CN104051050A - Parallel type PIN type alpha irradiation battery and preparing method thereof - Google Patents

Abstract

The invention discloses a parallel type PIN type alpha irradiation battery and a preparing method thereof to mainly solve the problems that a current nuclear battery is low in energy converting ratio and output power. The parallel type PIN type alpha irradiation battery comprises an upper PIN junction, a lower PIN junction and alpha irradiation sources, wherein the upper PIN junction and the lower PIN junction are connected in parallel, the lower PIN junction comprises an N type ohmic contact electrode, an N type highly-doped 4H-SiC substrate, an N type lightly-doped epitaxial layer, a P type highly-doped epitaxial layer and a P type ohmic contact electrode from bottom to top in sequence, the top-to-bottom structural distribution of the PIN junction is the same as the bottom-to-top structural distribution of the lower PIN junction, at least two grooves are formed in each PIN junction, and the alpha irradiation sources are placed in the grooves respectively. The two PIN junctions make contact with each other through the P type ohmic contact electrode, and the upper groove and the lower groove are in mirror symmetry and are communicated with each other. The parallel type PIN type alpha irradiation battery has the advantages that the contact area between the irradiation sources and a semiconductor is large, the nuclear raw material utilization rate and the energy collection rate are high, and the output voltage of the battery is large, and the battery can provide power for a small circuit continuously or can provide power for polar regions, deserts and other areas.

Description

Parallel PIN type α irradiation battery and its preparation method

technical field

The invention belongs to the field of microelectronics, and relates to a semiconductor device structure and a preparation method, specifically a silicon carbide-based parallel PIN type α irradiation battery and a preparation method thereof, which can be used in micro-circuits such as micro-nano electromechanical systems and aerospace , deep sea, polar regions and other occasions that require long-term power supply and are unattended.

technical background

With people's demand for low power consumption, long life, high reliability and small size power supply equipment, as well as concerns about nuclear waste disposal, micronuclear batteries have become more and more popular. Due to its outstanding characteristics, micronuclear batteries can be used to solve the long-term power supply problems of micropipe robots, implanted microsystems, wireless sensor node networks, artificial cardiac pacemakers, and portable mobile electronics. And it is expected to replace solar cells and thermoelectric radioisotope batteries, and solve the long-term power supply problems of micro/nano satellites, deep space unmanned probes and ion thrusters in the field of aerospace and aviation.

In 1953, it was discovered by Rappaport that the use of beta (β-Particle) rays produced by isotope decay can generate electron-hole pairs in semiconductors, and this phenomenon is called β-VoltaicEffect. In 1957, Elgin-Kidde first used β-VoltaicEffect in power supply and successfully manufactured the first isotope micro-battery β-VoltaicBattery. Since 2006, with the advancement of the wide-bandgap semiconductor material SiC preparation technology and process technology, there have been reports on SiC-based isotope micro-batteries.

Chinese patent CN101325093A discloses a SiC-based Schottky junction nuclear battery proposed by Zhang Lin, Guo Hui and others. Since the Schottky contact layer in the Schottky nodule cell covers the entire battery area, after the incident particles reach the surface of the device, they will be blocked by the Schottky contact layer, and only part of the particles can enter the device, while the particles entering the depletion region It will contribute to the output power of the battery. Therefore, the energy loss of the incident particles in the nuclear battery with this structure is large, and the energy conversion efficiency is low.

The document "Demonstrationofa4HSiCbetavoltaiccell" introduces the silicon carbide PN junction nuclear battery proposed by C.I.Tomas, M.V.S.Chandrashekhar, HuiLi, etc. of Cornell University in New York, USA. The substrate used in this structure is a P-type highly doped substrate, and the existing process of growing an epitaxial layer on the substrate is immature. Therefore, surface defects are easily introduced, the leakage current of the device is large, and the energy conversion rate is low.

The document "Demonstration of a tadiation resistant, hight efficiency SiC betavoltaic" introduced that C.J.Eiting, V.Krishnamoorthy and S.Rodgers, T.George of Qynergy Corporation in New Mexico, USA jointly proposed a silicon carbide p-i-n junction nuclear battery, such as Figure 1 shows. From top to bottom, the PIN nuclear battery is as follows: radioactive source 7, P-type ohmic contact electrode 6, P-type highly doped SiC layer 4, P-type SiC layer 3, intrinsic i layer 2, n-type highly doped SiC lining Bottom 1 and N-type ohmic contact electrode 5. In this structure, only the radiation-generated carriers within a minority carrier diffusion length in the depletion layer and its vicinity can be collected. Moreover, in order to prevent the ohmic contact electrode from blocking the incident ions, the P-type ohmic electrode is made at a corner of the device, so that the irradiated carriers far away from the P-type ohmic electrode are recombined during the transport process, which reduces the energy conversion. rate, reducing the output current and output voltage of the battery.

Contents of the invention

The purpose of the present invention is to address the deficiencies of the above-mentioned prior art, to propose a parallel PIN type α irradiation battery and its preparation method, to eliminate the blocking effect of metal electrodes on the high-energy α particles radiated by α radiation sources, and to increase the α The contact area between the radiation source and the semiconductor improves the utilization rate of the alpha radiation source, thereby increasing the output current and output voltage of the battery.

Technical scheme of the present invention is realized like this:

One. Parallel PIN type α radiation battery of the present invention, comprises: PIN unit and α radiation source, it is characterized in that:

The PIN unit is composed of upper and lower two PIN junctions connected in parallel; the lower PIN junctions are in order from bottom to top, N-type ohmic contact electrode 5, N-type highly doped 4H-SiC substrate 1, N-type low-doped Miscellaneous epitaxial layer 2, P-type highly doped epitaxial layer 3 and P-type ohmic contact electrode 4, the upper PIN junction is in order from bottom to top, P-type ohmic contact electrode 4, P-type highly doped epitaxial layer 3, N-type Low-doped epitaxial layer 2, N-type highly doped 4H-SiC substrate 1 and N-type ohmic contact electrode 5;

One side of the P-type ohmic contact electrode 4 of the two PIN junctions is in contact with each other, and the grooves in the upper and lower PIN junctions form a mirror-symmetrical and interconnected integrated structure;

Each PIN junction is provided with at least two grooves 6, and an alpha radiation source 7 is placed in each groove 6, so as to realize full utilization of high-energy alpha particles.

Preferably, the α radiation source 7 uses americium with a relative atomic mass of 241 or plutonium with a relative atomic mass of 238, namely Am ²⁴¹ or Pu ²³⁸ .

Preferably, the depth h of the trench 6 satisfies m+q<h<m+n+q, wherein m is the thickness of the P-type highly doped epitaxial layer 3, and n is the thickness of the N-type low-doped epitaxial layer 2. Thickness, q is the thickness of the P-type ohmic contact electrode 4 .

As preferably, the width L of the groove 6 satisfies L≦2g, wherein, g is the average incident depth of the high-energy alpha particles released by the alpha radiation source 7 in the alpha radiation source, and for the alpha radiation source Am ²⁴¹ , its The value is: g=7.5 μm, for the α radiation source is Pu ²³⁸ , the value is: g=10 μm.

Preferably, the distance d between two adjacent grooves 6 satisfies d≥i, wherein i is the average incident depth of the high-energy alpha particles released by the alpha radiation source 7 in 4H-SiC, and for the alpha radiation source, it is Am ²⁴¹ , the value is: i=10 μm, and for the α radiation source is Pu ²³⁸ , the value is: i=18.2 μm.

Preferably, the substrate 1 is N-type 4H-SiC with a doping concentration of 1×10 ¹⁸ cm ⁻³ , the P-type highly doped epitaxial layer 3 and the N-type low-doped epitaxial layer 2 are both 4H-SiC epitaxial, The doping concentration of the P-type highly doped epitaxial layer 3 is 1x10 ¹⁹ -5x10 ¹⁹ cm ^-3 , and the doping concentration of the N-type low-doping epitaxial layer 2 is 1x10 ¹⁵ -2x10 ¹⁵ cm ^-3 .

Two. preparation method of the present invention comprises the following steps:

(1) Make the lower PIN knot:

1.1) Cleaning: cleaning the SiC sample to remove surface pollutants;

1.2) Growth of N-type low-doped epitaxial layer: use the chemical vapor deposition CVD method to epitaxially grow a layer of N-type with a doping concentration of 1x10 ¹⁵ ~ 2x10 ¹⁵ cm ^-3 and a thickness of 5 ~ 10 μm on the surface of the cleaned SiC sample. Low-doped epitaxial layer;

1.3) Growth of P-type highly doped epitaxial layer: use chemical vapor deposition CVD method to epitaxially grow a layer of doping concentration 1x10 ¹⁹ ~ 5x10 ¹⁹ cm ^-3 on the surface of N type low doped epitaxial layer with a thickness of 1 ~ 2 μm P-type highly doped epitaxial layer;

1.4) Deposit P-type ohmic contact electrodes: Deposit a layer of Ni metal layer with a thickness of 300nm on the surface of P-type highly doped epitaxial layer by electron beam evaporation method, as a mask for etching trenches and P-type ohmic contact metal ;Deposit a Ni metal layer with a thickness of 300nm on the non-epitaxy backside of the SiC substrate by electron beam evaporation as an N-type ohmic contact electrode; rapid annealing in a nitrogen atmosphere at 1100°C for 3 minutes;

1.5) Photolithographic pattern: make a photolithographic plate according to the position of the nuclear battery groove; spin-coat a layer of photoresist on the surface of the deposited Ni metal layer, and use the photolithographic plate to expose the photoresist to electron beams to form a corrosion Window: corrode the Ni metal layer at the corrosion window to expose the P-type highly doped epitaxial layer to obtain a P-type ohmic contact electrode and a trench corrosion window;

1.6) Etching grooves: use inductively coupled plasma ICP etching technology to carve at least 6.5-12 μm in depth, 5-14 μm in width, and at least 12-25 μm in pitch on the exposed P-type highly doped SiC epitaxial layer. two grooves;

1.7) Place the α-radiation source: Place the α-radiation source in the groove by depositing or smearing to obtain a PIN junction with a groove;

(2) Repeat step 1.1) to step 1.7) to make the upper PIN junction.

(3) Press the P-type metal contact electrodes of the upper PIN junction and the lower PIN junction together by bonding to complete the fabrication of the parallel PIN type α-irradiated battery.

Compared with the prior art, the present invention has the following advantages:

1. The present invention places the alpha radiation source in the groove, so that the high-energy alpha particles produced by the alpha radiation source are directly injected into the space charge region of the PIN junction, reducing the energy loss of the high-energy alpha particles, thereby improving the energy collection rate and The output current of the battery;

2. The present invention significantly reduces the energy attenuation of high-energy alpha particles inside the alpha radiation source and improves energy collection because the groove width is not greater than twice the average incident depth of the high-energy alpha particles released by the alpha radiation source in the alpha radiation source material rate and the output current of the battery;

3. Since the bandgap width of the substrate material 4H-SiC adopted in the present invention is larger than that of traditional Si, the anti-radiation characteristics are better, which can reduce the damage of high-energy α particles to the device and improve the working voltage of the battery. At the same time prolong the service life of the battery;

4. The present invention improves the output voltage of the battery due to the parallel placement of two PIN junctions.

Description of drawings

Fig. 1 is the cross-sectional schematic view of existing PIN nuclear battery;

Fig. 2 is the schematic cross-sectional view of the parallel PIN type α irradiation battery of the present invention;

Fig. 3 is a schematic flow chart of the present invention for making a parallel PIN type α-irradiated battery.

Detailed ways

Referring to Fig. 2, the irradiation battery of the present invention includes: a PIN unit and an α radiation source, and the PIN unit is composed of upper and lower two PIN junctions in parallel; , N-type highly doped 4H-SiC substrate 1, N-type low-doped epitaxial layer 2, P-type highly doped epitaxial layer 3 and P-type ohmic contact electrode 4, and the upper PIN junction is in order from bottom to top, P Type ohmic contact electrode 4, P-type highly doped epitaxial layer 3, N-type low-doped epitaxial layer 2, N-type highly doped 4H-SiC substrate 1 and N-type ohmic contact electrode 5, the two PIN junctions are P Type ohmic contact electrodes 4 are contacted together by bonding; at least two grooves 6 are provided in each PIN junction, and the depth h satisfies m+q<h<m+n+q, where m is P-type highly doped The thickness of the hetero-epitaxial layer 3, n is the thickness of the N-type low-doped epitaxial layer 2, and q is the thickness of the P-type ohmic contact electrode 4. Its width L satisfies L≦2g, g is the average incident depth of the high-energy alpha particles released by the alpha radiation source 7 in the alpha radiation source, for the alpha radiation source Am ²⁴¹ , its value is: g=7.5μm, for the alpha radiation source If the radiation source is Pu ²³⁸ , its value is: g=10 μm, and the distance d between two adjacent trenches 6 satisfies d≥i, i is the average of high-energy alpha particles released by the alpha radiation source 7 in 4H-SiC The depth of incidence, for the α-radiation source of Am ²⁴¹ , its value is: i=10μm, and for the α-radiation source of Pu ²³⁸ , its value is: i=18.2μm; the grooves in the upper and lower PIN junctions form mirror symmetry , an integral structure that penetrates each other; the alpha radiation source 7 is placed in the groove 6 .

When the battery is working, most of the high-energy alpha particles emitted from the alpha radiation source are directly injected into the space charge region near the interface between the P-type highly doped epitaxial layer 3 and the N-type low-doped epitaxial layer 2, thereby exciting the current-carrying Sub, form the output current.

Referring to Fig. 3, the method for making a parallel PIN type α irradiation battery according to the present invention provides the following three embodiments:

Example 1, preparing a parallel-connected PIN type α-irradiation cell with Am ²⁴¹ as the α-radiation source and two grooves.

Step 1: Make the lower PIN knot.

(1) Clean the 4H-SiC sample to remove surface pollutants, as shown in Figure 3(a).

(1.1) Soak a highly doped n-type 4H-SiC substrate sample with a doping concentration of lx10 ¹⁸ cm ^-3 in NH ₄ OH + H ₂ O ₂ reagent for 10 minutes, take it out and dry it to remove the organic residue on the surface of the sample thing;

(1.2) Soak the 4H-SiC sample after removing the surface organic residues with HCl+H ₂ O ₂ reagent for 10 min, take it out and dry it to remove ionic pollutants.

(2) Epitaxial growth of an N-type low-doped epitaxial layer, as shown in FIG. 3( b ).

A nitrogen-doped N-type doped epitaxial layer is epitaxially grown on the cleaned SiC sample by chemical vapor deposition CVD. The process conditions are: the epitaxy temperature is 1570°C, the pressure is 100mbar, the reaction gas is silane and propane, the carrier gas is pure hydrogen, the magazine source is liquid nitrogen, and the nitrogen doping concentration is 1x10 ¹⁵ cm ^-3 , the thickness is 5μm. N-type low-doped epitaxial layer.

(3) Epitaxial growth of a P-type highly doped epitaxial layer, as shown in FIG. 3(c).

On the grown N-type low-doped epitaxial layer, the aluminum-doped P-type highly-doped epitaxial layer is epitaxially grown by chemical vapor deposition CVD. The process conditions are: the epitaxy temperature is 1570°C, the pressure is 100mbar, and the reaction gas Silane and propane, the carrier gas is pure hydrogen, and the impurity source is trimethylaluminum to obtain a P-type highly doped epitaxial layer with an aluminum doping concentration of 1×10 ¹⁹ cm ^-3 and a thickness of 1 μm.

(4) Deposit metal contact electrodes, as shown in Figure 3(d).

(4.1) Perform RCA standard cleaning on the SiC sample after the growth of the P-type highly doped epitaxial layer;

(4.2) Put the cleaned sample on the glass slide in the electron beam evaporation coating machine, adjust the distance from the glass slide to the target to 50cm, and pump the pressure of the reaction chamber to 5×10 ^-4 Pa to adjust the beam current A Ni metal layer with a thickness of 300nm is deposited on the surface of the P-type highly doped epitaxial layer of the SiC sample;

(4.3) Deposit a Ni metal layer with a thickness of 300nm on the non-epitaxy back side of the substrate SiC by electron beam evaporation;

(4.4) Rapid annealing in a nitrogen atmosphere at 1100°C for 3 minutes.

(5) Engraving a structural pattern window on the Ni metal layer deposited on the epitaxial side of SiC, as shown in Fig. 3(e).

(5.1) Spin-coat a layer of photoresist on the surface of the Ni metal layer deposited on the SiC epitaxial side, make a photoresist plate according to the positions of the two grooves of the battery, and expose the photoresist with an electron beam to form a corrosion window ;

(5.2) Etching the Ni metal layer by reactive ion technology, using oxygen as the reactive gas, exposing the P-type highly doped epitaxial layer, and obtaining the etching window of the P-type ohmic contact electrode and the trench.

(6) Etching the groove, as shown in Fig. 3(f).

Two grooves with a depth of 6.5 μm, a width of 5 μm, and a distance of 12 μm are etched on the P-type highly doped epitaxial layer exposed by the trench etching window by using the inductively coupled plasma ICP etching technology.

(7) Place the alpha radiation source, as shown in Figure 3(g).

By means of deposition or smearing, α-radiation source Am ²⁴¹ is placed in each groove to obtain a lower PIN junction with grooves.

Step 2: Make the upper PIN knot.

Repeat steps (1) to (7) to get the upper PIN junction.

Step 3: Using the bonding method, press the P-type ohmic contact electrode of the upper PIN junction and the P-type ohmic contact electrode of the lower PIN junction together to obtain a parallel PIN-type α-irradiated battery, as shown in Figure 3(h) .

Example 2, preparing a parallel-connected PIN type α-irradiation cell with Am ²⁴¹ as the α-radiation source and five grooves.

Step 1: Make the lower PIN knot.

1) Clean the 4H-SiC sample to remove surface pollutants, as shown in Figure 3(a).

This step is the same as step (1) of Example 1.

2) Epitaxial growth of an N-type low-doped epitaxial layer, as shown in Figure 3(b).

A nitrogen-doped N-type doped epitaxial layer is epitaxially grown on the cleaned SiC sample by chemical vapor deposition CVD. The process conditions are: the epitaxy temperature is 1570°C, the pressure is 100mbar, the reaction gas is silane and propane, the carrier gas is pure hydrogen, the magazine source is liquid nitrogen, the nitrogen doping concentration is 1.5x10 ¹⁵ cm ^-3 , and the thickness is 8μm Growth of N-type low-doped epitaxial layer.

3) Epitaxial growth of a P-type highly doped epitaxial layer, as shown in FIG. 3(c).

On the grown N-type low-doped epitaxial layer, a P-type highly-doped epitaxial layer doped with aluminum ions was epitaxially grown by chemical vapor deposition CVD. It is silane and propane, the carrier gas is pure hydrogen, and the impurity source is trimethylaluminum, and the growth of a P-type highly doped epitaxial layer with an aluminum doping concentration of 3x10 ¹⁹ cm ^-3 and a thickness of 1.5 μm is completed.

4) Deposit metal contact electrodes, as shown in Figure 3(d).

This step is the same as step (4) of Embodiment 1.

5) Engraving structural pattern windows on the Ni metal layer deposited on the epitaxial side of the SiC, as shown in Figure 3(e).

5.1) Spin-coat a layer of photoresist on the surface of the Ni metal layer deposited on the SiC epitaxial side, make a photoresist plate according to the positions of the five grooves of the battery, and expose the photoresist with an electron beam to form a corrosion window;

5.2) Etching the Ni metal layer by using reactive ion technology, using oxygen as the reactive gas, exposing the epitaxial P-type SiC, and obtaining the etching window of the P-type ohmic contact electrode and the trench.

6) Etching the trench, as shown in Figure 3(f).

Using inductively coupled plasma ICP etching technology, five trenches with a depth of 10 μm, a width of 10 μm, and a pitch of 20 μm are etched on the P-type highly doped epitaxial layer exposed by the trench etching window.

7) Place the alpha radiation source, as shown in Figure 3(g).

This step is the same as step (7) of Embodiment 1.

Step 2: Make the upper PIN knot.

Repeat steps 1) to 7) to get the upper PIN junction.

Step 3: Using the bonding method, press the P-type ohmic contact electrode of the upper PIN junction and the P-type ohmic contact electrode of the lower PIN junction together to obtain a parallel PIN-type α-irradiated battery, as shown in Figure 3(h).

Example 3, preparing a parallel-connected PIN type α-irradiation cell with Pu ²³⁸ as the α-radiation source and 10 grooves.

Step A: Make the upper PIN knot.

(A1) Clean the 4H-SiC sample to remove surface contamination, as shown in Figure 3(a).

This step is the same as step (1) of Example 1.

(A2) Epitaxially grow a nitrogen-doped N-type low-doped epitaxial layer on the cleaned SiC sample by chemical vapor deposition CVD. The process conditions are as follows: the epitaxy temperature is 1570°C, the pressure is 100mbar, the reaction gas is silane and propane, the carrier gas is pure hydrogen, and the magazine source is liquid nitrogen. An N-type low-doped epitaxial layer with a nitrogen doping concentration of 2x10 ¹⁵ cm ^-3 and a thickness of 10 μm is obtained as shown in Figure 3(b).

(A3) A P-type highly doped epitaxial layer doped with aluminum ions is epitaxially grown on the grown N-type low-doped epitaxial layer by chemical vapor deposition CVD method, and the process conditions are: the epitaxy temperature is 1570°C, and the pressure is 100mbar , the reaction gas is silane and propane, the carrier gas is pure hydrogen, and the impurity source is trimethylaluminum, the P-type highly doped epitaxial layer with an aluminum doping concentration of 5x10 ¹⁹ cm ^-3 and a thickness of 2 μm is obtained as shown in Figure 3(c ).

(A4) Deposit ohmic contact electrodes, as shown in Figure 3(d).

This step is the same as step (4) of Embodiment 1.

(A5) Spin-coat a layer of photoresist on the surface of the Ni metal layer deposited on the SiC epitaxial side, make a photoresist plate according to the positions of the 10 grooves of the battery, and expose the photoresist with an electron beam to form a corrosion window Then utilize the reaction ion process to etch the Ni metal layer, and the reaction gas adopts oxygen to expose the epitaxial P-type highly doped epitaxial layer SiC, and obtain the etching window of the P-type ohmic contact electrode and the trench as shown in Figure 3 (e).

(A6) Use inductively coupled plasma ICP etching technology to carve 10 trenches with a depth of 12 μm, a width of 14 μm, and a pitch of 25 μm on the P-type highly doped epitaxial layer exposed in the trench etching window, as shown in Figure 3 (f).

(A7) Place α radiation source Pu ²³⁸ in each trench by depositing or smearing to obtain a PIN junction with trenches as shown in Figure 3(g).

Step B: Make the upper PIN knot.

Repeat step (A1) to step (A7) to obtain the upper PIN junction.

Step C: Using the bonding method, press the P-type ohmic contact electrode of the upper PIN junction and the P-type ohmic contact electrode of the lower PIN junction together to obtain a parallel PIN-type α-irradiated battery as shown in Figure 3(h).

Claims (7)

1. a parallel PIN type alpha irradiation battery, comprising: PIN unit and αsource, is characterized in that:

Described PIN unit adopts by the parallel connection of upper and lower two PIN knot and forms; Lower PIN knot is followed successively by from bottom to top, N-type Ohm contact electrode (5), the highly doped 4H-SiC substrate of N-type (1), the low-doped epitaxial loayer of N-type (2), the highly doped epitaxial loayer of P type (3) and P type Ohm contact electrode (4), upper PIN knot is followed successively by from bottom to top, P type Ohm contact electrode (4), the highly doped epitaxial loayer of P type (3), the low-doped epitaxial loayer of N-type (2), the highly doped 4H-SiC substrate of N-type (1) and N-type Ohm contact electrode (5);

The one side that described two PIN tie its P type Ohm contact electrode (4) contacts, and in upper and lower PIN knot, groove forms Mirror Symmetry, the integrative-structure mutually connecting;

In each PIN knot, be provided with at least two grooves (6), in each groove (6), be all placed with αsource (7), to realize making full use of high-energyα-particle.

2. battery according to claim 1, is characterized in that αsource (7) adopts the plutonium element that americium element that relative atomic mass is 241 or relative atomic mass are 238, i.e. Am ²⁴¹or Pu ²³⁸.

3. battery according to claim 1, the degree of depth h that it is characterized in that groove (6) meets m+q<h<m+n+q, wherein m is the thickness of the highly doped epitaxial loayer of P type (3), n is the thickness of the low-doped epitaxial loayer of N-type (2), and q is the thickness of P type Ohm contact electrode (4).

4. battery according to claim 1 and 2, is characterized in that the width L of groove (6) meets L≤2g, and wherein, g is the average incident degree of depth of the high-energyα-particle that discharges of αsource (7) in αsource, for αsource, is Am ²⁴¹, its value is: g=7.5 μ m is Pu for αsource ²³⁸, its value is: g=10 μ m.

5. battery according to claim 1, is characterized in that the spacing d of adjacent two grooves (6) meets d>=i, and wherein, i is the average incident degree of depth of the high-energyα-particle that discharges of αsource (7) in 4H-SiC, for αsource, is Am ²⁴¹, its value is: i=10 μ m is Pu for αsource ²³⁸, its value is: i=18.2 μ m.

6. battery according to claim 1, is characterized in that it is lx10 that substrate (1) adopts doping content ¹⁸cm ^-3n-type 4H-SiC, the highly doped epitaxial loayer of P type (3) and the low-doped epitaxial loayer of N-type (2) are 4H-SiC extension, wherein the doping content of the highly doped epitaxial loayer of P type (3) is 1x10 ¹⁹～5x10 ¹⁹cm ^-3, the doping content of the low-doped epitaxial loayer of N-type (2) is 1x10 ¹⁵～2x10 ¹⁵cm ^-3.

7. a preparation method for parallel PIN type alpha irradiation battery, comprises the following steps:

(1) make lower PIN knot:

1.1) clean: SiC print is cleaned, to remove surface contaminant;

1.2) the low-doped epitaxial loayer of growth N-type: utilizing the SiC print surface epitaxial growth one deck doping content of chemical vapor deposition CVD method after cleaning is 1x10 ¹⁵～2x10 ¹⁵cm ^-3, thickness is the low-doped epitaxial loayer of the N-type of 5～10 μ m;

1.3) the highly doped epitaxial loayer of growing P-type: utilizing chemical vapor deposition CVD method is 1x10 in the low-doped epi-layer surface epitaxial growth of N-type one deck doping content ¹⁹～5x10 ¹⁹cm ^-3, thickness is the highly doped epitaxial loayer of P type of 1～2 μ m;

1.4) deposit Ohm contact electrode: utilize in the highly doped epi-layer surface of P type the Ni metal level that electron-beam vapor deposition method deposit a layer thickness is 300nm, as mask and the P type metal ohmic contact of etching groove; Utilize electron-beam vapor deposition method at the SiC substrate Ni metal level that back side deposition thickness of extension is not 300nm, as N-type Ohm contact electrode; Short annealing 3 minutes in nitrogen atmosphere at 1100 ℃;

1.5) litho pattern: the position according to nuclear battery groove is made into reticle; At the Ni of deposit layer on surface of metal spin coating one deck photoresist, utilize reticle to carry out electron beam exposure to photoresist, form corrosion window; Ni metal level to corrosion window place corrodes, and exposes the highly doped epitaxial loayer SiC of P type, obtains P type Ohm contact electrode and guttering corrosion window;

1.6) etching groove: utilize inductively coupled plasma ICP lithographic technique, carving the degree of depth on the highly doped SiC epitaxial loayer of the P type exposing is 6.5～12 μ m, and width is 5～14 μ m, and spacing is at least two grooves of 12～25 μ m;

1.7) place αsource: the method that adopts deposit or smear, in groove, place αsource, obtain being with fluted lower PIN knot.

(2) repeating step 1.1) to step 1.7) PIN ties in makings.

(3) utilize bonding method that the P type Ohm contact electrode of the P type Ohm contact electrode of upper PIN knot and lower PIN knot is pressed together, complete the making of parallel PIN type alpha irradiation battery.