U.S. patent application number 12/851555 was filed with the patent office on 2011-12-08 for high power density betavoltaic battery.
Invention is credited to MVS Chandrashekhar, Michael Spencer.
Application Number | 20110298071 12/851555 |
Document ID | / |
Family ID | 43534172 |
Filed Date | 2011-12-08 |
United States Patent
Application |
20110298071 |
Kind Code |
A9 |
Spencer; Michael ; et
al. |
December 8, 2011 |
HIGH POWER DENSITY BETAVOLTAIC BATTERY
Abstract
To increase total power in a betavoltaic device, it is desirable
to have greater radioisotope material and/or semiconductor surface
area, rather than greater radioisotope material volume. An example
of this invention is a high power density betavoltaic battery. In
one example of this invention, tritium is used as a fuel source. In
other examples, radioisotopes, such as Nickel-63, Phosphorus-33 or
promethium, may be used. The semiconductor used in this invention
may include, but is not limited to, Si, GaAs, GaP, GaN, diamond,
and SiC. For example (for purposes of illustration/example, only),
tritium will be referenced as an exemplary fuel source, and SiC
will be referenced as an exemplary semiconductor material. Other
variations and examples are also discussed and given.
Inventors: |
Spencer; Michael; (Ithaca,
NY) ; Chandrashekhar; MVS; (Columbia, SC) |
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20110031572 A1 |
February 10, 2011 |
|
|
Family ID: |
43534172 |
Appl. No.: |
12/851555 |
Filed: |
August 6, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61231863 |
Aug 6, 2009 |
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61306541 |
Feb 21, 2010 |
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Current U.S.
Class: |
257/429 ;
257/E29.166 |
Current CPC
Class: |
H01L 31/115 20130101;
G21H 1/06 20130101 |
Class at
Publication: |
257/429 ;
257/E29.166 |
International
Class: |
H01L 29/66 20060101
H01L029/66 |
Claims
1. A betavoltaic battery, comprising: a positive post; a negative
post; a radioisotope layer; one or more metal contacts; and
isolation material.
2. The betavoltaic battery as recited in claim 1, further
comprising: a lid to a battery case.
3. The betavoltaic battery as recited in claim 1, further
comprising: case isolation material.
4. The betavoltaic battery as recited in claim 1, further
comprising: a battery case.
5. The betavoltaic battery as recited in claim 1, further
comprising: a semiconductor material.
6. The betavoltaic battery as recited in claim 5, wherein said
semiconductor material is SiC.
7. The betavoltaic battery as recited in claim 1, further
comprising: an ohmic contact.
8. The betavoltaic battery as recited in claim 1, further
comprising: a split ring element.
9. The betavoltaic battery as recited in claim 1, further
comprising: an isolation element or material.
10. The betavoltaic battery as recited in claim 1, further
comprising one or more of the following: radioisotope tritium,
Nickel-63, Phosphorus-33, or Promethium.
11. The betavoltaic battery as recited in claim 5, wherein said
semiconductor material is Si, GaAs, GaP, GaN, or diamond.
12. The betavoltaic battery as recited in claim 1, wherein said
betavoltaic battery's cross section is in a shape of square or
circle.
13. The betavoltaic battery as recited in claim 1, further
comprising an electrical shielding material.
14. The betavoltaic battery as recited in claim 1, further
comprising a magnetic shielding material.
15. The betavoltaic battery as recited in claim 1, further
comprising Fe or Ni.
16. The betavoltaic battery as recited in claim 1, further
comprising a PN junction.
17. The betavoltaic battery as recited in claim 1, further
comprising a diode.
18. The betavoltaic battery as recited in claim 1, further
comprising titanium or scandium.
19. The betavoltaic battery as recited in claim 1, further
comprising AlN, SiO.sub.2, or sapphire.
20. The betavoltaic battery as recited in claim 1, wherein said
betavoltaic battery is based on a series circuit design and/or
parallel circuit design.
Description
[0001] This is a Continuation of (based on) a U.S. Provisional
Application Ser. No. 61/231,863, filed on 6 Aug. 2009, with the
same title, assignee, and inventors.
FIELD OF THE INVENTION
[0002] The field of the invention relates to semiconductor
materials, devices and semiconductor device packaging, plus
batteries.
BACKGROUND OF THE INVENTION
[0003] Beta-voltaic devices have very high energy density and
utilize radioisotopes as a fuel source. Radioisotope emissions
originate from within a few microns of a radioactive material's
surface at very low levels (nW/cm2-.mu.W/cm2), despite the high
power density in the bulk of the radioactive source (mW/cc-W/cc).
Several semiconductor materials, such as Si, GaAs, GaP, GaN and
diamond, may be used in betavoltaic devices.
[0004] However, silicon carbide (SiC) is the material used here for
the production of beta voltaic devices, due to its wide bandgap.
Moreover, in addition to its radiation hardness and ability not to
degrade over time at higher temperatures and in harsh environments,
SiC provides low leakage currents to effectively harvest low level
emission rates from the isotope. The wide availability of high
quality SiC substrates and epitaxy makes SiC the most practical of
all semiconductors for betavoltaics, when performance and
efficiency are considered. For example, Si provides 100 times less
power conversion efficiencies than SiC. Thus, betavoltaic devices
made from Si are suboptimal, due to this poor efficiency.
[0005] Semiconductor-based beta-voltaic batteries find applications
in several areas such as security systems and medical implants
(e.g. pacemakers). In order to increase power in these and other
applications in the presence of low emission levels from
radioisotopes, it is necessary to take advantage of the energy
density of the device and develop device geometries and packaging
which maximize the size and utilization of radioisotope surface
area. This invention uses novel device configurations and packaging
to maximize power in betavoltaic batteries and power output per
unit volume.
[0006] Beta-Voltaic Devices
[0007] A SiC based beta voltaic radioisotope battery can produce
several nanowatts (nWs) to milliwatts (mWs) of power, at 1 to 2
volts, with theoretical efficiencies in excess of 30% and measured
efficiencies of 20%. Radioisotopes provide fuel for these devices
and emit high energy electrons, or beta particles. The radioisotope
tritium may be used. Other radioactive materials, such as
Nickel-63, Phosphorus-33 and Promethium, may also be used.
Utilization of beta emitters is attractive because of the short
penetration distance of emitted electrons. For example, a high
energy electron emitted from nickel-63 is effectively stopped by 25
microns of plastic or a layer of dead skin. Moreover, beta
particles do not damage semiconductor materials and are easily
shielded from sensitive electronics.
[0008] For several decades, electronics have become smaller and
ubiquitous. In addition, power requirements for silicon-based
electronics have been made low enough to enable the realization of
nanowatt electronics, and asynchronous logic platform technologies
are either projecting or exhibiting a performance of 24
pJ/instruction and 28 MIPS at 0.6V. Many medical applications can
be powered with 1 to 10 microwatts (.mu.Ws) of average power. With
such low power consumption requirements, a beta-voltaic battery
source is able to continuously power the aforementioned
electronics. Using these low power electronic elements, it is also
possible to implement massive intelligent sensor networks which can
monitor a large range of environments and infrastructures, or power
a pacemaker or other implantable devices for over 25 years.
Silicon Carbide
[0009] SiC is a wide bandgap semiconductor, which is ideally suited
for use in radioisotope batteries. The material's wide bandgap
provides not only for radiation resistance in long term exposure to
high energy electrons, but perhaps, more importantly, the shunt
resistance of SiC diodes is high enough to allow efficient
extraction of energy from a radioisotope source. Silicon (Si), the
semiconductor industry workhorse, cannot realize sufficiently high
open circuit voltages or power conversion efficiencies to be an
optimal alternative for beta-voltaic batteries. Recent improvements
in SiC substrate and epitaxial technology will enable the low
dislocation and defect densities required for realization of
beta-voltaic devices (including batteries) which utilize this
material.
Theory of a Radiation Battery
[0010] The operation of a radiation cell is well-described by the
solar cell equations. The main relationship is given by
V.sub.oc=nV.sub.T ln(J.sub.gen/J.sub.ss), (1)
[0011] where Voc is the open circuit voltage, n the ideality
factor, V.sub.T the thermal voltage=25.9 mV at T=300K, J.sub.gen
the current generated by the radioactive source, and J.sub.ss is
the reverse saturation current of the diode used in the cell.
[0012] Using a tritium radiation source and SiC material, as
illustrative examples, the current generated in the cell can be
predicted as follows. The current generated in SiC by high energy
electrons emitted from tritium is given as:
J.sub.gen=(J.sub..beta.*E.sub.mean .beta.*(1-.eta.))/E.sub.e-h
(2)
[0013] where J.sub.Gen is the net generated electron current,
J.sub..beta. the net flux of beta electrons from the radiation
source (.about.3 nA/cm.sup.2 for tritiated water), E.sub.mean
.beta. the mean beta electron energy generated by tritium, which is
5.5 keV, E.sub.e-h the mean electron-hole pair creation energy,
which is 5 eV for SiC, and .eta. which is the backscattering yield,
which is (10%) for SiC.
[0014] It is worthwhile to mention that each high energy beta
particle from tritium generates .about.1100.times. (5.5 keV/5 eV)
current in the cell due to this e-h pair creation energy. The
expected maximum current density in SiC is .about.2 .mu.A/cm.sup.2.
This assumes 100% carrier collection efficiency in the absorption
region. For SiC, this absorption region is .about.0.5 .mu.m. Such a
predictive analysis can be carried out for any radiation source,
such as Ni-63, Tritium, Phosphorus-33, Pm-147 or others (e.g. see
the ref. MVS Chandrashekhar et al., Appl. Phys. Lett., 88, 033506
(2006)).
Radioisotopes
[0015] There are several candidate radioisotopes which can be
inserted as a power source for beta-voltaic batteries. These
radioisotopes include, but are not limited to Phosphorus-33, Ni-63,
Promethium and Tritium. All of the sources share the following
drawback. Although the Curie load is calculated from the total
volume of the radioactive material, the amount of useable energy is
limited to the number of high energy electrons which escape from
the surface of the source before they can be reabsorbed. The
self-absorption length of these radioisotopes is of the order of
microns (ref. Everhart and Hoff, J. Appl. Phys, 42, 5837 (1971)).
This means that the optimum thickness for the radioisotope source
material (such as foil) is microns. Only electrons from a very thin
layer of radioisotope source material are extracted. Therefore, to
increase total power in a betavoltaic device, it is desirable to
have greater radioisotope material and/or semiconductor surface
area rather than greater radioisotope material volume.
SUMMARY OF INVENTION
[0016] An embodiment of this invention is a high power density
betavoltaic battery. In one embodiment of this invention, tritium
is used as a fuel source. In other embodiments, radioisotopes, such
as Nickel-63, Phosphorus-33 or promethium, may be used. The
semiconductor used in this invention may include, but is not
limited to, Si, GaAs, GaP, GaN, diamond and SiC. For this
disclosure, and for purposes of illustration/example only, tritium
will be referenced as an exemplary fuel source, and SiC will be
referenced as an exemplary semiconductor material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIGS. 1 (a)-(c)--Cross-Section and Perspective Views of
Betavoltaic Device w/Elements and Case (Circular Geometry, Parallel
Circuit Design)
[0018] FIGS. 2 (a)-(c)--Cross-Section and Perspective Views of
Betavoltaic Device w/Elements and Case (Square Geometry, Parallel
Circuit Design)
[0019] FIGS. 3 (a)-(c)--Cross-Section and Perspective Views of
Betavoltaic Device w/Elements and Case (Circular Geometry, Series
and Parallel Circuit Design)
[0020] FIGS. 4 (a)-(c)--Cross-Section and Perspective Views of
Betavoltaic Device w/Elements and Case (Circular Geometry, Parallel
Circuit Design)
[0021] FIGS. 5 (a)-(c)--Cross-Section and Perspective Views of
Betavoltaic Device w/Elements and Case (Square Geometry, Parallel
Circuit Design)
[0022] FIGS. 6 (a)-(c)--Cross-Section and Perspective Views of
Betavoltaic Device w/Elements and Case (Circular Geometry, Series
and Parallel Circuit Design)
DETAILED DESCRIPTION OF INVENTION
[0023] One embodiment of the invention is a circularly symmetric
implementation, as shown in FIGS. 1 and 3. Square geometry, as
shown in FIG. 2, may be employed, as well. Other geometries may be
used to fit the application of interest.
[0024] The device is assembled one layer at a time, using various
elements described below. This assembly may be performed manually
or with robotic aid.
[0025] In one embodiment, the device is assembled in a case whose
core is comprised of insulating material, such as aluminum oxide,
and is plated with magnetic shielding material. Shielding
materials, such as Fe, Ni, u (Mu)-Metal or any other material with
a high magnetic susceptibility, may be used to screen stray and
intentionally applied magnetic fields. The inside of the case is
insulated to prevent device shorting.
[0026] In a further embodiment, the device is assembled in a case
whose core is also comprised of insulating material such as
aluminum oxide and is plated with electrical shielding material.
Shielding materials such as Au, Ti, Fe, Ni, u (Mu)-Metal or any
other material with a high electrical conductivity, may be used to
screen stray and intentionally applied electrical fields. In a
further embodiment, both electrical and magnetic shielding may be
employed together. In a still further embodiment, a case can be
made with two metal pieces fused together with an insulating
material such as glass or aluminum oxide positioned between the
metal pieces.
[0027] As shown in FIGS. 1, 2 and 3, cases for magnetic and/or
electrical shielding comprise an isolation area in the center that
is not plated with shielding material. The isolation area results
in symmetric isolation between positively and negatively charged
portions of the device.
[0028] Device with Parallel Circuit Design
[0029] Description of Device Elements for Parallel Circuit
Design--Reference FIGS. 1 and 2: Note: references to a "top side"
indicates surfaces of a device which face toward the device cap,
and references to a "bottom side" indicate surfaces of a device
which face away from the device cap. Moreover, when comparing the
position of elements with respect to other elements, "upper"
indicates a position closer to the device cap, and "lower"
indicates a position farther away from the device cap.
[0030] Element 1--Split Ring Element. The element provides
conduction feed-through for the package. In the drawings, region 1
or color red represents conduction regions, while region 2 or color
white indicates insulating regions. This element is preferably
fabricated from an insulating ceramic material, such as AlN,
although other materials, such as SiO2 and sapphire, may be used.
On top of this ceramic material, conduction material, such as thick
gold plate, is deposited and electroplated, so as to form a low
resistance path between the top and bottom of the element. A space
is machined in the ceramic so as to accommodate the betavoltaic
device (element 2 described below), which is inserted in the
space.
[0031] Element 2--SiC Betavoltaic Device. This element generates
power. Yellow color or region 3 represents the device and green
color or region 4 represents ohmic contacts used in the device.
Ohmic contacts are deposited on both the top and bottom sides of
the device, and the device is placed in a machined space inside of
split ring element 1. In placing the betavoltaic device in the
split ring element, an ohmic contact is made between the bottom
side of the device and one side of isolation element 4 (described
below), creating a positive polarity on that side of the overall
device structure. Ohmic contact is also made between the top side
of the betavoltaic device and one side of radioisotope element 3
(described below), creating a negative polarity on that side of the
overall device structure. Contacts made by the betavoltaic device
are electrically continuous on each side of the split ring
assembly. The device (a PN junction semiconductor diode) has a P
and N region. In the preferred implementation, the N-region is
formed by chemical vapor deposition (CVD), while the p-region is
formed by ion implantation and subsequent annealing, as discussed
in relevant published literature.
[0032] Element 3--Radioisotope Element. The element is a
radioisotope foil (represented in grey or region 5) integrated with
a conducting element, represented in red, or region 6. Insulating
regions are represented in white, or region 7. In one
implementation, the radioisotope is metal foil of titanium or
scandium, which is irradiated by annealing in gaseous tritium. In
other implementations/examples, tritium liquid may be used. Other
radioisotopes mentioned herein may also be used in solid or fluid
form. Insulating portions of the radioisotope element are
fabricated from insulating material, such as AlN, although other
materials, such as SiO.sub.2 and sapphire, may be used. Conducting
material shown in red, such as thick gold plate, is deposited and
electroplated, so as to form a low resistance path between the top
and bottom of the element.
[0033] Element 4--Isolation Element. Conducting material is shown
in red, and white regions indicate insulating areas. In one
implementation, the isolation element is fabricated from insulating
material, such as AlN, although other materials (such as SiO.sub.2
and sapphire) may be used. Conducting material shown in red, such
as thick gold plate, is deposited and electroplated, thus, forming
a low resistance path between the top and bottom of the
element.
[0034] In one embodiment of this invention, elements 1, 2, 3 and 4
(described above) are used to create a betavoltaic device which has
a parallel circuit configuration as shown in FIGS. 1 and 2. Each
element is placed into a case as shown in the figures.
[0035] The split ring element 1 is placed on top of the isolating
element 4. SiC device element 2 is placed inside of split ring
element 1 as described above. Radioisotope element 3 is placed on
top of elements 1 and 2. A lid containing positive and negative
terminals is placed on the entire element stack to complete the
device.
[0036] The above set of elements may be configured in a single set
or repeating sets, or stacks, which are configured in parallel,
until the desired power output is achieved. For the invention
described above, as an example, the total output power will be
approximately 0.1 .mu.W per cm.sup.2 of SiC betavoltaic device area
in a set/stack, multiplied by the number of sets/stacks. In other
embodiments, higher and lower output power levels in each stack may
be used. FIGS. 1 and 2 show a sample device with two sets of
elements. The assembly is closed with a press fit cap. This cap
compresses the conductive areas and ensures a good quality contact
between the layers. Although contact between elements is shown as
direct contact, contact between elements may also be achieved with
continuous solder or solder bumps, formed on conducting regions of
each element.
[0037] Device with Series and Parallel Circuit Design
[0038] Description of Device Elements for Series and Parallel
Circuit Design--Reference FIG. 3: Note: references to a "top side"
indicate surfaces of a device which face toward the device cap, and
references to a "bottom side" indicate surfaces of a device which
face away from the device cap. Moreover, when comparing the
position of elements with respect to other elements, "upper"
indicates a position closer to the device cap, and "lower"
indicates a position farther away from the device cap.
[0039] Element 1--Split Ring Elements. The elements provide
conduction feed-through for the package. In the drawings, red
represents conduction regions, while white indicates insulating
regions, with regions marked and labeled above. These elements are
preferably fabricated from an insulating ceramic material, such as
AlN, although other materials, such as SiO2 and sapphire, may be
used. On top of this ceramic material, conduction material, such as
thick gold plate, is deposited and electroplated, to form a low
resistance path between the top and bottom of the element. A space
is machined in the ceramic so as to accommodate the betavoltaic
device (element 2 described below), which is inserted in the
space.
[0040] Element 2--SiC Betavoltaic Device: This element generates
power. Yellow represents the device and green represents ohmic
contacts used in the device. Ohmic contacts are deposited on both
the top and bottom sides of the device and the device is placed in
a machined space inside of split ring element 1. In placing the
betavoltaic device in the split ring element, ohmic contact can be
made with certain elements, based on the desired series
configuration and the quantity of betavoltaic device elements
utilized. Examples include:
[0041] a). qty. (quantity) two device elements 2 in series--the
upper device element 2 makes ohmic contact between the top side of
the device and one side of radioisotope element 3 (described
below), creating a negative polarity on that side of the overall
device structure. This same device also makes ohmic contact between
the bottom side of the device and the top side of series element 5
(described below). The lower device element 2 makes ohmic contact
between the top side of the device and bottom side of element 5.
This same device element 2 makes ohmic contact between the bottom
side of the device and one side of isolation element 4 (described
below), creating a positive polarity on that side of the overall
device structure.
[0042] b). qty. of more than two device elements in series--the
configuration in a). above is used to start the series
configuration, and the combination of element 5 and lower device
element 2 mentioned in a) above is repeated and added to the
lowermost portion of the series configuration, until the desired
quantity of device elements configured in series is reached. The
final lowermost device element 2 makes ohmic contact between the
bottom side of the device and one side of isolation element 4
(described below), creating a positive charge on that side of the
overall device structure.
[0043] The device element (a PN junction semiconductor diode) has a
P and N region. In one implementation, the N-region is formed by
chemical vapor deposition (CVD), while the p-region is formed by
ion implantation and subsequent annealing, as discussed in relevant
published literature.
[0044] Element 3--Radioisotope Element: The element is a
radioisotope foil (represented in grey) integrated with a
conducting element, represented in red, as shown above for
different regions. Insulating regions are represented in white. In
one implementation, the radioisotope is metal foil of titanium or
scandium, which is irradiated by annealing in gaseous tritium. In
other implementations, tritium liquid may be used. Other
radioisotopes mentioned herein may also be used in solid or fluid
form. Insulating portions of the radioisotope element are
fabricated from insulating material, such as AlN, although other
materials, such as SiO.sub.2 and sapphire, may be used. Conducting
material shown in red, such as thick gold plate, is deposited and
electroplated, so as to form a low resistance path between the top
and bottom of the element.
[0045] Element 4--Isolation Element: Conducting material is shown
in red, and white regions indicate insulating areas. In one
implementation, the isolation element is fabricated from insulating
material such as AlN, although other materials such as SiO.sub.2
and sapphire may be used. Conducting material shown in red, such as
thick gold plate, is deposited and electroplated thus forming a low
resistance path between the top and bottom of the element.
[0046] Element 5--Series Element: This element contains a
radioisotope foil (represented in grey). The element also contains
isolation material (white regions) and conductive regions,
indicated in red. In one implementation, the isolation element is
fabricated from insulating material such as AlN, although other
materials such as SiO.sub.2 and sapphire may be used. Conducting
material shown in red, such as thick gold plate, is deposited and
electroplated on the outermost edge of the element, thus, forming a
low resistance path between the top and bottom of the element at
that outer edge. Conducting material which is proximal to the
radioisotope foil is not plated, but instead is formed through the
entire thickness of the element as a solid conductive ring, which
also provides a low resistance path between the top and bottom of
the element.
[0047] In one embodiment of this invention, elements 1, 2, 3, 4 and
5 (described above) are used to create a betavoltaic device which
has series and parallel circuit configurations as shown in FIG. 3.
Each element is placed into a case as shown in FIG. 3.
[0048] Split ring elements 1 containing device elements 2 are
placed in series, in accordance with the above, and with series
element 5 placed between each element 1 and 2 combination, also in
accordance with the above. The desired quantity of device elements
2 (along with split ring and series element(s) 1 and 5,
respectively) are placed on top of isolating element 4.
Radioisotope element 3 is placed on top of uppermost device element
2. This configuration comprises one complete set of elements. A lid
containing positive and negative terminals is placed on the entire
configuration to complete the device.
[0049] The above set of elements may be configured in a single set
or repeating sets, or stacks, which are configured in parallel,
until the desired power output is achieved. For the invention
described above, the total output power will be approximately 0.1
.mu.W per cm.sup.2 of SiC betavoltaic device area in a set/stack
multiplied by the number of sets/stacks.
[0050] In other embodiments, higher and lower output power levels
in each set/stack may be used. FIG. 3 shows a sample device with
two sets/stacks of elements. The assembly is closed with a press
fit cap. This cap compresses the conductive areas and ensures a
good quality contact between the layers. Although contact between
elements is shown as direct contact, contact between elements may
also be achieved with continuous solder or solder bumps formed on
conducting regions of each element.
[0051] Note that FIGS. 1-3 mirror FIGS. 4-6, respectively, showing
the same features in black/white drawings, versus color image, to
teach the features more easily and clearly. (Different regions of
the color figures are designated using colors, for the ease of
teaching of the invention to the reader.)
[0052] For FIG. 1 or 4, we have the following features or parts:
item 101 (Lid to Battery Case), 102 (negative post), 103 (positive
post), 104 (case isolation material, or isolation material), 105
(radioisotope element, 106 (radioisotope), 107 (isolation
material), 108 (metal contact), 109 (split ring element), 110 (SiC
Betavoltaic device), 111 (ohmic contact), 112 (isolation material),
113 (metal contact), 118 (isolation element), 119 (isolation
material), 120 (metal contact), 121 (battery case), and 122
(assembled device).
[0053] For FIG. 2 or 5, we have the following features or parts:
item 201 (Lid to Battery Case), 202 (negative post), 203 (positive
post), 204 (case isolation material, or isolation material), 205
(radioisotope element, 206 (radioisotope), 207 (isolation
material), 208 (metal contact), 209 (split ring element), 210 (SiC
Betavoltaic device), 211 (ohmic contact), 212 (isolation material),
213 (metal contact), 214 (isolation element), 215 (isolation
material), 216 (metal contact), 217 (battery case), and 218
(assembled device).
[0054] For FIG. 3 or 6, we have the following features or parts:
item 101 (Lid to Battery Case), 102 (negative post), 103 (positive
post), 104 (case isolation material, or isolation material), 105
(radioisotope element, 106 (radioisotope), 107 (isolation
material), 108 (metal contact), 109 (split ring element), 110 (SiC
Betavoltaic device), 111 (ohmic contact), 112 (isolation material),
113 (metal contact), 114 (series element, or element), 115
(radioisotope), 116 (isolation material), 117 (metal contact), 118
(isolation element), 119 (isolation material), 120 (metal contact),
121 (battery case), and 301 (assembled device).
[0055] The devices can be grown on different materials or
substrates, or implanted/annealed, or by any other deposition
methods. They can be stacked on top of each other in series or
side-by-side in parallel. The contacts may be by pressure, or
no-pressure, surface adhesion, or by removal of the layer and its
placement on a second substrate, or by flip-chip-type technology,
reversing the orientation or direction.
[0056] The supplied material may be in shape of liquid, fluid, gas,
powder, conventional semiconductor, polycrystalline, crystalline,
amorphous, or combination of different crystalline regions.
[0057] The thickness of the active region can be non-uniform, or
ramped thickness, variable thickness, so that different absorption
or current is obtained.
[0058] The regions on the surface can be patterned so that for heat
dissipation and transfer is done more efficiently, to reduce
overheating, or increasing efficiency, if that effect is desired,
to some optimum temperature.
[0059] The battery can be integrated on the same substrate, on same
circuit, to save energy, cost, space, efficiency, or time, and
increase speed.
[0060] Any other variations of the above are also meant to be
included in the coverage or scope of this invention.
* * * * *