X-ray photovoltaic radiation cell based on gallium-containing semiconductor and preparation method thereof

Abstract

The invention provides an X-ray photovoltaic radiation cell based on a gallium-containing semiconductor and a preparation method of the X-ray photovoltaic radiation cell. The gallium-containing semiconductor X-ray radiation photovoltaic cell comprises a gallium-containing semiconductor transduction unit and an X-ray radiation source 55Fe arranged on the semiconductor transduction unit, wherein the semiconductor transduction unit containing gallium comprises at least one of GaAs (gallium arsenide), GaInP (gallium indium phosphide), GaP (gallium phosphide) and Ga2O3 (gallium trioxide). According to the invention, the structure of a radiation photovoltaic cell is adopted, the output power density of an X-ray radioactive source 55Fe can be effectively improved, the penetration depth of the X-ray source 55Fe in a semiconductor can be effectively shortened by taking GaAs, GaInP, GaP and Ga2O3 as semiconductor materials, and meanwhile, the collection capability of current carriers is effectively improved by adjusting the total thickness of a semiconductor transduction unit and the doping concentration of each layer, so that the performance of the X-ray source 55Fe is improved. And finally, the preparation of the X-ray radiation photovoltaic cell with high output power and high energy conversion efficiency is realized.

Description

Technical Field

[0001] The invention relates to an X-ray voltaic cell based on a gallium-containing semiconductor and a preparation method thereof. Background Art

[0002] As the development and utilization of space continues to deepen, humans need a space energy source with appropriate power, light weight, long life, low cost, safety and reliability. As a type of nuclear battery, isotope batteries meet these requirements to varying degrees, and in some aspects they are even irreplaceable by other space energy sources (solar cells, chemical batteries, fuel cells).

[0003] The energy released by radioactive isotopes during nuclear decay is much higher than that of ordinary substances, and the decay time is very long. For example, the energy released by 1 gram of radium during decay is more than 600,000 times greater than the energy released by 1 gram of firewood during combustion, and its decay time is as long as 10,000 years. Therefore, radioactive isotopes can be used to manufacture special power sources - isotope batteries. The characteristics of space isotope batteries are: no need to be oriented to the sun, small size, and long service life.

[0004] At present, the radiation cells in isotope batteries mainly include β radiation sources and α radiation sources.

[0005] Irradiation cells based on beta-emitting sources are often used 3 H, 63 Low-energy beta sources (-10keV level) such as Ni are used as radiation sources for voltaic cells. For example, the article titled High open-circuit voltage betavoltaic cell based on GaNpin homojunction discloses an activity of 12.50mCi / cm 2 Beta radiation source 63 Combining Ni with planar PN structure GaN semiconductors, 10.7nW / cm 2 The battery output power density is 2.34W / cm2. This is because the penetration depth of low-energy β-rays in the body is in the micron level. Increasing the loading thickness of the radiation source per unit area will lead to serious self-absorption energy loss, resulting in a very low saturation output power of the low-energy β-radiation source (<10μW / cm2). 2 ), which fundamentally limits the output power of the battery. With the development of the preparation process of wide-bandgap semiconductors in recent years, the energy conversion efficiency has been significantly improved. Under the condition that the conversion efficiency has reached the theoretical limit, the output power density of β-source radiation voltaic cells is still very low (<1μW / cm 2 ), it is still difficult to solve the bottleneck problem of low output power and cannot meet the needs of practical work, such as the needs of micro-electromechanical systems (>10μW / cm 2 ), which greatly narrows the application scope of radiation batteries.

[0006] The radiation cell based on low-energy α radiation source has the same problem as the β radiation cell. The output power density of the cell (<0.5μW / cm 2 ) cannot meet the actual needs. For example, the α-radiation source is used as the energy source of the battery. The article is titled A Micro Nuclear Battery Based on SiC Schottky Barrier Diode, which discloses an activity of 1.00 mCi / cm 2 Beta radiation source 241 Combining Am with planar PIN structure SiC semiconductor, 1.30nW / cm 2 However, for high energy α sources, such as 238 Pu, 241 Am and other alpha rays have an energy level of 1MeV, which far exceeds the radiation damage threshold of general semiconductor materials (-100keV level). This will cause radiation damage to semiconductor energy conversion materials, leading to a significant performance decline over time for the radiation cell, i.e., a significant output decay of the battery.

[0007] Therefore, researchers began to study X-ray radiation sources as the energy source of the battery to improve the battery output power density. 55 Fe X-ray photovoltaic and 63 Nibetavoltaic cells, an X-ray radiation source with an activity of 182MBq, was disclosed 55 Fe is combined with AlGaAs semiconductor with planar PiN structure to achieve 1.44pW / cm 2 The output power density of the device is 2.20%, and the energy conversion efficiency of the device is 2.20%. However, the main problem with the X-ray radiation source of the radiovoltaic cell is that the X-ray radiation source has a strong penetrating ability, which greatly weakens the self-absorption loss, resulting in a large amount of X-rays penetrating the semiconductor energy conversion unit and not being utilized in the form of penetration loss, making the energy conversion efficiency of the semiconductor energy conversion unit at a low level, generally less than 3%.

[0008] In summary, no research has yet been conducted on a method with a power greater than 0.5 μW / cm 2 X-ray radiation source irradiation cell with high output power and high conversion efficiency greater than 3%. Summary of the invention

[0009] The present invention aims to solve the problems of low output power and low conversion efficiency of current X-ray radiation source voltaic cells, and proposes an X-ray voltaic cell based on gallium-containing semiconductors and a preparation method thereof.

[0010] The technical method of the present invention is as follows:

[0011] An X-ray voltaic cell based on a gallium-containing semiconductor, the X-ray voltaic cell based on a gallium-containing semiconductor comprising: a gallium-containing semiconductor transducer unit and an X-ray radiation source arranged on the gallium-containing semiconductor transducer unit 55 Fe; wherein the material of the gallium-containing semiconductor transducer unit includes at least one of GaAs, GaInP, GaP, and Ga2O3.

[0012] Specifically, the gallium-containing semiconductor transducer unit has a single layer or multiple layers, and each layer has a PN, PIN, or PNN structure.

[0013] The PNN structure includes P + Layer, N - Layer, N + Layer. + The doping concentration of the layer is 1×10 18 -1×10 20 cm -3 , P + The thickness of the layer is 0.1-0.3 μm. - The doping concentration of the layer is 1×10 14 -1×10 16 cm -3 , N - The thickness of the layer is 4-10 μm. + The doping concentration of the layer is 1×10 17 -1×10 19 cm -3 , N + The thickness of the layer was 190-220 μm.

[0014] Specifically, the X-ray radiation source 55 Fe is a single-sided radiation source or a double-sided radiation source.

[0015] Optionally, the X-ray voltaic cell based on gallium-containing semiconductor is also provided with a 55 Fe-permeable surface interdigitated electrodes, easily conductive back electrodes, and external encapsulation layers.

[0016] The present invention also provides a method for preparing the X-ray voltaic cell based on a gallium-containing semiconductor, the method comprising: using a liquid-sealed Czochralski method, epitaxial growth, chemical vapor deposition (LPCVD, PECVD, MOCVD), casting method and ion implantation method to obtain the structure required for the X-ray voltaic cell based on a gallium-containing semiconductor, and preparing a gallium-containing semiconductor energy conversion unit; placing an X-ray radiation source 55Fe is encapsulated on a gallium-containing semiconductor transducer unit, and electrical leads are led out to obtain an X-ray voltaic cell based on gallium-containing semiconductors.

[0017] Specifically, the preparation of the gallium-containing semiconductor transducer unit with a PNN structure includes: preparing a gallium-containing substrate by a liquid-sealed Czochralski method, wherein the material of the gallium-containing substrate includes at least one of GaAs, GaInP, GaP, and Ga2O3; doping the gallium-containing substrate with donor-type impurities to grow N + layer, and then by controlling the growth rate, we get N - layer, and then doped with acceptor impurities to obtain P + layer; wherein the concentration of the doped acceptor impurities is higher than the concentration of the doped donor impurities.

[0018] The beneficial effects of the present invention are:

[0019] (1) The isotope radiation source used in the present invention is an X-ray radiation source 55 Compared with high-energy α sources, when X-ray sources decay, they emit low-energy X-rays with energy in the order of several keV. Since the energy of the rays is lower than the radiation damage threshold of most semiconductor materials (-100 keV), they will not cause serious radiation damage to semiconductor materials, thereby greatly reducing the performance degradation of the battery and extending the service life of the radiation battery; Figure 1 As shown in the figure, the penetration energy of X-rays is much stronger than that of β-rays, so the self-absorption loss of the radiation source is very weak. The saturation thickness and saturation output power of the radiation source are 3 orders of magnitude higher than those of common β-ray sources, which meets the high output power requirements of the battery. Figure 2 As shown, when X-rays act on semiconductor materials, the proportion of backscattered rays is very low, so the backscattered energy loss is much lower than that of the β source, thereby maintaining the conversion efficiency of the battery. 55 Fe can extend the service life of radiation voltaic cells and effectively improve the output power and conversion efficiency of radiation voltaic cells.

[0020] (2) The present invention adopts the structure of a radiovoltaic cell, an X-ray radiation source 55 Fe can effectively increase the output power density of the source, and GaAs, GaInP, GaP, and Ga2O3 as semiconductor materials can effectively shorten the X-ray source. 55 The penetration depth of Fe in the semiconductor is adjusted, and the total thickness of the semiconductor transducer unit and the doping concentration of each layer are adjusted, thereby effectively improving the carrier collection capacity, and finally realizing the preparation of X-ray radiation cells with high output power and high energy conversion efficiency.

[0021] (3) The present invention is reasonably designed. The thickness, doping concentration and type of PN, PIN and PNN parameters are selected to ensure that X-ray55 Under the premise of Fe absorption, the carrier collection efficiency is improved as much as possible, thereby increasing the current density and output power density of the radiation voltaic cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a graph showing the relationship between the output power density of common β sources and X-ray sources and the thickness of the radiation source;

[0023] Figure 2 This is a schematic diagram of the process of β-rays and X-rays entering semiconductor materials;

[0024] FIG3 is a schematic diagram of an X-ray voltaic cell based on a gallium-containing semiconductor; wherein: Figure 3a An X-ray voltaic cell having a single layer of semiconductor transducer units containing gallium; Figure 3b The invention relates to an X-ray voltaic cell having two layers of semiconductor energy conversion units containing gallium.

[0025] Figure 4 for 55 Performance comparison of GaAs cells with Fe as X-ray radiation source and other currently reported radiovoltaic cells;

[0026] Figure 5 This is a schematic diagram of the radiation cell of Example 1;

[0027] Figure 6 Schematic diagram of the radiation cell of Example 2. Figure 7 is a schematic diagram of the structure of a β-radiation battery DETAILED DESCRIPTION

[0028] The technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The concept of the present invention is as follows: First, compared with high-energy α sources, when X-ray sources decay, they emit low-energy X-rays with energy in the order of several to tens of keV. Since the energy of the rays is lower than the radiation damage threshold of most semiconductor materials (-100 keV), they will not cause serious radiation damage to semiconductor materials, thereby greatly reducing the performance degradation of the battery and extending the service life of the radiation battery. Second, Figure 1 As shown in Figure 1, the penetration energy of X-rays is much stronger than that of β-rays, so the self-absorption loss of the radiation source is very weak. The saturation thickness and saturation output power of the radiation source are 3 orders of magnitude higher than those of common β-ray sources, which meets the high output power requirements of the battery. Figure 2As shown, when X-rays act on semiconductor materials, the proportion of backscattered rays is very low, so the backscattered energy loss is much lower than that of the β source, thereby maintaining the conversion efficiency of the battery. 55 Fe. Here, Figure 2 R Eb Represents the proportion of backscattered ray energy, R Ep represents the penetration energy ratio, R Ed Represents the energy ratio deposited in a semiconductor unit.

[0030] Based on X-ray radiation source 55 Fe seeks a suitable semiconductor material to reduce the penetration depth of X-rays in the semiconductor energy conversion unit, and at the same time optimizes the structure of the semiconductor energy conversion unit to increase the range of its energy collection area, improve the carrier collection capacity and energy conversion efficiency of the semiconductor energy conversion unit, and thus realize the design and preparation of a high output power density radiation cell.

[0031] Therefore, the present invention provides an X-ray voltaic cell based on a gallium-containing semiconductor. As shown in FIG3 , the X-ray voltaic cell based on a gallium-containing semiconductor includes: a gallium-containing semiconductor transducer unit and an X-ray radiation source disposed on the gallium-containing semiconductor transducer unit. 55 The material of the gallium-containing semiconductor transducer unit includes at least one of GaAs (gallium arsenide), GaInP, GaP, and Ga2O3.

[0032] In one embodiment, if Figure 3a As shown, the gallium-containing semiconductor transducer unit 2 is closely attached to the X-ray radiation source. 55 Fe 1. The number of layers of the gallium-containing semiconductor transducer unit is single or multi-layer, and each layer is one of the PN, PIN, and PNN structures. Here, the design parameters of each layer are consistent with the design parameters of the single layer, and the number of layers is reasonably adjusted according to the specific value of the layer thickness.

[0033] Specifically, Figure 3a As shown, when the number of layers of the semiconductor transducer unit containing gallium is a single layer, the X-ray radiation source 55 Fe 1 is provided with a PN, PIN or PNN structure. Figure 3b As shown in the figure, when the number of layers of the gallium-containing semiconductor transducer unit is 2, the X-ray radiation source 55 Fe 1 is arranged between the first layer of gallium-containing semiconductor transducer unit 2.1 and the second layer of gallium-containing semiconductor transducer unit 2.2. The first layer of gallium-containing semiconductor transducer unit 2.1 and the second layer of gallium-containing semiconductor transducer unit 2.2 are both PN, PIN or PNN structures, and the first layer of gallium-containing semiconductor transducer unit 2.1 and the second layer of gallium-containing semiconductor transducer unit 2.2 have the same structure.

[0034] The present invention uses an X-ray radiation source 55 Fe is the radiation source of the radiovoltaic cell. The radiovoltaic cell with the same thickness is used as the research object. Its saturated output power density is improved by 3 orders of magnitude on the basis of low-energy β radiation source and low-energy α radiation source, which effectively guarantees the output power density of the radiation source. At the same time, GaAs, GaInP, GaP, Ga2O3 large atomic number materials are selected as energy conversion units, and the design requirements of radiovoltaic cells with high output power density can be achieved by optimizing the thickness and doping concentration. Here, the X-ray radiation source 55 Fe can effectively increase the output power density of the source, and GaAs, GaInP, GaP, and Ga2O3 as semiconductor materials can effectively shorten the X-ray source. 55 The penetration depth of Fe in the semiconductor is adjusted, and the total thickness of the semiconductor transducer unit and the doping concentration of each layer are adjusted, thereby effectively improving the carrier collection capacity, and finally realizing the preparation of X-ray radiation cells with high output power and high energy conversion efficiency.

[0035] Specifically, X-ray sources 55 Fe can be a single-sided radiation source or a double-sided radiation source. At the same time, in order to meet the actual output power requirements of the battery, the thickness design of the radiation source can be optimized and selected.

[0036] Specifically, the gallium-containing semiconductor energy conversion unit is a radiation energy-electrical energy conversion unit. Semiconductor materials include GaAs, GaInP, GaP, Ga2O3 and other large atomic number materials.

[0037] Taking GaAs as an example, compared with previously reported isotope batteries, the main advantage of GaAs-based X-ray radiation voltaic batteries is that GaAs with a large atomic number can effectively realize the deposition of X-rays, achieving a high energy deposition rate in short-distance semiconductors, thereby improving the energy conversion efficiency of GaAs semiconductor radiation voltaic batteries, such as Figure 4 As shown, the efficiency of the semiconductor energy conversion unit is higher than that of other previously reported isotope irradiation batteries ( 63 Ni+SiC, 63 Ni+GaN、TiH 3 x +SiC, 241 Am+Diamond, 41 Am+SiC). At the same time, considering the diffusion length and the energy band structure of the semiconductor, GaAs semiconductor X-ray radiation cells can achieve a higher output power density, which is more conducive to broadening the application field and space of radiation cells.

[0038] like Figure 4 As shown, 63The reference for Ni+SiC is Appl.Phys.Lett.117,193901(2020); 63 The references for Ni+GaN are Electronics Letters Volume 47; TiH 3 x + The references for SiC are Issue 12; Appl. Phys. Lett. 108, 013505 (2016); 241 The reference of Am+Diamond is Diamond and Related Materials Volume 87, August 2018, Pages 35-42; 241 The reference for Am+SiC is Journal of Microelectromechanical Systems, vol. 20, no. 3, pp. 685-690, June 2011.

[0039] Specifically, the gallium-containing semiconductor transducer unit is one of the PN, PIN, and PNN structures. The specific semiconductor material can be selected according to different application scenarios. The structural details (for example, doping concentration, thickness, structure, etc.) can be adjusted according to the design requirements of the radiation cell.

[0040] In one embodiment, the PNN structure includes P + Layer, N - Layer, N + Specifically, P + The doping concentration of the layer is 1×10 18 -1×10 20 cm -3 , P + The thickness of the layer is 0.1-0.3 μm. For example, P + The doping concentration of the layer is 1×10 19 cm -3 , P + The thickness of the layer is 0.15μm, 0.2μm, and 0.25μm. - The doping concentration of the layer is 1×10 14 -1×10 16 cm -3 , N - The thickness of the layer is 4-10 μm. For example, N - The doping concentration of the layer is 1×10 15 cm -3 , N - The thickness of the layer is 5μm, 7μm, and 9μm. + The doping concentration of the layer is 1×1017 -1×10 19 cm -3 , N + The thickness of the layer is 190-220 μm. For example, N + The doping concentration of the layer is 1×10 18 cm -3 , N + The thickness of the layer is 195μm, 200μm, 210μm, and 215μm. This is because the P-type layer is set as a heavily doped layer to form an ohmic contact, and the doping concentration range is 1×10 18 -1×10 20 cm -3 In order to form a wider depletion region width and longer diffusion length, N - The layer is set to a low doping concentration of 1×10 14 -1×10 16 cm -3 To achieve complete deposition of energy, the overall thickness of the PNN structure (eg, GaAs) is set to 150-300 μm.

[0041] The present invention designs P + The thickness of the layer is 0.1-0.3μm, which is to reduce the junction depth of the PN junction and allow more X-ray energy to be deposited in the efficient carrier collection area (depletion region). + The doping concentration of the layer is designed to be high (1×10 18 -1×10 20 cm -3 ), N - The doping concentration of the layer is designed to be low doped 1×10 14 -1×10 16 cm -3 , which is conducive to forming a higher potential barrier at the PN junction, accelerating the separation of carriers, and at the same time maximizing the depletion region and the diffusion length of minority carriers, effectively broadening the carrier collection area and improving the final energy conversion efficiency of the battery. + The thickness of the layer is designed to be 190-220μm. If the semiconductor transducer unit is designed as a single layer, this thickness range is conducive to the realization of X-ray radiation source 55 The energy deposition of Fe inside it is maximized, which is beneficial to improve the energy conversion efficiency of the battery; if the semiconductor energy conversion unit is designed to be multi-layer, the thickness is appropriately thinned to the required value, and its value is inversely proportional to the designed number of layers.

[0042] In one embodiment, the X-ray radiation source 55 Fe is a single-sided radiation source or a double-sided radiation source. Single-sided radiation source or double-sided radiation source can be selected according to different application scenarios.

[0043] Optionally, the X-ray voltaic cell based on gallium-containing semiconductor is also provided with a 55 Fe-permeable surface interdigitated electrodes, easily conductive back electrodes, and external encapsulation layers.

[0044] The present invention also provides a method for preparing an X-ray voltaic cell based on a gallium-containing semiconductor, the preparation method comprising:

[0045] S1. The structure required for the X-ray voltaic cell based on gallium-containing semiconductor is obtained by liquid-sealed Czochralski method, epitaxial growth and ion implantation, and a gallium-containing semiconductor transducer unit is prepared.

[0046] Specifically, the preparation of the gallium-containing semiconductor transducer unit as a PNN structure includes:

[0047] A1. Prepare a gallium-containing substrate by a liquid-sealed Czochralski method, wherein the material of the gallium-containing substrate includes at least one of GaAs, GaInP, GaP, and Ga2O3.

[0048] Optionally, the gallium-containing substrate can also be subjected to high-tech processes such as shaping, slicing, wafer grinding, polishing, testing, and cleaning to obtain a transparent or semi-transparent substrate with no damage layer and low roughness.

[0049] A2. Add donor impurities to the gallium-containing substrate to grow N + layer, and then by controlling the growth rate, we get N - layer, and then doped with acceptor impurities to obtain P + layer; wherein the concentration of the doped acceptor impurities is higher than the concentration of the doped donor impurities.

[0050] Here, the donor impurity may be Se or Te, and the acceptor impurity may be Zn or Cd.

[0051] Here, the PN structure can also be prepared by the above method.

[0052] S2, the X-ray radiation source 55 Fe is encapsulated on a gallium-containing semiconductor transducer unit, and electrical leads are led out to obtain an X-ray voltaic cell based on gallium-containing semiconductors.

[0053] In one embodiment, the electrical leads may be made of a conductive metal material, such as Au, Ag, Cu, etc.

[0054] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0055] Example 1

[0056] This embodiment provides an optimal GaAs semiconductor-based 55 The preparation method of the Fe-X-ray irradiation cell comprises the following steps:

[0057] Step S1, preparation of N-type GaAs semiconductor: GaAs semiconductor substrate is prepared by liquid-sealed Czochralski method. The specific steps include: first, using the medium-frequency induction coil as the heating power source, the high-density graphite heating element will be heated under the action of eddy current, the GaAs powder is filled at the bottom of the graphite crucible, and the GaAs seed crystal is bonded to the inside of the graphite crucible cover at a certain distance from the raw material surface, and then the graphite crucible is placed as a whole in the graphite heating element, and the temperature of the external graphite felt is adjusted to place the GaAs raw material in the high temperature zone, and the GaAs seed crystal is correspondingly in the low temperature zone. At a high temperature exceeding 2000°C, the GaAs raw material decomposes into gas phase substances such as sublimated gallium atoms and GaAs molecules. The gas phase substances are transported to the low temperature zone driven by the temperature gradient, nucleate and crystallize on the C surface of the GaAs seed crystal, and then grow into GaAs crystals.

[0058] Here, in order to improve the utilization rate of GaAs raw materials, the raw materials at the bottom of the graphite crucible can be smoothly transported up, and the raw materials will slowly move upward during the growth process; the GaAs crystal is processed through a series of machining processes such as shaping, slicing, wafer grinding, polishing, testing, and cleaning to obtain a transparent or translucent, damage-free, low-roughness GaAs substrate.

[0059] Step S2, preparation of PNN type GaAs semiconductor energy conversion unit: Figure 5 As shown in the figure, the PNN structure GaAs energy conversion unit firstly dopes donor-type impurities into the semiconductor, so that part of the crystal grown on the GaAs substrate is N-type GaAs. The required growth thickness in this embodiment is 200 μm, and the doping concentration of the substrate is 1×10 18 The growth rate and doping concentration were controlled, and the doping concentration was set to 1×10 15 cm -3 , slowly epitaxially grow to obtain an N-type middle layer GaAs with a thickness of 50μm, which is used to increase the width of the effective carrier collection area. Then, acceptor impurities are doped, and its concentration is much higher than the donor impurities doped first. The grown part of the crystal becomes P-type, and the growth thickness is set to 0.2μm. Finally, the PNN-type GaAs semiconductor energy conversion unit is prepared. The top P-type layer is set as a heavily doped layer to form an ohmic contact. In order to form a wider depletion region width and a longer diffusion length, it is set to a high doping concentration of 1×10 19 cm -3. In order to achieve complete energy deposition, the overall thickness of the GaAs device is set to 250μm. Metal electrodes are prepared by evaporation on the upper and lower surfaces of the semiconductor energy conversion unit to form a GaAs X-ray irradiation cell energy conversion unit. Here, as shown in FIG3 , the PNN-type GaAs semiconductor energy conversion unit can be a single layer or two layers.

[0060] Step S3: X-ray source 55 Fe radioactive source loading: Figure 5 (Can be Figure 3a Medium X-ray radiation source 55 Fe1 and gallium-containing semiconductor transducer unit 2, or Figure 3b X-ray sources in 55 Fe 1 and the second layer of gallium-containing semiconductor transducer unit 2.2), the X-ray loading method is a single-sided radiation source (if the actual output power density of the battery is required to be high during actual operation, a single-sided source is difficult to achieve and can be designed as a double-sided radiation source), 55 The thickness of the Fe radiation source is 100 μm, and its thickness can be adjusted according to the actual incident power requirement. The energy conversion unit is a GaAs semiconductor. The X-ray radiation source is placed on the surface of the GaAs semiconductor energy conversion unit of the PNN structure to provide the energy required by the battery. The X-rays emitted by the X-ray source pass through the GaAs-based semiconductor, and the electron-hole pairs formed by ionization near the PN junction are finally collected by the GaAs energy conversion unit battery to form current.

[0061] Step S4, performance prediction of PNN type GaAs radiation voltaic cell: Based on the ideal Shockley equation, 55 The Fe radiation source is a real radiation source. 55 The dose rate of Fe radiation source is 1.80 Gyairs -1 The open circuit voltage of the X-ray GaAs irradiation cell was 0.80 V, the short circuit current was 24.50 μA, the energy conversion efficiency of the cell device was 14.14%, and the output power density was 16.90 μW / cm 2 , the filling factor is 86.01%.

[0062] Example 2

[0063] This embodiment provides a common GaAs semiconductor-based 55 The preparation method of the Fe-X-ray irradiation cell comprises the following steps:

[0064] Step S1, preparation of PNN type GaAs semiconductor energy conversion unit: This step is similar to the step in Example 1. By considering the energy deposition process of X-rays in GaAs and the influence of specific parameters such as diffusion length and depletion region width on battery performance, the doping concentration and thickness of each layer of the PN junction are optimized to obtain the best battery device structure. At the same time, considering the limitations of the actual preparation process, the total thickness of the device is finally prepared to be 200 μm, and the first P layer is set as a high-doping area with a doping concentration of 1×10 19 cm -3 , the thickness is set to 0.2 μm. The thickness of the middle N region is determined by the current preparation process conditions. Different from Example 1, the effective thickness is 10 μm and the doping concentration is set to 1×10 15 cm -3 The doping concentration of the substrate N-type GaAs is 1×10 18 , the thickness is designed to be 200 μm. In the same way as in Example 1, metal electrodes are prepared by evaporation on the upper and lower surfaces of the semiconductor energy conversion unit to form a GaAs X-ray irradiation cell energy conversion unit. Here, as shown in FIG3 , the PNN-type GaAs semiconductor energy conversion unit can be a single layer or two layers.

[0065] Step S2: X-ray source 55 Fe radioactive source loading: Figure 6 (Can be Figure 3a Medium X-ray radiation source 55 Fe1 and gallium-containing semiconductor transducer unit 2, or Figure 3b X-ray sources in 55 Fe 1 and the second layer of gallium-containing semiconductor transducer unit 2.2), the ray loading method in this embodiment is a single-sided radiation source (if the actual output power density of the battery is required to be high during actual operation, the single-sided source is difficult to achieve and can be designed as a double-sided radiation source), its thickness is 100 microns, and the energy conversion unit is a GaAs semiconductor. The X-ray radiation source is placed on the surface of the PNN-type GaAs semiconductor energy conversion unit to provide the energy required by the battery. The X-rays emitted by the X-ray source pass through the GaAs semiconductor, and the electron-hole pairs formed by ionization near the PN junction are finally collected by the GaAs energy conversion unit battery to form a current.

[0066] Step S3, performance prediction of PNN type GaAs radiation voltaic cell: Based on the ideal Shockley equation, 55 The Fe radiation source is a real radiation source. 55 The dose rate of Fe radiation source is 1.80 Gyairs -1The open circuit voltage of the X-ray GaAs irradiation cell was 0.66 V, the short circuit current was 1.75 μA, the energy conversion efficiency of the cell device was 3.40%, and the output power density was 3.90 μW / cm 2 .

[0067] Step S4: Based on GaAs semiconductor 55 The electrical performance test of Fe-X-ray irradiation cell was carried out by simulation test under X-ray tube. The actual test conditions were 10kV, 1mA, and the average energy was 5kV. Based on the ideal Shockley equation, in the context of the equivalent circuit diagram, the influence of the composite current on the final output performance of the device was considered. The theoretical output performance of the X-ray silicon carbide irradiation cell in this example was obtained as follows. The short-circuit current density was 1.39μA / cm 2 , the open circuit voltage is 0.65V, and the maximum output power density is 0.66μW / cm 2 , the energy conversion efficiency is 2.85%. This measured value is lower than the performance of the GaAs-based X-ray voltammetry cell in Example 1, mainly due to the inherent difference between the parameter design of this GaAs device and the example, which is not the optimal structure. At the same time, the simulated test conditions are different from the actual 55 There are some differences in Fe radiation sources, but the overall output power density is higher than that of other radiation-based energy sources.

[0068] Comparative Example 1:

[0069] This comparative example provides a design scheme for a Si-based β-source radiation voltaic cell, comprising the following steps:

[0070] Step S1, structural design and optimization of PN junction Si semiconductor energy conversion unit: The common β radiation source 63Ni is used as the energy source of the β radiation cell, such as Figure 7 As shown in the figure, the schematic diagram of the β-radiation cell structure is designed as follows. In order to achieve high energy output power of the β-radiation cell, the junction depth is designed to be 200nm, and the P layer doping concentration is 1.5×10 18 cm -3 , the doping concentration of the N layer is 1×10 15 cm -3 , the thickness of the N layer is 160μm.

[0071] Step S2, output performance of β-source Si-based radiation voltaic cell: 63 The electrical performance of the radiation cell with Ni as the β-radiation source is based on the optimal device structure after optimization design in S1, with an open circuit voltage of 0.25 V, a short circuit current of 573.30 nA, and an output power density of 99.85 nW / cm 2 .

[0072] In summary, it can be seen that 55The excellent output performance of Fe-X-ray radiation cell can meet the application requirements of actual micro-electromechanical devices and effectively solve the problem of low output power density of radiation cell. At the same time, choosing GaAs as the energy conversion unit can effectively shorten the penetration depth of X-rays in semiconductors and improve the energy conversion efficiency of semiconductor energy conversion units.

[0073] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An X-ray voltaic cell based on a gallium-containing semiconductor, characterized in that: The X-ray voltaic cell based on gallium-containing semiconductors comprises: a gallium-containing semiconductor transducer unit and an X-ray radiation source arranged on the gallium-containing semiconductor transducer unit. 55 Fe; wherein the material of the gallium-containing semiconductor transducer unit includes at least one of GaAs, GaInP, GaP, and Ga2O3.

2. The X-ray photovoltaic cell based on gallium-containing semiconductor according to claim 1, characterized in that: The gallium-containing semiconductor transducer unit has a single layer or multiple layers, and each layer has a PN, PIN, or PNN structure.

3. The X-ray photovoltaic cell based on gallium-containing semiconductor according to claim 2, characterized in that: The PNN structure includes P + Layer, N - Layer, N + layer.

4. The X-ray photovoltaic cell based on gallium-containing semiconductor according to claim 3, characterized in that: The P + The doping concentration of the layer is 1×10 18 -1×10 20 cm -3 , P + The thickness of the layer is 0.1-0.3 μm.

5. The X-ray photovoltaic cell based on gallium-containing semiconductor according to claim 3, characterized in that: The N - The doping concentration of the layer is 1×10 14 -1×10 16 cm -3 , N - The thickness of the layer is 4-10 μm.

6. The X-ray photovoltaic cell based on gallium-containing semiconductor according to claim 3, characterized in that: The N + The doping concentration of the layer is 1×10 17 -1×10 19 cm -3 , N + The thickness of the layer was 190-220 μm.

7. The X-ray photovoltaic cell based on gallium-containing semiconductor according to claim 1, characterized in that: The X-ray radiation source 55 Fe is a single-sided radiation source or a double-sided radiation source.

8. The X-ray photovoltaic cell based on gallium-containing semiconductor according to claim 1, characterized in that: The X-ray voltaic cell based on gallium-containing semiconductor is also provided with a 55 Fe-permeable surface interdigitated electrodes, easily conductive back electrodes, and external encapsulation layers.

9. The method for preparing an X-ray voltaic cell based on a gallium-containing semiconductor according to any one of claims 1 to 8, characterized in that: The preparation method comprises: The structure required for the X-ray voltaic cell based on gallium-containing semiconductors is obtained by liquid-sealed Czochralski method, epitaxial growth, chemical vapor deposition, casting and ion implantation, and a gallium-containing semiconductor energy conversion unit is prepared; X-ray radiation source 55 Fe is encapsulated on a gallium-containing semiconductor transducer unit, and electrical leads are led out to obtain an X-ray voltaic cell based on gallium-containing semiconductors.

10. The preparation method according to claim 9, characterized in that: The preparation of the gallium-containing semiconductor transducer unit as a PNN structure includes: preparing a gallium-containing substrate by a liquid-sealed Czochralski method, wherein the material of the gallium-containing substrate includes at least one of GaAs, GaInP, GaP, and Ga2O3; doping the gallium-containing substrate with donor-type impurities to grow N + layer, and then by controlling the growth rate, we get N - layer, and then doped with acceptor impurities to obtain P + layer; wherein the concentration of the doped acceptor impurities is higher than the concentration of the doped donor impurities.

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