A strip-shaped PIN junction beta-radiation voltaic effect isotope battery based on tritium source

Abstract

The present invention provides a strip-shaped PIN junction beta-radiovoltaic isotope battery based on a tritium source, relating to the field of isotope battery technology. The semiconductors of two unit modules are positioned opposite each other, connected and supported by a cathode metal electrode. The semiconductor intrinsic layer and P+ layer are strip-shaped, with a tritium-based radioactive source plated in the side gap. In the present invention, the majority of beta particles generated by the tritium-based radioactive source, upon entering the semiconductor, will fall into the depletion layer, resulting in a high probability of collection of the generated electron-hole pairs. This avoids the low penetration depth of tritium-based radioactive sources in traditional solutions, which results in low collection efficiency due to the P+ layer. Furthermore, electrons emitted from both sides of the tritium-based radioactive source can be captured by the semiconductor, enabling the realization of a highly efficient tritium-based beta-radiovoltaic isotope battery.

Description

Technical Field

[0001] The present invention relates to the technical field of isotope batteries, in particular to a strip-shaped PIN junction type beta radiation voltaic effect isotope battery based on a tritium source. Background Art

[0002] In recent years, MEMS devices have developed rapidly, but the further development of MEMS has been restricted by the lack of micro power supplies. Combined with the characteristics of MEMS devices, their requirements for micro power supplies generally include the following aspects: (2) Long working time. Due to the physical size and special functions of MEMS devices, their processing technology is relatively difficult. Therefore, once these devices are put into use, if the service life of the power supply is short, the working state of the entire system will be affected. However, reloading the micro power supply will not only affect the working state of the original electronic equipment, but also increase the production cost. (2) Integration. The electronic devices of MEMS are usually integrated. In order to achieve energy supply and facilitate application, the micro power supply needs to be integrated with the electronic devices to adapt to the physical size and stable working requirements of the MEMS. (3) Miniaturization. The physical size of the MEMS has developed from the initial millimeter level and micron level to the nanometer level or even smaller. Therefore, the physical size of the MEMS devices and micro power supplies contained in the MEMS also needs to reach the micrometer level, nanometer level or even smaller. (4) Strong adaptability. Micro-electromechanical systems often need to work simultaneously with other devices, and improving the environmental adaptability of micro power sources is essential for micro-electromechanical systems. Traditional micro batteries mainly include micro fuel cells, micro chemical batteries, micro solar cells, micro internal combustion engines, etc. (5) The power supply is small. The power required by micro-electromechanical systems is generally in the milliwatt, microwatt or even nanowatt range. If the output voltage and power of the micro power source are too large, it will seriously affect the normal operation of the micro-electromechanical equipment. Therefore, micro power sources with high energy density and meeting low power requirements are necessary for micro-electromechanical systems. Studies have shown that compared with traditional micro batteries, beta-radiation voltaic effect isotope batteries have the characteristics of light weight, miniaturization, integration, long service life, high energy density, stable output performance, low maintenance service frequency, and no need for external sunlight. Therefore, beta-radiation voltaic effect isotope batteries have received attention from researchers and gradually become a research hotspot for micro power sources.

[0003] In 1913, Mosley first demonstrated a beta-ray isotope battery, which directly converted beta-ray energy into electricity. In 1937, Becker and Kruppke observed the generation of electron-hole pairs when bombarding a selenium photoelectric element with cathode electron beams. This phenomenon became known as the electron-voltaic effect. This was the first report of the electron-voltaic effect. It wasn't until the 1950s and 1960s, with the development of space technology, that research on isotope batteries gained attention and further research. In 1953, the first true beta-voltaic effect isotope battery was developed. Rappaport et al. used a beta-emitting source (90S / 90Y) to irradiate a silicon-based PN junction semiconductor device, generating electron-hole pairs within the semiconductor. These pairs were collected by electrodes, converting the decay energy of the beta-emitting source into electricity. This battery is known as a beta-voltaic effect isotope battery. Since the 1960s and 1970s, beta-radiovoltaic isotope batteries have been used and researched in space exploration and medical fields. With the rapid development of micro-electromechanical systems (MEMS) in the 1990s, research on beta-radiovoltaic isotope batteries has rapidly advanced.

[0004] Tritium has a half-life of 12 years and undergoes beta decay. Its radiation energy is mild, less likely to damage semiconductors, and its cost is relatively low, making it a preferred radiation source in isotope batteries. However, tritium's beta penetration is relatively weak. Traditionally, tritium sources are placed close to the P or N layers. Upon entering the semiconductor, beta rays quickly deposit energy but do not reach the semiconductor's depletion layer, significantly reducing the electron-hole collection rate. Without the separation effect of a built-in electric field, the resulting electron-hole pairs easily recombine, making it difficult to increase the current of the isotope battery when using a tritium source, resulting in a significant loss of power generation efficiency. Summary of the Invention

[0005] The purpose of the present invention is to provide a tritium source beta radiation voltaic effect isotope battery that solves the problem of difficult-to-collect electron-hole pairs generated outside the depletion region after beta rays enter the semiconductor, thereby increasing the current of the isotope battery and improving energy utilization efficiency.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A strip-shaped PIN junction type beta-radiation voltaic effect isotope battery based on a tritium source, characterized in that: it comprises a semiconductor unit module, the semiconductor unit module is composed of a semiconductor intrinsic layer (1), a heavily doped semiconductor P+ layer (2) and a heavily doped semiconductor thin film N+ layer (3), the top and bottom of the semiconductor unit module are respectively provided with an anode metal electrode (7) and a cathode metal electrode (6), two semiconductor unit modules share a cathode metal electrode (6) and are arranged relative to each other with the cathode metal electrode (6) as the center;

[0008] The semiconductor P+ layer (2) is loaded on the top of the semiconductor intrinsic layer (1), and the semiconductor thin film N+ layer (3) is located at the bottom of the semiconductor intrinsic layer (1);

[0009] The anode metal electrode (7) is plated on the top of the semiconductor P+ layer (2), a tritium-based radioactive source (5) is plated on the side of the semiconductor intrinsic layer (1), and a passivation layer (4) is provided between the semiconductor intrinsic layer (1) and the tritium-based radioactive source (5).

[0010] Preferably, the passivation layer (4) covers the outer surface of the semiconductor intrinsic layer (1), the top surface of the semiconductor P+ layer (2) and the top surface of the semiconductor thin film N+ layer (3).

[0011] Preferably, the tritium-based radioactive source (5) is a titanium tritide radioactive source, which is in the form of a thin sheet with a thickness not greater than 2 μm, or powder particles with a diameter of 50-200 nm.

[0012] Preferably, the semiconductor intrinsic layer (1) has a thickness of 20-100 μm and a width of ≤20 μm, and the spacing width between adjacent semiconductor intrinsic layers (1) is ≤20 μm.

[0013] Preferably, the thickness of the semiconductor thin film N+ layer (3) is ≤10 μm, the thickness of the cathode metal electrode (6) is ≥10 μm, and the cathode metal electrode (6) has a supporting function for the semiconductors on both sides.

[0014] Preferably, the semiconductor intrinsic layer (1) can be Si, GaAs, GaN or diamond.

[0015] Preferably, the semiconductor P+ layer (2) can be formed by injection or by etching after epitaxy.

[0016] Production process of PIN junction type beta radiation voltaic effect isotope battery based on tritium source:

[0017] The semiconductor uses (100)GaAs as the semiconductor, which has mature processing technology, few impurities, and high lattice quality. The semiconductor thin film N+ layer (3) is first epitaxially grown on the substrate to form a transition layer, and then the N+ layer is epitaxially grown, with a doping concentration of 10E18 and a thickness of 5μm. Further, a stripe pattern of the semiconductor intrinsic layer (1) is etched on the top of the semiconductor thin film N+ layer (3), and the intrinsic layer is grown to a thickness of 100μm. The semiconductor P+ layer (2) is further loaded by ion beam implantation, with a thickness of 1μm and a doping concentration of 10E18. The width of the stripe intrinsic layer is 20μm, and the spacing is 20μm.

[0018] After the semiconductor P+ layer (2) is loaded, a SiO2 passivation layer is plated, wherein the SiO2 passivation layer covers the outer surface of the semiconductor intrinsic layer (1), the top surface of the semiconductor P+ layer (2) and the top surface of the semiconductor thin film N+ layer (3);

[0019] An anode metal electrode (7) is further loaded on the top of the semiconductor P+ layer (2). The anode metal electrode (7) is Au / Ge / Ni / Au. The shape of the anode metal electrode (7) is formed by applying photoresist, exposing, developing, and removing the resist. Annealing is then performed to improve the quality of the ohmic contact. The width of the anode metal electrode (7) is substantially the same as the width of the semiconductor P+ layer (2).

[0020] The radioactive source used in isotope batteries is a tritium-based source, chemically in the form of titanium tritide (TiHx), where x is ~1.6. It is plated on the outside of the SiO2 passivation layer. Considering tritium's own self-absorption, the thickness is selected to be 0.7μm, achieving a thickness close to saturation output. Tritium's beta particles penetrate the SiO2 passivation layer and enter the semiconductor's intrinsic layer. Because the P+ and N+ layers are all heavily doped, the intrinsic layer is entirely a depletion layer. The beta particles bombard the semiconductor material, generating electron-hole pairs. These separate in the depletion layer, with a low probability of recombination. Most of the electrons are collected by the P+ and N+ layers, enabling relatively efficient current collection.

[0021] Finally, the bottom substrate is chemically dissolved to expose the transition layer, and a cathode metal electrode (6) is loaded on the bottom. The two semiconductor unit modules are loaded together on the same cathode metal material with a thickness of 25 μm. The cathode metal material plays a supporting role for the overall structure to ensure that the semiconductor elements are not damaged.

[0022] Finally, the electrodes are connected to an external circuit via gold wires to achieve current output, achieving a theoretical power generation efficiency of over 4%. Furthermore, by stacking multiple layers of modules, a higher power density can be achieved per unit volume.

[0023] The beneficial effects of the present invention are:

[0024] The advantage of the present invention is that since the tritium-based radioactive source is arranged on the side of the intrinsic layer, and in the semiconductor with a PIN structure, the intrinsic layer is almost entirely a depletion layer, therefore, after the generated β particles are incident on the semiconductor, most of them will fall into the depletion layer, and the generated electron holes will be collected with a high probability after being split. This can avoid the problem of low collection efficiency caused by the tritium-based radioactive source falling outside the depletion layer due to low penetration depth, and can realize a high-efficiency radiovoltaic effect isotope battery based on the tritium source.

[0025] The semiconductors of the two unit modules are positioned opposite each other, connected and supported by a cathode metal electrode. The semiconductor intrinsic layer and P+ layer are strip-shaped, with a tritium-based radioactive source plated in the side gaps. In this invention, the beta particles generated by the tritium-based radioactive source, upon entering the semiconductor, will mostly fall into the depletion layer, resulting in a high probability of collection of the generated electron-hole pairs. This avoids the low penetration depth of tritium-based radioactive sources in traditional solutions, which often result in low collection efficiency due to the P+ layer. Furthermore, electrons emitted from both sides of the tritium-based radioactive source are captured by the semiconductor, enabling the realization of a highly efficient radiovoltaic isotope battery based on a tritium source. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of a strip-shaped PIN junction type beta-radiovoltaic effect isotope battery based on a tritium source according to the present invention;

[0027] Reference numerals: 1 - semiconductor intrinsic layer; 2 - semiconductor P+ layer; 3 - semiconductor thin film N+ layer; 4 - passivation layer; 5 - tritium-based radioactive source; 6 - cathode metal electrode; 7 - anode metal electrode. DETAILED DESCRIPTION

[0028] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific embodiments and drawings. However, the following embodiments are only preferred embodiments of the present invention and are not exhaustive. Based on the embodiments in the implementation manner, other embodiments obtained by those skilled in the art without making any creative work are all within the scope of protection of the present invention.

[0029] Specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0030] Example 1

[0031] See also Figure 1A PIN junction type beta radiation voltaic effect isotope battery based on a tritium source includes a semiconductor unit module, which is composed of a semiconductor intrinsic layer 1, a heavily doped semiconductor P+ layer 2 and a heavily doped semiconductor thin film N+ layer 3. An anode metal electrode 7 and a cathode metal electrode 6 are respectively provided on the top and bottom of the semiconductor unit module. The two semiconductor unit modules share a cathode metal electrode 6 and are arranged relative to each other with the cathode metal electrode 6 as the center. The cathode metal electrode 6 supports the overall structure. The semiconductor P+ layer 2 is loaded on the top of the semiconductor intrinsic layer 1, and the semiconductor thin film N+ layer 3 is located at the bottom of the strip-shaped semiconductor intrinsic layer 1; the anode metal electrode 7 is plated on the top of the semiconductor P+ layer 2, and a tritium-based radioactive source 5 is plated on the side of the semiconductor intrinsic layer 1. A passivation layer 4 is provided between the semiconductor intrinsic layer 1 and the tritium-based radioactive source 5.

[0032] Production process of PIN junction type beta radiation voltaic effect isotope battery based on tritium source:

[0033] The semiconductor uses (100)GaAs as the semiconductor, which has mature processing technology, few impurities, and high lattice quality. The semiconductor thin film N+ layer 3 is first epitaxially grown on the substrate to form a transition layer, and then an N+ layer, with a doping concentration of 10E18 and a thickness of 5μm. The stripe pattern of the semiconductor intrinsic layer 1 is further etched on the top of the semiconductor thin film N+ layer 3, and the intrinsic layer is grown to a thickness of 100μm. The semiconductor P+ layer 2 is further loaded by ion beam implantation, with a thickness of 1μm and a doping concentration of 10E18. The width of the stripe intrinsic layer is 20μm, and the spacing is 20μm.

[0034] After the semiconductor P+ layer 2 is loaded, a SiO2 passivation layer is plated, where the SiO2 passivation layer covers the outer surface of the semiconductor intrinsic layer 1, the top surface of the semiconductor P+ layer 2 and the top surface of the semiconductor thin film N+ layer (3);

[0035] Anode metal electrode 7 is then added to the top of semiconductor P+ layer 2. The material is made of Au / Ge / Ni / Au. The shape of anode metal electrode 7 is formed by applying photoresist, exposing, developing, and removing the resist. Annealing is then performed to improve the quality of the ohmic contact. The width of anode metal electrode 7 is substantially the same as that of semiconductor P+ layer 2.

[0036] The radioactive source used in isotope batteries is a tritium-based source, chemically in the form of titanium tritide (TiHx), where x is ~1.6. It is plated on the outside of the SiO2 passivation layer. Considering tritium's own self-absorption, the thickness is selected to be 0.7μm, achieving a thickness close to saturation output. Tritium's beta particles penetrate the SiO2 passivation layer and enter the semiconductor's intrinsic layer. Because the P+ and N+ layers are all heavily doped, the intrinsic layer is entirely a depletion layer. The beta particles bombard the semiconductor material, generating electron-hole pairs. These separate in the depletion layer, with a low probability of recombination. Most of the electrons are collected by the P+ and N+ layers, enabling relatively efficient current collection.

[0037] Finally, the bottom substrate is chemically dissolved to expose the transition layer, and the cathode metal electrode 6 is loaded on the bottom. The two semiconductor unit modules are loaded together on the same cathode metal material with a thickness of 25μm. The cathode metal material plays a supporting role for the overall structure to ensure that the semiconductor components are not damaged.

[0038] Finally, the electrodes are connected to an external circuit via gold wires to achieve current output, achieving a theoretical power generation efficiency of over 4%. Furthermore, by stacking multiple layers of modules, a higher power density can be achieved per unit volume.

[0039] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A strip-shaped PIN junction beta-radiation voltaic effect isotope battery based on a tritium source, characterized by: The invention comprises a semiconductor unit module, wherein the semiconductor unit module is composed of a semiconductor intrinsic layer (1), a heavily doped semiconductor P+ layer (2) and a heavily doped semiconductor thin film N+ layer (3); an anode metal electrode (7) and a cathode metal electrode (6) are provided on the top and bottom of the semiconductor unit module respectively; two semiconductor unit modules share a cathode metal electrode (6) and are arranged relative to each other with the cathode metal electrode (6) as the center; The semiconductor P+ layer (2) is loaded on the top of the semiconductor intrinsic layer (1), and the semiconductor thin film N+ layer (3) is located at the bottom of the semiconductor intrinsic layer (1); The anode metal electrode (7) is plated on the top of the semiconductor P+ layer (2), the side of the semiconductor intrinsic layer (1) is plated with a tritium-based radioactive source (5), and a passivation layer (4) is provided between the semiconductor intrinsic layer (1) and the tritium-based radioactive source (5); The semiconductor intrinsic layer (1) is strip-shaped with a width of ≤20 μm, the interval width between adjacent semiconductor intrinsic layers (1) is ≤20 μm, and the tritium-based radioactive source (5) is located in the interval, so that beta particles are directly incident on the depletion region of the semiconductor intrinsic layer (1) from both sides.

2. The strip-shaped PIN junction beta-radiation voltaic effect isotope battery based on a tritium source according to claim 1, characterized in that: The passivation layer (4) covers the outer surface of the semiconductor intrinsic layer (1), the top surface of the semiconductor P+ layer (2), and the top surface of the semiconductor thin film N+ layer (3).

3. The strip-shaped PIN junction beta-radiation voltaic effect isotope battery based on a tritium source according to claim 1, characterized in that: The tritium-based radioactive source (5) is a titanium tritide radioactive source, which is in the form of a thin sheet with a thickness not greater than 2 μm, or powder particles with a diameter of 50-200 nm.

4. The strip-shaped PIN junction beta-radiation voltaic effect isotope battery based on a tritium source according to claim 1, characterized in that: The thickness of the semiconductor intrinsic layer (1) is 20-100 μm.

5. The strip-shaped PIN junction beta-radiation voltaic effect isotope battery based on a tritium source according to claim 1, characterized in that: The thickness of the semiconductor thin film N+ layer (3) is ≤10 μm, the thickness of the cathode metal electrode (6) is ≥10 μm, and the cathode metal electrode (6) has a supporting function for the semiconductors on both sides.

6. The strip-shaped PIN junction beta-radiation voltaic effect isotope battery based on a tritium source according to claim 1, characterized in that: The semiconductor intrinsic layer (1) is Si, GaAs, GaN or diamond.

7. The production process of the strip-shaped PIN junction beta-radiation voltaic effect isotope battery based on a tritium source according to claim 1, characterized in that: The steps are: The semiconductor thin film N+ layer (3) is first epitaxially grown on a substrate to form a transition layer, and then the semiconductor thin film N+ layer (3) is epitaxially grown, with a doping concentration of 10E18 and a thickness of 5 μm; a stripe pattern of a semiconductor intrinsic layer (1) is further etched on the top of the semiconductor thin film N+ layer (3), and the semiconductor intrinsic layer is grown to a thickness of 100 μm; a semiconductor P+ layer (2) is further loaded by ion beam implantation, with a thickness of 1 μm and a doping concentration of 10E18; the width of the strip-shaped semiconductor intrinsic layer is 20 μm, and the spacing is 20 μm; After the semiconductor P+ layer (2) is loaded, a SiO2 passivation layer is plated, where the SiO2 passivation layer covers the outer surface of the semiconductor intrinsic layer (1), the top surface of the semiconductor P+ layer (2) and the top surface of the semiconductor thin film N+ layer (3); An anode metal electrode (7) is further loaded on the top of the semiconductor P+ layer (2), and the width of the anode metal electrode (7) is consistent with the width of the semiconductor P+ layer (2); The radioactive source used in the isotope battery is a tritium-based radioactive source, the chemical form of which is a titanium tritide radioactive source with the chemical formula TiHx, where x is ~1.

6. It is plated on the outside of the SiO2 passivation layer. Considering the self-absorption of tritium itself, the thickness is selected to be 0.7μm, achieving a thickness close to saturation output. The tritium β particles penetrate the SiO2 passivation layer and enter the semiconductor intrinsic layer. Since the semiconductor P+ layer and the semiconductor thin film N+ layer are all heavily doped, the semiconductor intrinsic layer is all depletion region. The β particles bombard the semiconductor material to generate electron-hole pairs, which separate in the depletion region with a small recombination probability. Most of them are collected through the semiconductor P+ layer and the semiconductor thin film N+ layer, achieving efficient current collection. The bottom substrate is chemically dissolved to expose the transition layer, and a cathode metal electrode (6) is loaded on the bottom. Two semiconductor unit modules are loaded on the same cathode metal electrode with a thickness of 25 μm. The cathode metal electrode plays a supporting role for the overall structure to ensure that the semiconductor element is not damaged; Finally, the electrodes are connected to the external circuit through gold wires to achieve current output, with a theoretical power generation efficiency of more than 4%.

8. The production process of the strip-shaped PIN junction beta-radiation voltaic effect isotope battery based on a tritium source according to claim 7, characterized in that: The anode metal electrode (7) is Au / Ge / Ni / Au, and the shape of the anode metal electrode (7) is formed by applying photoresist, exposing, developing, and removing the resist, and annealing is performed to improve the quality of the ohmic contact.

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