Heterogeneous tuberculosis battery taking 90Sr / 90Y source as radioactive source and AlxGa1-xAs / GaAs as transducer

Abstract

The invention discloses a heterogeneous tuberculosis battery taking a 90Sr / 90Y source as a radioactive source and Al < x > Ga < 1-x > As / GaAs as a transducer material, and belongs to the technical field of nuclear energy. A transducer device of the beta-radiation volt effect nuclear battery disclosed by the invention is divided into six layers from top to bottom, wherein the six layers are a P-GaAs layer, a P-Al < 0.9 > Ga < 0.1 > As layer, an I-GaAs emission layer, an I-GaAs base layer, an N-Al < 0.1 > Ga < 0.9 > As layer and an N-GaAs layer in sequence. A radioactive source is taken in from the P layer, electron hole pairs are generated through the radiation ionization effect, and current is formed under the action of a built-in electric field; meanwhile, Al < x > Ga < 1-x > As is used as the electron transport layer and the hole transport layer, so that the electron and hole recombination probability of the surface and the back surface of the cell is reduced. According to the invention, the transportation of carriers is facilitated through the self structure, the reverse saturation current is reduced, and the energy conversion efficiency of the nuclear battery is improved.

Description

Technical Field

[0001] The present invention belongs to the field of nuclear energy technology and specifically relates to a 90 Sr / 90 Y source is a radioactive source, Al x Ga 1-x As / GaAs is a heterojunction cell with energy conversion device materials. Background Art

[0002] With the rapid development of micro-electromechanical systems (MEMS) technology, micro-nuclear batteries have become a research hotspot in the field of micro-energy. Nuclear batteries (also known as radioisotope batteries) are devices that convert the energy-carrying particles (such as α particles, β particles or γ rays) released by the decay of radioisotopes into electrical energy. However, since the energy of the particles generated by the decay of α radiation sources and γ radiation sources is too large and difficult to protect, they are likely to cause damage to the transducer devices and surrounding electronic equipment. The energy of the energy-carrying β particles released by the β radiation source is very low compared to the other two. These low-energy β particles have little radiation damage effect on the nuclear battery transducer devices and other surrounding electronic equipment, making them easier to protect, and general nuclear battery packaging materials can meet the protection requirements. Therefore, β radiation sources are generally selected as the radiation source of nuclear batteries, and are called β radiation voltaic effect nuclear batteries. Compared with traditional micro batteries, β radiation voltaic effect nuclear batteries have the characteristics of miniaturization, integration, light weight, long service life, high energy density, and stable output performance.

[0003] The β-radiation voltaic effect nuclear battery is mainly composed of an isotope radiation source and a semiconductor energy conversion device, that is, a transducer. The high-energy particles released by the isotope radiation source interact with the transducer, forming a built-in electric field through the diffusion of majority carriers, and the drift of minority carriers forms a reverse saturation current. Then, under the action of the built-in electric field, the radiation-generated electron-hole pairs are separated to complete the energy conversion. In the β-radiation voltaic effect nuclear battery, the commonly used isotope radiation sources are 3 H. 63 You, 90 Sr / 90 Y. 147 Pm, etc. 147 As for the Pm source, it achieved high efficiency in early β nuclear batteries, but its development in the application field of nuclear batteries was limited due to its relatively short half-life, the fact that it is usually in gaseous form, which is not conducive to storage, and the release of γ particles during the decay process that causes lattice defects. 3 The β particles released by the decay of H sources have a high specific power, a moderate half-life, but low average and maximum energies, making 3 The H source generates fewer electron-hole pairs in the semiconductor material, resulting in a smaller battery output power. 3The H source is in gaseous state and is inconvenient to store. 63 The half-life of the Ni source is long, and the average energy and maximum energy of the energetic β particles it releases are moderate, but 63 The specific power of Ni source is low, the conversion efficiency of the prepared nuclear battery is not high, and the current 63 Ni is mainly prepared artificially, which is too costly to meet the practical application of nuclear batteries. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0006] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a 90 Sr / 90 Y source is a radioactive source, Al x Ga 1-x As / GaAs is a heterojunction cell with energy conversion device materials.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: 90 Sr / 90 Y source is a radioactive source, Al x Ga 1-x The heterogeneous nodule battery with As / GaAs as the transducer material is characterized in that: the structure of the heterogeneous nodule battery is sequentially as follows: a radiation source 90 Sr / 90 Y, P surface electrode, P-GaAs layer, P-Al 0.9 Ga 0.1 As layer, I-GaAs emission layer, I-GaAs base layer, N-Al 0.1 Ga 0.9 As layer, N-GaAs layer, N-surface electrode;

[0008] Among them, the radiation source is absorbed from the P layer, and through the radiation ionization effect, electron-hole pairs are generated, and under the action of the built-in electric field, current is formed; at the same time, AlxGa1-xAs is used as the electron transport layer and the hole transport layer to reduce the recombination probability of electrons and holes on the surface and back surface of the battery.

[0009] As a preferred embodiment of the heterogeneous nodule battery of the present invention, the P-GaAs layer, the P-Al 0.9Ga 0.1 As layer, I-GaAs emission layer, I-GaAs base layer, N-Al 0.1 Ga 0.9 As layer, N-GaAs layer constitutes P + PINN + Heterojunction.

[0010] As a preferred solution of the heterojunction battery of the present invention, the P-GaAs layer and the N-GaAs layer are provided with Ti / Pt / Au alloy and Au / Ge / Ni alloy as positive and negative electrodes respectively, and a resistor is provided between the electrodes.

[0011] As a preferred solution of the heterogeneous nodule battery of the present invention, the thickness of the metal electrode formed by the Ti / Pt / Au alloy on the P-GaAs layer is 260nm.

[0012] As a preferred solution of the heterojunction battery of the present invention, the thickness of the metal electrode formed by the Au / Ge / Ni alloy on the N-GaAs layer is 260nm.

[0013] As a preferred embodiment of the heterojunction battery of the present invention, the doping concentration of the P-GaAs layer is 1.1×10 19 cm -3 , thickness is 50nm.

[0014] As a preferred embodiment of the heterogeneous nodule battery of the present invention, the P-Al 0.9 Ga 0.1 The doping concentration of the As layer is 1.1×10 19 cm -3 , thickness is 80nm.

[0015] As a preferred solution of the heterojunction battery of the present invention, the doping concentrations of the I-GaAs emission layer and the I-GaAs base layer are 3×10 18 cm -3 With 1.4×10 18 cm -3 , with thicknesses of 3500nm and 8500nm respectively.

[0016] As a preferred embodiment of the heterogeneous nodule battery of the present invention, the N-Al 0.1 Ga 0.9 The doping concentration of the As layer is 1.5×10 19 cm -3 , with a thickness of 400nm.

[0017] As a preferred solution of the heterojunction battery of the present invention, the doping concentration of the N-GaAs layer is 1.8×10 16 cm -3 , thickness is 1000nm.

[0018] Beneficial effects of the present invention:

[0019] (1) The present invention provides 90 Sr / 90 Y source is a radioactive source, Al x Ga 1-x The heterojunction nuclear battery with As / GaAs as the energy conversion device material reduces the self-absorption effect and adverse effects of the β-radiation voltaic effect nuclear battery caused by the thick radiation source, improves the conversion efficiency of the nuclear battery, increases the open circuit voltage and output power of the nuclear battery, and thus improves the output performance of the nuclear battery.

[0020] (2) The energy conversion device of the β-radiation voltaic effect nuclear battery disclosed in the present invention is mainly divided into six layers from top to bottom, which are: P-GaAs, P-Al 0.9 Ga 0.1 As, I-GaAs emitter layer and I-GaAs base layer (although the materials used are the same, the doping concentrations are different), N-Al 0.1 Ga 0.9 As, N-GaAs. The radiation source is taken in from the P layer, and through the radiation ionization effect, electron-hole pairs are generated, and under the action of the built-in electric field, current is formed; at the same time, AlxGa1-xAs is used as the electron transport layer and the hole transport layer to reduce the recombination probability of electrons and holes on the surface and back surface of the battery.

[0021] (3) The present invention has high carrier mobility and its own structure facilitates carrier transport, reduces reverse saturation current, and improves the energy conversion efficiency of the nuclear battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0023] Figure 1 For 90 Sr / 90 Y source is a radioactive source, Al x Ga 1-x Schematic diagram of the structure of a heterojunction β-radiation voltaic effect nuclear battery with As / GaAs as the energy conversion device. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0025] 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.

[0026] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0027] Example 1

[0028] like Figure 1 As shown, the first embodiment of the present invention provides 90 Sr / 90 Y source is a radioactive source, Al x Ga 1-x As / GaAs is a heterojunction β-radiation voltaic effect nuclear battery with energy conversion device, where 1 is the radiation source 90 Sr / 90 Y, 2 is P-surface electrode, 3 is P-GaAs, 4 is P-Al 0.9 Ga 0.1 As layer, 5 is I-GaAs emission layer, 6 is I-GaAs base layer, 7 is N-Al 0.1 Ga 0.9 As layer, 8 is N-GaAs layer, 9 is N-surface electrode, 12 is load, and 11 and 13 are wires.

[0029] Said 90 Sr / 90 The beta particles emitted by the Y source generate electron-hole pairs through the radiation ionization effect. Under the action of the built-in electric field, the electrons and holes are separated and collected on both sides to form an electric current.

[0030] Example 2

[0031] This embodiment provides 90 Sr / 90 Y source is a radioactive source, Al x Ga 1-xThe preparation method of heterojunction β-radiation voltaic effect nuclear battery with As / GaAs as the transducer device is proposed, and the output performance of the nuclear battery is theoretically simulated by MCNP and COMSOL software to obtain the parameters of each layer of the optimized battery; specifically:

[0032] The epitaxial material is grown on the GaAs substrate using metal organic chemical vapor deposition and low pressure chemical vapor deposition technology; the P-side electrode and N-side electrode are grown on the epitaxial wafer using magnetron sputtering technology; the substrate thickness is adjusted using chemical mechanical polishing;

[0033] The optimization results obtained by the present invention are as follows:

[0034] The self-absorption effect of a radioactive source refers to the phenomenon that particles released by the decay of a radioactive isotope source lose energy during the transport process inside the source. As the thickness of the radioactive source increases, the particle emission activity increases, and the energy loss inside the radioactive source also increases, resulting in the gradual strengthening of the self-absorption effect of the radioactive source. Therefore, when selecting a radioactive source, it is necessary to consider the emission activity of particles at a certain thickness. In order to minimize the impact of the self-absorption effect on the output performance of the nuclear battery, the radioactive source described in the present invention has a surface emission activity of 200 mci / cm -2 Rectangular solid-state radiation source 90 Sr / 90 Y.

[0035] The doping concentration of the P-GaAs layer is 1.1×10 19 cm -3 , with a thickness of 50nm. Heavy doping of this layer is conducive to forming a good ohmic contact with the electrode. In addition, the area with a high rate of electron-hole pair generation in the nuclear battery should be consistent with the depletion layer as much as possible, so the thickness of this layer should be as thin as possible.

[0036] The P-Al 0.9 Ga 0.1 The doping concentration of the As layer is 1.1×10 19 cm -3 , with a thickness of 80nm. This layer is used as a hole transport layer, mainly to block the radiation-generated minority carrier electrons from diffusing to the interface, thereby reducing the surface recombination probability of the battery. The larger the Al coefficient, the higher the P-Al x Ga 1-x The larger the bandgap width of As, the larger the potential barrier difference between this layer and the P-GaAs layer, which is more conducive to suppressing the diffusion of minority electrons and reducing the recombination of minority electrons at the interface.

[0037] Since the selected radiation source is 90 Sr / 90The average decay energy of the Y source is relatively high. If all its decay energy is deposited in the transducer as much as possible, the transducer will be too thick, which not only fails to meet the original design intention of miniaturization, but also increases the production cost of the nuclear battery. Therefore, the total thickness of the I layer selected in the present invention is mainly obtained by calculating the diffusion length of electrons and holes and the width of the depletion layer, and then the specific thickness of the two layers of materials is determined by COMSOL simulation.

[0038] The I-GaAs emission layer and the I-GaAs base layer are made of the same material, but with different doping concentrations, wherein the doping concentrations are 3×10 18 cm -3 With 1.4×10 18 cm -3 , with thicknesses of 3500nm and 8500nm respectively. These two layers are the core areas of the present invention, and the electron-hole pairs are separated mainly by the built-in electric field of these two layers. 90 Sr / 90 The activity density of the Y source is too strong. In order to better utilize the decay energy of the radiation source, the thickness of the two layers is determined by calculating the minority carrier diffusion length of the two layers of material and the width of the depletion layer.

[0039] The N-Al 0.1 Ga 0.9 The doping concentration of the As layer is 1.5×10 19 cm -3 , with a thickness of 400nm. This layer, as an electron transport layer, can reflect the radiation-generated minority carrier holes back to the middle two layers, further reducing the recombination probability on the back surface. The smaller the Al coefficient, the more conducive it is to improving the battery output performance. Through simulation calculation, Al 0.1 Ga 0.9 As.

[0040] The doping concentration of the N-GaAs layer is 1.8×10 16 cm -3 , with a thickness of 1000 μm. The existence of this layer is beneficial to improving the stability of the transducer device, improving the performance of the device, and increasing the life of the device, so it does not need to be too thick.

[0041] The P-side electrode is Ti / Pt / Au alloy, and the N-side electrode is Au / Ge / Ni alloy, both with a thickness of 260nm. Wires are welded on the electrode surfaces to facilitate connection to external circuits.

[0042] In summary, the present invention provides a 90 Sr / 90 Y source is a radioactive source, Al x Ga 1-x As / GaAs is a heterojunction β-radiation voltaic effect nuclear battery for energy conversion devices. xGa 1-x As / GaAs heterojunction cells are composed of a variety of semiconductor materials. Compared with GaAs homojunction cells, they have lower reverse saturation current and higher open circuit voltage. 90 Sr / 90 The Y source reduces the adverse effects of the self-absorption effect, thereby improving the output performance of the nuclear battery.

[0043] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the present invention.

Claims

1. A 90 Sr / 90 Y source is a radioactive source, Al x Ga 1-x As / GaAs is a heterojunction cell with energy conversion device materials, characterized by: The structure of the heterogeneous nodule battery is as follows from top to bottom: a radiation source 90 Sr / 90 Y(1), P-surface electrode(2), P-GaAs layer(3), P-Al 0.9 Ga 0.1 As layer (4), I-GaAs emission layer (5), I-GaAs base layer (6), N-Al 0.1 Ga 0.9 As layer (7), N-GaAs layer (8), N-surface electrode (9); Among them, the radiation source is absorbed from the P layer, and through the radiation ionization effect, electron-hole pairs are generated, and under the action of the built-in electric field, current is formed; at the same time, AlxGa1-xAs is used as the electron transport layer and the hole transport layer to reduce the recombination probability of electrons and holes on the surface and back surface of the battery.

2. The heterogeneous nodule battery according to claim 1, characterized in that: The P-GaAs layer (3), the P-Al 0.9 Ga 0.1 As layer (4), I-GaAs emission layer (5), I-GaAs base layer (6), N-Al 0.1 Ga 0.9 As layer (7) and N-GaAs layer (8) constitute P + PINN + Heterojunction.

3. The heterogeneous nodule battery according to claim 1, characterized in that: The P-GaAs layer (3) and the N-GaAs layer (8) are provided with Ti / Pt / Au alloy and Au / Ge / Ni alloy as positive and negative electrodes respectively, and a resistor is provided between the electrodes.

4. The heterogeneous nodule battery according to claim 1, characterized in that: The thickness of the metal electrode formed by the Ti / Pt / Au alloy on the P-GaAs layer (3) is 260 nm.

5. The heterogeneous nodule battery according to claim 1, characterized in that: The thickness of the metal electrode formed by the Au / Ge / Ni alloy on the N-GaAs layer (8) is 260 nm.

6. The heterogeneous nodule battery according to claim 1, characterized in that: The doping concentration of the P-GaAs layer (3) is 1.1×10 19 cm -3 , thickness is 50nm.

7. The heterogeneous nodule battery according to claim 1, characterized in that: The P-Al 0.9 Ga 0.1 The doping concentration of the As layer (4) is 1.1×10 19 cm -3 , thickness is 80nm.

8. The heterogeneous nodule battery according to claim 1, characterized in that: The doping concentrations of the I-GaAs emission layer (5) and the I-GaAs base layer (6) are 3×10 18 cm -3 With 1.4×10 18 cm -3 , with thicknesses of 3500nm and 8500nm respectively.

9. The heterogeneous nodule battery according to claim 1, characterized in that: N-Al 0.1 Ga 0.9 The doping concentration of the As layer (7) is 1.5×10 19 cm -3 , with a thickness of 400nm.

10. The heterogeneous nodule battery according to claim 1, characterized in that: The doping concentration of the N-GaAs layer (8) is 1.8×10 16 cm -3 , thickness is 1000nm.

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