Semiconductor neutron detector

Abstract

The utility model belongs to the technical field of neutron detection, and provides a semiconductor neutron detector, which comprises a semiconductor single crystal substrate; the Schottky contact electrode is evaporated on the front surface of the semiconductor single crystal substrate, and the Schottky contact electrode is provided with a positive electrode leading-out contact; the ohmic contact electrode is sputtered on the back surface of the semiconductor single crystal substrate, and the ohmic contact electrode is provided with a back electrode leading-out contact; the AlN substrate is provided with a notch, and the notch and the positive electrode leading-out contact are oppositely arranged, so that a positive electrode outer lead is led out through the notch; the 6LiF neutron conversion layer is evaporated on the front surface or the back surface of the AlN substrate except the notch; a groove which is the same as the Schottky contact electrode in shape and size is formed in the face, away from the AlN substrate, of the 6LiF neutron conversion layer, and the Schottky contact electrode is embedded into the groove so that the 6LiF neutron conversion layer can be attached to the semiconductor single crystal substrate. The conversion layer provided by the utility model can realize rapid switching of a plurality of detectors, is high in utilization rate, is not liable to fall off, and is low in cost.

Description

Technical Field

[0001] The utility model belongs to the technical field of neutron detection, and specifically relates to a semiconductor neutron detector. Background Technique

[0002] Neutron detectors have been widely used in many fields such as aerospace applications, nuclear medicine and clinical diagnosis, industrial safety assurance, environmental radiation detection, nuclear explosion and well logging. Traditional semiconductor neutron detectors have excellent performance at low temperatures, are light in weight and low in power consumption, making up for many deficiencies of gas neutron detectors and scintillator neutron detectors, and play an important role in the field of nuclear radiation detection.

[0003] The neutron conversion layer is an essential component for a semiconductor neutron detector to achieve neutron detection. Commonly used neutron conversion layer materials include 10 B4C and 6 LiF. When neutrons enter the neutron conversion layer containing 10 B and 6 Li, nuclear reactions will occur to generate secondary charged particles. The generated secondary charged particles generate electron-hole pairs in the sensitive layer and are finally collected by the semiconductor neutron detector. Because 10 B is prone to interference from rays as a neutron conversion layer material, which is not conducive to the discrimination of semiconductor neutron detectors. Therefore, 6 LiF is more commonly used as the neutron conversion layer material. Common semiconductor neutron detectors all directly prepare the 6 LiF neutron conversion layer on the detector surface. The 6 utilization rate of the LiF neutron conversion layer is low, the consumption is large, and the 6 price of LiF powder is expensive, resulting in a high cost of semiconductor neutron detectors. Secondly, to improve the sensitivity and detection efficiency of semiconductor neutron detectors, it is usually necessary to prepare a large-area and thick neutron conversion layer. However, there is a thermal mismatch problem between the metal electrode on the detector surface and 6 LiF, resulting in 6 LiF being more likely to fall off. Content of the Utility Model

[0004] The utility model aims at the above problems existing in the existing semiconductor neutron detectors, such as low utilization rate of the neutron conversion layer and easy falling off, and provides a semiconductor neutron detector with a high utilization rate of the neutron conversion layer and not easy to fall off.

[0005] To achieve the above purpose, the utility model provides a semiconductor neutron detector, including:

[0006] A semiconductor single crystal substrate;

[0007] A Schottky contact electrode is deposited on the front surface of a semiconductor single crystal substrate. The Schottky contact electrode has a positive electrode lead-out contact for leading out the positive electrode external lead through the positive electrode lead-out contact;

[0008] An ohmic contact electrode is sputtered on the back surface of the semiconductor single crystal substrate. The ohmic contact electrode has a back electrode lead-out contact for leading out the back electrode external lead through the back electrode lead-out contact;

[0009] An AlN substrate has a notch. The notch is disposed opposite to the positive electrode lead-out contact for leading out the positive electrode external lead through the notch;

[0010] 6 A LiF neutron conversion layer is deposited on the front surface or the back surface of the AlN substrate except at the notch; 6 A groove having the same shape and size as the Schottky contact electrode is provided on the side of the LiF neutron conversion layer away from the AlN substrate. The Schottky contact electrode is embedded in the groove so that 6 the LiF neutron conversion layer is bonded to the semiconductor single crystal substrate.

[0011] In some embodiments, the semiconductor neutron detector further includes a packaging base. The ohmic contact electrode is fixed on the packaging base. The packaging base has an outlet hole. The outlet hole is disposed opposite to the back electrode lead-out contact for leading out the back electrode external lead through the outlet hole.

[0012] In some embodiments, the semiconductor single crystal substrate includes a single crystal matrix, a single crystal buffer layer grown on the front surface of the single crystal matrix, and a single crystal epitaxial layer grown on the front surface of the single crystal buffer layer. The Schottky contact electrode is deposited on the front surface of the single crystal epitaxial layer, and the ohmic contact electrode is sputtered on the back surface of the single crystal matrix.

[0013] In some embodiments, the thickness of the semiconductor single crystal substrate is 0.3 - 10 mm, wherein the thickness of the epitaxial layer is 5 - 200 μm, and the thickness of the buffer layer is 0.01 - 1 μm.

[0014] In some embodiments, the thickness of the Schottky contact electrode is 50 - 120 nm. The shape of the Schottky contact electrode is square, or circular, or oval, or rhombus; when the shape of the Schottky contact electrode is square, the side length is 7 - 9 mm; when the shape of the Schottky contact electrode is circular or rhombus, the diameter is 7 - 9 mm; when the shape of the Schottky contact electrode is oval, the major diameter is 7 - 9 mm; when the shape of the Schottky contact electrode is rhombus, the major diagonal is 7 - 9 mm.

[0015] In some embodiments, the thickness of the ohmic contact electrode is 50 - 120 nm.

[0016] In some embodiments, the thickness of the AlN substrate is 50 - 500 μm.

[0017] In some embodiments, the notch is located at the corner, or side, or center of the AlN substrate, and the shape of the notch is a geometric shape or a special-shaped shape.

[0018] In some embodiments, 6 The thickness of the LiF neutron conversion layer is 5 - 20 μm.

[0019] In some embodiments, the semiconductor single crystal substrate and the ohmic contact electrode have the same size.

[0020] Compared with the prior art, the advantages and positive effects of the present utility model are as follows:

[0021] (1) For the semiconductor neutron detector of the present utility model, an independent 6 LiF neutron conversion layer is adopted. 6 The LiF neutron conversion layer is not directly connected to the semiconductor single crystal substrate, but is embedded through the Schottky contact electrode 6 The LiF neutron conversion layer is attached to the semiconductor crystal substrate in such a way. 6 The above assembly method between the LiF neutron conversion layer and the semiconductor single crystal substrate can, on the one hand, protect the semiconductor single crystal substrate from being damaged due to 6 the detachment of the LiF neutron conversion layer. On the other hand, 6 the LiF neutron conversion layer can be reused, combined with different semiconductor single crystal substrates to form a semiconductor neutron detector, realizing the rapid switching of different detectors, reducing costs, and avoiding material waste.

[0022] (2) For the semiconductor neutron detector of the present utility model, the 6 LiF neutron conversion layer is vapor-deposited on the surface of the AlN substrate. Since 6 the lattice constants of LiF are similar, it can effectively solve the problem of thermal lattice mismatch between the metal electrode and 6 the LiF lattice, 6 and the LiF neutron conversion layer is not easily detached.

[0023] (3) For the semiconductor neutron detector of the present utility model, the notch design of the AlN substrate can separately lead out the positive electrode lead wire of the Schottky contact electrode, without affecting the connection effect of the positive electrode lead-out contact, ensuring 6 the close fitting between the LiF neutron conversion layer and the semiconductor single crystal substrate, and the signal does not pass through 6 the LiF neutron conversion layer and is directly output from the Schottky contact electrode, reducing the output loss of the electrical signal, maximizing the detection area and detection efficiency, and thus improving the detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a side view of the semiconductor neutron detector according to the embodiment of the present utility model;

[0025] Figure 2 The bottom view of the semiconductor neutron detector according to the embodiment of the present invention;

[0026] Figure 3 The top view of the semiconductor neutron detector according to Embodiment 1 of the present invention;

[0027] Figure 4 The plan view of the AlN substrate according to Embodiment 1 of the present invention;

[0028] Figure 5 The schematic diagram of the packaged semiconductor neutron detector according to Embodiment 1 of the present invention;

[0029] Figure 6 The top view of the semiconductor neutron detector according to Embodiment 2 of the present invention;

[0030] Figure 7 The plan view of the AlN substrate according to Embodiment 2 of the present invention;

[0031] Figure 8 The schematic diagram of the packaged semiconductor neutron detector according to Embodiment 2 of the present invention;

[0032] Figure 9 The top view of the semiconductor neutron detector according to Embodiment 3 of the present invention;

[0033] Figure 10 The plan view of the AlN substrate according to Embodiment 3 of the present invention;

[0034] Figure 11 The schematic diagram of the packaged semiconductor neutron detector according to Embodiment 3 of the present invention;

[0035] Figure 12 The top view of the semiconductor neutron detector according to Embodiment 4 of the present invention;

[0036] Figure 13 The plan view of the AlN substrate according to Embodiment 4 of the present invention;

[0037] Figure 14 The schematic diagram of the packaged semiconductor neutron detector according to Embodiment 4 of the present invention.

[0038] In the figure, 1, semiconductor single crystal substrate; 2, Schottky contact electrode, 201, positive electrode lead-out contact, 202, positive electrode external lead; 3, ohmic contact electrode, 301, back electrode lead-out contact, 302, back electrode external lead; 4, AlN substrate, 401, notch; 5, 6 LiF neutron conversion layer; 6, packaging base. Detailed implementation manners

[0039] Next, the present utility model will be specifically described through exemplary embodiments. However, it should be understood that, without further description, the elements, structures, and features in one embodiment can also be beneficially combined into other embodiments.

[0040] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. is based on the positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0041] Embodiment 1: Refer to Figures 1 to 4 , a semiconductor neutron detector, comprising:

[0042] A semiconductor single crystal substrate 1;

[0043] A Schottky contact electrode 2, deposited on the front surface of the semiconductor single crystal substrate 1. The thickness of the Schottky contact electrode 2 is 50 nm, the shape of the Schottky contact electrode 2 is square, and the side length is 9 mm. One corner of the Schottky contact electrode 2 has a positive electrode lead-out contact 201 to lead out the positive electrode external lead 202 through the positive electrode lead-out contact 201;

[0044] An ohmic contact electrode 3, sputtered on the back surface of the semiconductor single crystal substrate 1. The thickness of the ohmic contact electrode is 50 nm. The ohmic contact electrode 3 has a back electrode lead-out contact 301 to lead out the back electrode external lead 302 through the back electrode lead-out contact 301;

[0045] An AlN substrate 4, with a thickness of 200 μm. The AlN substrate 4 has a notch 401, which is located at the corner of the AlN substrate, and the shape of the notch is a square of 3 mm × 3 mm. The notch 401 is arranged opposite to the positive electrode lead-out contact 201 to lead out the positive electrode external lead 202 through the notch 401;

[0046] 6 A LiF neutron conversion layer 5, deposited on the front surface or the back surface of the AlN substrate 4 except at the notch 401, with a thickness of 5 μm; 6 On the side of the LiF neutron conversion layer 5 away from the AlN substrate 4, there is a groove 501 with the same shape and size as the Schottky contact electrode 2. The Schottky contact electrode 2 is embedded in the groove 501 so that 6 The LiF neutron conversion layer 5 is attached to the semiconductor single crystal substrate 1.

[0047] In a specific embodiment, refer to Figure 5, the above semiconductor neutron detector in this embodiment further includes a packaging base 6. The ohmic contact electrode 3 is pasted on the packaging base 6 through conductive silver glue. The packaging base 6 has an outlet hole (not shown in the figure). The outlet hole is arranged opposite to the back electrode lead-out contact 301 to lead out the back electrode external lead 302 through the outlet hole. Fixing the ohmic contact electrode 3 on the packaging base 6 can, on the one hand, protect the ohmic contact electrode 3 through the packaging base 1 to prevent damage to the ohmic contact electrode 3. On the other hand, the packaging base forms a stable connection with the detector to carry high-frequency signals and couple the detector with the external acquisition circuit to form an effective signal output.

[0048] Specifically, the semiconductor single crystal substrate 1 includes a single crystal matrix 101, a single crystal buffer layer 102 grown on the front surface of the single crystal matrix 101, and a single crystal epitaxial layer 103 grown on the front surface of the single crystal buffer layer 102. The Schottky contact electrode 2 is evaporated on the front surface of the single crystal epitaxial layer 103, and the ohmic contact electrode 3 is sputtered on the back surface of the single crystal matrix 101. The thickness of the semiconductor single crystal substrate 1 is 350 μm, the thickness of the single crystal epitaxial layer 103 is 30 μm, and the thickness of the buffer layer 102 is 0.5 μm.

[0049] It should be noted that the thickness of the semiconductor single crystal substrate varies according to the different single crystal materials after the incident particles are converted into charged particles in the back conversion layer. The higher the energy of the incident charged particles, the thicker the thickness of the semiconductor single crystal substrate required to completely deplete its energy. In addition, the thickness of the semiconductor single crystal substrate also needs to ensure that the overall detector has basic mechanical strength. The thickness of the AlN substrate varies according to the different particle energies measured in the detector design. The higher the incident neutron energy, the thicker the thickness of the AlN substrate required to completely deplete its energy.

[0050] Specifically, the semiconductor single crystal substrate and the ohmic contact electrode have the same size. It should be noted that the same size of the semiconductor single crystal substrate and the ohmic contact electrode can reduce the contact resistance 6 The size of the LiF neutron conversion layer is larger than that of the Schottky contact electrode, better disperse the current, improve the current transmission efficiency, reduce the performance degradation or damage caused by local overheating of the detector, and improve the stability of the detector.

[0051] The preparation method of the above semiconductor neutron detector in this embodiment is as follows:

[0052] AlN substrate manufacturing steps: Select an AlN substrate with a size of 10 mm × 10 mm and a thickness of 200 μm. Make a cut corner with a side length of 3 mm on the AlN substrate. Use the standard RCA cleaning process to remove the organic and inorganic impurities on the surface of the AlN substrate, and blow it dry with a high-purity N2 (purity of 99.999%) gun.

[0053] 6Steps for fabricating the LiF neutron conversion layer: Select LiF powder with a purity of 99.95%, 6 where the Li isotope abundance is 95 atom%. Weigh 0.5 - 2 g of 6 LiF powder, mix it with 2 - 6 ml of ethanol and acetone to form a mixed solution. After loading it into a test tube and ultrasonically mixing it evenly, use a dropper to 6 dropwise add the LiF mixed solution into a polished tungsten evaporation boat. Let it stand still. After the ethanol and acetone have evaporated, fix the evaporation boat in the chamber of a thermal evaporation coating equipment. Use the thermal evaporation coating equipment to thermally evaporate a 6 LiF neutron conversion layer on the front or back surface of the AlN substrate except at the notch. The background vacuum of the thermal evaporation equipment is better than 4×10 6 Pa, and segmented coating is adopted. First, coat at a low rate, with the coating rate controlled at 1 - 3 nm / s to control the thermal stress, ensure that the film layer reaches the required thickness while improving the density of the film and making it not easy to fall off, and ensure the coating bonding effect. Later, coat at a high rate, with the rate controlled at 5 - 7 nm / s, and evaporate a 5 - μm - thick -4 LiF neutron conversion layer. 6

[0054] Steps for fabricating the semiconductor single - crystal substrate: Select a semiconductor single - crystal substrate (such as 4H - SiC) with a thickness of 350 μm, a surface roughness lower than 6 nm, and a deviation of 4° from the <112—0> direction. Use standard RCA cleaning to remove organic and inorganic impurities on the surface of the semiconductor single - crystal substrate, and dry it with a high - purity N2 (purity 99.999%) gun.

[0055] Steps for fabricating the Schottky contact electrode: After covering a customized mask on the front surface (i.e., the single - crystal epitaxial layer surface) of the cleaned semiconductor single - crystal substrate, thermally evaporate metal Ni or Ti using a thermal evaporation method to form a patterned Schottky contact electrode. The thickness of the Schottky contact electrode 2 is 50 nm, and the shape of the Schottky contact electrode 2 is square, with a side length of 9 mm.

[0056] Steps for fabricating the ohmic contact electrode: On the back surface of the cleaned semiconductor single - crystal substrate, sputter Ni / Pt or Ti / Pt in sequence using radio - frequency magnetron sputtering, with a thickness of 50 nm, to form a back - side ohmic contact electrode. The background vacuum of the magnetron sputtering chamber is 4×10 -4 Pa, the argon gas flow rate is 40 sccm, and the working pressure is 0.4 Pa. Perform rapid annealing, with the annealing temperature at 600 - 1000°C, the annealing time at 1 - 5 min, and the annealing atmosphere being N2 or a vacuum atmosphere less than 4 Pa. Under these conditions, make the ohmic contact electrode and the semiconductor single - crystal substrate obtain good ohmic contact.

[0057] Lamination steps: Place 6The groove of the LiF neutron conversion layer is aligned with the Schottky contact electrode, and the Schottky contact electrode is embedded in the groove, so that 6 the LiF neutron conversion layer is attached to the front surface of the semiconductor single crystal substrate.

[0058] Lead connection step: Fix the ohmic contact electrode on the package base with silver paste. Among them, the outer lead of the back electrode is led out from the package base, and the outer lead of the positive electrode is led out through the notch, and the preparation of the semiconductor neutron detector is completed.

[0059] Example 2: Refer to Figures 1 to 2 、 Figures 6 to 7 a semiconductor neutron detector, comprising:

[0060] a semiconductor single crystal substrate 1;

[0061] a Schottky contact electrode 2, deposited on the front surface of the semiconductor single crystal substrate 1, the thickness of the Schottky contact electrode 2 is 100 nm, the shape of the Schottky contact electrode 2 is circular, and the diameter is 9 mm; the Schottky contact electrode 2 has a positive electrode lead-out contact 201 to lead out the outer lead 202 of the positive electrode through the positive electrode lead-out contact 201;

[0062] an ohmic contact electrode 3, sputtered on the back surface of the semiconductor single crystal substrate 1, the thickness of the ohmic contact electrode is 100 nm, and the ohmic contact electrode 3 has a back electrode lead-out contact 301 to lead out the outer lead 302 of the back electrode through the back electrode lead-out contact 301;

[0063] an AlN substrate 4, with a thickness of 200 μm, the AlN substrate 4 has a notch 401, the notch is located on the side of the AlN substrate, and the shape of the notch is a square of 3 mm × 3 mm; the notch 401 is arranged opposite to the positive electrode lead-out contact 201 to lead out the outer lead 202 of the positive electrode through the notch 401;

[0064] 6 a LiF neutron conversion layer 5, deposited on the front surface or the back surface of the AlN substrate 4 except at the notch 401, with a thickness of 10 μm; 6 a groove 501 with the same shape and size as the Schottky contact electrode 2 is provided on the side of the LiF neutron conversion layer 5 away from the AlN substrate 4, and the Schottky contact electrode 2 is embedded in the groove 501, so that 6 the LiF neutron conversion layer 5 is attached to the semiconductor single crystal substrate 1.

[0065] In a specific embodiment, refer to Figure 5, the above semiconductor neutron detector of this embodiment further includes a packaging base 6. The ohmic contact electrode 3 is pasted on the packaging base 6 through conductive silver paste. The packaging base 6 has an outlet hole (not shown in the figure). The outlet hole is disposed opposite to the back electrode lead-out contact 301 to lead out the back electrode external lead 302 through the outlet hole. Fixing the ohmic contact electrode 3 on the packaging base 6, on the one hand, protects the ohmic contact electrode 3 through the packaging base 1 to prevent damage to the ohmic contact electrode 3. On the other hand, the packaging base forms a stable connection with the detector to carry high-frequency signals and couple the detector with an external acquisition circuit to form an effective signal output.

[0066] Specifically, the semiconductor single crystal substrate 1 includes a single crystal matrix 101, a single crystal buffer layer 102 grown on the front surface of the single crystal matrix 101, and a single crystal epitaxial layer 103 grown on the front surface of the single crystal buffer layer 102. The Schottky contact electrode 2 is evaporated on the front surface of the single crystal epitaxial layer 103, and the ohmic contact electrode 3 is sputtered on the back surface of the single crystal matrix 101. The thickness of the single crystal matrix 101 is 500 μm, the thickness of the single crystal epitaxial layer 103 is 50 μm, and the thickness of the buffer layer 102 is 2 μm.

[0067] It should be noted that the thickness of the semiconductor single crystal substrate varies according to the different single crystal materials after the incident particles are converted into charged particles in the back conversion layer. The higher the energy of the incident charged particles, the thicker the thickness of the semiconductor single crystal substrate required to completely deplete its energy. In addition, the thickness of the semiconductor single crystal substrate also needs to ensure that the overall detector has basic mechanical strength. The thickness of the AlN substrate varies according to the different particle energies measured in the detector design. The higher the incident neutron energy, the thicker the thickness of the AlN substrate required to completely deplete its energy.

[0068] Specifically, the semiconductor single crystal substrate and the ohmic contact electrode have the same size. It should be noted that the same size of the semiconductor single crystal substrate and the ohmic contact electrode can reduce the contact 6 The size of the LiF neutron conversion layer is larger than that of the Schottky contact electrode. Resistance, better disperse the current, improve the current transmission efficiency, reduce the performance degradation or damage caused by local overheating of the detector, and improve the stability of the detector.

[0069] The preparation method of the above semiconductor neutron detector of this embodiment is as follows:

[0070] AlN substrate manufacturing steps: Select an AlN substrate with a size of 10 mm × 10 mm and a thickness of 200 μm. Open a square notch with a side length of 3 mm on the side of the AlN substrate. Use the standard RCA cleaning process to remove the organic and inorganic impurities on the surface of the AlN substrate, and blow it dry with a high-purity N2 (purity of 99.999%) gun.

[0071] 6Steps for fabricating the LiF neutron conversion layer: Select LiF powder with a purity of 99.95%, 6 whose 6 Li isotope abundance is 95 atom%. Weigh 0.5 - 2 g of 6 LiF powder and form a mixed solution with 2 - 6 ml of ethanol and acetone. After loading it into a test tube and ultrasonically mixing it evenly, use a dropper to 6 dropwise add the LiF mixed solution into a polished tungsten evaporation boat. Let it stand. After the ethanol and acetone have evaporated, fix the evaporation boat in the chamber of a thermal evaporation coating equipment. Use the thermal evaporation coating equipment to thermally evaporate 6 the LiF neutron conversion layer on the front or back surface of the AlN substrate except at the notch. The background vacuum of the thermal evaporation equipment is better than 4×10 -4 Pa, and segmented coating is adopted. First, coat at a low rate, with the coating rate controlled at 1 - 3 nm / s to control the thermal stress, ensure that the film layer reaches the required thickness while improving the density of the film and making it not easy to fall off, and ensure the coating bonding effect. Later, coat at a high rate, with the rate controlled at 5 - 7 nm / s, and evaporate a 10 - μm - thick 6 LiF neutron conversion layer.

[0072] Steps for fabricating the semiconductor single - crystal substrate: Select a semiconductor single - crystal substrate with a thickness of 500 μm, a surface roughness lower than 6 nm, and a deviation of 4° from the <112—0> direction (for example: 4H - SiC). Use standard RCA cleaning to remove organic and inorganic impurities on the surface of the semiconductor single - crystal substrate, and dry it with a high - purity N2 (purity of 99.999%) gun.

[0073] Steps for fabricating the Schottky contact electrode: After covering a customized mask on the front surface (i.e., the single - crystal epitaxial layer surface) of the cleaned semiconductor single - crystal substrate, thermally evaporate the metal Ni or Ti using a thermal evaporation method to form a patterned Schottky contact electrode. The thickness of the Schottky contact electrode 2 is 100 nm, the shape of the Schottky contact electrode 2 is circular, and the diameter is 9 mm.

[0074] Steps for fabricating the ohmic contact electrode: On the back surface of the cleaned semiconductor single - crystal substrate, sequentially sputter Ni / Pt or Ti / Pt using radio - frequency magnetron sputtering with a thickness of 100 nm to form a back - side ohmic contact electrode. The background vacuum of the magnetron sputtering chamber is 4×10 -4 Pa, the argon flow rate is 40 sccm, and the working pressure is 0.4 Pa. Perform rapid annealing, with the annealing temperature being 600 - 1000 °C, the annealing time being 1 - 5 min, and the annealing atmosphere being N2 or a vacuum atmosphere of less than 4 Pa. Under these conditions, enable the ohmic contact electrode to obtain good ohmic contact with the semiconductor single - crystal substrate.

[0075] Lamination steps: Place 6The groove of the LiF neutron conversion layer is aligned with the Schottky contact electrode, and the Schottky contact electrode is embedded in the groove, so that 6 the LiF neutron conversion layer is attached to the front surface of the semiconductor single crystal substrate.

[0076] Lead connection step: Fix the ohmic contact electrode on the package base with silver paste. Among them, the back electrode external lead is led out from the package base, and the positive electrode external lead is led out through the notch, completing the preparation of the semiconductor neutron detector.

[0077] Example 3: Refer to Figure 1 、 Figures 8 to 10 A semiconductor neutron detector, comprising:

[0078] A semiconductor single crystal substrate 1;

[0079] A Schottky contact electrode 2, which is evaporated on the front surface of the semiconductor single crystal substrate 1. The thickness of the Schottky contact electrode 2 is 120 nm, and the shape of the Schottky contact electrode 2 is oval, with a major diameter of 9 mm and a minor diameter of 8 mm; The Schottky contact electrode 2 has a positive electrode lead-out contact 201 to lead out the positive electrode external lead 202 through the positive electrode lead-out contact 201;

[0080] An ohmic contact electrode 3, which is sputtered on the back surface of the semiconductor single crystal substrate 1. The thickness of the ohmic contact electrode is 120 nm, and the ohmic contact electrode 3 has a back electrode lead-out contact 301 to lead out the back electrode external lead 302 through the back electrode lead-out contact 301;

[0081] An AlN substrate 4, with a thickness of 300 μm. The AlN substrate 4 has a notch 401, and the notch is located on the side of the AlN substrate. The shape of the notch is a rectangle of 3 mm × 2 mm; The notch 401 is arranged opposite to the positive electrode lead-out contact 201 to lead out the positive electrode external lead 202 through the notch 401;

[0082] 6 A LiF neutron conversion layer 5, which is evaporated on the front surface or the back surface of the AlN substrate 4 except at the notch 401, and its thickness is 15 μm; 6 On the side of the LiF neutron conversion layer 5 away from the AlN substrate 4, there is a groove 501 with the same shape and size as the Schottky contact electrode 2, and the Schottky contact electrode 2 is embedded in the groove 501, so that 6 the LiF neutron conversion layer 5 is attached to the semiconductor single crystal substrate 1.

[0083] In a specific embodiment, refer to Figure 5, the above semiconductor neutron detector of this embodiment further includes a packaging base 6. The ohmic contact electrode 3 is pasted on the packaging base 6 through conductive silver paste. The packaging base 6 has an outlet hole (not shown in the figure). The outlet hole is disposed opposite to the back electrode lead-out contact 301 to lead out the back electrode external lead 302 through the outlet hole. Fixing the ohmic contact electrode 3 on the packaging base 6 can, on the one hand, protect the ohmic contact electrode 3 through the packaging base 1 to prevent damage to the ohmic contact electrode 3. On the other hand, the packaging base forms a stable connection with the detector to carry high-frequency signals and couple the detector with an external acquisition circuit to form an effective signal output.

[0084] Specifically, the semiconductor single crystal substrate 1 includes a single crystal matrix 101, a single crystal buffer layer 102 grown on the front surface of the single crystal matrix 101, and a single crystal epitaxial layer 103 grown on the front surface of the single crystal buffer layer 102. The Schottky contact electrode 2 is evaporated on the front surface of the single crystal epitaxial layer 103, and the ohmic contact electrode 3 is sputtered on the back surface of the single crystal matrix 101. The thickness of the single crystal matrix 101 is 400 μm, the thickness of the single crystal epitaxial layer 103 is 50 μm, and the thickness of the buffer layer 102 is 1 μm.

[0085] It should be noted that the thickness of the semiconductor single crystal substrate varies according to the type of single crystal material used after the incident particles are converted into charged particles in the back conversion layer. The higher the energy of the incident charged particles, the thicker the thickness of the semiconductor single crystal substrate required to completely deplete its energy. In addition, the thickness of the semiconductor single crystal substrate also needs to ensure that the overall detector has basic mechanical strength. The thickness of the AlN substrate varies according to the particle energy measured in the detector design. The higher the incident neutron energy, the thicker the thickness of the AlN substrate required to completely deplete its energy.

[0086] Specifically, the semiconductor single crystal substrate and the ohmic contact electrode have the same size. It should be noted that the same size of the semiconductor single crystal substrate and the ohmic contact electrode can reduce the contact resistance, better disperse the current, improve the current transmission efficiency, reduce the performance degradation or damage caused by local overheating of the detector, and improve the stability of the detector. 6 The size of the LiF neutron conversion layer is larger than that of the Schottky contact electrode, which can reduce the contact resistance, better disperse the current, improve the current transmission efficiency, reduce the performance degradation or damage caused by local overheating of the detector, and improve the stability of the detector.

[0087] The preparation method of the above semiconductor neutron detector of this embodiment is as follows:

[0088] AlN substrate manufacturing step: Select an AlN substrate with a size of 10 mm × 10 mm and a thickness of 300 μm. Open a rectangular notch of 3 mm × 2 mm on the side of the AlN substrate. Use the standard RCA cleaning process to remove the organic and inorganic impurities on the surface of the AlN substrate, and blow it dry with a high-purity N2 (purity of 99.999%) gun.

[0089] 6Steps for fabricating the LiF neutron conversion layer: Select LiF powder with a purity of 99.95%, 6 whose 6 Li isotope abundance is 95 atom%. Weigh 0.5 - 2 g of 6 LiF powder, form a mixed solution with 2 - 6 ml of ethanol and acetone. After loading it into a test tube and ultrasonically mixing it evenly, use a dropper to drop the 6 LiF mixed solution drop by drop into a polished tungsten evaporation boat. Let it stand. After the ethanol and acetone have evaporated, fix the evaporation boat in the chamber of a thermal evaporation coating equipment. Use the thermal evaporation coating equipment to thermally evaporate a 6 LiF neutron conversion layer on the front or back surface of the AlN substrate except at the notch. The background vacuum of the thermal evaporation equipment is better than 4×10 -4 Pa, and segmented coating is adopted. First, coat at a low rate, with the coating rate controlled at 1 - 3 nm / s to control the thermal stress, ensure that the film layer reaches the required thickness while improving the density of the film and making it not easy to fall off, and ensure the coating bonding effect. Later, coat at a high rate, with the rate controlled at 5 - 7 nm / s, and evaporate a 15 - μm - thick 6 LiF neutron conversion layer.

[0090] Steps for fabricating the semiconductor single - crystal substrate: Select a semiconductor single - crystal substrate with a thickness of 400 μm, a surface roughness lower than 6 nm, and a deviation of 4° from the <112—0> direction (e.g., 4H - SiC). Adopt standard RCA cleaning to remove organic and inorganic impurities on the surface of the semiconductor single - crystal substrate, and dry it with a high - purity N2 (purity 99.999%) gun.

[0091] Steps for fabricating the Schottky contact electrode: After covering a customized mask on the front surface (i.e., the single - crystal epitaxial layer) of the cleaned semiconductor single - crystal substrate, thermally evaporate the metal Ni or Ti using the thermal evaporation method to form a patterned Schottky contact electrode. The thickness of the Schottky contact electrode 2 is 120 nm, and the shape of the Schottky contact electrode 2 is oval, with a long diameter of 9 mm and a short diameter of 8 mm.

[0092] Steps for fabricating the ohmic contact electrode: On the back surface of the cleaned semiconductor single - crystal substrate, sputter Ni / Pt or Ti / Pt in sequence using the radio - frequency magnetron sputtering method, with a thickness of 120 nm, to form a back - surface ohmic contact electrode. The background vacuum of the magnetron sputtering chamber is 4×10 -4 Pa, the argon flow rate is 40 sccm, and the working pressure is 0.4 Pa. Perform rapid annealing, with the annealing temperature of 600 - 1000 °C, the annealing time of 1 - 5 min, and the annealing atmosphere being N2 or a vacuum atmosphere less than 4 Pa. Under these conditions, make the ohmic contact electrode and the semiconductor single - crystal substrate obtain good ohmic contact.

[0093] Lamination steps: Place 6The groove of the LiF neutron conversion layer is aligned with the Schottky contact electrode, and the Schottky contact electrode is embedded in the groove so that 6 the LiF neutron conversion layer is attached to the front surface of the semiconductor single crystal substrate.

[0094] Lead connection step: Fix the ohmic contact electrode on the package base with silver paste. Among them, the back electrode external lead is led out from the package base, and the positive electrode external lead is led out through the notch, completing the preparation of the semiconductor neutron detector.

[0095] Example 4: Refer to Figure 1 、 Figures 11 to 13 a semiconductor neutron detector, comprising:

[0096] a semiconductor single crystal substrate 1;

[0097] a Schottky contact electrode 2, evaporated on the front surface of the semiconductor single crystal substrate 1, the thickness of the Schottky contact electrode 2 is 100 nm, the shape of the Schottky contact electrode 2 is a rhombus, the length of the long diagonal is 9 mm, and the length of the short diagonal is 8 mm; the Schottky contact electrode 2 has a positive electrode lead-out contact 201 to lead out the positive electrode external lead 202 through the positive electrode lead-out contact 201;

[0098] an ohmic contact electrode 3, sputtered on the back surface of the semiconductor single crystal substrate 1, the thickness of the ohmic contact electrode is 100 nm, and the ohmic contact electrode 3 has a back electrode lead-out contact 301 to lead out the back electrode external lead 302 through the back electrode lead-out contact 301;

[0099] an AlN substrate 4, with a thickness of 300 μm, the AlN substrate 4 has a notch 401, the notch is located on the side of the AlN substrate, and the shape of the notch is a U shape composed of a semicircle with a diameter of 3 mm and a rectangle of 3 mm × 1.5 mm; the notch 401 is disposed opposite to the positive electrode lead-out contact 201 to lead out the positive electrode external lead 202 through the notch 401;

[0100] 6 a LiF neutron conversion layer 5, evaporated on the front surface or the back surface of the AlN substrate 4 except at the notch 401, with a thickness of 10 μm; 6 a groove 501 with the same shape and size as the Schottky contact electrode 2 is provided on the side of the LiF neutron conversion layer 5 away from the AlN substrate 4, and the Schottky contact electrode 2 is embedded in the groove 501 so that 6 the LiF neutron conversion layer 5 is attached to the semiconductor single crystal substrate 1.

[0101] In a specific embodiment, refer to Figure 14, the above-mentioned semiconductor neutron detector of this embodiment further includes a packaging base 6. The ohmic contact electrode 3 is pasted on the packaging base 6 through conductive silver paste. The packaging base 6 has an outlet hole (not shown in the figure), and the outlet hole is disposed opposite to the back electrode lead-out contact 301 to lead out the back electrode external lead 302 through the outlet hole. Fixing the ohmic contact electrode 3 on the packaging base 6 can, on the one hand, protect the ohmic contact electrode 3 through the packaging base 1 to prevent damage to the ohmic contact electrode 3. On the other hand, the packaging base forms a stable connection with the detector to carry high-frequency signals and couple the detector with an external acquisition circuit to form an effective signal output.

[0102] Specifically, the semiconductor single crystal substrate 1 includes a single crystal matrix 101, a single crystal buffer layer 102 grown on the front surface of the single crystal matrix 101, and a single crystal epitaxial layer 103 grown on the front surface of the single crystal buffer layer 102. The Schottky contact electrode 2 is evaporated on the front surface of the single crystal epitaxial layer 103, and the ohmic contact electrode 3 is sputtered on the back surface of the single crystal matrix 101. The thickness of the single crystal matrix 101 is 450 μm, the thickness of the single crystal epitaxial layer 103 is 50 μm, and the thickness of the buffer layer 102 is 1 μm.

[0103] It should be noted that the thickness of the semiconductor single crystal substrate varies according to the different single crystal materials after the incident particles are converted into charged particles in the back conversion layer. The higher the energy of the incident charged particles, the thicker the thickness of the semiconductor single crystal substrate required to completely deplete its energy. In addition, the thickness of the semiconductor single crystal substrate also needs to ensure that the overall detector has basic mechanical strength. The thickness of the AlN substrate varies according to the different particle energies measured in the detector design. The higher the incident neutron energy, the thicker the thickness of the AlN substrate required to completely deplete its energy.

[0104] Specifically, the semiconductor single crystal substrate and the ohmic contact electrode have the same size. It should be noted that the same size of the semiconductor single crystal substrate and the ohmic contact electrode can reduce the contact resistance, better disperse the current, improve the current transmission efficiency, reduce the performance degradation or damage caused by local overheating of the detector, and improve the stability of the detector. 6 The size of the LiF neutron conversion layer is larger than that of the Schottky contact electrode, which can reduce the contact resistance, better disperse the current, improve the current transmission efficiency, reduce the performance degradation or damage caused by local overheating of the detector, and improve the stability of the detector.

[0105] The preparation method of the above-mentioned semiconductor neutron detector of this embodiment is as follows:

[0106] AlN substrate manufacturing steps: Select an AlN substrate with a size of 10 mm × 10 mm and a thickness of 300 μm. Open a U-shaped notch composed of a semicircle with a diameter of 3 mm and a rectangle of 3 mm × 1.5 mm on the side of the AlN substrate. Use the standard RCA cleaning process to remove organic and inorganic impurities on the surface of the AlN substrate, and blow it dry with a high-purity N2 (purity of 99.999%) gun.

[0107] 6 Steps for fabricating the LiF neutron conversion layer: Select LiF powder with a purity of 99.95%, 6 whose 6 Li isotope abundance is 95 atom%. Weigh 0.5 - 2 g of 6 LiF powder, mix it with 2 - 6 ml of ethanol and acetone to form a mixed solution. After ultrasonic mixing in a test tube until homogeneous, use a dropper to 6 dropwise add the LiF mixed solution into a polished tungsten evaporation boat. Let it stand. After the ethanol and acetone have evaporated, fix the evaporation boat in the chamber of a thermal evaporation coating equipment. Use the thermal evaporation coating equipment to thermally evaporate a 6 LiF neutron conversion layer on the front or back surface of the AlN substrate except at the notch. The background vacuum of the thermal evaporation equipment is better than 4×10 -4 Pa, and segmented coating is adopted. First, coat at a low rate, with the coating rate controlled at 1 - 3 nm / s to control the thermal stress, ensure that the film layer reaches the required thickness while improving the density of the film and making it not easy to fall off, and ensure the coating bonding effect. Later, coat at a high rate, with the rate controlled at 5 - 7 nm / s, and evaporate a 10μm 6 LiF neutron conversion layer.

[0108] Steps for fabricating the semiconductor single crystal substrate: Select a semiconductor single crystal substrate with a thickness of 450μm, a surface roughness lower than 6nm, and a deviation of 4° from the <112—0> direction (for example: 4H - SiC). Use standard RCA cleaning to remove organic and inorganic impurities on the surface of the semiconductor single crystal substrate, and dry it with a high - purity N2 (purity 99.999%) gun.

[0109] Steps for fabricating the Schottky contact electrode: After covering a customized mask on the front surface (i.e., the single - crystal epitaxial layer surface) of the cleaned semiconductor single crystal substrate, thermally evaporate the metal Ni or Ti using a thermal evaporation method to form a patterned Schottky contact electrode. The thickness of the Schottky contact electrode 2 is 100nm, the shape of the Schottky contact electrode 2 is a rhombus, the length of the long diagonal is 9mm, and the length of the short diagonal is 8mm.

[0110] Steps for fabricating the ohmic contact electrode: On the back surface of the cleaned semiconductor single crystal substrate, sequentially sputter Ni / Pt or Ti / Pt using radio - frequency magnetron sputtering with a thickness of 100 nm to form a back - side ohmic contact electrode. The background vacuum of the magnetron sputtering chamber is 4×10 -4 Pa, the argon flow rate is 40 sccm, and the working pressure is 0.4 Pa. Perform rapid annealing, with the annealing temperature at 600 - 1000℃, the annealing time at 1 - 5 min, and the annealing atmosphere being N2 or a vacuum atmosphere less than 4 Pa. Under these conditions, make the ohmic contact electrode and the semiconductor single crystal substrate obtain good ohmic contact.

[0111] Laminating step: Align the groove of the 6 LiF neutron conversion layer with the Schottky contact electrode, embed the Schottky contact electrode into the groove, and make 6 the LiF neutron conversion layer laminate to the front surface of the semiconductor single crystal substrate.

[0112] Lead connection step: Fix the ohmic contact electrode on the package base with silver paste. Among them, the external lead of the back electrode is led out from the package base, and the external lead of the positive electrode is led out through the notch, completing the preparation of the semiconductor neutron detector.

[0113] The above embodiments are used to explain the present invention, rather than limiting the present invention. Any modification and change made to the present invention within the spirit and scope of the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A semiconductor neutron detector, characterized in that, Comprising: A semiconductor single crystal substrate; A Schottky contact electrode, evaporated on the front surface of the semiconductor single crystal substrate, the Schottky contact electrode having a positive electrode lead-out contact for leading out a positive electrode external lead through the positive electrode lead-out contact; An ohmic contact electrode, sputtered on the back surface of the semiconductor single crystal substrate, the ohmic contact electrode having a back electrode lead-out contact for leading out a back electrode external lead through the back electrode lead-out contact; An AlN substrate having a notch, the notch being disposed opposite to the positive electrode lead-out contact for leading out the positive electrode external lead through the notch; 6 The LiF neutron conversion layer is vapor-deposited on the front or back surface of the AlN substrate except at the notch. 6 A groove with the same shape and size as the Schottky contact electrode is provided on the side of the LiF neutron conversion layer away from the AlN substrate, and the Schottky contact electrode is embedded in the groove so that 6 the LiF neutron conversion layer is bonded to the semiconductor single crystal substrate.

2. The semiconductor neutron detector according to claim 1, characterized in that, The semiconductor neutron detector further includes a packaging base, the semiconductor single crystal substrate is fixed on the packaging base, the packaging base having an outlet hole disposed opposite to the back electrode lead-out contact for leading out the back electrode external lead through the outlet hole.

3. The semiconductor neutron detector according to claim 1 or 2, characterized in that, The semiconductor single crystal substrate includes a single crystal matrix, a single crystal buffer layer grown on the front surface of the single crystal matrix, and a single crystal epitaxial layer grown on the front surface of the single crystal buffer layer, the Schottky contact electrode is evaporated on the front surface of the single crystal epitaxial layer, and the ohmic contact electrode is sputtered on the back surface of the single crystal matrix.

4. The semiconductor neutron detector according to claim 3, wherein The thickness of the semiconductor single crystal substrate is 0.3 - 10 mm, wherein the thickness of the epitaxial layer is 5 - 200 μm, and the thickness of the buffer layer is 0.01 - 1 μm.

5. The semiconductor neutron detector according to claim 1 or 2, characterized in that, The thickness of the Schottky contact electrode is 50 - 120 nm, and the shape of the Schottky contact electrode is square, or circular, or oval, or rhombic; when the shape of the Schottky contact electrode is square, the side length is 7 - 9 mm; when the shape of the Schottky contact electrode is circular or rhombic, the diameter is 7 - 9 mm; when the shape of the Schottky contact electrode is oval, the major diameter is 7 - 9 mm; when the shape of the Schottky contact electrode is rhombic, the major diagonal is 7 - 9 mm.

6. The semiconductor neutron detector according to claim 1 or 2, wherein The thickness of the ohmic contact electrode is 50 - 120 nm.

7. The semiconductor neutron detector according to claim 1 or 2, characterized in that, The thickness of the AlN substrate is 50 - 500 μm.

8. The semiconductor neutron detector according to claim 1 or 2, wherein The notch is located at the corner, or side edge, or center of the AlN substrate, and the shape of the notch is a geometric shape or an irregular shape.

9. The semiconductor neutron detector according to claim 1 or 2, characterized in that, 6 The thickness of the LiF neutron conversion layer is 5 - 20 μm.

10. The semiconductor neutron detector according to claim 1 or 2, characterized in that, The semiconductor single crystal substrate and the ohmic contact electrode have the same size.

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