X-ray semiconductor detector and method for producing same

Abstract

An X-ray semiconductor detector (2) comprises a first i-type nitride semiconductor substrate (10), a second i-type nitride semiconductor substrate (15), a p-type semiconductor layer (20), an n-type semiconductor layer (22), a first electrode (25), and a second electrode (26). The first i-type nitride semiconductor substrate (10) includes a first gallium surface (11). The second i-type nitride semiconductor substrate includes a second gallium surface (17). The p-type semiconductor layer (20) is formed on the first gallium surface. The n-type semiconductor layer (22) is formed on the second gallium surface. The first electrode (25) is formed on the p-type semiconductor layer (20). The second electrode (26) is formed on the n-type semiconductor layer (22).

Description

X-ray semiconductor detector and method for manufacturing the same

[0001] This disclosure relates to an X-ray semiconductor detector and a method for manufacturing the same.

[0002] Japanese Patent Publication No. 2002-503389 (Patent Document 1) discloses an X-ray detection device. This X-ray detection device comprises an i-type semiconductor layer having a first surface portion and a second surface portion, a p-type semiconductor region on the first surface portion, an n-type semiconductor region on the second surface portion, a first electrical contact on the p-type semiconductor region, and a second electrical contact on the n-type semiconductor region. The i-type semiconductor layer is made of In ｘ Ga １－ｘ It is formed by N, and x is between 0 and 40%.

[0003] Special Publication No. 2002-503389

[0004] The first object of this disclosure is to provide an X-ray semiconductor detector having improved detection sensitivity for X-rays. The second object of this disclosure is to provide an X-ray semiconductor detector having improved detection accuracy for X-rays.

[0005] An X-ray semiconductor detector in the first aspect of this disclosure comprises a first i-type nitride semiconductor substrate, a second i-type nitride semiconductor substrate, a p-type semiconductor layer, an n-type semiconductor layer, a first electrode, and a second electrode. The first i-type nitride semiconductor substrate includes a first gallium plane and a first nitrogen plane opposite to the first gallium plane. The second i-type nitride semiconductor substrate includes a second gallium plane and a second nitrogen plane opposite to the second gallium plane. The second nitrogen plane faces the first nitrogen plane. The p-type semiconductor layer is formed on the first gallium plane. The n-type semiconductor layer is formed on the second gallium plane. The first electrode is formed on the p-type semiconductor layer. The second electrode is formed on the n-type semiconductor layer.

[0006] The X-ray semiconductor detector of the second aspect of this disclosure comprises a first i-type nitride semiconductor substrate, a second i-type nitride semiconductor substrate, a two-dimensional semiconductor layer, a p-type semiconductor layer, an n-type semiconductor layer, a first electrode, and a second electrode. The first i-type nitride semiconductor substrate includes a first surface and a second surface opposite to the first surface. The second i-type nitride semiconductor substrate includes a third surface facing the second surface and a fourth surface opposite to the third surface. The two-dimensional semiconductor layer is joined to the second surface and the third surface by van der Waals forces. The p-type semiconductor layer is formed on the first surface. The n-type semiconductor layer is formed on the fourth surface. The first electrode is formed on the p-type semiconductor layer. The second electrode is formed on the n-type semiconductor layer. The bandgap energy of the two-dimensional semiconductor layer is smaller than the bandgap energy of the first i-type nitride semiconductor substrate and smaller than the bandgap energy of the second i-type nitride semiconductor substrate.

[0007] An X-ray semiconductor detector of the third aspect of this disclosure comprises at least one i-type nitride semiconductor substrate, a p-type semiconductor layer, an n-type semiconductor layer, a first electrode, and a second electrode. The at least one i-type nitride semiconductor substrate includes a gallium plane and a nitrogen plane opposite to the gallium plane. The p-type semiconductor layer is formed on the nitrogen plane. The n-type semiconductor layer is formed on the gallium plane. The first electrode is formed on the p-type semiconductor layer. The second electrode is formed on the n-type semiconductor layer.

[0008] A method for manufacturing an X-ray semiconductor detector according to the first aspect of this disclosure includes forming a first type i nitride semiconductor substrate on a first growth substrate. The first type i nitride semiconductor substrate includes a first surface and a second surface opposite to the first surface and facing the first growth substrate. The first surface is a first gallium surface. The second surface is a first nitrogen surface. A method for manufacturing an X-ray semiconductor detector according to the first aspect of this disclosure includes forming a p-type semiconductor layer on the first surface of the first type i nitride semiconductor substrate and removing the first growth substrate from the first type i nitride semiconductor substrate. A method for manufacturing an X-ray semiconductor detector according to the first aspect of this disclosure includes forming a second type i nitride semiconductor substrate on a second growth substrate. The second type i nitride semiconductor substrate includes a third surface facing the second growth substrate and a fourth surface opposite to the third surface. The third surface is a second nitrogen surface. The fourth surface is a second gallium surface. A method for manufacturing an X-ray semiconductor detector according to the first aspect of this disclosure includes forming an n-type semiconductor layer on the fourth surface of a second i-type nitride semiconductor substrate, removing a second growth substrate from the second i-type nitride semiconductor substrate, and bonding the first i-type nitride semiconductor substrate and the second i-type nitride semiconductor substrate together by facing the second surface of the first i-type nitride semiconductor substrate and the third surface of the second i-type nitride semiconductor substrate toward each other. A method for manufacturing an X-ray semiconductor detector according to the first aspect of this disclosure also includes forming a first electrode on a p-type semiconductor layer and forming a second electrode on an n-type semiconductor layer.

[0009] A method for manufacturing an X-ray semiconductor detector according to the second aspect of this disclosure includes forming a p-type semiconductor layer on a first growth substrate. The surface of the p-type semiconductor layer opposite to the first growth substrate is a gallium surface. A method for manufacturing an X-ray semiconductor detector according to the second aspect of this disclosure includes forming a first i-type nitride semiconductor substrate on the surface of the p-type semiconductor layer. The first i-type nitride semiconductor substrate includes a first surface facing the p-type semiconductor layer and a second surface opposite to the first surface. The first surface is a first nitrogen surface. The second surface is a first gallium surface. A method for manufacturing an X-ray semiconductor detector according to the second aspect of this disclosure includes removing the first growth substrate from the p-type semiconductor layer. A method for manufacturing an X-ray semiconductor detector according to the second aspect of this disclosure includes forming a second i-type nitride semiconductor substrate on a second growth substrate. The second i-type nitride semiconductor substrate includes a third surface facing the second growth substrate and a fourth surface opposite to the third surface. The third surface is a second nitrogen surface. The fourth surface is the second gallium surface. A method for manufacturing an X-ray semiconductor detector of the second aspect of this disclosure includes forming an n-type semiconductor layer on the fourth surface of the second i-type nitride semiconductor substrate, removing the second growth substrate from the second i-type nitride semiconductor substrate, and bonding the first i-type nitride semiconductor substrate and the second i-type nitride semiconductor substrate together by facing the second surface of the first i-type nitride semiconductor substrate and the third surface of the second i-type nitride semiconductor substrate toward each other. A method for manufacturing an X-ray semiconductor detector of the second aspect of this disclosure includes forming a first electrode on a p-type semiconductor layer and forming a second electrode on an n-type semiconductor layer.

[0010] The X-ray semiconductor detector in the first aspect of this disclosure and the X-ray semiconductor detector in the third aspect of this disclosure have improved detection sensitivity for X-rays. The X-ray semiconductor detector in the second aspect of this disclosure has improved detection accuracy for X-rays. The method for manufacturing the X-ray semiconductor detector in the first aspect of this disclosure and the method for manufacturing the X-ray semiconductor detector in the second aspect of this disclosure can provide an X-ray semiconductor detector having improved detection sensitivity for X-rays.

[0011] Figure 1 is a schematic cross-sectional view showing an X-ray semiconductor detector according to Embodiment 1. Figure 2 is a flowchart showing the manufacturing method of the X-ray semiconductor detector according to Embodiment 1. Figure 3 is a schematic partially enlarged cross-sectional view showing one step in the manufacturing method of the X-ray semiconductor detector according to Embodiment 1. Figure 4 is a schematic partially enlarged cross-sectional view showing another step in the manufacturing method of the X-ray semiconductor detector according to Embodiment 1. Figure 5 is a schematic cross-sectional view showing an X-ray semiconductor detector according to Embodiment 2. Figure 6 is a diagram showing the energy band of the X-ray semiconductor detector when a reverse bias voltage is applied to the X-ray semiconductor detector according to Embodiment 2. Figure 7 is a flowchart showing the manufacturing method of the X-ray semiconductor detector according to Embodiment 2. Figure 8 is a schematic cross-sectional view showing an X-ray semiconductor detector according to Embodiment 3. Figure 9 is a schematic cross-sectional view showing an X-ray semiconductor detector according to Embodiment 4. Figure 10 is a flowchart showing the manufacturing method of the X-ray semiconductor detector according to Embodiment 4. Figure 11 is a schematic partially enlarged cross-sectional view showing one step in the manufacturing method of the X-ray semiconductor detector according to Embodiment 4. Figure 12 is a schematic partially enlarged cross-sectional view showing another step in the manufacturing method of the X-ray semiconductor detector according to Embodiment 4. Figure 13 is a schematic cross-sectional view showing a modified example of the X-ray semiconductor detector according to Embodiment 4. Figure 14 is a flowchart showing a method for manufacturing an X-ray semiconductor detector according to a modified example of Embodiment 4. Figure 15 is a schematic cross-sectional view showing an X-ray semiconductor detection device according to Embodiment 5. Figure 16 is a flowchart showing a method for manufacturing an X-ray semiconductor detector according to Embodiment 5. Figure 17 is a schematic cross-sectional view showing an X-ray semiconductor detection device according to Embodiment 6. Figure 18 is a schematic partially enlarged cross-sectional view showing an X-ray semiconductor detector according to Embodiment 7. Figure 19 is a schematic plan view showing an X-ray semiconductor detection device according to Embodiment 8.

[0012] Embodiments of the present disclosure will be described below. The same components will be given the same reference numerals, and their descriptions will not be repeated.

[0013] Embodiment 1. The X-ray semiconductor detection device 1 of Embodiment 1 will be described with reference to Figure 1. The X-ray semiconductor detection device 1 of this embodiment can be mounted on, for example, an X-ray diagnostic device such as a mammography device, an X-ray computed tomography device, or a satellite.

[0014] The X-ray semiconductor detector device 1 includes an X-ray semiconductor detector 2, an electrical connection member 31, and a detection circuit 32. The X-ray semiconductor detector device 1 may further include a voltage source 40. The X-ray semiconductor detector 2 includes a semiconductor laminate 5, a first electrode 25, and a second electrode 26. The semiconductor laminate 5 includes a first i-type nitride semiconductor substrate 10, a second i-type nitride semiconductor substrate 15, a p-type semiconductor layer 20, and an n-type semiconductor layer 22.

[0015] The first i-type nitride semiconductor substrate 10 is, for example, an i-type gallium nitride substrate. The first i-type nitride semiconductor substrate 10 has, for example, an electrical resistivity of 1×10 ６ Ωcm or more. The first i-type nitride semiconductor substrate 10 is a high-purity nitride semiconductor substrate. For example, the concentration of silicon (Si) as an impurity contained in the first i-type nitride semiconductor substrate 10 is 1×10 １５ atms / cm ３ or less. The concentration of boron (B) as an impurity contained in the first i-type nitride semiconductor substrate 10 is 1×10 １５ atms / cm ３ or less. The concentration of oxygen (O) as an impurity contained in the first i-type nitride semiconductor substrate 10 is 1×10 １５ atms / cm ３ or less. The concentration of iron (Fe) as an impurity contained in the first i-type nitride semiconductor substrate 10 is 1×10 １５ atms / cm ３ or less.

[0016] The first i-type nitride semiconductor substrate 10 includes a first surface 11 and a second surface 12 opposite to the first surface 11. The first surface 11 is terminated with a gallium (Ga) atomic layer and is a gallium surface (Ga surface). The second surface 12 is terminated with a nitrogen (N) atomic layer and is a nitrogen surface (N surface). The Ga surface is a chemically more stable surface than the N surface. A plurality of through dislocations 13 exist in the first i-type nitride semiconductor substrate 10. The plurality of through dislocations 13 extend, for example, from the first surface 11 to the second surface 12.

[0017] The thickness of the first type i nitride semiconductor substrate 10 is, for example, 400 μm or more. As the distance over which the X-rays 50 pass through the first type i nitride semiconductor substrate 10 increases, the detection sensitivity of the X-ray semiconductor detector 2 for the X-rays 50 is improved. The thickness of the first type i nitride semiconductor substrate 10 is determined by the distance between the first surface 11 and the second surface 12.

[0018] The second type i nitride semiconductor substrate 15 is, for example, a type i gallium nitride substrate. The second type i nitride semiconductor substrate 15 may be formed from the same material as the first type i nitride semiconductor substrate 10. The second type i nitride semiconductor substrate 15 is, for example, 1 × 10 ６ It has an electrical resistivity of Ωcm or more. The second i-type nitride semiconductor substrate 15 is a high-purity nitride semiconductor substrate. For example, the concentration of silicon (Si) as an impurity contained in the second i-type nitride semiconductor substrate 15 is 1 × 10⁻⁶ １５ atms / cm ３ It is less than 1 × 10⁻¹⁰. The concentration of boron (B) as an impurity in the second i-type nitride semiconductor substrate 15 is 1 × 10⁻¹⁰. １５ atms / cm ３ It is less than 1 × 10⁻¹⁰. The concentration of oxygen (O) as an impurity contained in the second i-type nitride semiconductor substrate 15 is 1 × 10⁻¹⁰. １５ atms / cm ３ It is less than 1 × 10⁻¹⁰. The concentration of iron (Fe) as an impurity in the second i-type nitride semiconductor substrate 15 is 1 × 10⁻¹⁰. １５ atms / cm ３ It is less than.

[0019] The second i-type nitride semiconductor substrate 15 includes a third surface 16 and a fourth surface 17 opposite to the third surface 16. The third surface 16 of the second i-type nitride semiconductor substrate 15 faces the second surface 12 of the first i-type nitride semiconductor substrate 10. The third surface 16 of the second i-type nitride semiconductor substrate 15 is in contact with the second surface 12 of the first i-type nitride semiconductor substrate 10. The first i-type nitride semiconductor substrate 10 has a dangling bond on its second surface 12. The second i-type nitride semiconductor substrate 15 has a dangling bond on its third surface 16. Therefore, the second i-type nitride semiconductor substrate 15 is bonded to the first i-type nitride semiconductor substrate 10 by covalent bonds. The third surface 16 is terminated by a nitrogen (N) atomic layer and is the nitrogen surface (N surface). The fourth surface 17 is terminated by a gallium (Ga) atomic layer and is a gallium surface (Ga surface). Multiple threading dislocations 18 exist in the second i-type nitride semiconductor substrate 15. These threading dislocations 18 extend, for example, from the third surface 16 to the fourth surface 17.

[0020] The thickness of the second type i nitride semiconductor substrate 15 is, for example, 400 μm or more. As the distance over which the X-rays 50 pass through the second type i nitride semiconductor substrate 15 increases, the detection sensitivity of the X-ray semiconductor detector 2 for the X-rays 50 is improved. The thickness of the second type i nitride semiconductor substrate 15 is determined by the distance between the third surface 16 and the fourth surface 17.

[0021] The p-type semiconductor layer 20 is, for example, a nitride semiconductor layer doped with a p-type dopant. The p-type semiconductor layer 20 is, for example, a p-type gallium nitride layer. The p-type dopant is, for example, magnesium (Mg). The p-type semiconductor layer 20 is formed on the first surface 11 of the first i-type nitride semiconductor substrate 10.

[0022] The n-type semiconductor layer 22 is, for example, a nitride semiconductor layer doped with an n-type dopant. The n-type semiconductor layer 22 is, for example, an n-type gallium nitride layer. The n-type dopant is, for example, silicon (Si). The n-type semiconductor layer 22 is formed on the fourth surface 17 of the second i-type nitride semiconductor substrate 15. The p-type semiconductor layer 20, the first i-type nitride semiconductor substrate 10, the second i-type nitride semiconductor substrate 15, and the n-type semiconductor layer 22 form a PIN junction.

[0023] The first electrode 25 is formed on the p-type semiconductor layer 20 and is a p-type electrode. The first electrode 25 is, for example, a Ni / Au electrode. The semiconductor laminate 5 includes a plurality of pixels (for example, the first pixel 2a, the second pixel 2b, and the third pixel 2c). The first electrode 25 is formed, for example, across a plurality of pixels.

[0024] The second electrode 26 is formed on the n-type semiconductor layer 22 and is an n-type electrode. The second electrode 26 is, for example, a Ti / Al / Ti / Au electrode. The second electrode 26 is formed, for example, separately for each of the plurality of pixels of the semiconductor laminate 5.

[0025] The voltage source 40 supplies a reverse bias voltage between the first electrode 25 and the second electrode 26. Specifically, the voltage applied to the first electrode 25 is lower than the voltage applied to the second electrode 26.

[0026] The electrical connection member 31 electrically connects each of the second electrodes 26 and the detection circuit 32 to each other. The electrical connection member 31 is, for example, a conductive bump such as a solder bump or an electrical wiring such as a copper wiring.

[0027] The detection circuit 32 detects the magnitude of the current pulse of each of the plurality of pixels (the first pixel 2a, the second pixel 2b, the third pixel 2c) of the semiconductor laminate 5 when the X-ray 50 is incident on the X-ray semiconductor detector 2. The detection circuit 32 is, for example, a semiconductor integrated circuit.

[0028] An example of a method for manufacturing the X-ray semiconductor detector 2 and the X-ray semiconductor detection device 1 according to the present embodiment will be described.

[0029] The first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 are created by hydride vapor phase epitaxy (HVPE). A p-type semiconductor layer 20 is formed on the first surface 11 of the first i-type nitride semiconductor substrate 10 by metalorganic chemical vapor deposition (MOCVD). In the present embodiment, the first surface 11 is a Ga surface. An n-type semiconductor layer 22 is formed on the fourth surface 17 of the second i-type nitride semiconductor substrate 15 by MOCVD. In the present embodiment, the fourth surface 17 is a Ga surface.

[0030] While bringing the second surface 12 of the first i-type nitride semiconductor substrate 10 into contact with the third surface 16 of the second i-type nitride semiconductor substrate 15, the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 are heat-treated to bond the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 together. In the present embodiment, the second surface 12 and the third surface 16 are N surfaces. The first electrode 25 is formed on the p-type semiconductor layer 20 by vapor deposition. The second electrode 26 is formed on the n-type semiconductor layer 22 by vapor deposition. Thus, the X-ray semiconductor detector 2 is obtained.

[0031] Referring to FIGS. 2 to 4, a specific example of the manufacturing method of the X-ray semiconductor detector 2 described above will be described.

[0032] Referring to FIGS. 2 and 3, the first i-type nitride semiconductor substrate 10 is formed on the first growth substrate 52 by the HVPE method (step S1).

[0033] The first growth substrate 52 is, for example, a gallium nitride (GaN) template 53. The GaN template 53 includes a sapphire substrate 54, a low-temperature grown GaN layer 55 formed on the sapphire substrate 54, and a GaN buffer layer 56 formed on the low-temperature grown GaN layer 55. The thickness of the low-temperature grown GaN layer 55 is, for example, 10 nm. The thickness of the GaN buffer layer 56 is larger than the thickness of the low-temperature grown GaN layer 55 and is, for example, 0.1 µm. The outermost surface of the GaN buffer layer 56 (the surface of the GaN buffer layer 56 on the side opposite to the sapphire substrate 54) is a Ga surface. A mask layer 58 having a plurality of openings is formed on the GaN buffer layer 56. The mask layer 58 is, for example, a SiO ２ layer.

[0034] The first i-type nitride semiconductor substrate 10 is formed on a GaN template 53 (more specifically, a GaN buffer layer 56) by an epitaxial transverse growth (ELO) method using a mask layer 58. Therefore, the density of threading dislocations 13 in the first i-type nitride semiconductor substrate 10 can be reduced. The first i-type nitride semiconductor substrate 10 includes a first surface 11 opposite to the first growth substrate 52 and a second surface 12 opposite to the first surface 11. The first surface 11 is a Ga surface. The second surface 12 faces the first growth substrate 52 and is an N surface.

[0035] Referring to Figures 2 and 3, a p-type semiconductor layer 20 is formed on the first surface 11 of the first i-type nitride semiconductor substrate 10 by the MOCVD method (step S2). In nitride semiconductors, the gallium surface is a more chemically stable surface than the nitrogen surface. Therefore, when forming the p-type semiconductor layer 20 on the first surface 11 of the first i-type nitride semiconductor substrate 10, the detachment of nitrogen atoms from the first i-type nitride semiconductor substrate 10 is suppressed. This prevents deterioration of the crystallinity of the first i-type nitride semiconductor substrate 10.

[0036] Referring to Figure 2, the first growth substrate 52 is removed from the first i-type nitride semiconductor substrate 10 (step S3). Specifically, when the temperature of the laminate of the first i-type nitride semiconductor substrate 10, the p-type semiconductor layer 20, and the first growth substrate 52 is lowered from the growth temperature of the p-type semiconductor layer 20 to room temperature, the first i-type nitride semiconductor substrate 10 peels off from the first growth substrate 52 and the mask layer 58 due to the difference between the thermal expansion coefficient of the first i-type nitride semiconductor substrate 10 and the thermal expansion coefficient of the sapphire substrate 54.

[0037] Referring to Figures 2 and 4, a second i-type nitride semiconductor substrate 15 is formed on the second growth substrate 60 by the HVPE method (step S4).

[0038] The second growth substrate 60 is, for example, a GaN template 61. The GaN template 61 includes a sapphire substrate 62, a low-temperature grown GaN layer 63 formed on the sapphire substrate 62, and a GaN buffer layer 64 formed on the low-temperature grown GaN layer 63. The thickness of the low-temperature grown GaN layer 63 is, for example, 10 nm. The thickness of the GaN buffer layer 64 is greater than the thickness of the low-temperature grown GaN layer 63, for example, 0.1 μm. The outermost surface of the GaN buffer layer 64 (the surface of the GaN buffer layer 64 opposite to the sapphire substrate 62) is the Ga surface. A mask layer 65 with a plurality of openings is formed on the GaN buffer layer 64. The mask layer 65 is, for example, SiO ２ It is a layer.

[0039] The second i-type nitride semiconductor substrate 15 is formed on a GaN template 61 (more specifically, a GaN buffer layer 64) by epitaxial lateral growth (ELO) using a mask layer 65. Therefore, the density of threading dislocations 18 in the second i-type nitride semiconductor substrate 15 can be reduced. The second i-type nitride semiconductor substrate 15 includes a third surface 16 facing the second growth substrate 60 and a fourth surface 17 opposite to the third surface 16. The third surface 16 is an N surface. The fourth surface 17 is a Ga surface.

[0040] Referring to Figures 2 and 4, an n-type semiconductor layer 22 is formed on the fourth surface 17 of the second i-type nitride semiconductor substrate 15 by the MOCVD method (step S5). In nitride semiconductors, the gallium surface is a more chemically stable surface than the nitrogen surface. Therefore, when forming the n-type semiconductor layer 22 on the fourth surface 17 of the second i-type nitride semiconductor substrate 15, the detachment of nitrogen atoms from the second i-type nitride semiconductor substrate 15 is suppressed. This prevents deterioration of the crystallinity of the second i-type nitride semiconductor substrate 15.

[0041] Referring to Figure 2, the second growth substrate 60 is removed from the second i-type nitride semiconductor substrate 15 (step S6). Specifically, when the temperature of the laminate of the second i-type nitride semiconductor substrate 15, the n-type semiconductor layer 22, and the second growth substrate 60 is lowered from the growth temperature of the n-type semiconductor layer 22 to room temperature, the second i-type nitride semiconductor substrate 15 peels off from the second growth substrate 60 and the mask layer 65 due to the difference between the thermal expansion coefficient of the second i-type nitride semiconductor substrate 15 and the thermal expansion coefficient of the sapphire substrate 62.

[0042] Referring to Figure 2, the second surface 12 of the first i-type nitride semiconductor substrate 10 and the third surface 16 of the second i-type nitride semiconductor substrate 15 are placed facing each other, and the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 are bonded together (step S7). Specifically, the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 are heat-treated while the second surface 12 of the first i-type nitride semiconductor substrate 10 and the third surface 16 of the second i-type nitride semiconductor substrate 15 are in contact with each other.

[0043] A first electrode 25 is formed on the p-type semiconductor layer 20 by vapor deposition (step S8). A second electrode 26 is formed on the n-type semiconductor layer 22 by vapor deposition (step S9). In this way, an X-ray semiconductor detector 2 is obtained.

[0044] Next, the second electrode 26 of the X-ray semiconductor detector 2 is electrically connected to the detection circuit 32 using the electrical connection member 31. The voltage source 40 is connected to the first electrode 25 and the second electrode 26. In this way, the X-ray semiconductor detection device 1 is obtained.

[0045] The operation of the X-ray semiconductor detection apparatus 1 and X-ray semiconductor detector 2 of this embodiment will now be described. X-rays 50 are incident on the X-ray semiconductor detector 2. Carriers (electrons and holes) are generated in the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15. The p-type semiconductor layer 20, the first i-type nitride semiconductor substrate 10, the second i-type nitride semiconductor substrate 15, and the n-type semiconductor layer 22 form a PIN junction. Due to the internal electric field of the PIN junction, holes move to the first electrode 25 and electrons move to the second electrode 26. When the voltage source 40 is connected to the X-ray semiconductor detector 2, the internal electric field of the PIN junction and the reverse bias voltage supplied from the voltage source 40 to the X-ray semiconductor detector 2 cause holes to move to the first electrode 25 and electrons to move to the second electrode 26. In this way, a current pulse corresponding to the intensity of the X-rays 50 (number of photons of X-rays 50) is generated. The current pulse flows through the electrical connection member 31 to the detection circuit 32. The detection circuit 32 detects the magnitude of the current pulses of each of the multiple pixels (for example, the first pixel 2a, the second pixel 2b, and the third pixel 2c) of the semiconductor laminate 5. In this way, the intensity of the X-rays 50 incident on each of the multiple pixels of the semiconductor laminate 5 is measured.

[0046] The effects of the X-ray semiconductor detector 2 of this embodiment and its manufacturing method will be described. The X-ray semiconductor detector 2 of this embodiment comprises a first i-type nitride semiconductor substrate 10, a second i-type nitride semiconductor substrate 15, a p-type semiconductor layer 20, an n-type semiconductor layer 22, a first electrode 25, and a second electrode 26. The first i-type nitride semiconductor substrate 10 includes a first gallium surface (first surface 11) and a first nitrogen surface (second surface 12) opposite to the first gallium surface. The second i-type nitride semiconductor substrate 15 includes a second gallium surface (fourth surface 17) and a second nitrogen surface (third surface 16) opposite to the second gallium surface. The second nitrogen surface faces the first nitrogen surface. The p-type semiconductor layer 20 is formed on the first gallium surface. The n-type semiconductor layer 22 is formed on the second gallium surface. The first electrode 25 is formed on the p-type semiconductor layer 20. The second electrode 26 is formed on the n-type semiconductor layer 22.

[0047] The p-type semiconductor layer 20 is formed on the first gallium surface (first surface 11) of the first i-type nitride semiconductor substrate 10, and the n-type semiconductor layer 22 is formed on the second gallium surface (fourth surface 17) of the second i-type nitride semiconductor substrate 15. In nitride semiconductors, the gallium surface is a more chemically stable surface than the nitrogen surface. Therefore, when forming the p-type semiconductor layer 20 and the n-type semiconductor layer 22, the desorption of nitrogen atoms from the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 is suppressed. This prevents deterioration of the crystallinity of the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15. The detection sensitivity of the X-rays 50 of the X-ray semiconductor detector 2 is improved.

[0048] In the X-ray semiconductor detector 2 of this embodiment, the second nitrogen surface (third surface 16) is in contact with the first nitrogen surface (second surface 12).

[0049] The p-type semiconductor layer 20 is formed on the first gallium surface (first surface 11) of the more chemically stable first i-type nitride semiconductor substrate 10. The n-type semiconductor layer 22 is formed on the second gallium surface (fourth surface 17) of the more chemically stable second i-type nitride semiconductor substrate 15. As a result, the detection sensitivity of the X-rays 50 of the X-ray semiconductor detector 2 is improved.

[0050] The method for manufacturing the X-ray semiconductor detector 2 of this embodiment includes forming a first i-type nitride semiconductor substrate 10 on a first growth substrate 52 (step S1). The first i-type nitride semiconductor substrate 10 includes a first surface 11 and a second surface 12 that is opposite to the first surface 11 and faces the first growth substrate 52. The first surface 11 is the first gallium surface. The second surface 12 is the first nitrogen surface. The method for manufacturing the X-ray semiconductor detector 2 of this embodiment includes forming a p-type semiconductor layer 20 on the first surface 11 of the first i-type nitride semiconductor substrate 10 (step S2) and removing the first growth substrate 52 from the first i-type nitride semiconductor substrate 10 (step S3). The method for manufacturing the X-ray semiconductor detector 2 of this embodiment includes forming a second i-type nitride semiconductor substrate 15 on a second growth substrate 60 (step S4). The second i-type nitride semiconductor substrate 15 includes a third surface 16 facing the second growth substrate 60 and a fourth surface opposite to the third surface 16. The third surface 16 is the second nitrogen surface. The fourth surface 17 is the second gallium surface. The manufacturing method of the X-ray semiconductor detector 2 of this embodiment includes forming an n-type semiconductor layer 22 on the fourth surface 17 of the second i-type nitride semiconductor substrate 15 (step S5), removing the second growth substrate 60 from the second i-type nitride semiconductor substrate 15 (step S6), and bonding the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 by facing the second surface 12 of the first i-type nitride semiconductor substrate 10 and the third surface 16 of the second i-type nitride semiconductor substrate 15 to each other (step S7). The method for manufacturing the X-ray semiconductor detector 2 of this embodiment includes forming a first electrode 25 on a p-type semiconductor layer 20 (step S8) and forming a second electrode 26 on an n-type semiconductor layer 22 (step S9).

[0051] The p-type semiconductor layer 20 is formed on the first gallium surface (first surface 11) of the first i-type nitride semiconductor substrate 10, and the n-type semiconductor layer 22 is formed on the second gallium surface (fourth surface 17) of the second i-type nitride semiconductor substrate 15. In nitride semiconductors, the gallium surface is a more chemically stable surface than the nitrogen surface. Therefore, when forming the p-type semiconductor layer 20 and the n-type semiconductor layer 22, the desorption of nitrogen atoms from the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 is suppressed. This prevents deterioration of the crystallinity of the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15. The detection sensitivity of the X-rays 50 of the X-ray semiconductor detector 2 is improved.

[0052] Embodiment 2. The X-ray semiconductor detection apparatus 1 of Embodiment 2 will be described with reference to Figures 5 and 6. The X-ray semiconductor detection apparatus 1 of this embodiment has the same configuration as the X-ray semiconductor detection apparatus 1 of Embodiment 1, but differs in the configuration of the X-ray semiconductor detector 2.

[0053] The X-ray semiconductor detector 2 further comprises a two-dimensional semiconductor layer 33. The band gap energy of the two-dimensional semiconductor layer 33 is smaller than the band gap energy of the first i-type nitride semiconductor substrate 10 and also smaller than the band gap energy of the second i-type nitride semiconductor substrate 15. The two-dimensional semiconductor layer 33 is made of molybdenum disulfide (MoS ２ ), molybdenum diselenide (MoSe ２ ), tungsten disulfide (WS ２ ), tungsten diselenide (WSe ２ ), rhenium disulfide (ReS ２ ), rhenium diselenide (ReSe ２ ), titanium disulfide (TiS ２ ), Titanium diselenium (TiSe ２ ), zirconium disulfide (ZrS ２ ), zirconium diselenide (ZrSe ２ ), hafnium disulfide (HfS ２ ) or hafnium diselenide (HfSe ２It is formed of a transition metal dichalcogenide such as ). The two-dimensional semiconductor layer 33 may be formed of multiple layers of the same material or multiple layers of different materials. The two-dimensional semiconductor layer 33 has a thickness of at least the thickness of a single atomic layer. The two-dimensional semiconductor layer 33 has a thickness of, for example, 1 μm or less.

[0054] The two-dimensional semiconductor layer 33 is positioned between the second surface 12 of the first i-type nitride semiconductor substrate 10 and the third surface 16 of the second i-type nitride semiconductor substrate 15. The two-dimensional semiconductor layer 33 is in contact with the second surface 12 and the third surface 16. The two-dimensional semiconductor layer 33 does not have dangling bonds on its surface. Therefore, the two-dimensional semiconductor layer 33 is bonded to the second surface 12 of the first i-type nitride semiconductor substrate 10 and the third surface 16 of the second i-type nitride semiconductor substrate 15 by van der Waals forces (van der Waals junction). Referring to Figure 6, a van der Waals barrier 34 is formed at the interface between the two-dimensional semiconductor layer 33 and the first i-type nitride semiconductor substrate 10. A van der Waals barrier 35 is formed at the interface between the two-dimensional semiconductor layer 33 and the second i-type nitride semiconductor substrate 15. A two-dimensional semiconductor layer 33 is formed as a quantum well between the van der Waals barrier 34 and the van der Waals barrier 35.

[0055] Referring to Figure 7, an example of a manufacturing method for the X-ray semiconductor detector 2 of this embodiment will be described. The manufacturing method for the X-ray semiconductor detector 2 of this embodiment includes the same steps as the manufacturing method for the X-ray semiconductor detector 2 of Embodiment 1 shown in Figure 2, but differs from the manufacturing method for the X-ray semiconductor detector 2 of Embodiment 1 in the following points.

[0056] The manufacturing method of the X-ray semiconductor detector 2 of this embodiment further includes forming a two-dimensional semiconductor layer 33 on a first i-type nitride semiconductor substrate 10 or a second i-type nitride semiconductor substrate 15 (step S10). Specifically, the two-dimensional semiconductor layer 33 is formed on the second surface 12 of the first i-type nitride semiconductor substrate 10 or the third surface 16 of the second i-type nitride semiconductor substrate 15 by a transfer method or chemical vapor deposition (CVD) method, etc.

[0057] In step S7 of this embodiment, the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 are bonded together via a two-dimensional semiconductor layer 33. Specifically, the second surface 12 of the first i-type nitride semiconductor substrate 10 and the two-dimensional semiconductor layer 33 are brought into contact with each other, and the third surface 16 of the second i-type nitride semiconductor substrate 15 and the two-dimensional semiconductor layer 33 are brought into contact with each other, while the first i-type nitride semiconductor substrate 10, the two-dimensional semiconductor layer 33, and the second i-type nitride semiconductor substrate 15 are heat-treated. In this way, an X-ray semiconductor detector 2 is obtained.

[0058] The operation of this embodiment will now be explained. When the X-ray semiconductor detector 2 is not irradiated with X-rays 50, a dark current is generated in the X-ray semiconductor detector 2. The dark current flows across the surface of multiple threading dislocations 13 and 18. Energy levels caused by the multiple threading dislocations 13 and 18 are formed within the band gaps of the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15. As a result, many of the carriers (electrons 37a and holes 37b) flowing as dark current are trapped in quantum wells formed by the two-dimensional semiconductor layer 33. In this way, the two-dimensional semiconductor layer 33 reduces the dark current.

[0059] When X-rays 50 are incident on the X-ray semiconductor detector 2, electrons are excited by the X-rays 50 from the valence band to the conduction band. Holes are generated in the valence band. In this way, carriers (electrons 38a and holes 38b) corresponding to the intensity of the X-rays 50 are generated in the first i-type nitride semiconductor substrate 10 and the second i-type i-type nitride semiconductor substrate 15. The electrons 38a generated by the X-rays 50 are in the conduction band, and the holes 38b generated by the X-rays 50 are in the valence band. These carriers are accelerated by the reverse bias voltage supplied from the voltage source 40 to the X-ray semiconductor detector 2 and tunnel through the van der Waals barriers 34 and 35. Because electrons 37a and holes 37b caused by dark current are trapped in quantum wells formed by the two-dimensional semiconductor layer 33, the carriers generated by the X-rays 50 pass through the quantum wells without being trapped. The current caused by the X-rays 50 flows through the first electrode 25 and the second electrode 26 to the detection circuit 32. The detection circuit 32 detects the current caused by the X-rays 50. In this way, the intensity of the X-rays 50 incident on the X-ray semiconductor detector 2 is measured.

[0060] In a modified example of this embodiment, the first surface 11 of the first i-type nitride semiconductor substrate 10 and the fourth surface 17 of the second i-type nitride semiconductor substrate 15 may be N-planes, and the second surface 12 of the first i-type nitride semiconductor substrate 10 and the third surface 16 of the second i-type nitride semiconductor substrate 15 may be Ga-planes.

[0061] In addition to the effects of the X-ray semiconductor detector 2 and its manufacturing method of Embodiment 1, the following effects of the X-ray semiconductor detector 2 and its manufacturing method of this embodiment are described below.

[0062] The X-ray semiconductor detector 2 of this embodiment comprises a first i-type nitride semiconductor substrate 10, a second i-type nitride semiconductor substrate 15, a two-dimensional semiconductor layer 33, a p-type semiconductor layer 20, an n-type semiconductor layer 22, a first electrode 25, and a second electrode 26. The first i-type nitride semiconductor substrate 10 includes a first surface 11 and a second surface 12 opposite to the first surface 11. The second i-type nitride semiconductor substrate 15 includes a third surface 16 facing the second surface 12 and a fourth surface 17 opposite to the third surface 16. The two-dimensional semiconductor layer 33 is bonded to the second surface 12 and the third surface 16 by van der Waals forces. The p-type semiconductor layer 20 is formed on the first surface 11. The n-type semiconductor layer 22 is formed on the fourth surface 17. The first electrode 25 is formed on the p-type semiconductor layer 20. The second electrode 26 is formed on the n-type semiconductor layer 22. The band gap energy of the two-dimensional semiconductor layer 33 is smaller than the band gap energy of the first i-type nitride semiconductor substrate 10 and also smaller than the band gap energy of the second i-type nitride semiconductor substrate 15.

[0063] Numerous threading dislocations 13 and 18 are present in the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15. The two-dimensional semiconductor layer 33 reduces the dark current passing through the threading dislocations 13 and 18. As a result, the detection accuracy of the X-rays 50 of the X-ray semiconductor detector 2 is improved.

[0064] In the X-ray semiconductor detector 2 of this embodiment, the two-dimensional semiconductor layer 33 is formed of a transition metal dichalcogenide.

[0065] The two-dimensional semiconductor layer 33 reduces the dark current passing through the threading dislocations 13 and 18. As a result, the detection accuracy of the X-rays 50 by the X-ray semiconductor detector 2 is improved.

[0066] In the X-ray semiconductor detector 2 of this embodiment, the two-dimensional semiconductor layer 33 is formed of molybdenum disulfide, molybdenum diselenide, tungsten disulfide, tungsten diselenide, rhenium disulfide, rhenium diselenide, titanium disulfide, titanium diselenide, zirconium disulfide, zirconium diselenide, hafnium disulfide, or hafnium diselenide.

[0067] The two-dimensional semiconductor layer 33 reduces the dark current passing through the threading dislocations 13 and 18. As a result, the detection accuracy of the X-rays 50 by the X-ray semiconductor detector 2 is improved.

[0068] The method for manufacturing an X-ray semiconductor detector according to this embodiment further includes forming a two-dimensional semiconductor layer 33 on the second surface 12 of the first i-type nitride semiconductor substrate 10 or on the third surface 16 of the second i-type nitride semiconductor substrate 15 (step S10). Bonding the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 (step S7) means bonding the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 via the two-dimensional semiconductor layer 33. The two-dimensional semiconductor layer 33 is bonded to the second surface 12 and the third surface 16 by van der Waals forces. The band gap energy of the two-dimensional semiconductor layer 33 is smaller than the band gap energy of the first i-type nitride semiconductor substrate 10 and smaller than the band gap energy of the second i-type nitride semiconductor substrate 15.

[0069] The two-dimensional semiconductor layer 33 reduces the dark current passing through the threading dislocations 13 and 18. As a result, the detection accuracy of the X-rays 50 by the X-ray semiconductor detector 2 is improved.

[0070] Embodiment 3. The X-ray semiconductor detection apparatus 1 of Embodiment 3 will be described with reference to Figure 8. The X-ray semiconductor detection apparatus 1 of this embodiment has the same configuration as the X-ray semiconductor detection apparatus 1 of Embodiment 2, but differs mainly in the following points.

[0071] The X-ray semiconductor detector 2 further comprises intermediate electrodes 27 and 28 arranged on a two-dimensional semiconductor layer 33. The intermediate electrodes 27 and 28 are formed of, for example, Ti.

[0072] The X-ray semiconductor detector 1 is equipped with a voltmeter 41. The voltmeter 41 is connected to the intermediate electrode 27 using electrical wiring. The voltmeter 41 can measure the voltage of the two-dimensional semiconductor layer 33.

[0073] The X-ray semiconductor detector 1 further comprises a switch 42, an ammeter 43, and a variable voltage source 44. The ammeter 43 is connected to the intermediate electrode 28 via the switch 42. The ammeter 43 is connected to ground potential via the variable voltage source 44. The voltage of the variable voltage source 44 is set to the voltage of the two-dimensional semiconductor layer 33 measured by the voltmeter 41. Then, the switch 42 is closed. The dark current of the X-ray semiconductor detector 2 does not flow in the thickness direction of the two-dimensional semiconductor layer 33, but may flow in the in-plane direction of the two-dimensional semiconductor layer 33 due to drift diffusion. The ammeter 43 can measure the dark current of the X-ray semiconductor detector 2.

[0074] In addition to the effects of the X-ray semiconductor detector 2 of Embodiment 2, the following effects of the X-ray semiconductor detector 2 of this embodiment will be described.

[0075] The X-ray semiconductor detector 2 of this embodiment further includes an intermediate electrode (at least one of the intermediate electrode 27 or intermediate electrode 28) disposed on the two-dimensional semiconductor layer 33. Therefore, it becomes possible to measure at least one of the voltage of the two-dimensional semiconductor layer 33 or the dark current of the X-ray semiconductor detector 2.

[0076] Embodiment 4. The X-ray semiconductor detection apparatus 1 of Embodiment 4 will be described with reference to Figure 9. The X-ray semiconductor detection apparatus 1 of this embodiment has the same configuration as the X-ray semiconductor detection apparatus 1 of Embodiment 1, but differs mainly in the following points.

[0077] In this embodiment, the first surface 11 of the first i-type nitride semiconductor substrate 10 is the nitrogen surface (N surface), and the second surface 12 of the first i-type nitride semiconductor substrate 10 is the gallium surface (Ga surface).

[0078] The electronegativity of nitrogen (N) in nitride semiconductors is greater than that of galvanic acid (Ga). Therefore, the spontaneous polarization of nitride semiconductors is directed from the N-plane to the Ga-plane, and the electric field formed within the nitride semiconductor by this spontaneous polarization is directed from the Ga-plane to the N-plane.

[0079] The electric field EP1 formed within the first i-type nitride semiconductor substrate 10 by the spontaneous electrodes of the first i-type nitride semiconductor substrate 10 is oriented from the Ga surface (second surface 12) to the N surface (first surface 11). The direction of the electric field EP1 is the same as the direction of the internal electric field of the PIN junction formed by the p-type semiconductor layer 20, the first i-type nitride semiconductor substrate 10, the second i-type nitride semiconductor substrate 15, and the n-type semiconductor layer 22. Furthermore, when the voltage source 40 is connected to the X-ray semiconductor detector 2, the direction of the electric field EP1 is the same as the direction of the reverse bias electric field formed within the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 by the reverse bias voltage supplied from the voltage source 40 to the X-ray semiconductor detector 2.

[0080] Similarly, the electric field EP2 formed within the second i-type nitride semiconductor substrate 15 by the spontaneous electrodes of the second i-type nitride semiconductor substrate 15 is oriented from the Ga surface (fourth surface 17) to the N surface (third surface 16). The direction of the electric field EP2 is the same as the direction of the electric field EP1. The direction of the electric field EP2 is the same as the direction of the internal electric field of the PIN junction formed by the p-type semiconductor layer 20, the first i-type nitride semiconductor substrate 10, the second i-type nitride semiconductor substrate 15, and the n-type semiconductor layer 22. Furthermore, when the voltage source 40 is connected to the X-ray semiconductor detector 2, the direction of the electric field EP2 is the same as the direction of the reverse bias electric field formed within the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 by the reverse bias voltage supplied from the voltage source 40 to the X-ray semiconductor detector 2.

[0081] Therefore, carriers (electrons and holes) generated in the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 when X-rays 50 are incident on the X-ray semiconductor detector 2 can be accelerated by the electric fields EP1, EP2 and the internal electric field of the PIN junction, or by the electric fields EP1, EP2 and the internal electric field of the PIN junction and the reverse bias electric field, and can be extracted from the X-ray semiconductor detector 2 more efficiently.

[0082] An example of a manufacturing method for the X-ray semiconductor detector 2 and X-ray semiconductor detection device 1 of this embodiment will be described with reference to Figures 10 to 12.

[0083] Referring to Figures 10 and 11, a p-type semiconductor layer 20 is formed on the first growth substrate 52 by the MOCVD method (step S11). The first growth substrate 52 in this embodiment is, for example, the same as the first growth substrate 52 in Embodiment 1, and is a GaN template 53. A mask layer 58 with a plurality of openings is formed on the GaN buffer layer 56. The mask layer 58 in this embodiment is the same as the mask layer 58 in Embodiment 1. The p-type semiconductor layer 20 is formed on the GaN template 53 (more specifically, the GaN buffer layer 56) by epitaxial transverse growth (ELO) using the mask layer 58. Therefore, the density of through-dislocations 13 in the p-type semiconductor layer 20 can be reduced. The surface of the p-type semiconductor layer 20 opposite to the first growth substrate 52 is the Ga surface.

[0084] Referring to Figures 10 and 11, a first i-type nitride semiconductor substrate 10 is formed on the Ga surface of the p-type semiconductor layer 20 by the HVPE method (step S12). In nitride semiconductors, the gallium surface is a more chemically stable surface than the nitrogen surface. Since the first i-type nitride semiconductor substrate 10 is formed on the Ga surface of the p-type semiconductor layer 20, it is possible to prevent deterioration of the crystallinity of the first i-type nitride semiconductor substrate 10. The first i-type nitride semiconductor substrate 10 includes a first surface 11 facing the p-type semiconductor layer 20 and a second surface 12 opposite to the first surface 11. Since the first i-type nitride semiconductor substrate 10 is formed on the Ga surface of the p-type semiconductor layer 20, the first surface 11 is the N surface and the second surface 12 is the Ga surface.

[0085] Referring to Figure 10, the first growth substrate 52 is removed from the p-type semiconductor layer 20 (step S13). Specifically, when the temperature of the laminate of the first i-type nitride semiconductor substrate 10, the p-type semiconductor layer 20, and the first growth substrate 52 is lowered from the growth temperature of the first i-type nitride semiconductor substrate 10 to room temperature, the p-type semiconductor layer 20 peels off from the first growth substrate 52 and the mask layer 58 due to the difference between the thermal expansion coefficient of the p-type semiconductor layer 20 and the thermal expansion coefficient of the sapphire substrate 54.

[0086] Referring to Figures 10 and 12, a second i-type nitride semiconductor substrate 15 is formed on the second growth substrate 60 by the HVPE method (step S14). An n-type semiconductor layer 22 is formed on the fourth surface 17 of the second i-type nitride semiconductor substrate 15 by the MOCVD method (step S15). The second growth substrate 60 is removed from the second i-type nitride semiconductor substrate 15 (step S16). Steps S14, S15, and S16 in this embodiment are the same as steps S4, S5, and S6 in Embodiment 1.

[0087] Referring to Figure 10, the second surface 12 of the first i-type nitride semiconductor substrate 10 and the third surface 16 of the second i-type nitride semiconductor substrate 15 are placed facing each other, and the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 are bonded together (step S17). Specifically, the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 are heat-treated while the second surface 12 of the first i-type nitride semiconductor substrate 10 and the third surface 16 of the second i-type nitride semiconductor substrate 15 are in contact with each other.

[0088] Referring to Figure 10, a first electrode 25 is formed on the p-type semiconductor layer 20 by vapor deposition (step S18). A second electrode 26 is formed on the n-type semiconductor layer 22 by vapor deposition (step S19). In this way, the X-ray semiconductor detector 2 shown in Figure 9 is obtained.

[0089] Next, the second electrode 26 of the X-ray semiconductor detector 2 is electrically connected to the detection circuit 32 using the electrical connection member 31. The voltage source 40 is connected to the first electrode 25 and the second electrode 26. In this way, the X-ray semiconductor detection device 1 shown in Figure 9 is obtained.

[0090] Referring to Figure 13, a modified example of the X-ray semiconductor detection apparatus 1 of this embodiment will be described. The modified example of the X-ray semiconductor detection apparatus 1 of this embodiment is configured similarly to the X-ray semiconductor detection apparatus 1 of this embodiment shown in Figure 9, but differs from the X-ray semiconductor detection apparatus 1 of this embodiment mainly in the following points.

[0091] In a modified version of this embodiment, the X-ray semiconductor detector 2 does not include a second i-type nitride semiconductor substrate 15. The n-type semiconductor layer 22 is formed on the second surface 12 of the first i-type nitride semiconductor substrate 10.

[0092] The first surface 11 is the nitrogen surface (N surface), and the second surface 12 is the gallium surface (Ga surface). Therefore, the electric field EP1 formed within the first i-type nitride semiconductor substrate 10 by the spontaneous electrodes of the first i-type nitride semiconductor substrate 10 is directed from the Ga surface (second surface 12) to the N surface (first surface 11). The direction of the electric field EP1 is the same as the direction of the internal electric field of the PIN junction formed by the p-type semiconductor layer 20, the first i-type nitride semiconductor substrate 10, and the n-type semiconductor layer 22. Furthermore, when the voltage source 40 is connected to the X-ray semiconductor detector 2, the direction of the electric field EP1 is the same as the direction of the reverse bias electric field formed within the first i-type nitride semiconductor substrate 10 by the reverse bias voltage supplied from the voltage source 40 to the X-ray semiconductor detector 2. Therefore, carriers (electrons and holes) generated in the first i-type nitride semiconductor substrate 10 when X-rays 50 are incident on the X-ray semiconductor detector 2 can be accelerated by the electric field EP1 and the internal electric field of the pin junction, or by the electric field EP1, the internal electric field of the pin junction and the reverse bias electric field, and can be extracted from the X-ray semiconductor detector 2 more efficiently.

[0093] Referring to Figure 14, an example of a manufacturing method for a modified X-ray semiconductor detector 2 and X-ray semiconductor detection device 1 of this embodiment will be described. The manufacturing method for the modified X-ray semiconductor detector 2 and X-ray semiconductor detection device 1 of this embodiment includes steps similar to those of the manufacturing method for the X-ray semiconductor detector 2 and X-ray semiconductor detection device 1 of this embodiment shown in Figure 10, but differs from the manufacturing method for the X-ray semiconductor detector 2 and X-ray semiconductor detection device 1 of this embodiment mainly in the following points.

[0094] A modified manufacturing method of this embodiment involves forming an n-type semiconductor layer 22 on the second surface 12 of the first i-type nitride semiconductor substrate 10 by MOCVD, following step S13 (step S15b). The second surface 12 is the gallium surface. In nitride semiconductors, the gallium surface is a more chemically stable surface than the nitrogen surface. Therefore, when forming the n-type semiconductor layer 22 on the first i-type nitride semiconductor substrate 10, the detachment of nitrogen atoms from the first i-type nitride semiconductor substrate 10 is suppressed. This prevents deterioration of the crystallinity of the first i-type nitride semiconductor substrate 10.

[0095] Next, a first electrode 25 is formed on the p-type semiconductor layer 20 by vapor deposition (step S18). A second electrode 26 is formed on the n-type semiconductor layer 22 by vapor deposition (step S19). In this way, the X-ray semiconductor detector 2 shown in Figure 13 is obtained.

[0096] Next, the second electrode 26 of the X-ray semiconductor detector 2 is electrically connected to the detection circuit 32 using the electrical connection member 31. The voltage source 40 is connected to the first electrode 25 and the second electrode 26. In this way, the X-ray semiconductor detection device 1 shown in Figure 13 is obtained.

[0097] The effects of the X-ray semiconductor detector 2 of this embodiment and its manufacturing method will be described. The X-ray semiconductor detector 2 of this embodiment comprises at least one i-type nitride semiconductor substrate (for example, a first i-type nitride semiconductor substrate 10), a p-type semiconductor layer 20, an n-type semiconductor layer 22, a first electrode 25, and a second electrode 26. The at least one i-type nitride semiconductor substrate includes a gallium surface (second surface 12) and a nitrogen surface (first surface 11) opposite to the gallium surface. The p-type semiconductor layer 20 is formed on the nitrogen surface. The n-type semiconductor layer 22 is formed on the gallium surface. The first electrode 25 is formed on the p-type semiconductor layer 20. The second electrode 26 is formed on the n-type semiconductor layer 22.

[0098] Therefore, the direction of the electric field (e.g., electric field EP1) formed within at least one i-type nitride semiconductor substrate by the spontaneous polarization of at least one i-type nitride semiconductor substrate (e.g., the first i-type nitride semiconductor substrate 10) is the same as the direction of the internal electric field of the PIN junction formed by the p-type semiconductor layer 20, at least one i-type nitride semiconductor substrate, and the n-type semiconductor layer 22. When the voltage source 40 is connected to the X-ray semiconductor detector 2, the direction of the electric field formed within at least one i-type nitride semiconductor substrate by the spontaneous electrode of at least one i-type nitride semiconductor substrate is the same as the direction of the reverse bias electric field formed within at least one i-type nitride semiconductor substrate by the reverse bias voltage supplied from the voltage source 40 to the X-ray semiconductor detector 2. Therefore, carriers (electrons and holes) generated in at least one i-type nitride semiconductor substrate when X-rays 50 are incident on the X-ray semiconductor detector 2 can be accelerated by the electric field (e.g., electric field EP1) and the internal electric field of the PIN junction, or by the electric field (e.g., electric field EP1), the internal electric field of the PIN junction, and the reverse bias electric field, and can be extracted from the X-ray semiconductor detector 2 more efficiently. The detection sensitivity of the X-rays 50 in the X-ray semiconductor detector 2 is improved.

[0099] In the X-ray semiconductor detector 2 of this embodiment, at least one i-type nitride semiconductor substrate includes a first i-type nitride semiconductor substrate 10 and a second i-type nitride semiconductor substrate 15. The first i-type nitride semiconductor substrate 10 includes a first gallium surface (second surface 12) and a first nitrogen surface (e.g., first surface 11) opposite to the first gallium surface. The second i-type nitride semiconductor substrate 15 includes a second gallium surface (fourth surface 17) and a second nitrogen surface (third surface 16) opposite to the second gallium surface. The second nitrogen surface faces the first gallium surface. The p-type semiconductor layer 20 is formed on the first nitrogen surface. The n-type semiconductor layer 22 is formed on the second gallium surface.

[0100] Therefore, the electric field EP1 formed within the first i-type nitride semiconductor substrate 10 by the spontaneous polarization of the first i-type nitride semiconductor substrate 10, and the electric field EP2 formed within the second i-type nitride semiconductor substrate 15 by the spontaneous polarization of the second i-type nitride semiconductor substrate 15, are in the same direction as the internal electric field of the PIN junction formed by the p-type semiconductor layer 20, the first i-type nitride semiconductor substrate 10, the second i-type nitride semiconductor substrate 15, and the n-type semiconductor layer 22. When the voltage source 40 is connected to the X-ray semiconductor detector 2, the electric fields EP1 and EP2 are in the same direction as the reverse bias electric field formed within the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 by the reverse bias voltage supplied from the voltage source 40 to the X-ray semiconductor detector 2. Therefore, when X-rays 50 are incident on the X-ray semiconductor detector 2, the carriers (electrons and holes) generated in the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 are accelerated by the electric fields EP1, EP2 and the internal electric field of the PIN junction, or by the electric fields EP1, EP2 and the internal electric field of the PIN junction and the reverse bias electric field, and can be extracted from the X-ray semiconductor detector 2 more efficiently. The detection sensitivity of the X-rays 50 in the X-ray semiconductor detector 2 is improved.

[0101] In the X-ray semiconductor detector 2 of this embodiment, the second nitrogen surface (third surface 16) is in contact with the first gallium surface (second surface 12).

[0102] Therefore, carriers (electrons and holes) generated in the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 when X-rays 50 are incident on the X-ray semiconductor detector 2 can be extracted from the X-ray semiconductor detector 2 more efficiently. The detection sensitivity of X-rays 50 in the X-ray semiconductor detector 2 is improved.

[0103] The method for manufacturing the X-ray semiconductor detector 2 of this embodiment includes forming a p-type semiconductor layer 20 on a first growth substrate 52 (step S11). The surface of the p-type semiconductor layer 20 opposite to the first growth substrate 52 is a gallium surface. The method for manufacturing the X-ray semiconductor detector 2 of this embodiment includes forming a first i-type nitride semiconductor substrate 10 on the surface of the p-type semiconductor layer 20 (step S12). The first i-type nitride semiconductor substrate 10 includes a first surface 11 facing the p-type semiconductor layer 20 and a second surface opposite to the first surface 11. The first surface is a first nitrogen surface. The second surface 12 is a first gallium surface. The method for manufacturing the X-ray semiconductor detector 2 of this embodiment includes removing the first growth substrate 52 from the p-type semiconductor layer 20 (step S13) and forming a second i-type nitride semiconductor substrate 15 on a second growth substrate 60 (step S14). The second i-type nitride semiconductor substrate 15 includes a third surface 16 facing the second growth substrate 60 and a fourth surface 17 opposite to the third surface 16. The third surface 16 is the second nitrogen surface. The fourth surface 17 is the second gallium surface. The manufacturing method of the X-ray semiconductor detector 2 of this embodiment includes forming an n-type semiconductor layer 22 on the fourth surface 17 of the second i-type nitride semiconductor substrate 15 (step S15), removing the second growth substrate 60 from the second i-type nitride semiconductor substrate 15 (step S16), and bonding the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 by facing the second surface 12 of the first i-type nitride semiconductor substrate 10 and the third surface 16 of the second i-type nitride semiconductor substrate 15 to each other (step S17). The method for manufacturing the X-ray semiconductor detector 2 of this embodiment includes forming a first electrode 25 on a p-type semiconductor layer 20 (step S18) and forming a second electrode 26 on an n-type semiconductor layer 22 (step S19).

[0104] Therefore, the electric field EP1 formed within the first i-type nitride semiconductor substrate 10 by the spontaneous polarization of the first i-type nitride semiconductor substrate 10, and the electric field EP2 formed within the second i-type nitride semiconductor substrate 15 by the spontaneous polarization of the second i-type nitride semiconductor substrate 15, are in the same direction as the internal electric field of the PIN junction formed by the p-type semiconductor layer 20, the first i-type nitride semiconductor substrate 10, the second i-type nitride semiconductor substrate 15, and the n-type semiconductor layer 22. When the voltage source 40 is connected to the X-ray semiconductor detector 2, the electric fields EP1 and EP2 are in the same direction as the reverse bias electric field formed within the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 by the reverse bias voltage supplied from the voltage source 40 to the X-ray semiconductor detector 2. Therefore, when X-rays 50 are incident on the X-ray semiconductor detector 2, the carriers (electrons and holes) generated in the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 are accelerated by the electric fields EP1, EP2 and the internal electric field of the PIN junction, or by the electric fields EP1, EP2 and the internal electric field of the PIN junction and the reverse bias electric field, and can be extracted from the X-ray semiconductor detector 2 more efficiently. The detection sensitivity of the X-rays 50 in the X-ray semiconductor detector 2 is improved.

[0105] Furthermore, in nitride semiconductors, the gallium plane is a more chemically stable surface than the nitrogen plane. Since the first i-type nitride semiconductor substrate 10 is formed on the gallium plane of the p-type semiconductor layer 20, degradation of the crystallinity of the first i-type nitride semiconductor substrate 10 can be prevented. Since the n-type semiconductor layer 22 is formed on the gallium plane (fourth plane 17) of the second i-type nitride semiconductor substrate 15, degradation of the crystallinity of the second i-type nitride semiconductor substrate 15 can be prevented. The detection sensitivity of the X-rays 50 of the X-ray semiconductor detector 2 is improved.

[0106] Embodiment 5. The X-ray semiconductor detection apparatus 1 of Embodiment 5 will be described with reference to Figure 15. The X-ray semiconductor detection apparatus 1 of this embodiment has the same configuration as the X-ray semiconductor detection apparatus 1 of Embodiment 4, but differs mainly in the following points.

[0107] The X-ray semiconductor detector 2 of this embodiment further comprises a two-dimensional semiconductor layer 33. The two-dimensional semiconductor layer 33 of this embodiment is formed of the same material as the two-dimensional semiconductor layer 33 of Embodiment 2. The band gap energy of the two-dimensional semiconductor layer 33 is smaller than the band gap energy of the first i-type nitride semiconductor substrate 10 and smaller than the band gap energy of the second i-type nitride semiconductor substrate 15.

[0108] The two-dimensional semiconductor layer 33 does not have dangling bonds on its surface. Therefore, the two-dimensional semiconductor layer 33 is bonded to the first gallium surface (second surface 12) of the first i-type nitride semiconductor substrate 10 and the second nitrogen surface (third surface 16) of the second i-type nitride semiconductor substrate 15 by van der Waals forces.

[0109] Referring to Figure 16, an example of a manufacturing method for the X-ray semiconductor detector 2 of this embodiment will be described. The manufacturing method for the X-ray semiconductor detector 2 of this embodiment includes the same steps as the manufacturing method for the X-ray semiconductor detector 2 of Embodiment 4 shown in Figure 10, but differs from the manufacturing method for the X-ray semiconductor detector 2 of Embodiment 4 in the following points.

[0110] The manufacturing method of the X-ray semiconductor detector 2 of this embodiment further includes forming a two-dimensional semiconductor layer 33 on a first i-type nitride semiconductor substrate 10 or a second i-type nitride semiconductor substrate 15 (step S20). Specifically, the two-dimensional semiconductor layer 33 is formed on the second surface 12 of the first i-type nitride semiconductor substrate 10 or the third surface 16 of the second i-type nitride semiconductor substrate 15 by a transfer method or chemical vapor deposition (CVD) method, etc.

[0111] In step S17 of this embodiment, the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 are bonded together via a two-dimensional semiconductor layer 33. Specifically, the second surface 12 of the first i-type nitride semiconductor substrate 10 and the two-dimensional semiconductor layer 33 are brought into contact with each other, and the third surface 16 of the second i-type nitride semiconductor substrate 15 and the two-dimensional semiconductor layer 33 are brought into contact with each other, while the first i-type nitride semiconductor substrate 10, the two-dimensional semiconductor layer 33, and the second i-type nitride semiconductor substrate 15 are heat-treated. In this way, an X-ray semiconductor detector 2 is obtained.

[0112] The X-ray semiconductor detector 2 and its manufacturing method of this embodiment provide the advantages of the X-ray semiconductor detector 2 and its manufacturing method of Embodiment 4, as well as the advantages of the X-ray semiconductor detector 2 and its manufacturing method of Embodiment 2.

[0113] Embodiment 6. The X-ray semiconductor detection apparatus 1 of Embodiment 6 will be described with reference to Figure 17. The X-ray semiconductor detection apparatus 1 of this embodiment has the same configuration as the X-ray semiconductor detection apparatus 1 of Embodiment 5, but differs mainly in the following points.

[0114] The X-ray semiconductor detector 2 further comprises intermediate electrodes 27 and 28 arranged on a two-dimensional semiconductor layer 33. The intermediate electrodes 27 and 28 in this embodiment are the same as those in Embodiment 3.

[0115] The X-ray semiconductor detection device 1 is equipped with a voltmeter 41. The X-ray semiconductor detection device 1 further includes a switch 42, an ammeter 43, and a variable voltage source 44. The voltmeter 41, switch 42, ammeter 43, and variable voltage source 44 in this embodiment are the same as those in Embodiment 3.

[0116] The X-ray semiconductor detector 2 of this embodiment provides the effects of the X-ray semiconductor detector 2 of Embodiment 5, in addition to the effects of the X-ray semiconductor detector 2 of Embodiment 3.

[0117] Embodiment 7. The X-ray semiconductor detector 2 of Embodiment 7 will be described with reference to Figure 18. The X-ray semiconductor detector 2 of this embodiment has the same configuration as the X-ray semiconductor detector 2 of any of Embodiments 1 to 6, but differs mainly in the following points.

[0118] In this embodiment, the p-type semiconductor layer 20 is formed of multiple layers with different p-type dopant concentrations. The p-type dopant concentrations in the multiple layers increase as they approach the first electrode 25. For example, the p-type semiconductor layer 20 includes a first p-type semiconductor layer 20a and a second p-type semiconductor layer 20b. The second p-type semiconductor layer 20b is closer to the first electrode 25 than the first p-type semiconductor layer 20a. The p-type dopant concentration in the second p-type semiconductor layer 20b is higher than that in the first p-type semiconductor layer 20a. The number of layers constituting the p-type semiconductor layer 20 may be three or more.

[0119] In semiconductor layers, the mobility of holes is lower than that of electrons. In particular, in nitride semiconductor layers such as gallium nitride, the mobility of holes is significantly lower than that of electrons. By forming the p-type semiconductor layer 20 with multiple layers having different p-type dopant concentrations, and increasing the p-type dopant concentration of the multiple layers as they approach the first electrode 25, holes can more easily pass through the p-type semiconductor layer 20. Therefore, carriers (e.g., holes) generated in the first i-type nitride semiconductor substrate 10 and the second i-type nitride semiconductor substrate 15 when X-rays 50 are incident on the X-ray semiconductor detector 2 can be more efficiently extracted from the X-ray semiconductor detector 2. The detection sensitivity of the X-rays 50 of the X-ray semiconductor detector 2 is improved.

[0120] Embodiment 8. The X-ray semiconductor detection apparatus 1 of Embodiment 8 will be described with reference to Figure 19. The X-ray semiconductor detection apparatus 1 of this embodiment has the same configuration as the X-ray semiconductor detection apparatus 1 of any of Embodiments 1 to 7, but differs mainly in the following points.

[0121] The X-ray semiconductor detection device 1 includes a support substrate 45. Multiple X-ray semiconductor detectors 2 are arranged two-dimensionally on the support substrate 45. The X-ray semiconductor detection device 1 is an X-ray flat panel detector (FPD). The support substrate 45 may also include a detection circuit 32 (see Figures 1 and 5). According to the X-ray semiconductor detection device 1 of this embodiment, the intensity distribution (or X-ray image) of X-rays 50 can be measured over a wider area.

[0122] The various aspects of this disclosure are described below in summary as appendices. (Appendix 1) An X-ray semiconductor detector comprising: a first i-type nitride semiconductor substrate including a first gallium surface and a first nitrogen surface opposite to the first gallium surface; a second i-type nitride semiconductor substrate including a second gallium surface and a second nitrogen surface opposite to the second gallium surface, wherein the second nitrogen surface faces the first nitrogen surface; a p-type semiconductor layer formed on the first gallium surface; an n-type semiconductor layer formed on the second gallium surface; a first electrode formed on the p-type semiconductor layer; and a second electrode formed on the n-type semiconductor layer. (Note 2) The X-ray semiconductor detector according to Note 1, further comprising a two-dimensional semiconductor layer joined to the first nitrogen surface and the second nitrogen surface by van der Waals forces, wherein the bandgap energy of the two-dimensional semiconductor layer is smaller than the bandgap energy of the first i-type nitride semiconductor substrate and smaller than the bandgap energy of the second i-type i nitride semiconductor substrate. (Note 3) The X-ray semiconductor detector according to Note 1, wherein the second nitrogen surface is in contact with the first nitrogen surface. (Note 4) An X-ray semiconductor detector comprising: a first i-type nitride semiconductor substrate including a first surface and a second surface opposite to the first surface; a second i-type nitride semiconductor substrate including a third surface facing the second surface and a fourth surface opposite to the third surface; a two-dimensional semiconductor layer joined to the second surface and the third surface by van der Waals forces; a p-type semiconductor layer formed on the first surface; an n-type semiconductor layer formed on the fourth surface; a first electrode formed on the p-type semiconductor layer; and a second electrode formed on the n-type semiconductor layer, wherein the bandgap energy of the two-dimensional semiconductor layer is smaller than the bandgap energy of the first i-type nitride semiconductor substrate and smaller than the bandgap energy of the second i-type nitride semiconductor substrate.(Note 5) An X-ray semiconductor detector comprising: at least one i-type nitride semiconductor substrate including a gallium surface and a nitrogen surface opposite to the gallium surface; a p-type semiconductor layer formed on the nitrogen surface; an n-type semiconductor layer formed on the gallium surface; a first electrode formed on the p-type semiconductor layer; and a second electrode formed on the n-type semiconductor layer. (Note 6) The X-ray semiconductor detector according to Note 5, wherein the at least one i-type nitride semiconductor substrate comprises a first i-type nitride semiconductor substrate and a second i-type nitride semiconductor substrate, the first i-type nitride semiconductor substrate comprises a first gallium surface and a first nitrogen surface opposite to the first gallium surface, the second i-type nitride semiconductor substrate comprises a second gallium surface and a second nitrogen surface opposite to the second gallium surface, the second nitrogen surface facing the first gallium surface, the p-type semiconductor layer is formed on the first nitrogen surface, and the n-type semiconductor layer is formed on the second gallium surface. (Note 7) The X-ray semiconductor detector according to Note 6, wherein the second nitrogen surface is in contact with the first gallium surface. (Note 8) The X-ray semiconductor detector according to Note 6, further comprising a two-dimensional semiconductor layer bonded to the first gallium surface and the second nitrogen surface by van der Waals forces, wherein the band gap energy of the two-dimensional semiconductor layer is smaller than the band gap energy of the first i-type nitride semiconductor substrate and smaller than the band gap energy of the second i-type nitride semiconductor substrate. (Note 9) The X-ray semiconductor detector according to Note 2, Note 4, or Note 8, wherein the two-dimensional semiconductor layer is formed of a transition metal dichalcogenide. (Note 10) The X-ray semiconductor detector according to Note 9, wherein the two-dimensional semiconductor layer is formed of molybdenum disulfide, molybdenum diselenium, tungsten disulfide, tungsten diselenium, rhenium disulfide, rhenium diselenium, titanium disulfide, titanium diselenium, zirconium disulfide, zirconium diselenium, hafnium disulfide, or hafnium diselenium. (Note 11) The X-ray semiconductor detector according to Note 2, Note 4, Note 8, Note 9, or Note 10, further comprising an intermediate electrode disposed on the two-dimensional semiconductor layer.(Note 12) The X-ray semiconductor detector according to any one of Notes 1 to 11, wherein the p-type semiconductor layer is formed of a plurality of layers with different p-type dopant concentrations, and the p-type dopant concentrations of the plurality of layers increase as they approach the first electrode. (Note 13) The method includes forming a first i-type nitride semiconductor substrate on a first growth substrate, wherein the first i-type nitride semiconductor substrate includes a first surface and a second surface opposite to the first surface and facing the first growth substrate, wherein the first surface is a first gallium surface and the second surface is a first nitrogen surface, forming a p-type semiconductor layer on the first surface of the first i-type nitride semiconductor substrate, removing the first growth substrate from the first i-type nitride semiconductor substrate, forming a second i-type nitride semiconductor substrate on a second growth substrate, wherein the second i-type nitride semiconductor substrate includes a third surface facing the second growth substrate and a fourth surface opposite to the third surface, wherein the third surface is a second nitrogen surface and the fourth surface is a second gallium surface, forming an n-type semiconductor layer on the fourth surface of the second i-type nitride semiconductor substrate, and removing the second growth substrate from the second i-type nitride semiconductor substrate. A method for manufacturing an X-ray semiconductor detector, comprising: bonding the first i-type nitride semiconductor substrate and the second i-type nitride semiconductor substrate together by facing the second surface of the first i-type nitride semiconductor substrate and the third surface of the second i-type nitride semiconductor substrate toward each other; forming a first electrode on the p-type semiconductor layer; and forming a second electrode on the n-type semiconductor layer.(Note 14) The process includes forming a p-type semiconductor layer on a first growth substrate, wherein the surface of the p-type semiconductor layer opposite to the first growth substrate is a gallium surface; forming a first i-type nitride semiconductor substrate on the surface of the p-type semiconductor layer, wherein the first i-type nitride semiconductor substrate includes a first surface facing the p-type semiconductor layer and a second surface opposite to the first surface, wherein the first surface is a first nitrogen surface and the second surface is a first gallium surface; removing the first growth substrate from the p-type semiconductor layer; and forming a second i-type nitride semiconductor substrate on a second growth substrate, wherein the second i-type nitride semiconductor substrate includes a third surface facing the second growth substrate and a fourth surface opposite to the third surface, wherein the third surface is a second nitrogen surface and the fourth surface is a second gallium surface; and forming an n-type semiconductor layer on the fourth surface of the second i-type nitride semiconductor substrate. A method for manufacturing an X-ray semiconductor detector, comprising: removing the second growth substrate from the second i-type nitride semiconductor substrate; bonding the first i-type nitride semiconductor substrate and the second i-type nitride semiconductor substrate together by facing the second surface of the first i-type nitride semiconductor substrate and the third surface of the second i-type nitride semiconductor substrate toward each other; forming a first electrode on the p-type semiconductor layer; and forming a second electrode on the n-type semiconductor layer. (Note 15) A method for manufacturing an X-ray semiconductor detector according to Note 13 or Note 14, further comprising forming a two-dimensional semiconductor layer on the second surface of the first type i nitride semiconductor substrate or on the third surface of the second type i nitride semiconductor substrate, wherein bonding the first type i nitride semiconductor substrate and the second type i nitride semiconductor substrate means bonding the first type i nitride semiconductor substrate and the second type i nitride semiconductor substrate via the two-dimensional semiconductor layer, the two-dimensional semiconductor layer is bonded to the second surface and the third surface by van der Waals forces, and the band gap energy of the two-dimensional semiconductor layer is smaller than the band gap energy of the first type i nitride semiconductor substrate and smaller than the band gap energy of the second type i nitride semiconductor substrate.

[0123] Embodiments 1-8 disclosed herein should be considered in all respects to be illustrative and not restrictive. To the extent that they do not contradict each other, at least two of Embodiments 1-8 disclosed herein may be combined. The scope of this disclosure is indicated by the claims rather than the foregoing description and is intended to include all modifications within the meaning and scope of the claims equivalents.

[0124] 1 X-ray semiconductor detection device, 2 X-ray semiconductor detector, 2a first pixel, 2b second pixel, 2c third pixel, 5 semiconductor laminate, 10 first i-type nitride semiconductor substrate, 11 first surface, 12 second surface, 13, 18 through dislocations, 15 second i-type nitride semiconductor substrate, 16 third surface, 17 fourth surface, 20 p-type semiconductor layer, 20a first p-type semiconductor layer, 20b second p-type semiconductor layer, 22 n-type semiconductor layer, 25 first electrode, 26 second electrode, 27, 28 intermediate electrodes, 31 electrical connection member, 32 detection circuit, 33 two-dimensional semiconductor layer, 34, 35 van der Waals barrier, 37a, 38a electrons, 37b, 38b holes, 40 voltage source, 41 voltmeter, 42 switch, 43 ammeter, 44 variable voltage source, 45 Support substrate, 50 X-ray, 52 First growth substrate, 53, 61 GaN template, 54, 62 Sapphire substrate, 55, 63 Low-temperature grown GaN layer, 56, 64 GaN buffer layer, 58, 65 Mask layer, 60 Second growth substrate.

Claims

1. An X-ray semiconductor detector comprising: a first i-type nitride semiconductor substrate including a first gallium surface and a first nitrogen surface opposite to the first gallium surface; a second i-type nitride semiconductor substrate including a second gallium surface and a second nitrogen surface opposite to the second gallium surface, wherein the second nitrogen surface faces the first nitrogen surface; a p-type semiconductor layer formed on the first gallium surface; an n-type semiconductor layer formed on the second gallium surface; a first electrode formed on the p-type semiconductor layer; and a second electrode formed on the n-type semiconductor layer.

2. The X-ray semiconductor detector according to claim 1, further comprising a two-dimensional semiconductor layer joined to the first nitrogen plane and the second nitrogen plane by van der Waals forces, wherein the band gap energy of the two-dimensional semiconductor layer is smaller than the band gap energy of the first i-type nitride semiconductor substrate and smaller than the band gap energy of the second i-type nitride semiconductor substrate.

3. The X-ray semiconductor detector according to claim 1, wherein the second nitrogen surface is in contact with the first nitrogen surface.

4. An X-ray semiconductor detector comprising: a first i-type nitride semiconductor substrate including a first surface and a second surface opposite to the first surface; a second i-type nitride semiconductor substrate including a third surface facing the second surface and a fourth surface opposite to the third surface; a two-dimensional semiconductor layer joined to the second surface and the third surface by van der Waals forces; a p-type semiconductor layer formed on the first surface; an n-type semiconductor layer formed on the fourth surface; a first electrode formed on the p-type semiconductor layer; and a second electrode formed on the n-type semiconductor layer, wherein the bandgap energy of the two-dimensional semiconductor layer is smaller than the bandgap energy of the first i-type nitride semiconductor substrate and smaller than the bandgap energy of the second i-type nitride semiconductor substrate.

5. An X-ray semiconductor detector comprising: at least one i-type nitride semiconductor substrate including a gallium surface and a nitrogen surface opposite to the gallium surface; a p-type semiconductor layer formed on the nitrogen surface; an n-type semiconductor layer formed on the gallium surface; a first electrode formed on the p-type semiconductor layer; and a second electrode formed on the n-type semiconductor layer.

6. The X-ray semiconductor detector according to claim 5, wherein the at least one i-type nitride semiconductor substrate comprises a first i-type nitride semiconductor substrate and a second i-type nitride semiconductor substrate, the first i-type nitride semiconductor substrate comprises a first gallium surface and a first nitrogen surface opposite to the first gallium surface, the second i-type nitride semiconductor substrate comprises a second gallium surface and a second nitrogen surface opposite to the second gallium surface, the second nitrogen surface facing the first gallium surface, the p-type semiconductor layer is formed on the first nitrogen surface, and the n-type semiconductor layer is formed on the second gallium surface.

7. The X-ray semiconductor detector according to claim 6, wherein the second nitrogen surface is in contact with the first gallium surface.

8. The X-ray semiconductor detector according to claim 6, further comprising a two-dimensional semiconductor layer joined to the first gallium plane and the second nitrogen plane by van der Waals forces, wherein the band gap energy of the two-dimensional semiconductor layer is smaller than the band gap energy of the first i-type nitride semiconductor substrate and smaller than the band gap energy of the second i-type nitride semiconductor substrate.

9. The X-ray semiconductor detector according to claim 2, claim 4, or claim 8, wherein the two-dimensional semiconductor layer is formed of a transition metal dichalcogenide.

10. The X-ray semiconductor detector according to claim 9, wherein the two-dimensional semiconductor layer is formed of molybdenum disulfide, molybdenum diselenide, tungsten disulfide, tungsten diselenide, rhenium disulfide, rhenium diselenide, titanium disulfide, titanium diselenide, zirconium disulfide, zirconium diselenide, hafnium disulfide, or hafnium diselenide.

11. The X-ray semiconductor detector according to claim 2, claim 4, claim 8, claim 9, or claim 10, further comprising an intermediate electrode disposed on the two-dimensional semiconductor layer.

12. The X-ray semiconductor detector according to any one of claims 1 to 11, wherein the p-type semiconductor layer is formed of a plurality of layers with different p-type dopant concentrations, and the p-type dopant concentrations of the plurality of layers increase as they approach the first electrode.

13. A method comprising forming a first i-type nitride semiconductor substrate on a first growth substrate, wherein the first i-type nitride semiconductor substrate includes a first surface and a second surface opposite to the first surface and facing the first growth substrate, wherein the first surface is a first gallium surface and the second surface is a first nitrogen surface, forming a p-type semiconductor layer on the first surface of the first i-type nitride semiconductor substrate, removing the first growth substrate from the first i-type nitride semiconductor substrate, forming a second i-type nitride semiconductor substrate on a second growth substrate, wherein the second i-type nitride semiconductor substrate includes a third surface facing the second growth substrate and a fourth surface opposite to the third surface, wherein the third surface is a second nitrogen surface and the fourth surface is a second gallium surface, forming an n-type semiconductor layer on the fourth surface of the second i-type nitride semiconductor substrate, and removing the second growth substrate from the second i-type nitride semiconductor substrate. A method for manufacturing an X-ray semiconductor detector, comprising: bonding the first i-type nitride semiconductor substrate and the second i-type nitride semiconductor substrate together by facing the second surface of the first i-type nitride semiconductor substrate and the third surface of the second i-type nitride semiconductor substrate toward each other; forming a first electrode on the p-type semiconductor layer; and forming a second electrode on the n-type semiconductor layer.

14. The process includes forming a p-type semiconductor layer on a first growth substrate, wherein the surface of the p-type semiconductor layer opposite to the first growth substrate is a gallium surface; forming a first i-type nitride semiconductor substrate on the surface of the p-type semiconductor layer, wherein the first i-type nitride semiconductor substrate includes a first surface facing the p-type semiconductor layer and a second surface opposite to the first surface, wherein the first surface is a first nitrogen surface and the second surface is a first gallium surface; removing the first growth substrate from the p-type semiconductor layer; forming a second i-type nitride semiconductor substrate on a second growth substrate, wherein the second i-type nitride semiconductor substrate includes a third surface facing the second growth substrate and a fourth surface opposite to the third surface, wherein the third surface is a second nitrogen surface and the fourth surface is a second gallium surface; and forming an n-type semiconductor layer on the fourth surface of the second i-type nitride semiconductor substrate. A method for manufacturing an X-ray semiconductor detector, comprising: removing the second growth substrate from the second i-type nitride semiconductor substrate; bonding the first i-type nitride semiconductor substrate and the second i-type nitride semiconductor substrate together by facing the second surface of the first i-type nitride semiconductor substrate and the third surface of the second i-type nitride semiconductor substrate toward each other; forming a first electrode on the p-type semiconductor layer; and forming a second electrode on the n-type semiconductor layer.

15. A method for manufacturing an X-ray semiconductor detector according to claim 13 or 14, further comprising forming a two-dimensional semiconductor layer on the second surface of the first type i nitride semiconductor substrate or on the third surface of the second type i nitride semiconductor substrate, wherein bonding the first type i nitride semiconductor substrate and the second type i nitride semiconductor substrate means bonding the first type i nitride semiconductor substrate and the second type i nitride semiconductor substrate via the two-dimensional semiconductor layer, the two-dimensional semiconductor layer is bonded to the second surface and the third surface by van der Waals forces, and the bandgap energy of the two-dimensional semiconductor layer is smaller than the bandgap energy of the first type i nitride semiconductor substrate and smaller than the bandgap energy of the second type i nitride semiconductor substrate.

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