge carrier, and an
increase in carrier effective mass.
[0086] Referring to FIG. 5, one embodiment adds a nanoscopic
thermal gradient converter 501-503 to the chemically energized
pre-equilibrium electric generator 505-508. Heat 500 rejected by
the hotter, chemically energized pre-equilibrium electric generator
505-508 (the primary energy conversion system), energizes electrons
at the input side 501 of the nanoscopic thermal gradient converter
501-503 (the secondary energy conversion system). In a
configuration including other primary energy conversion systems in
general, nanoscopic thermal gradient converters are connected in
series thermally and electrically. This interconnection referred to
as "series-parallel" does not preclude series parallel
configurations used to assure reliability. For example, the
negative electrode 508 of the chemically energized generator is
electrically and thermally coupled to the positive electrode of low
charge carrier effective mass region 501 of the nanoscopic thermal
gradient converter. The negative electrode 503 and the high carrier
effective mass material 502 of the thermal gradient converter are
coupled thermally to the colder, heat sink 510. Electricity is
taken from the positive electrode of 506 and the negative electrode
503, and because the devices are in series for this example, also
from positive electrode of 501 and negative electrode 503. Note the
output voltage may be tapped from any of the positive and negative
electrode pairs. Note that such multiple outputs are highly
advantageous.
[0087] This configuration permits the chemically energized
generator to operate at a higher catalyst temperature than without
the nanoscopic thermal gradient converter, permitting an increase
in reaction rates and therefore higher power density. The increased
temperature also permits use of a wider range of reactants and
operation at the ignition temperature of some reactants.
Recursive Nanoscopic Thermal Gradient Converters
[0088] Referring to FIG. 6, one embodiment recursively repeats
nanoscopic thermal gradient converters, each connected in series to
the next both electrically and thermally. The first stage 601 can
be an electric generator energized by any of the many known
methods
[0089] The recursively repeated nanoscopic thermal gradient
converters 602 then generate electricity from the higher
temperature reject heat of the first stage 601 and the lower
temperature ambient heat sink. Estimates suggest that a recursively
repeated nanoscopic thermal gradient converter can achieve
.about.80% of the Carnot limit efficiency between its heat source
and heat sink temperatures.
[0090] Note again, an output voltage may be tapped from any of the
positive and negative electrode pairs.
Ballistic Refraction Energy Converters
[0091] One generalized embodiment is the surface ballistic
refraction energy converter. Another is the volumetric ballistic
refraction energy converter. Other forms and combinations may also
be used.
[0092] The term "volumetric" refers to configuration where the
active surfaces and reactant and coolant flow channels are formed
on or using three dimensional structures.
Surface Ballistic Refraction Energy Converter (SBREC)
[0093] One embodiment uses a primary energy converter attached to a
series of secondary nanoscopic thermal gradient converters attached
to a heat sink. FIG. 6 shows such a typical surface ballistic
refraction energy converter. A number of secondary nanoscopic
thermal gradient converters 602 are connected in series. One end of
the series 602 is attached to a heat sink 603. The other end of the
series 602 is connected to a primary energy converter 601 based on
the pre-equilibrium ballistic charge carrier refraction process.
The primary energy converter may be energized by chemical
reactions, thermal gradients, photo-voltaic or other means. The
number of components 602 may be from 0 to a desired number, both
inclusive. The main function of the components of 602 is to convert
a fraction of the reject heat energy from the previously connected
energy conversion component to an electrical potential.
[0094] One embodiment includes a primary converter 601, with a step
increase in charge carrier mass between the junction materials,
where the electrons are energized by chemical reactions on or near
the conducting surface, with 0 to desired number of nanoscopic
thermal gradient converters 602 connected in series electrically
and thermally and attached to a heat sink.
[0095] One embodiment includes a primary converter 601, without a
step increase in charge carrier mass between the junction
materials, where the electrons are energized by chemical reactions
on or near the conducting surface, with one to a desired number of
nanoscopic thermal gradient converters 602 connected in series
electrically and thermally and attached to a heat sink.
[0096] One embodiment includes a primary converter 601, using a
photo-voltaic energy source with or without the step increase in
charge carrier mass between the junction materials, and with one to
a desired number of nanoscopic thermal gradient converters 602
connected in series electrically and thermally and attached to a
heat sink.
[0097] One embodiment includes a primary converter 601, a
thermionic energy converter where charge carrier ballistic
transport occurs in the first material instead of the second
material, with zero to a desired number of nanoscopic thermal
gradient converters 602 connected in series electrically and
thermally and attached to a heat sink.
[0098] One embodiment includes a primary converter 601, a
thermionic energy converter with a second material effective charge
carrier mass greater than the first material charge carrier mass,
with 0 to desired number of nanoscopic thermal gradient converters
602 connected in series electrically and thermally and attached to
a heat sink.
[0099] One embodiment includes a primary converter 601, a
thermionic energy converter with a second material effective charge
carrier mass greater than the first material charge carrier mass
and where charge carrier ballistic transport occurs in the first
material instead of the second material, with 0 to desired number
of nanoscopic thermal gradient converters 602 connected in series
electrically and thermally and attached to a heat sink.
[0100] One embodiment includes a primary converter 601, attached to
a series of nanoscopic thermal gradient converters 602, one or more
of which may include a dielecrtic--conductor--dielecrtic junction
for the region generally referred to as the low carrier effective
mass region, and connected in series electrically and thermally and
attached to a heat sink. The number of nanoscopic thermal gradient
converters may be from 0 to the number desired, both inclusive.
Volumetric Ballistic Refraction Energy Converter (VBREC)
[0101] One embodiment includes volumetric ballistic refraction
energy converters on a pillar-like form. A desirable feature of the
pillar is a high area per length, which results in a high volume
power density resulting from the pillar's relatively large area per
volume. The cross section of such a high area pillar may include
deep corrugations, holes and pits, all of which may be irregular.
The cross section of a pillar is limited mainly by the constraints
imposed by the converters formed on it and has no general
constraints. For example, the cross section may be any combination
from the group including at least: wire-like, circular, bar-like,
square, rectangular, irregular, wrinkled, sponge-like, a truncated
cone, a tapered cone, and a cross section like that of wings or
other aerodynamic forms.
[0102] Referring to FIG. 7, the pillar itself 701 can be can be any
material, such as strands, fibers, strips formed with one or more
materials each chosen for their strength, thermal conductivity,
electrical conductivity, or any other desirable property.
[0103] A pillar would first be at least partly coated with a
conductor 702 to form the back electrode of the device. Then as
many as required secondary nanoscopic thermal gradient converters
703 are formed over the pillar and under a final primary energy
converter 704, with or without a step increase in charge carrier
mass between the junction materials. The primary energy converter
704 may be energized either chemically, photo-voltaically, by
thermal gradients or other means. The outer region 705 is the
source energizing region. The number of units 703 range from zero
to the required number, both inclusive. The positive electrode
connection 706 is in electrical contact with the final converter
704. An insulator 707 separates the positive electrode connection
706 from the negative electrode connection 708, which is in
electrical contact with the conductor 702. Heat sink can be
provided by the reactants and gasses surrounding the pillar region
705 and or by the substrate 709 which can be physically connected
to a heat sink.
[0104] One embodiment includes a primary converter 704 where the
electrons are energized by chemical reactions on or near the
conducting surface, with 0 to a desired number of nanoscopic
thermal gradient converters connected in series electrically and
thermally and attached to a heat sink.
[0105] One embodiment includes a primary converter 704, a
photo-voltaic energy converter with 0 to a desired number of
nanoscopic thermal gradient converters connected in series
electrically and thermally and attached to a heat sink.
[0106] One embodiment includes a primary converter 704, a
thermionic energy converter with 0 to a desired number of
nanoscopic thermal gradient converters connected in series
electrically and thermally and attached to a heat sink.
[0107] One embodiment includes long mean free path semiconductors
as well as long mean free path metals as the materials forming the
minimum charge carrier effective mass region. Band gap alignments
may be used to form potential barriers.
[0108] One embodiment includes a primary converter 704, a solid
state thermal gradient energy converter using a
dilectric--conductor--dilectric junction attached to a series of
similar nanoscopic thermal gradient converters connected in series
electrically and thermally and attached to a heat sink. The number
of nanoscopic thermal gradient converters may be from 0 to the
number desired, both inclusive.
[0109] In general, ballistic refraction energy converters can be
attached to various kinds of objects, including to devices used to
cause reactant flow, air flow, and cooling, such as such fan
blades. It can take the form of a sheet following the contour of
the objects. For example, the converters can be "coated" on to the
air flow system. Alternatively, the converters can be separately
made and "pasted" on to the system. Or, they can be integral to the
system.
[0110] Placing ballistic refraction energy converters directly on
the fan blade maximizes the efficiency with which the fan provides
cooling, heat transfer and heat removal.
[0111] As suggested by FIGS. 8-A through 8-C, ballistic refraction
energy converters 801, shown in FIG. 8-A, affixed to the pillar
with cross section profile 802 may be any shape consistent with the
requirements for making the ballistic refraction energy converters.
A large energy collection area is desirable and may be achieved in
many ways, including forming the profile to include long, thin
forms 802, shown in FIG. 8-B, as well as wedges 803, channels 804,
irregular polygonal sides 805, deep narrow channels or pores 806,
pores that completely go through the pillar 807, symmetric forms
808 and 803, almost symmetric forms 809, and smoothly symmetric
forms 810, each of which is seen in FIG. 8-C.
[0112] Pores can take the form of deep holes into the stack 804, or
as holes that go entirely through the stack 807.
Wire Geometry
[0113] One embodiment forms a converter geometry resembling a long
thin device such as a wire 802. The converter wire can be preformed
and poked into the surface or otherwise attached to the surface in
regular or irregular patterns.
Flow Geometry
[0114] One embodiment provides a heat sink for ballistic refraction
energy converters. A heat sink for cooling can be achieved in many
ways, including by convective flow, phase change or evaporative
cooling, and heat pipes. Reactants or reactant components may be
used. For example, FIG. 9 illustrates an embodiment using channels,
ducts or pipes associated with the structure supporting the
converters and with the interior of the converter assembly, through
which coolant may flow, reactants may flow, additives may flow, or
any combination of these materials may flow. Each case has its
advantages. Materials 901 flow from the colder side 902, through
pores or holes 903 to the hot region 904. Both the cold side 902
and the hot side 904 may include reactants or additives, and the
hot side is associated with both exhausts and air flow.
[0115] Evaporation of reactants 901 on the cold side 902 as well as
the flow of colder materials 901 causes cooling. Reactants 901 can
be concentrated and fuel rich near the stack hot surface 905.
[0116] Using liquid reactants or evaporative coolant 901 that
becomes gas upon contact with warmer, reaction surface 905 provides
a desirable gas specie for chemically energized hot electron
processes.
[0117] One embodiment forms converters directly on aerodynamic
surfaces. This permits both direct generation of electricity as
well as using the gas generated by the liquid-gas transformation as
mass flow to push a turbine or other mechanical extraction of
useful work and generation of shaft energy.
[0118] One embodiment uses liquid air and other liquid gasses 901
for their low temperature heat sink in an electric generator.
Liquid air and similar inert liquid gasses may provide a heat sink
to the region 902, the ambient air in the exhaust region 904 may
provide the heat source, and the device may thereby generate
electricity directly using the temperature difference. The
liquid/gas phase transition may also operate a mechanical energy
converter such as a turbine, at the same time.
[0119] One embodiment uses natural convection to provide air flow.
It is noted that the cooling air volume can typically be orders of
magnitude greater than the reaction air volume.
[0120] One embodiment based on FIG. 9 may also represent the cross
section of generalized tube geometry, such as flattened tubes. A
generalized tube is coated on one or more faces with ballistic
refraction energy converters. "Tube" here refers to something with
any partly hollow geometry, with any relative wall thickness,
including non-uniform walls. For example, a tube can be flattened
so that it looks like two sheets with an enclosed space between
them to allow gas or fluid flow and with the volume enclosed at the
edges. Note that the concepts of FIG. 9 could be used in surface as
well as volumetric devices (SBREC and VBREC).
Stacking Geometry
[0121] Referring to FIG. 10, an elementary stackable unit is placed
on a structure that includes one or more of the electrically
conducting layer, thermally conducting layer, and the structural
support layer.
[0122] Embodiments connect and stack together more than one
ballistic refraction energy converter (surface (SBREC), or
volumetric (VBREC)) assembly to create a volume of electric
generators instead of just an area provided by the surface of a
single converter assembly. The stacks can be connected electrically
in series or parallel.
[0123] One embodiment of an elementary stackable unit, shown in
cross section in FIG. 10, includes the key element: ballistic
refraction energy converter assembly 1001 (which may comprise of
primary only or primary and secondary energy converters) to be
connected electrically with positive and energized side 1004 up and
negative side down. The ballistic refraction energy converters are
supported and connected with positive electrode connection 1002,
negative electrode connection 1003. Structure 1003, which may
include one or more of an electrically conducting element, a
thermally conducting element and a strength structure element.
Stacking involves placing the elementary stackable unit on top of
other elementary stackable units, leaving a space above the active
surface of the converter 1001 for energizing and heat sources. The
same may be accomplished in any workable configuration or
arrangement.
[0124] The embodiment shown in FIG. 10 connects the positive
electrode 1002 to the negative electrode 1003 of the converter
above it. A cross section of this is shown in FIG. 11. Note that
each elemental structure of FIG. 11 may be recursively stacked in
the vertical and/or in the horizontal direction to form a matrix of
the three-dimensional elemental stacked structures.
[0125] FIG. 10-b provides detail related to electrical and thermal
connections and interfaces that have been deliberately left out for
clarity in the embodiments.
[0126] Referring to FIG. 10-b, for example, the positive
electrode-1002 would not be directly placed on the active surface
of the converter 1001 as shown because the active surface is
typically a nanometers-thick structure that is easily damaged. In
practice, those generally skilled in the art would use one of many
known methods to connect the electrode to the converter. One
embodiment places the positive electrode 1002 on an insulator 1005
formed directly on the structure 1003 and then an electrical bridge
1006 is formed to electrically connect the positive electrode 1002
to the positive end and active surface 1004 of the ballistic
refraction converter assembly. The structure element 1003 would in
practice include an electrical conductor connected to the negative
side of the converter and would also include a thermal connection
to the converter. A simple embodiment forms the structure 1003 to
be both electrically and thermally conducting, for example a 5
micron thick aluminum or copper foil.
[0127] One embodiment stacks the elementary stackable units shown
in FIG. 10 on top of each other, forming a volume of electric
generator energy converters. Reactants and coolants 1100 flow into
the spaces 1101 between the stacks and exhausts flow out through
the spaces.
[0128] One embodiment connects the converters in series along the
plane of the stack by connecting the positive electrode to the
negative electrode of adjacent converters in the same plane. This
can be accomplished several ways, one of which is shown in FIG. 12.
An electrical connection 1202 is made to the positive side and
active surface of a first converter 1201 and is connected to an
interconnecting conductor 1203 isolated by insulators 1204. The
interconnect 1203 electrically contacts the negative side 1205 of a
second converter. The insulating spacer 1200 is shown conceptually
behind a converter in the Fig.
[0129] One embodiment provides coolants and/or reactants 1300
through the body of an elementary stackable unit, as sketched in
FIG. 13. For example, ballistic refraction energy converters 1301
and spacers 1302 are formed on a structure and substrate 1303
inside of which 1304 flow reactants and/or coolants 1300. Referring
to FIG. 18, the device of this embodiment can be rolled up and the
spaces 1305 between the roll formed by spacers 1302 permit
reactants to flow into and exhausts can flow out of the spaces
1305. The spacers and electrical interconnects are shown in FIG. 13
for clarity. Detailed connections could also be like those
explained in FIG. 12 and FIG. 10-b.
[0130] In each of these embodiments, the converters can take on
many forms, including the pillar forms described above, and can be
attached on many surfaces of nearly arbitrary shapes.
Tunneling Cluster Catalysts
[0131] One embodiment uses physically disconnected, electrically
tunneling connected nanoscopic catalyst clusters to enhance the
effective temperature gradient of excitations on the active surface
of a ballistic refraction energy converter. FIG. 14 schematically
shows conductor catalyst structures 1400 with typical dimension D
and typical separation S on the converter 1401 with active surface
1402. The dimension D is formed to be less than the mean free path
for hot carriers in the cluster 1400, chosen to allow the carrier
transit time to be shorter than the period of the highest lattice
vibration of the cluster 1400 and hence decouples carrier
temperature from lattice temperature. This dimension is typically
in the range of order 4 to 50 nm in materials such as Cu, Ag, Au,
Pd, and Pd. The cluster separation D is chosen to be small enough
to permit charge carrier electron tunneling between clusters 1400.
This dimension is typically in the range 1-20 nm. Electrical
connections to the cluster are formed by electrical conductor
contacts 1403 and 1404. In an ideal case, the disconnected clusters
are formed on a low electrical conductivity and low thermal
conductivity material. This cluster arrangement can then form a
Schottky barrier with the converter 1401, permitting the clusters
to be an integral part of a ballistic refraction energy
converter.
[0132] One embodiment uses the enhanced catalyst activity of
catalyst clusters in contact with ceramic substrates such as
converter material. One embodiment uses the enhanced cluster
electron temperature to increase reaction rates and therefore
increased power output. One embodiment applies an electrical
potential across electrodes 1403-1404, which has been shown to heat
the clusters to temperatures (2000 K-5000 K) far in excess the
substrate temperature (.about.300 K) and hence can greatly increase
reaction power without increasing converter diode temperature.
Coupling and Conversion Layers
[0133] One embodiment uses a quantum well superlattice for the
lowest charge carrier effective mass material. To maximize
conversion efficiency, the superlattice is tailored such that it
filters carriers with energies slightly greater than the barrier
height from the low carrier effective mass region to the high
carrier effective mass region.
[0134] One embodiment forms closely spaced buss bars on the active
surface to minimize ohmic losses across the surface. Chemically
inactive buss bars are formed as close as 100 nm apart, with active
material such as tunneling cluster catalysts between the buss
bars.
[0135] One embodiment uses very thin semiconductor for the
barrier-presenting material. The minimum thickness is typically of
order 5 nm. A preferable semiconductor thickness is in the range
between 20 and 100 nm although other thicknesses are
contemplated.
Thermal Conductivity Management
[0136] Referring to FIG. 15, one embodiment tailors the lower
charge carrier effective mass region 1500-1501 to include elements
for controlling and limiting the transfer of heat, and enhancing
the transfer of charge carrier kinetic energy. These elements
include one or more of low thermal conductivity materials, long
carrier mean free path materials, thermal diode elements, quantum
confinement elements and graded carrier effective mass elements.
The principle is to present multiple regions of increasing carrier
effective mass to the charge carrier as it travels ballistically
towards the barrier region. FIG. 15 show two such regions 1500,
1501.
[0137] Referring to FIG. 15, one embodiment uses a semiconductor
(S) 1500 with a charge carrier effective mass as low as practical,
such as silicon with a charge carrier effective mass .about.0.3 m_e
in contact with a conductor (C) 1501 with a higher charge carrier
effective mass and known to have unusually long electron mean free
paths at .about.1 eV. Such conductors 1501 include, for example, Au
(.about.20-100 nm), Ag (.about.20 nm) and Cu (reported as high as
60 nm) and Al (.about.20 nm). A ballistic charge carrier refraction
effect then exists between the semiconductor 1500 and the conductor
1501. The semiconductor 1500 may then inject its hotter charge
carriers via a narrow range of directions into the conductor C
1501. The conductor C 1501 is chosen to have a thickness less than
approximately 2 times a charge carrier mean free path. Nearly all
charge carriers traveling through the conductor C 1501 are already
directed towards the semiconductor S_barrier 1502, for example
TiO.sub.2 with charge carrier effective mass .about.25 m_e, higher
than 1501 charge carrier effective mass.
[0138] Materials with electron effective mass less than 1.1 and
materials with relatively long electron mean free paths can be used
for either semiconductor 1500 or lowest charge carrier effective
mass material 1500, including, but not limited to: air, aluminum,
conducting carbon nanotubes, conductors, copper, degeneratively
doped materials, gasseous material, gold, metals, metals,
molybdenum, nickel, palladium, platinum, rhodium, ruthenium,
silver, tantalum, vacuum. The materials with a ZT figure of merit
greater than approximately 0.05 and generally preferred for
thermoelectric applications may also be used for lowest charge
carrier effective mass material 1500, including but not limited to:
aluminum antimonide (AlSb), aluminum arsenide (AlAs), aluminum
gallium nitride (AlxGa1-xN), bismuth selenide (Bi2Se3), bismuth
telluride (Bi2Te3), and boron nitride (BN), gallium aluminum
arsenide (GaxAl1 xAs), gallium aluminum arsenide antimonide (GaxAl1
xAs1 y), gallium antimonide (GaSb), gallium arsenide phosphide
(GaAsyP1 y), gallium arsenide, gallium indium antimonide
(GaxIn1-xSb), gallium indium phosphide (GaxIn1 xP), gallium nitride
(GaN), gallium phosphide (GaP), germanium (Ge), indium aluminum
arsenide (InxAl1 xAs), indium antimonide (InSb), indium arsenide
(InAs), indium arsenide phosphide (InAsyP1-y), indium gallium
aluminum arsenide (InxGyAl1 x yAs), indium gallium arsenide
(InxGa1-xAs), indium gallium arsenide antimonide (InxGa1 xAsySB1 y)
indium gallium arsenide phosphide (InxGa1 xAsyP1 y), indium gallium
nitride (InxGa1-xN), indium phosphide, lead telluride, lead tin
telluride (Pbx Sn1 xTe), mercury cadmium selenide (HgxCd.1 xSe),
mercury cadmium telluride (HgxCd1-xTe), silicon germanium, silicon,
zinc selenide (ZnSe), zinc telluride (ZnTe), where the subscripts
x, y, z, 1-x, and 1-y denote the relative amounts of the atomic
species in each ternary or quartenary materials and range from zero
to one, inclusive.
[0139] The barrier-presenting layer 1502 may be made from materials
including but not limited to semiconductors known to have carrier
effective masses greater than 2, including but not limited to:
rutile TiO2, anatase TiO2, porous anatase TiO2, SrTiO3, BaTiO3,
Sr_x-Ba_y-TiO_z, LiNiO, LaSrVO3, organic semiconductors PTCDA,
(3,4,9,10-perylenetetracarboxylicacid-dianhydride). The following
materials and semiconductors with at least favorable ZT figure of
merits and generally preferred for thermoelectric applications may
also be used when their charge carrier effective masses are greater
than two times that of the material chosen for their junction,
including but not limited to: aluminum antimonide, aluminum gallium
arsenide, aluminum oxide, bismuth selenide, bismuth telluride,
boron nitride, gallium aluminum arsenide antimonide, indium
aluminum arsenide phosphide, indium gallium alluminum nitride,
indium gallium arsenide antimonide, indium gallium arsenide
phosphide, lead europium telluride, lead telluride, and air. lead
tin telluride, mercury cadmium selenide, mercury cadmium telluride,
silicon germanium, silicon oxide, zinc selenide, zinc
telluride.
[0140] The conductor becomes more like an insulator against heat
energy transport, on the timescale of ballistic transport, and a
very good, one directional conductor for charge carrier energy
transport in the present thermoelectric and thermionic energy
converters. Within this nanoscopic dimension the conductor can
sustain a useful temperature gradient across it. The thermal
isolation of the nanoscopic sandwich 1500-1501-1502 increases the
efficiency of the electric generator process.
[0141] The addition of a low charge carrier effective mass
material, a conductor 1501, between a lower charge carrier
effective mass material 1500 (with values as low as 0.02 m_e), and
a highest charge carrier effective mass material 1502 (with values
as high as 200, m_e, such as TiO.sub.2), expands the range of
materials that may be used in a solid state energy converter.
[0142] One embodiment includes catalyst clumps 505 physically
isolated and electrically connected through electron tunneling. The
clumps 505 replace at least some and in some configurations the
entire conductor 506 on the surface of an electric potential
barrier (dielectric) material 507.
[0143] Another embodiment uses such nanoscopic constraints on the
dimension of conducting catalyst clusters, sheets, nano-wires,
nano-dots, nano-tubes, quantum dots, layers and constructs 505 to
enhance reaction rates in chemically energized pre-equilibrium
energy converters.
Tailoring Charge Carrier Thermal Coupling
[0144] According to one embodiment the energy transfer between
materials in contact with the heat or hotter electron source and
the colder region are controlled to be predominantly by ballistic
charge carrier transport. Referring to FIGS. 16-A through 16-D, we
show a cross section of a device using three materials or regions.
As a general governing principle, the first and second regions,
1601 and 1602, are designed to block heat and transmit energized,
ballistic carriers with minimal energy loss. The ideal condition is
the transport of energy only by ballistic electrons (charge
carriers) and not by heat, from region 1601, 1602 to region 1603.
As a general governing principle, third region 1603 is designed to
pass only the more energetic ballistic charge carriers against and
over an electrical potential barrier, and to refract the direction
of the ballistic carriers so they transport directly into the
potential. The refraction is enhanced when the third region 1603
has a carrier effective mass at least two times higher that of the
conductor region 1602, and is overwhelmingly so when it is higher
by at least a factor of 2. The first and second regions 1601, 1602
are generally characterized by a favorable ZT thermoelectric figure
of merit. The second region 1602 is generally characterized by an
enhanced tendency to transmit a large number of ballistic
electrons, and this is generally referred to as having a relatively
long mean free path.
[0145] The first material 1601 may have a higher, equal or lower
charge carrier effective mass than the second material 1602. In
addition, the first material 1601 may or may not present an
electrical potential barrier to carriers traveling, backwards from
the second material 1602 back into the first material 1601. These
two options result in four cases, each case having relative
advantages. The choice depends on material availability,
manufacturability, cost, stability and other factors.
[0146] One embodiment including the first case FIG. 16-A, with
minimal or no barrier in the first material and an increasing
charge carrier effective mass from left to right 1601, 1602, 1603,
offers the fastest and shortest path transfer of energetic electron
energy into the barrier material with highest charge carrier
effective mass 1603. Nearly any of the common semiconductors may be
used as the first material because virtually all of them are
commercially valuable precisely in part because their charge
carrier effective masses are all low, less than 1 m_e. This means
that all the known favorable ZT materials can be used very
effectively. A minimal barrier can be achieved by band gap
engineering or degenerative doping.
[0147] One embodiment including the second case FIG. 16-B, with
minimal or no barrier in the first material 1601 and since the
middle material 1602 has the lowest charge carrier effective mass,
it allows charge carriers in the middle material to exit the
material more easily than allowing entry of charge carriers from
materials 1601 and 1603. For example, electrons that have energies
too low to surmount the barrier in material 1603 are not only
reflected back into middle material 1602 but also are quickly
transported to the warmer material 1601 for reheating and
reprocessing. The middle, inner region 1602 is electronically, and
therefore in the case of ballistic transport, thermally isolated to
the outer regions 1601, 1603. This tends to minimize energy
transfer from electrons to lattice, which in turn minimizes heat
conductivity losses. The back-to-back ballistic refraction tends to
isolate the two heat bath regions 1601 and 1603.
[0148] One embodiment including the third case FIG. 16-C, with a
barrier in the first material 1601 and an increasing charge carrier
effective mass, provides fastest transport of only the hottest
charge carrier of the first material 1601.
[0149] One embodiment including the fourth case FIG. 16-D, presents
electrical barriers against charge carrier transport back into the
hotter material 1601 and into the colder material 1603, and has the
minimum charge carrier effective mass in the middle material 1602.
This configuration almost reversibly communicates carrier energy
between two heat baths, which is a key property, and because of the
ballistic transport, and preferentially transports charge carrier
energy faster than by lattice phonon or other energy transfer. Note
that ballistic transport is only necessary in the middle region
1602 and not in the surrounding regions 1601, 1603. The charge
carrier may be negative or positive, and the barriers are designed
to retard transport. Example materials for the regions can be, for
example, TiO2 for the outer regions and Silicon for the middle
region, where band gap alignments provide the barrier. The middle
region 1602 materials can be chosen from the group including at
least metals with long mean free paths, such as Cu, Au, Ag, Al, and
materials with high ZT.
[0150] One embodiment uses the same barrier region material on both
sides of the conductor.
[0151] One embodiment to use thermally energized ballistic
refraction energy converters as refrigerators utilizes one or more
stacked converters and applies a positive potential across the
terminals instead of the negative potential obtained from the same
device used as a generator. The heat sink may then be hotter than
the heat source, and cooling occurs because the hot electrons are
efficiently removed from the cooled regions. The use of ballistic
refraction enhances the efficiency of such a cooling method and
device over devices where carriers are not directed predominantly
into the potentials at the interfaces of low and high charge
carrier effective mass materials.
[0152] Embodiments form one or more refrigerating ballistic
refraction energy converters directly on integrated circuits to
cool them. A similar embodiment forms a refrigerating ballistic
refraction energy converter directly on chemical reaction surfaces,
for example, to control reaction pathways and control
reactions.
Fuels, Oxidizers, Autocatalysts, Stimulators
[0153] Embodiments use storable reactants including oxidizers,
autocatalytic reaction accelerators, decelerators, and
monopropellants. The liquid phase, such as liquid hydrogen peroxide
H.sub.2O.sub.2 at standard pressure and temperature, are convenient
because their heat of vaporization is used as coolant and the
liquid is conveniently storable. Monopropellants such as
H.sub.2O.sub.2 and monomethylhydrazine (MMH) are similarly
convenient and energize the active surface of converters.
Autocatalytic accelerators include monopropellants such as
H.sub.2O.sub.2.
[0154] One embodiment uses thermally isolated catalysts in close
proximity to the active surface of ballistic refraction converter
assemblies to enhance reaction rates and concentrate thermally hot
entities to the thermally hot region of the converter.
[0155] FIG. 17 shows an embodiment where a highly reactive catalyst
1701 is placed on a thermally isolated pillar structure 1702 in
close proximity to the active surface 1703 of a converter. Gas
phase reaction products created in the vicinity of the catalyst
energize the converter. The products may include one or more of at
least highly vibrationally excited molecules, reactive molecules,
and hot gases.
[0156] Embodiments use energetic reactants chosen to maximize the
energizing of highly energetic specie, which include one or more of
highly vibrationally excited molecules (HVEM), hot atoms, charged
adsorbate intermediates such as peroxo and superoxo specie formed
during precursor mediated dissociative adsorbsion, adsorbates
participating in association reactions both of the
Langmuir-Hinshelwood and of the Eley-Rideal type, and reaction
intermediates such as radicals, free radicals and specie considered
to be catalytic or autocatalytic.
[0157] Embodiments provide means for the energizing to occur
directly on or in the vicinity of a conductor. The term "vicinity"
refers here to a distance less than a few mean free paths of the
particular energetic excitation. Embodiments use these excitations
to energize a low charge carrier effective mass material of the
ballistic refraction energy converter.
[0158] Chemical reactions using reactants of this kind result in
pre-equilibrium excitation including reaction effective
temperatures and effective carrier temperatures in excess of 10,000
Kelvin on and in metals, conductors, catalysts, semiconductors and
ceramics, and where the carriers include excitons, carriers in the
conduction and/or valence band of semiconductors and
insulators.
[0159] One embodiment uses reactions and reactants to energize
these excitations. The reactions, reactants and additives include
at least monopropellants, high energy fuels with oxidizers,
hypergolic mixtures, and additives and combinations of reactants
known to produce autocatalytic specie, reactants chosen to
accelerate reactions or to control reactions, and combinations
thereof. The reactants and/or additives include but are not limited
to the following reactants:
TABLE-US-00001 TABLE I energetic fuels more storable than ammonia
amine substituted ammonias Di-Methyl-Amine (CH.sub.3).sub.2NH
Tri-Methyl-Amine (CH.sub.3).sub.3N Mono-Ethyl-Amine (C2H5)NH2
Di-Ethyl-Amine (C.sub.2H.sub.5).sub.2NH) other classes more easily
storable Methanol, CH.sub.3OH Ethanol, EtOH CH3CH2OH Formic Acid,
HCOOH diesel fuels gasoline alchohols slurries including solid
fuels Carbon Suboxide, C.sub.3O.sub.2, CO.dbd.C.dbd.CO,
Formaldehyde HCHO, Paraformaldehyde, = better HCHO).sub.n,
sublimeable to Formaldehyde gas. (Potentially a cell coolant at the
same time). less storable fuels Carbon Monoxide Hydrogen Ammonia
NH3 energetic fuels containing Nitrogen Nitromethane,
CH.sub.3NO.sub.2 Nitromethane "cut" with Methanol = model airplane
"glow plug" engine fuel High energy fuels with wide fuel/air ratio
Epoxy-Ethane, = Oxirane or Ethylene-Oxide CH2--CH2 O
1,3-Epoxy-Propane = Oxetane and Tri-Methylene-Oxide =
1,3-Methylene- Oxide CH.sub.2--(CH.sub.2)--CH.sub.2 O Epoxy-Propane
CH2--(CH2)--CH2 O Acetylene, C.sub.2H.sub.2 Diacetylene =
1,3-Butadiyne 1,3-Butadiene CH.sub.2.dbd.CH--CH.dbd.CH.sub.2, less
exotic high energy fuels Di-Ethyl-Ether or surgical ether Acetone =
Di-Methyl-Ketone less exotic, volatile fuels Cyclo-Propane
Cyclo-Butane Hydrocarbons such as methane, propane, butane,
pentane, etc. other storable fuels Methyl Formate
HCOO--C.sub.2H.sub.5 Formamide HCO--NH.sub.2 N,
N,-Di-Methyl-Formamide HCO--N--(CH.sub.3).sub.2 Ethylene-Diamine
H.sub.2N--CH.sub.2--CH.sub.2--NH.sub.2 Ethylene-Glycol 1,4-Dioxane
= bimolecular cyclic ether of Ethylene-Glycol Paraldehyde
(CH.sub.3CHO).sub.3 cyclic trimer of Acetaldehyde powerful oxidizer
Tetra-Nitro-Methane, C(NO.sub.2).sub.4 . . . does not spontaneously
decompose . . . just pass the two separate vapors over the reaction
surface of the cell in the gas phase Hydrogen Peroxide H2O2 low
initiation energy mixtures Cyclo-Propane with Oxygen = surgical
anesthetic, microjoules initiator Hypergolics UDMH = Unsymmetrical
DiMethyl Hydrazine = 1,1-DiMethyl Hydrazine
(CH.sub.3).sub.2NNH.sub.2 UDMH is hypergolic usually with
N.sub.2O.sub.4 and is a very potent carcinogen MMH MonoMethyl
Hydrazine (CH.sub.3)HNNH.sub.2 hypergolic with any oxidizers, e.g.
N.sub.2O.sub.4 Corrosive Toxic energetic monopropellant Hydrazine =
H.sub.2NNH.sub.2 decomposed easily with a catalyst (usually Pt or
Pd or Molybdenum Oxide Hydrazine Hydrate
[0160] A method and system for ballistic charge carrier refraction
have been disclosed. Although the present methods and systems have
been described with respect to specific examples and subsystems, it
will be apparent to those of ordinary skill in the art that it is
not limited to these specific examples or subsystems but extends to
other embodiments as well.
* * * * *