Gamma nuclear radiation detector based on PIN type silicon carbide and preparation method thereof
By introducing nitrogen doping and optimizing epitaxial process and electrode design into the PIN-type silicon carbide gamma nuclear radiation detector, the problem of degradation in existing detectors in high radiation and high temperature environments is solved, and high sensitivity, low leakage current and long-term stable gamma ray detection effects are achieved.
Patent Information
- Application Number
- CN202411779177.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-05
- Publication Date
- 2025-04-01
AI Technical Summary
The existing semiconductor nuclear radiation detectors have deteriorated detection performance under high radiation intensity and extreme environments, and have insufficient performance in high-temperature environments, which cannot meet the long-term and stable gamma ray monitoring needs.
Using a gamma nuclear radiation detector based on PIN type silicon carbide, an epitaxial process and electrode design are optimized to form an efficient P-type and N-type ohmic contact electrode layer by introducing nitrogen doping into the intrinsic SiC sensitive layer.
It significantly improves the detector's sensitivity and signal capture efficiency, reduces leakage current, and ensures long-term stable and efficient detection of gamma rays in high radiation and high temperature environments.
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Figure CN119744011A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of nuclear radiation detection, and in particular to a PIN-type silicon carbide-based gamma nuclear radiation detector and a preparation method thereof. Background Art
[0002] In the field of nuclear radiation detection, gamma-ray detection is an important application in nuclear safety, nuclear accident response and radiation monitoring. However, the current mainstream semiconductor nuclear radiation detectors are mainly based on conventional semiconductor materials such as silicon and high-purity germanium. Although these materials perform well in certain application scenarios, due to their poor radiation resistance, their detection performance will drop rapidly in high radiation intensity and extremely harsh environments such as nuclear and radiation accident sites. The radiation damage effect is significant, and long-term, stable gamma-ray monitoring is impossible. In addition, the performance of silicon or germanium-based detectors in high-temperature environments is also significantly insufficient, further limiting their scope of application.
[0003] In order to improve the applicability of gamma-ray detection, silicon carbide (SiC) has attracted attention due to its excellent radiation resistance, high temperature resistance and stability in extreme environments. However, the current gamma-ray detectors based on SiC are still mainly Schottky-type structures. Although the structure of Schottky-type detectors is relatively simple, they still have defects such as poor temperature characteristics, limited thickness of sensitive area, and gold-semiconductor contact interface state problems, which makes it difficult to further improve its detection performance. On the other hand, although PN junction detectors can theoretically improve some problems, due to their thin epitaxial layers and the difficulty of thick epitaxial growth, the absorption coefficient of gamma rays is small, the detection efficiency is low, and it cannot meet the needs of efficient detection. Therefore, in strong radiation fields and extremely harsh environments, semiconductor detectors that can detect gamma rays stably and efficiently for a long time are still in urgent need of development.
[0004] In view of the above problems, the present invention is proposed. Summary of the invention
[0005] The invention discloses a gamma nuclear radiation detector based on PIN type silicon carbide and a preparation method thereof, aiming to solve the technical problems existing in the prior art.
[0006] According to one aspect of the present invention, a γ-nuclear radiation detector based on PIN-type silicon carbide is provided, comprising a P-type ohmic contact electrode layer, a P + Type SiC epitaxial layer, intrinsic SiC sensitive layer, N + Type buffer layer, N + type substrate and N-type ohmic contact electrode layer, P-type ohmic contact electrode layer, P + Type SiC epitaxial layer, intrinsic SiC sensitive layer, N + Type buffer layer, N + The N-type substrate and the N-type ohmic contact electrode layer are distributed sequentially from top to bottom;
[0007] The P-type ohmic contact electrode layer includes a first P-type ohmic contact electrode and a second P-type ohmic contact electrode. The first P-type ohmic contact electrode and the second P-type ohmic contact electrode are respectively distributed on the P + In the middle and at both ends of the upper surface of the SiC epitaxial layer, the spacing between the first P-type ohmic contact electrode and the second P-type ohmic contact electrode is 0.5 mm-1 mm;
[0008] The N-type ohmic contact electrode layer includes a first N-type ohmic contact electrode and a second N-type ohmic contact electrode. The first N-type ohmic contact electrode and the second N-type ohmic contact electrode are respectively distributed on the N + In the middle and at both ends of the lower surface of the N-type substrate, the spacing between the first N-type ohmic contact electrode and the second N-type ohmic contact electrode is 0.5 mm-1 mm.
[0009] As a preferred technical solution, the first P-type ohmic contact electrode and the second P-type ohmic contact electrode are both made of Ti / Al / Au alloy with a thickness of 100nm / 100nm / 100nm.
[0010] As a preferred technical solution, P + The SiC epitaxial layer uses a concentration of 1×10 18 / cm 3 Up to 2×10 19 / cm 3 of aluminum doping.
[0011] As a preferred technical solution, the thickness of the intrinsic SiC sensitive layer is 30 μm-120 μm.
[0012] As a preferred technical solution, the intrinsic SiC sensitive layer adopts a concentration of ≤1×10 14 / cm 3 of nitrogen doping.
[0013] As a preferred technical solution, N + Type buffer layer and N + The type substrates are all made of 1×10 18 / cm 3 -2×10 19 / cm 3 of nitrogen doping.
[0014] According to another aspect of the present invention, there is also provided a method for preparing the above-mentioned gamma nuclear radiation detector, comprising:
[0015] In N + The N + Type buffer layer;
[0016] In N +The upper surface of the buffer layer is formed by epitaxial process to form an intrinsic SiC sensitive layer;
[0017] On the surface of the intrinsic SiC sensitive layer, P + Type SiC epitaxial layer;
[0018] Through magnetron sputtering process, + The upper surface of the SiC epitaxial layer and the N + A Ti / Al / Au alloy is formed on the lower surface of the substrate;
[0019] At a certain temperature, an annealing process is performed to form a P-type ohmic contact electrode layer and an N-type ohmic contact electrode layer respectively.
[0020] As a preferred technical solution, the temperature used in the epitaxial process is 1600° C., the pressure is 100 Mbar, and the growth gases are SiH4, H2, and C3H8.
[0021] As a preferred technical solution, the magnetron sputtering process is carried out in a high vacuum magnetron sputtering device using a customized metal Mo hard mask.
[0022] As a preferred technical solution, the annealing treatment adopts a vacuum 800°C slow annealing treatment.
[0023] The technical solution adopted by the present invention can achieve at least one of the following beneficial effects:
[0024] 1. The PIN type gamma nuclear radiation detector based on silicon carbide (SiC) material provided by the present invention introduces a concentration of ≤1×10 14 / cm 3 The nitrogen doping and thickness control between 30μm-120μm significantly improve the sensitivity of the detector and ensure the efficient capture of signals in gamma-ray detection. At the same time, the precisely optimized epitaxial process and electrode design effectively reduce the leakage current of the device, making it more reliable and overcoming the defect of large leakage current of conventional semiconductor detectors under strong irradiation environment.
[0025] 2. The present invention uses SiC as the detector material, which makes the present invention have natural strong radiation resistance and high temperature resistance. By using high concentration (1×10 18 / cm 3 Up to 2×10 19 / cm 3 ) further improves its stability under extreme conditions, making it particularly suitable for long-term use in high-radiation and high-temperature environments. This design makes up for the defect that traditional semiconductor detectors are prone to failure in harsh environments and expands the application scenarios of gamma-ray detectors.
[0026] 3. The present invention significantly improves the ohmic contact interface performance by using Ti / Al / Au alloy with a thickness of 100nm / 100nm / 100nm in the P-type ohmic contact electrode and the N-type ohmic contact electrode, and adopts processes such as high vacuum magnetron sputtering and 800℃ vacuum annealing treatment, thereby avoiding the common gold-semi-contact interface state problem in the Schottky structure. This optimized design not only improves the breakdown voltage of the detector, but also makes the detected gamma-ray signal of higher quality, and has important application prospects in strong radiation harsh environments. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] 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, which constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions explain the present invention and do not constitute improper limitations on the present invention. In the drawings:
[0028] Figure 1 It is a structural schematic diagram of a γ nuclear radiation detector based on PIN type silicon carbide of the present invention;
[0029] Figure 2 Made for this invention Figure 1 Schematic diagram of the structure;
[0030] Figure 3 The present invention is a schematic diagram of the process flow of a method for preparing a γ nuclear radiation detector based on PIN-type silicon carbide.
[0031] Description of reference numerals:
[0032] 1. P-type ohmic contact electrode layer; 11. First P-type ohmic contact electrode; 12. Second P-type ohmic contact electrode; 2. P + Type SiC epitaxial layer; 3. Intrinsic SiC sensitive layer; 4. N + Type buffer layer; 5.N + type substrate; 6. N-type ohmic contact electrode layer; 61. first N-type ohmic contact electrode; 62. second N-type ohmic contact electrode. DETAILED DESCRIPTION
[0033] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. In the description of the present invention, it should be noted that the term "or" is usually used in the sense of including "and / or", unless the content clearly indicates otherwise.
[0034] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or a magnetic connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.
[0035] In addition, unless the steps are specifically described or must occur in sequence, the order of the above steps is not limited to the above list, and can be changed or rearranged according to the required design. And the above embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments.
[0036] Obviously, the described embodiments are only some embodiments of the present invention, not all 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.
[0037] In order to solve the problems existing in the prior art, the embodiment of the present invention provides a γ nuclear radiation detector based on PIN type silicon carbide, such as Figure 1 As shown, it includes a P-type ohmic contact electrode layer 1, a P-type ohmic contact electrode layer 2, and a P-type ohmic contact electrode layer 3. + Type SiC epitaxial layer 2, intrinsic SiC sensitive layer 3, N + Type buffer layer 4, N + The P-type ohmic contact electrode layer 1 and the N-type ohmic contact electrode layer 6 are used to ensure efficient charge transfer between the external circuit and the detector, while optimizing the power plant distribution to improve the detection performance. + The SiC epitaxial layer 2 is used to optimize electrode contact and improve detection performance. As a highly doped P-type region, P + The N-type SiC epitaxial layer 2 forms an ohmic contact with the P-type ohmic contact electrode 1 to significantly reduce the resistance and energy loss during signal transmission. The intrinsic SiC sensitive layer 3 plays a core role in the detector as a sensitive area for gamma ray detection. + Type buffer layer 4 and N + The substrate 5 mainly plays the role of support and conductivity, N + The buffer layer 4 is used as the intrinsic SiC sensitive layer 3, N +The transition region between the N-type substrate 5 can reduce the defects caused by lattice mismatch, improve the crystal quality, and thus improve the stability and performance of the detector; + The N-type substrate 5 serves as the mechanical support layer of the detector and provides a low resistance path for the external circuit. By connecting with the N-type ohmic contact electrode 6, it ensures efficient charge transmission, reduces signal loss and enhances the overall conductivity and structural strength of the device. + Type SiC epitaxial layer 2 uses P + The intrinsic SiC sensitive layer 3 adopts the intrinsic low-doped N - Type SiC sensitive layer; N + Type substrate 5 uses N + Type 4H-SiC substrate.
[0038] like Figure 1 As shown, the P-type ohmic contact electrode layer 1 includes a first P-type ohmic contact electrode 11 and a second P-type ohmic contact electrode 12, which are respectively distributed on the P + The middle and both ends of the upper surface of the N-type SiC epitaxial layer 2; the N-type ohmic contact electrode layer 6 includes a first N-type ohmic contact electrode 61 and a second N-type ohmic contact electrode 62, which are respectively distributed in the N + The middle and both ends of the lower surface of the substrate 5. Preferably, the + The spacing between the first P-type ohmic contact electrode 11 and the second P-type ohmic contact electrode 12 on the upper surface of the N-type SiC epitaxial layer 2 is 0.5 mm-1 mm; + The distance between the first N-type ohmic contact electrode 61 and the second N-type ohmic contact electrode 62 on the lower surface of the substrate 5 is 0.5 mm-1 mm.
[0039] Through the above structural design, the detector provided by the present invention has a highly optimized layered structure and superior performance advantages. The detector is composed of an N-type ohmic contact electrode layer 6, N + Type substrate 5, N + Type buffer layer 4, intrinsic SiC sensitive layer 3, P + The P-type SiC epitaxial layer 2 and the P-type ohmic contact electrode layer 1 are composed of these parts, which work together to achieve efficient and stable gamma-ray detection. + The N-type SiC epitaxial layer 2 achieves low contact resistance through high doping and optimizes charge transfer performance; the intrinsic SiC sensitive layer 3 serves as the detection core area, providing a wide depletion region to efficiently separate and collect electron-hole pairs generated by gamma rays; + Type buffer layer 4 and N +The substrate 5 plays a role in supporting, reducing lattice mismatch defects and enhancing conductivity. The P-type ohmic contact electrode layer 1 and the N-type ohmic contact electrode layer 6 further optimize the electric field uniformity through distributed design, significantly improving the sensitivity, signal response speed and radiation resistance of the detector, and are suitable for high-performance gamma-ray detection applications.
[0040] In some preferred embodiments, the first P-type ohmic contact electrode 11 and the second P-type ohmic contact electrode 12 are made of Ti / Al / Au alloy with a thickness of 100 nm / 100 nm / 100 nm.
[0041] In some preferred embodiments, P + The SiC epitaxial layer 2 is doped with aluminum, and the aluminum doping concentration is 1×10 18 / cm 3 -2×10 19 / cm 3 ;P + The thickness of the SiC epitaxial layer 2 is 2 μm.
[0042] In some preferred embodiments, the intrinsic SiC sensitive layer 3 is doped with nitrogen, and the nitrogen doping concentration is ≤1×10 14 / cm 3 ; The thickness of the intrinsic SiC sensitive layer 3 is 30μm-120μm.
[0043] In some preferred embodiments, N + The buffer layer 4 is doped with nitrogen, and the nitrogen doping concentration is 1×10 18 / cm 3 -2×10 19 / cm 3 ; N + The thickness of the buffer layer 4 is 1 μm.
[0044] In some preferred embodiments, N + The substrate 5 is doped with nitrogen, and the nitrogen doping concentration is 1×10 18 / cm 3 -2×10 19 / cm 3 ; N + The thickness of the mold substrate 5 is 360 μm.
[0045] In some preferred embodiments, the first N-type ohmic contact electrode 61 and the second N-type ohmic contact electrode 62 are made of Ti / Al / Au alloy with a thickness of 100 nm / 100 nm / 100 nm.
[0046] like Figure 2As shown, the embodiment of the present invention further provides a method for preparing the above-mentioned PIN-type silicon carbide-based gamma nuclear radiation detector, comprising the following steps:
[0047] S1: In N + The upper surface of the substrate 5 is formed by epitaxial process. + Type buffer layer 4;
[0048] S2: In N + On the upper surface of the buffer layer 4, an intrinsic SiC sensitive layer 3 is formed by an epitaxial process;
[0049] S3: On the surface of the intrinsic SiC sensitive layer 3, P is formed by epitaxial process. + Type SiC epitaxial layer 2;
[0050] S4: Through magnetron sputtering process, + The upper surface of the SiC epitaxial layer 2 and the N + A Ti / Al / Au alloy is formed on the lower surface of the substrate 5;
[0051] S5: performing annealing treatment on the above structure at a certain temperature to form a P-type ohmic contact electrode layer 1 and an N-type ohmic contact electrode layer 6 respectively.
[0052] In some preferred embodiments, in steps S1, S2 and S3, the temperature used in the epitaxial process is 1600°C, the pressure is 100 Mbar, and the growth gas is SiH4, H2, C3H8.
[0053] In some preferred embodiments, in step S4, the magnetron sputtering process is performed in a high vacuum magnetron sputtering device using a customized metal Mo hard mask.
[0054] In some preferred embodiments, in step S5, the annealing process adopts a vacuum 800° C. slow annealing process.
[0055] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.
Claims
1. A γ nuclear radiation detector based on PIN type silicon carbide, characterized in that: Including P-type ohmic contact electrode layer, P + Type SiC epitaxial layer, intrinsic SiC sensitive layer, N + Type buffer layer, N + type substrate and an N-type ohmic contact electrode layer, the P-type ohmic contact electrode layer, the P + Type SiC epitaxial layer, intrinsic SiC sensitive layer, N + Type buffer layer, N + The N-type substrate and the N-type ohmic contact electrode layer are distributed sequentially from top to bottom; The P-type ohmic contact electrode layer includes a first P-type ohmic contact electrode and a second P-type ohmic contact electrode, wherein the first P-type ohmic contact electrode and the second P-type ohmic contact electrode are respectively distributed on the P + In the middle and at both ends of the upper surface of the P-type SiC epitaxial layer, the spacing between the first P-type ohmic contact electrode and the second P-type ohmic contact electrode is 0.5 mm-1 mm; The N-type ohmic contact electrode layer includes a first N-type ohmic contact electrode and a second N-type ohmic contact electrode, wherein the first N-type ohmic contact electrode and the second N-type ohmic contact electrode are respectively distributed on the N + In the middle and at both ends of the lower surface of the N-type substrate, the distance between the first N-type ohmic contact electrode and the second N-type ohmic contact electrode is 0.5 mm-1 mm.
2. The gamma nuclear radiation detector according to claim 1, characterized in that: The first P-type ohmic contact electrode and the second P-type ohmic contact electrode are both made of Ti / Al / Au alloy with a thickness of 100nm / 100nm / 100nm.
3. The gamma nuclear radiation detector according to claim 1, characterized in that: The P + The SiC epitaxial layer adopts a concentration of 1×10 18 / cm 3 Up to 2×10 19 / cm 3 of aluminum doping.
4. The gamma nuclear radiation detector according to claim 1, characterized in that: The thickness of the intrinsic SiC sensitive layer is 30 μm-120 μm.
5. The gamma nuclear radiation detector according to claim 4, characterized in that: The intrinsic SiC sensitive layer has a concentration of ≤1×10 14 / cm 3 of nitrogen doping.
6. The gamma nuclear radiation detector according to claim 1, characterized in that: The N + type buffer layer and the N + The type substrates are all made of 1×10 18 / cm 3 -2×10 19 / cm 3 of nitrogen doping.
7. A method for preparing a gamma nuclear radiation detector as claimed in claims 1 to 6, characterized in that: include: In the N + The N + Type buffer layer; In the N + The upper surface of the buffer layer is formed by the epitaxial process to form the intrinsic SiC sensitive layer; On the upper surface of the intrinsic SiC sensitive layer, the P + Type SiC epitaxial layer; By magnetron sputtering process, the P + The upper surface of the SiC epitaxial layer and the N + A Ti / Al / Au alloy is formed on the lower surface of the substrate; Annealing is performed at a certain temperature to form the P-type ohmic contact electrode layer and the N-type ohmic contact electrode layer respectively.
8. The preparation method according to claim 7, characterized in that: The temperature used in the epitaxial process is 1600° C., the pressure is 100 Mbar, and the growth gases used are Si H4, H2, and C3H8.
9. The preparation method according to claim 7, characterized in that: The magnetron sputtering process is carried out in a high vacuum magnetron sputtering device using a customized metal Mo hard mask.
10. The preparation method according to claim 7, characterized in that: The annealing treatment adopts vacuum 800° C. slow annealing treatment.