Diamond semiconductor equipment

Abstract

This invention is NV - The objective is to provide a diamond semiconductor device capable of emitting electroluminescent (EL) radiation through electrical excitation. [Solution] The diamond semiconductor device according to the present invention is characterized by comprising, for example, a first diamond semiconductor layer 22 doped with phosphorus, a second diamond semiconductor layer 24 doped with n-type impurities at a higher concentration than the phosphorus concentration in the first diamond semiconductor layer 22, a third diamond semiconductor layer 25 spaced apart from the second diamond semiconductor layer 24 and doped with p-type impurities at a higher concentration than the phosphorus concentration in the first diamond semiconductor layer 22, and an NV-centered diamond semiconductor layer 23 having NV centers formed in its crystal structure and positioned on the surface of the first diamond semiconductor layer 22 at a location sandwiched between the second diamond semiconductor layer 24 and the third diamond semiconductor layer 25.

Description

[Technical Field]

[0001] The present invention relates to a diamond semiconductor device having diamond in which NV centers are formed in the crystal structure. [Background technology]

[0002] An NV center (Nitrogen-Vacancy Center, also called a nitrogen-vacancy center, nitrogen vacancy center, or NVC) is a type of lattice defect in the diamond crystal structure, consisting of a nitrogen atom that replaces a carbon atom in the crystal lattice and a vacancy left by the absence of a carbon atom at an adjacent position to that nitrogen atom. When an electron is trapped in the vacancy, the NV center becomes negatively charged (hereinafter referred to as "NV"). - The electron spin state of NV centers (referred to as "NV") can be artificially manipulated by applying an external magnetic field or irradiating them with microwaves or RF waves, and because the coherence time at room temperature is relatively long, research on NV centers is actively being conducted.

[0003] For example, by forming the NV centers in an n-type phosphorus-doped diamond, the charge state of the NV centers is changed to the NV - It has been reported that methods such as stabilizing the diamond (see Patent Document 1), extending the coherence time by distributing phosphorus atoms more broadly than nitrogen atoms in the diamond (see Patent Document 2), and increasing the orientation of the NV axis of the NV centers formed in the grown diamond by epitaxially growing a (111) oriented diamond crystal (see Patent Document 3) have been reported.

[0004] Furthermore, as a quantum device utilizing the NV center, the NV - A device has been developed for initializing and reading out the electron spin state in (see Non-Patent Document 1). In such a device, excitation by laser irradiation is performed on the NV - Through optically detected magnetic resonance (ODMR), which detects the resonant magnetic field from the intensity of the red fluorescence emitted from, the NV- It enables the control and reading of the electron spin state in However, when exciting the NV - by laser irradiation, the optical system composed of an objective lens, an excitation laser, etc. is extremely large-scale. From the viewpoint of miniaturization and integration, an electrical excitation of the NV - without using the optical system is required.

[0005] Regarding this point, a diamond semiconductor device having a lateral PIN diode structure (see Non-Patent Document 2) configured by ion-implanting phosphorus and boron into a selected region of a diamond substrate layer (i-layer) in which the NV center is formed, or a vertical PIN diode structure in which a p-type diamond layer is disposed on one side of a diamond layer (i-layer) with a low impurity concentration in which the NV center is formed and an n-type diamond layer is disposed on the other side (see Non-Patent Document 3), electrical excitation of the NV - has also been attempted. However, in these proposals, while electrical excitation of the NV center (hereinafter referred to as "NV" 0 ") in a neutral charged state is possible, electrical excitation of the NV - required for quantum sensing has not been successful. It is considered that this is because the NV - was dominant due to the instability of the charge state in the NV 0 . Therefore, at present, there is no diamond semiconductor device that can electrically excite the NV <00000​​​​​​​​​​​​​​​​​​ [Patent Document 3] Japanese Patent Publication No. 2022-191959 [Non-patent literature]

[0007] [Non-Patent Document 1] A. Gruber, et.al., Science 276, 2012 (1997). [Non-Patent Document 2] A. Lohrmann et.al., Appl. Phys. Lett. 99, 251106 (2011). [Non-Patent Document 3] N. Mizuochi et.al., Nat. Photonics 6, 299 (2012). [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The present invention solves the aforementioned problems of the conventional NV - The objective is to provide a diamond semiconductor device capable of emitting electroluminescent (EL) light through electrical excitation. [Means for solving the problem]

[0009] The means to solve the aforementioned problem are as follows: <1> A diamond semiconductor device comprising: a first diamond semiconductor layer doped with phosphorus; a second diamond semiconductor layer disposed on the surface of the first diamond semiconductor layer and doped with n-type impurities at a higher concentration than the phosphorus concentration in the first diamond semiconductor layer, thereby having an n-type conductivity; a third diamond semiconductor layer disposed on the surface of the first diamond semiconductor layer, spaced apart from the second diamond semiconductor layer, and doped with p-type impurities at a higher concentration than the phosphorus concentration in the first diamond semiconductor layer, thereby having a p-type conductivity; and an NV-centered diamond semiconductor layer having NV centers formed in its crystal structure and disposed on the surface of the first diamond semiconductor layer sandwiched between the second and third diamond semiconductor layers, or disposed on the back surface of the first diamond semiconductor layer opposite to the surface of the first diamond semiconductor layer at a position sandwiched between the second and third diamond semiconductor layers. <2> The NV axis at at least one NV center and the path of the current flowing in the intralayer direction of the first diamond semiconductor layer from the third diamond semiconductor layer toward the second diamond semiconductor layer are configured to be orthogonal. <1> The diamond semiconductor device described above. <3> The surface of the first diamond semiconductor layer is a (111) plane. <1> from <2> A diamond semiconductor device as described in any of the following. <4> The phosphorus concentration in the first diamond semiconductor layer is 1 × 10⁻⁶ 15 cm -3 ~1 × 10 18 cm -3 The aforementioned <1> from <3> A diamond semiconductor device as described in any of the following. <5> The thickness of the first diamond semiconductor layer is said to be 0.1 μm to 50 μm. <1> from <4> A diamond semiconductor device as described in any of the following. <6> The concentration of NV centers in the NV-centered diamond semiconductor layer is 1 × 10⁻⁶ 19 cm -3 The above is <1> from <5> A diamond semiconductor device as described in any of the following. <7> The product of the phosphorus concentration in the first diamond semiconductor layer and the thickness of the first diamond semiconductor layer is greater than the product of the NV center concentration in the NV center diamond semiconductor layer and the thickness of the NV center diamond semiconductor layer. <1> from <6> A diamond semiconductor device as described in any of the following. <8> Multiple layers of NV-containing diamond semiconductor layers are arranged in the above <1> from <7> A diamond semiconductor device as described in any of the following. <9> The distance between the second diamond semiconductor layer and the third diamond semiconductor layer is set to 0.1 μm to 50 μm. <1> from <8> A diamond semiconductor device as described in any of the following. <10> The second diamond semiconductor layer has hopping conductivity. <1> from <9> A diamond semiconductor device as described in any of the following. <11> The third diamond semiconductor layer has hopping conductivity. <1> from <10> A diamond semiconductor device as described in any of the following. [Effects of the Invention]

[0010] According to the present invention, the aforementioned problems in the prior art can be solved, and the NV - By electrically exciting the diamond, it is possible to provide a diamond semiconductor device capable of emitting electroluminescent light. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view showing an overview of a diamond semiconductor device according to the first embodiment. [Figure 2] This is an explanatory diagram illustrating the relationship between the current path and the NV axis. [Figure 3] This is an explanatory diagram showing the top surface of a diamond semiconductor device having an antenna circuit. [Figure 4] This is a cross-sectional view showing an overview of a diamond semiconductor device according to the second embodiment. [Figure 5] This is a cross-sectional view showing an overview of a diamond semiconductor device according to the third embodiment. [Figure 6]This figure shows an optical microscope image of the diamond semiconductor device according to Example 1, taken from above. [Figure 7] This figure shows the current-voltage characteristics of the diamond semiconductor device according to Example 1. [Figure 8(a)] This figure shows a two-dimensional mapping image of the photoluminescence of a diamond semiconductor device according to Example 1. [Figure 8(b)] This figure shows a two-dimensional mapping image of the electroluminescence of a diamond semiconductor device according to Example 1. [Figure 9] This figure shows an optical microscope image of the diamond semiconductor device according to Example 2, taken from above. [Figure 10] This figure schematically shows the structure of a diamond semiconductor device according to Example 2. [Figure 11] This figure shows a two-dimensional mapping image of the luminescence of the NV-containing diamond semiconductor layer observed from the first diamond semiconductor layer in the diamond semiconductor device according to Example 2. [Figure 12] This figure shows the photoluminescence (PL) and electroluminescence (EL) emission spectra of the diamond semiconductor device according to Example 2. [Figure 13] This figure shows a two-dimensional mapping image of the electroluminescence of the NV-containing diamond semiconductor layer observed from the first diamond semiconductor layer in the diamond semiconductor device according to Example 3. [Figure 14] This figure shows the relationship between the voltage applied to the lateral PIN diode structure and the electroluminescence intensity in the diamond semiconductor device according to Example 3. [Figure 15] This figure shows the SIMS analysis results for a diamond semiconductor device according to Example 4, in which five NV-containing diamond semiconductor layers are embedded in the first diamond semiconductor layer. [Modes for carrying out the invention]

[0012] [First Embodiment] First, a diamond semiconductor device according to the first embodiment of the present invention will be described with reference to Figure 1.

[0013] As shown in Figure 1, the diamond semiconductor device 10 according to the first embodiment includes a diamond substrate 11, a first diamond semiconductor layer 12 (12a, 12b), an NV-containing diamond semiconductor layer 13, a second diamond semiconductor layer 14, and a third diamond semiconductor layer 15.

[0014] The first diamond semiconductor layer 12 is formed of phosphorus-doped diamond. The phosphorus is doped at a lower concentration than the impurity concentration in the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15, and i(n) in a known lateral PIN diode structure. - It is positioned in the ) layer. There are no particular restrictions on the specific phosphorus concentration in the first diamond semiconductor layer 12 under these settings, but 1 × 10 15 cm -3 ~1 × 10 18 cm -3 It is preferable that this is the case. With such a phosphorus concentration, the NV centers formed in the NV-containing diamond semiconductor layer 13 are NV - It is easily stabilized in this state.

[0015] There are no particular limitations on the method for forming the first diamond semiconductor layer 12, but one example is deposition and growth on a known diamond substrate by the CVD (Chemical Vapor Deposition) method. One example is microwave plasma chemical vapor deposition using source gases that serve as a diamond source and a phosphorus source. Here, a diamond substrate 11 is preferred in which the diamond substrate is offset by a small off-angle (approximately 1° to 8°) and the surface (main surface) is a (111) plane. When a first diamond semiconductor layer 12 is deposited and grown on such a diamond substrate 11 by CVD, a first diamond semiconductor layer 12 is obtained in which the surface is a (111) plane, following the surface properties of the diamond substrate 11. Commercially available diamond substrates (for example, Ib substrates from TISNCM or Sumitomo Electric Industries) can be used as the diamond substrate 11. Using the first diamond semiconductor layer 12 obtained in this way, the NV axis of the NV center (the axis in the direction from the nitrogen atom to the vacancy in the NV center) can be oriented in the

[0111] direction based on its crystal plane. In other words, the NV axis is oriented perpendicular to the plane of the (111) diamond. In this case, as shown in Figure 2, the current path flowing in the in-layer direction (x direction in Figure 1) of the first diamond semiconductor layer 12, controlled by the formation positions of the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15, is orthogonal to the NV axis (y direction in Figure 1) at the NV center. This allows multiple NV centers formed in the NV-containing diamond semiconductor layer 13 to be electrically excited under the same conditions, and quantum sensing can be performed under the same conditions using a simple optical system in which a photodetector is arranged to observe the EL from one direction.

[0016] Let's refer to Figure 1 again for further explanation. There are no particular restrictions on the thickness of the first diamond semiconductor layer 12, but 0.1 μm to 50 μm is preferred. If it is too thin, it becomes difficult to form the NV-containing diamond semiconductor layer 13, and if it is too thick, regions that do not participate in current injection into the NV-containing diamond semiconductor layer 13 are likely to occur.

[0017] The second diamond semiconductor layer 14 is disposed on the surface of the first diamond semiconductor layer and is formed of diamond doped with n-type impurities at a higher concentration than the phosphorus concentration in the first diamond semiconductor layer 12, thereby having an n-type conductivity. There are no particular restrictions on the n-type impurity, and it can be appropriately selected from known ones. However, if phosphorus is used, the second diamond semiconductor layer 14 can be formed using the same raw material gas as the first diamond semiconductor layer 12, making it easier to manufacture.

[0018] Furthermore, the third diamond semiconductor layer 15 is disposed on the surface of the first diamond semiconductor layer 12, spaced apart from the second diamond semiconductor layer 14, and is formed of diamond doped with p-type impurities at a higher concentration than the phosphorus concentration in the first diamond semiconductor layer 12, resulting in a p-type conductivity. There are no particular restrictions on the p-type impurity, and it can be appropriately selected from known impurities, for example, boron.

[0019] The impurity concentrations in the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15 are both higher than the phosphorus concentration in the first diamond semiconductor layer 12, and the n in a known lateral PIN diode structure + layer, p + It is positioned within a layer. There are no particular restrictions on the impurity concentrations in the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15, but 1 × 10⁻⁶ is a good example. 20 cm -3 ~1 × 10 21 cm -3 It is preferable that the impurities are present at such a high concentration, which gives the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15 having hopping conductivity. The aforementioned hopping conductivity means that, unlike band conduction, the movement of holes and electrons occurs via dense impurity levels, allowing a large current to be supplied to the first diamond semiconductor layer 12, which is in contact with the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15. The target for providing the hopping conductivity may be either the second diamond semiconductor layer 14 or the third diamond semiconductor layer 15, but it is particularly preferable to use both.

[0020] Metal electrodes (not shown) are formed on the surfaces of the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15. There are no particular restrictions on the metal electrode, but from the viewpoint of achieving low contact resistance, it is preferable that it be a single layer or laminate formed from gold, platinum, titanium, nickel, aluminum, or an alloy thereof. Furthermore, there are no particular limitations on the method for forming the metal electrodes, and known methods such as vacuum deposition and ALD (Atomic Layer Deposition) can be used.

[0021] There are no particular restrictions on the distance between the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15 (the shortest distance in the x-direction in Figure 1), but it is preferably 0.1 μm to 50 μm. If it is too short, the current path in the first diamond semiconductor layer 12 will also be short, affecting the effect of current injection into the NV-containing diamond semiconductor layer 13, that is, the NV - When stabilized, the effect of electrically exciting the NV centers may be weakened, and if the length is too long, the device tends to become larger, the light-emitting area of ​​the NV-centered diamond semiconductor layer 13 also increases, and the optical system for detecting EL tends to become more complicated.

[0022] There are no particular restrictions on the method for forming the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15, but one example is deposition growth by CVD. As an example, microwave plasma chemical vapor deposition using raw material gases that serve as the diamond source and the impurity source (phosphorus and boron) is used. Furthermore, these second diamond semiconductor layer 14 and third diamond semiconductor layer 15 are selectively formed at desired locations on the surface of the first diamond semiconductor layer, and such selective formation can be carried out by a known selective processing method using a mask. First diamond semiconductor layer 12(i(n - ) layer) and the second diamond semiconductor layer 14(n + (p layer) and third diamond semiconductor layer 15(p +The arrangement of the layers is positioned as being similar to that of a known lateral PIN diode structure.

[0023] The NV-containing diamond semiconductor layer 13 is embedded in the first diamond semiconductor layer 12, facing the surface of the first diamond semiconductor layer 12 at a position where the NV centers are formed in the crystal structure and sandwiched between the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15. In other words, in the diamond semiconductor device 10, the formation positions of the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15 are controlled based on the lateral PIN diode structure, and the NV-containing diamond semiconductor layer 13 is positioned at a location corresponding to the current path from the third diamond semiconductor layer 15 to the second diamond semiconductor layer 14. In the diamond semiconductor device 10, based on this configuration, current is stably injected into the NV-containing diamond semiconductor layer 13, and in the electrical excitation, the charged state of the NV center is the NV - It is stabilized to this state.

[0024] As a method for forming the NV-containing diamond semiconductor layer 13, firstly, an ion implantation method is used in which N ions are implanted into the surface of the first diamond semiconductor layer 12 from a direction perpendicular to the surface. The N ions are, 14 N ions, 15 This may be either N ions or a mixture thereof. During ion implantation, the implantation depth of N ions can be changed within a range of several nanometers to tens of micrometers from the surface by changing the energy used to accelerate the N ions by adjusting the voltage setting. Furthermore, in forming the NV-containing diamond semiconductor layer 13, it is preferable to anneal it for about 10 minutes to 2 hours at a temperature of 800 to 1,000 degrees Celsius after ion implantation. In the first method, the NV-containing diamond semiconductor layer 13 can be directly formed in the first diamond semiconductor layer 12.

[0025] Secondly, a method of deposition growth using CVD (Chemical Vapor Deposition) is also possible, one example being microwave plasma chemical vapor deposition using a raw material gas and nitrogen gas as the diamond source. In the second method, after depositing and forming an NV-containing diamond semiconductor layer 13 on the first diamond semiconductor layer 12a, the first diamond semiconductor layer 12b is grown further on the NV-containing diamond semiconductor layer 13 to obtain a first diamond semiconductor layer 12 in which the NV-containing diamond semiconductor layer 13 is embedded. In other words, by switching between a phosphorus source gas (phosphine gas) and nitrogen gas in the raw material gas, the first diamond semiconductor layer 12a, the NV-containing diamond semiconductor layer 13, and the first diamond semiconductor layer 12b can be grown continuously in this order.

[0026] Furthermore, due to differences in the formation method, in the first method, the NV-containing diamond semiconductor layer 13 may be a phosphorus-containing layer, while in the second method, the NV-containing diamond semiconductor layer 13 may be a phosphorus-free layer. With this in mind, the details of the first diamond semiconductor layer 12 (12a, 12b) and the NV-containing diamond semiconductor layer 13 will be explained.

[0027] There are no particular restrictions on the concentration of NV centers in the NV-centered diamond semiconductor layer 13, but in any method, 1 × 10 19 cm -3 The following is preferable: If the concentration is too high, the concentration of the NV centers will also increase, which may disperse the injected electrons and weaken the effect of current injection on each individual NV center. Furthermore, the lower limit of the NV center concentration is sufficient if it is the concentration necessary for the formation of the NV center, which is 1 × 10⁻⁶ 12 cm -3 It is to that extent.

[0028] There are no particular restrictions on the thickness of the NV-containing diamond semiconductor layer 13, but it is preferable that the following conditions are met. In other words, it is preferable that the product of the phosphorus concentration in the first diamond semiconductor layer 12 and the thickness of the first diamond semiconductor layer 12 is greater than the product of the concentration of NV centers in the NV-centered diamond semiconductor layer 13 and the thickness of the NV-centered diamond semiconductor layer 13. If this relationship is reversed, the total amount of NV centers will be greater than the total amount of phosphorus, and the effect of stabilizing the charge state of the NV centers may be weakened. Furthermore, regarding the thickness of the first diamond semiconductor layer 12 under the above conditions, in the case of the first method, the thickness of the first diamond semiconductor layer 12 itself is applied, and in the case of the second method, the total thickness of the first diamond semiconductor layer 12a and the first diamond semiconductor layer 12b (the thickness obtained by subtracting the thickness of the NV-containing diamond semiconductor layer 13 from the thickness of the first diamond semiconductor layer 12) is applied.

[0029] There are no particular restrictions on the embedding depth of the NV-containing diamond semiconductor layer 13 embedded in the first diamond semiconductor layer 12 as viewed from the surface of the first diamond semiconductor layer 12 (the shortest distance between the surface and the NV-containing diamond semiconductor layer 13 in the y-direction in Figure 1), but it is preferable to keep it within 25 μm in any formation method. If it is too deep, it may deviate from the current path and the electroluminescent emission from the NV-containing center may be weakened. The shallowest embedding depth is about 1 nm, taking into account the deposition limit of the first diamond semiconductor layer 12b (single layer). In this specification, "embedding" includes not only the case where the front and back surfaces of the NV-containing diamond semiconductor layer 13 are covered with the first diamond semiconductor layer 12 (12a, 12b), as shown in Figure 1, but also the case where the entire NV-containing diamond semiconductor layer 13, including its sides, is covered with the first diamond semiconductor layer 12. In other words, if the NV-containing diamond semiconductor layer 13 is a layer positioned opposite the surface of the first diamond semiconductor layer 12 at a location sandwiched between the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15, it can receive the effect of current injection corresponding to the current path between the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15. For example, the extending length of the NV-containing diamond semiconductor layer 13 may be restricted to the length that faces the surface of the first diamond semiconductor layer 12 at a location sandwiched between the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15 (cutting the left and right ends in Figure 1), so that the entire NV-containing diamond semiconductor layer 13, including its sides, is covered by the first diamond semiconductor layer 12. As a selective method for forming such an NV-containing diamond semiconductor layer 13 on the first diamond semiconductor layer 12, for example, a selective processing method using a known mask can be mentioned.

[0030] Furthermore, the NV-containing diamond semiconductor layer 13 does not necessarily have to be embedded in the first diamond semiconductor layer 12, and a modified version is provided in which the diamond semiconductor device 10 shown in Figure 1 does not form the first diamond semiconductor layer 12a. In other words, a modified example is also given in which the first diamond semiconductor layer is placed on the back surface of the first diamond semiconductor layer 12b, facing the surface of the first diamond semiconductor layer 12b at a position sandwiched between the second diamond semiconductor layer 14 and the third diamond semiconductor layer 15. In such modified examples, the arrangement structure of the NV-containing diamond semiconductor layer 13 can be obtained by depositing the NV-containing diamond semiconductor layer 13 on a diamond substrate 11 using the second method (CVD method), and then forming a first diamond semiconductor layer 12b on the NV-containing diamond semiconductor layer 13.

[0031] In the diamond semiconductor device 10 according to the first embodiment configured as described above, by applying a forward bias voltage, the NV centers in the NV-containing NV-centered diamond semiconductor layer 13 become NV -In a stabilized state, it is electrically excitable, and the NV center is required for quantum sensing. - It can emit electroluminescent (EL).

[0032] The detected NV - The EL of the NV provides information about the electron spin state (up spin, down spin) at the NV center. - There are no particular restrictions on the method for obtaining information about the electron spin state from the electroluminescent (EL), and a well-known method is optically detected magnetic resonance (ODMR).

[0033] Furthermore, there are no particular limitations on the method for controlling the electron spin state of the NV center, and a known method can be appropriately selected. For example, one method is to irradiate the NV center with microwave or RF (Radio Frequency) waves to induce Rabi oscillations in the electrons trapped in the NV center.

[0034] Here, Figure 3 shows an example of the apparatus configuration when using microwaves or RF waves. As shown in Figure 3, in the diamond semiconductor device 100, the element structure of the diamond semiconductor device 10 (see Figure 1) is integrated at four locations. Here, if the NV axis at the NV center is oriented perpendicular to the (111) plane diamond (y-direction in Figures 1 and 3), then by arranging the antenna circuit 16 so that this NV axis and the extension direction of the antenna of the antenna circuit 16 (x-direction in Figure 3) are orthogonal, it is possible to provide consistent electron spin control for all four element structures. In other words, the element structures of the diamond semiconductor device 10 can be densely arranged around the antenna of the antenna circuit 16 to achieve high integration.

[0035] Furthermore, since the diamond semiconductor device 10 according to the first embodiment (see Figure 1) has a PIN diode structure, it can be operated in the same way as a known photodetector. When irradiated with light carrying electron spin information while a reverse bias voltage is applied, it generates a photocurrent of a magnitude corresponding to the electron spin state. In other words, the diamond semiconductor device 10 according to the first embodiment can be used not only as a light source for light carrying electron spin information, but also as a photodetector for reading the electron spin state from light carrying electron spin information.

[0036] [Second Embodiment] Next, a diamond semiconductor device according to a second embodiment of the present invention will be described with reference to Figure 4.

[0037] As shown in Figure 4, the diamond semiconductor device 20 according to the second embodiment includes a diamond substrate 21, a first diamond semiconductor layer 22, an NV-containing diamond semiconductor layer 23, a second diamond semiconductor layer 24, and a third diamond semiconductor layer 25. The diamond substrate 21, the first diamond semiconductor layer 22, the second diamond semiconductor layer 24, and the third diamond semiconductor layer 25 are configured in the same way as the diamond substrate 11, the first diamond semiconductor layer 12, the second diamond semiconductor layer 14, and the third diamond semiconductor layer 15 in the diamond semiconductor device 10 according to the first embodiment.

[0038] In the diamond semiconductor device 20 according to the second embodiment, unlike the diamond semiconductor device 10 according to the first embodiment, the NV-containing diamond semiconductor layer 23 is disposed on the surface of the first diamond semiconductor layer 22, which is sandwiched between the second diamond semiconductor layer 24 and the third diamond semiconductor layer 25.

[0039] As a method for forming the NV-containing diamond semiconductor layer 23, the second method described above for the first diamond semiconductor layer 12a, as explained in the diamond semiconductor device 10, is an example. Furthermore, the NV-containing diamond semiconductor layer 23 can be constructed in the same way as the NV-containing diamond semiconductor layer 13 in the diamond semiconductor device 10, except for explanations related to the formation position.

[0040] In the diamond semiconductor device 20 according to the second embodiment configured in this way, the formation positions of the second diamond semiconductor layer 24 and the third diamond semiconductor layer 25 are controlled, and the NV-containing diamond semiconductor layer 23 is arranged on the current path from the third diamond semiconductor layer 25 to the second diamond semiconductor layer 24, so that the NV centers are - It is made electrically excitable in a stabilized state, and the NV center is made electrically excitable from the NV - It can emit electroluminescent (EL).

[0041] [Third Embodiment] Next, a diamond semiconductor device according to a third embodiment of the present invention will be described with reference to Figure 5.

[0042] As shown in Figure 5, the diamond semiconductor device 30 according to the third embodiment includes a diamond substrate 31, a first diamond semiconductor layer 32 (32a, 32b, 32c, 32d), NV-containing diamond semiconductor layers 33a, 33b, 33c, a second diamond semiconductor layer 34, and a third diamond semiconductor layer 35. The diamond substrate 31, the first diamond semiconductor layer 32, the second diamond semiconductor layer 34, and the third diamond semiconductor layer 35 are configured in the same way as the diamond substrate 11, the first diamond semiconductor layer 12, the second diamond semiconductor layer 14, and the third diamond semiconductor layer 15 in the diamond semiconductor device 10 according to the first embodiment.

[0043] In the diamond semiconductor device 30 according to the third embodiment, unlike the diamond semiconductor device 10 according to the first embodiment, three NV-centered diamond semiconductor layers 33a, 33b, and 33c are embedded in the first diamond semiconductor layer 32.

[0044] As a method for forming the NV-containing diamond semiconductor layers 33a, 33b, and 33c, the second method described above for the diamond semiconductor device 10 (continuous growth method for diamond layers) can be mentioned. Each of the NV-containing diamond semiconductor layers 33a, 33b, and 33c can be configured in the same way as the NV-containing diamond semiconductor layer 13 in the diamond semiconductor device 10. However, in the diamond semiconductor device 10 according to the first embodiment, with respect to the condition that the product of the phosphorus concentration in the first diamond semiconductor layer and the thickness of the first diamond semiconductor layer is greater than the product of the concentration of NV centers in the NV-centered diamond semiconductor layer and the thickness of the NV-centered diamond semiconductor layer, the average concentration in the NV-centered diamond semiconductor layers 33a, 33b, and 33c is applied to the NV center concentration, and the total thickness of the NV-centered diamond semiconductor layers 33a, 33b, and 33c is applied to the thickness of the NV-centered diamond semiconductor layer. Furthermore, regarding the conditions relating to the embedding depth position of the NV-containing diamond semiconductor layer embedded in the first diamond semiconductor layer as viewed from the surface of the first diamond semiconductor layer, if the NV-containing diamond semiconductor layer 33a, which is located at the deepest position, satisfies the conditions, then the NV-containing diamond semiconductor layers 33b and 33c will also satisfy the conditions.

[0045] In the diamond semiconductor device 30 according to the third embodiment, the NV-containing diamond semiconductor layer 33c, which is located on the outermost surface, is configured as a layer embedded in the first diamond semiconductor layer 32. However, a modified example is also provided in which the NV-containing diamond semiconductor layer 33c is located on the surface of the first diamond semiconductor layer 32, similar to the NV-containing diamond semiconductor layer 23 in the diamond semiconductor device 20 according to the second embodiment. Furthermore, a modified version is provided that is configured similarly to the diamond semiconductor device 30 according to the third embodiment, except that the first diamond semiconductor layer 32a constituting the bottom layer is not formed, and the NV-containing diamond semiconductor layer 33a is directly placed on the diamond substrate 31. Furthermore, there are no particular restrictions on the number of NV-containing diamond semiconductor layers, and they can be changed arbitrarily.

[0046] In the diamond semiconductor device 30 according to the third embodiment configured in this way, the formation positions of the second diamond semiconductor layer 34 and the third diamond semiconductor layer 35 are controlled, and the NV-containing diamond semiconductor layers 33a, 33b, and 33c are arranged on the current path from the third diamond semiconductor layer 35 to the second diamond semiconductor layer 34, so that the NV centers are the NV - It is made electrically excitable in a stabilized state, and the NV center is made electrically excitable from the NV - It can emit electroluminescent (EL). [Examples]

[0047] (Example 1) A diamond semiconductor device according to Example 1 was manufactured in accordance with the configuration shown in Figure 1. The following provides a detailed explanation.

[0048] <First diamond semiconductor layer: i(n - ) layer> First, a diamond substrate (TISNCM, Type Ib substrate) was prepared, which was offset at a slight angle and whose main surface was designated as the (111) plane. The off-angle and off-direction of the diamond substrate were measured by X-ray diffraction, and the off-angle was found to be 2.5°, and the off-direction was <-1-12>.

[0049] Next, using a microwave-based plasma vapor deposition system (Cornes Technology, AX5250), a first diamond semiconductor layer i(n - A diamond semiconductor layer of the ) type was formed. Specifically, hydrogen gas, methane gas, and phosphine gas to impart n-type conductivity were used as raw materials. The hydrogen gas flow rate was 996 sccm, the methane gas flow rate was 4 sccm, and the hydrogen-diluted phosphine gas (phosphine content: 0.1 volume%) flow rate was 2 sccm, respectively, and these were introduced into the plasma vapor deposition apparatus. The deposition conditions of the plasma vapor deposition apparatus were set to a plasma input power of 3,600 W, a pressure of 150 Torr, and a deposition time of 4 hours, thereby forming the first diamond semiconductor layer on the diamond substrate.

[0050] Furthermore, the phosphorus concentration in the first diamond semiconductor layer, as measured by a SIMS (Secondary Ion Mass Spectrometry) instrument (CAMECA Corporation, IMS-0f), was 6 × 10⁻⁶. 16 cm -3 Other impurities, hydrogen and nitrogen, were below the background level of SIMS analysis, and boron was below the detection limit. Furthermore, the thickness of the first diamond semiconductor layer, as measured by the SIMS analyzer, was 10 μm. Furthermore, the surface of the first diamond semiconductor layer had a shape in which terrace surfaces and step surfaces were alternately formed in one direction, following the surface shape of the diamond substrate. In addition, the terrace surfaces had (111) planes, following the surface shape of the diamond substrate.

[0051] <Second diamond semiconductor layer: n + Layer> Next, the first diamond semiconductor layer has a conductivity type of n (n + The second diamond semiconductor layer of type () was formed as follows.

[0052] First, the surface of the first diamond semiconductor layer was cleaned by boiling it in a mixture of sulfuric acid and nitric acid.

[0053] Next, a resist material was applied to the first diamond semiconductor layer by spin coating, and then a resist pattern was formed on the first diamond semiconductor layer so as to cover only the region where the second diamond semiconductor layer was to be formed, by exposure treatment using a mask and subsequent development treatment. Subsequently, a metal mask material (Ti) was deposited on the first diamond semiconductor layer to a thickness of 500 nm. After that, the resist pattern was removed by lift-off, and the metal mask was formed in the region other than the region where the second diamond semiconductor layer was to be formed.

[0054] Next, the second diamond semiconductor layer was selectively grown using the plasma vapor deposition apparatus in the region on the first diamond semiconductor layer where the metal mask was not formed. Specifically, hydrogen gas, methane gas, and phosphine gas to impart n-type conductivity were used as raw materials. The hydrogen gas flow rate was 400 sccm, the methane gas flow rate was 0.2 sccm, and the hydrogen-diluted phosphine gas (phosphine content: 5 volume%) flow rate was 0.2 sccm, respectively, and these were introduced into the plasma vapor deposition apparatus. The deposition conditions of the plasma vapor deposition apparatus were set to a plasma input power of 750 W, a pressure of 75 Torr, and a deposition time of 1 hour, and the deposition was carried out. After that, the metal mask was removed by acid cleaning.

[0055] Furthermore, the phosphorus concentration in the second diamond semiconductor layer, as measured by the SIMS analyzer, was 2 × 10⁻⁶ 20 cm -3 That was the case. Furthermore, the thickness of the second diamond semiconductor layer, as measured by the SIMS analyzer, was 0.2 μm.

[0056] <Third diamond semiconductor layer: p + Layer> Next, the first diamond semiconductor layer has a conductivity type of p (p + The third diamond semiconductor layer of type () was formed as follows.

[0057] First, the surface of the first diamond semiconductor layer was cleaned by boiling it in a mixture of sulfuric acid and nitric acid.

[0058] Next, a resist material was applied to the surfaces of the first diamond semiconductor layer and the second diamond semiconductor layer by spin coating. Then, a resist pattern covering only the region where the third diamond semiconductor layer was formed was formed by exposure treatment using a mask and subsequent development treatment. Subsequently, a metal mask material (Ti) was deposited onto the first diamond semiconductor layer and the second diamond semiconductor layer to a thickness of 500 nm. After that, the resist pattern was removed by lift-off, and the metal mask was formed in the region other than the region where the third diamond semiconductor layer was formed.

[0059] Next, the third diamond semiconductor layer was selectively grown using the plasma vapor deposition apparatus in a region on the first diamond semiconductor layer where the metal mask was not formed. Specifically, hydrogen gas, methane gas, and trimethylboron, which imparts a p-type conductivity, were used as raw materials. The hydrogen gas flow rate was 399 sccm, the methane gas flow rate was 0.8 sccm, and the hydrogen-diluted trimethylboron gas (trimethylboron content: 1 volume%) flow rate was 0.8 sccm, respectively, and these were introduced into the plasma vapor deposition apparatus. The deposition conditions of the plasma vapor deposition apparatus were set to a plasma input power of 1,200 W, a pressure of 50 Torr, and a deposition time of 0.16 hours, and the deposition was carried out. After that, the metal mask was removed by acid washing.

[0060] Furthermore, the boron concentration in the third diamond semiconductor layer, as measured by the SIMS analyzer, was 8 × 10⁻⁶. 20 cm -3 That was the case. Furthermore, the thickness of the third diamond semiconductor layer, as measured by the SIMS analyzer, was 0.05 μm. In this embodiment, the second diamond semiconductor layer is formed before the third diamond semiconductor layer, but the order in which these layers are formed does not matter.

[0061] <Formation of NV-containing diamond semiconductor layer: Ion implantation method> Next, an NV-containing diamond semiconductor layer was formed in the first diamond semiconductor layer by ion implantation.

[0062] First, the surface of the first diamond semiconductor layer was cleaned by boiling it in a mixture of sulfuric acid and nitric acid.

[0063] next, 14 N ions were accelerated at 350 keV, and a dose of 5 × 10 was applied to the surface of the first diamond semiconductor layer heated to 600 degrees. 8 cm -2 It was injected under the following conditions. Subsequently, a high-temperature heat treatment was performed in an Ar atmosphere at 850°C for 30 minutes to form an NV-centered diamond semiconductor layer containing NV centers in the first diamond semiconductor layer. From the Stopping and Range Ion in Matter (SRIM) simulation, the depth position of the NV-containing diamond semiconductor layer formed in the first diamond semiconductor layer, as viewed from the surface of the first diamond semiconductor layer, was 340 nm.

[0064] <Electrode> Next, electrodes were formed on the surfaces of the second diamond semiconductor layer and the third diamond semiconductor layer as follows.

[0065] First, the surfaces of the second diamond semiconductor layer and the third diamond semiconductor layer were cleaned by boiling them in a mixture of sulfuric acid and nitric acid.

[0066] Next, a resist material was applied to the surfaces of the first diamond semiconductor layer, the second diamond semiconductor layer, and the third diamond semiconductor layer by spin coating. Then, a resist pattern was formed that did not cover the surfaces of the second diamond semiconductor layer and the third diamond semiconductor layer by exposure treatment using a mask and subsequent development treatment. Subsequently, a multilayer electrode of Au (100 nm) / Pt (30 nm) / Ti (30 nm) was deposited using a vacuum deposition apparatus (electron beam deposition apparatus manufactured by Eiko Engineering Co., Ltd.). After that, the resist pattern was removed by lift-off, and the electrode was formed on the surfaces of the second diamond semiconductor layer and the third diamond semiconductor layer.

[0067] The diamond semiconductor device according to Example 1 was manufactured through the above process. Figure 6 shows an optical microscope image of the diamond semiconductor device according to Example 1, taken from above. The cross-sectional structure of the region along the line A-A' in the magnified portion of Figure 6 corresponds to the cross-sectional structure in Figure 1. The diamond semiconductor device according to Example 1 is manufactured in accordance with the diamond semiconductor device shown in Figure 1, but at the position below the second diamond semiconductor layer and the third diamond semiconductor layer, the material is injected from above the surface of the second diamond semiconductor layer and the third diamond semiconductor layer. 14 The implantation position of the N ions is located on the surface side of the first diamond semiconductor layer by the thickness of the second and third diamond semiconductor layers, compared to the position in the first diamond semiconductor layer. 14 N ions are not involved in the operation of the diamond semiconductor device according to Example 1.

[0068] <Semiconductor Characteristics> In the diamond semiconductor device according to Example 1, the first diamond semiconductor layer (i(n - ) layer), the aforementioned second diamond semiconductor layer (n + (p layer) and the third diamond semiconductor layer (p+ The semiconductor properties of each layer were measured using a Hall effect measurement device (RESITEST 8300, manufactured by Tokyo Technica). This measurement was performed on the first diamond semiconductor layer (i(n) in a single-layer state. - ) layer), the aforementioned second diamond semiconductor layer (n + (p layer) and the third diamond semiconductor layer (p + This was performed on the layer. As a result, the phosphorus-doped first diamond semiconductor layer exhibited a negative Hall electromotive force, confirming the n-type semiconductor characteristics where the carriers are electrons. Furthermore, even in the second diamond semiconductor layer doped with a high concentration of phosphorus, the Hall electromotive force showed a negative value, indicating that the carriers were electrons and confirming n-type semiconductor characteristics exhibiting hopping conduction. Furthermore, in the third diamond semiconductor layer doped with a high concentration of boron, the Hall electromotive force showed a positive value, indicating that the carriers were holes, and p-type semiconductor characteristics exhibiting hopping conduction were confirmed.

[0069] <Current-voltage characteristics> The current-voltage characteristics of the diamond semiconductor device according to Example 1 were measured using a semiconductor parameter analyzer (Keithley 4200A). The measurement was performed by measuring the current flow when the voltage was swept within the range of -50V to +50V. Figure 7 shows the current-voltage characteristics of the diamond semiconductor device according to Example 1. As shown in Figure 7, the diamond semiconductor device according to Example 1 was confirmed to have clean rectification characteristics. In other words, it was confirmed that the lateral PIN diode was formed correctly. Specifically, when a forward voltage of 5V or greater is applied, the diode turns ON, and at voltages below this magnitude, the diode turns OFF. Furthermore, electroluminescent emission was observed when the device was in the ON state.

[0070] <Luminous properties> To clarify the luminescence characteristics of the diamond semiconductor device according to Example 1, the following analysis was performed using a confocal fluorescence microscope and other methods.

[0071] First, the first diamond semiconductor layer (i(n) near the center of the lateral PIN diode structure - Figures 8(a) and 8(b) show two-dimensional mapping images of the emission from the NV-containing central diamond semiconductor layer observed from the ) layer. Figure 8(a) shows the photoluminescence image, and Figure 8(b) shows the electroluminescence image. In the confocal microscope, the focal point is imaged through a 30 μm pinhole, so the emission point can be detected with high spatial resolution. Here, the photoluminescence image maps the intensity of PL light emitted from the sample when irradiated with a laser beam of wavelength 532 nm, while the electroluminescence image maps the intensity of EL light emission during current injection, obtained by applying a voltage of 30 V to the lateral PIN diode.

[0072] As shown in Figures 8(a) and (b), the first diamond semiconductor layer (i(n - From the ) layer, emission is observed as bright spots (emission from a single NV center), and these bright spots are observed at the same location in both the photoluminescence image and the electroluminescence image. These findings confirm that electrical excitation and EL emission occur at a single NV center. Furthermore, when antibunching measurements and spectral evaluations of the emission were performed in accordance with the references 1 and 2 below, these bright spots were found to be negatively charged NV - It was confirmed that the emission originated from a single photon. In other words, the NV caused by optical excitation as described above - Rather than relying on a method to obtain single-photon emission from, by using the diamond semiconductor device according to Example 1, the NV due to electrical excitation can be obtained. - We have succeeded for the first time in obtaining single-photon emission from it. Reference 1: A. Beveratos et al. Eur. Phys. J. D 18, 191 (2002). Reference 2: N. Mizuochi et al., Nat. Photonics 6, 299 (2012).

[0073] (Example 2) A diamond semiconductor device according to Example 2 was manufactured according to the configuration shown in Figure 4. In Example 2, the method for forming the NV-containing diamond semiconductor layer was changed from the ion implantation method in Example 1 to the CVD method to form the NV-containing diamond semiconductor layer. The following provides a detailed explanation.

[0074] <First diamond semiconductor layer: i(n - ) layer> First, a diamond substrate (Sumitomo Electric Industries, Type Ib substrate) was prepared, which was offset at a slight angle and whose main surface was designated as the (111) plane. When the off-angle and off-direction of the diamond substrate were measured by X-ray diffraction, the off-angle was found to be 2.7°, and the off-direction was a direction shifted by +10° from <-1-12>.

[0075] Next, except that the flow rate of the hydrogen dilution gas for the phosphine was changed from 2 sccm to 1 sccm and the film deposition time was changed from 4 hours to 5 hours, the same procedure as in Example 1 was followed to create a first diamond semiconductor layer i(n) on the diamond substrate. - A diamond semiconductor layer of the ) type was formed.

[0076] Furthermore, the phosphorus concentration in the first diamond semiconductor layer, as measured by the SIMS analyzer, was 3 × 10⁻⁶. 16 cm -3 Other impurities, hydrogen and nitrogen, were below the background level of SIMS analysis, and boron was below the detection limit. Furthermore, the thickness of the first diamond semiconductor layer, as measured by the SIMS analyzer, was 15 μm. Furthermore, the surface of the first diamond semiconductor layer had a shape in which terrace surfaces and step surfaces were alternately formed in one direction, following the surface shape of the diamond substrate. In addition, the terrace surfaces had (111) planes, following the surface shape of the diamond substrate.

[0077] <Second diamond semiconductor layer: n + Layer> Next, the second diamond semiconductor layer was selectively grown on the first diamond semiconductor layer using the metal mask, in the same manner as in Example 1, except that the film deposition pressure conditions were changed from 75 Torr to 25 Torr.

[0078] Furthermore, the phosphorus concentration in the second diamond semiconductor layer, as measured by the SIMS analyzer, was 2 × 10⁻⁶ 20 cm -3 That was the case. Furthermore, the thickness of the second diamond semiconductor layer, as measured by the SIMS analyzer, was 0.15 μm.

[0079] <Third diamond semiconductor layer: p + Layer> Next, the third diamond semiconductor layer was selectively grown on the first diamond semiconductor layer using the metal mask, in the same manner as in Example 1. The boron concentration and thickness of the third diamond semiconductor layer, as measured by the SIMS analyzer, were the same as in Example 1.

[0080] <Formation of NV-containing diamond semiconductor layer: CVD method> Next, the NV-containing diamond semiconductor layer was formed in the first diamond semiconductor layer by CVD as follows.

[0081] First, a resist material was applied to the first diamond semiconductor layer by spin coating. Then, through an exposure process using a mask and a subsequent development process, a resist pattern was formed in a manner that covers only the surface of the first diamond semiconductor layer. After that, a metal mask material (Ti) was deposited on the resist pattern. Subsequently, the resist pattern was removed by lift-off to form the metal mask only on the surfaces of the second diamond semiconductor layer and the third diamond semiconductor layer.

[0082] Next, for the region on the first diamond semiconductor layer where the metal mask was not formed, a nitrogen-doped diamond layer containing the NV center was formed as the NV-center-containing diamond semiconductor layer by the plasma vapor deposition apparatus. Specifically, hydrogen gas, methane gas, and nitrogen gas for forming the NV center were used as raw materials. The flow rate of hydrogen gas was 999 sccm, the flow rate of methane gas was 1 sccm, and the flow rate of nitrogen gas was 0.05 sccm, which were respectively introduced into the plasma vapor deposition apparatus. The film formation conditions of the plasma vapor deposition apparatus were set as a plasma input power of 3,500 W, a pressure of 120 Torr, and a film formation time of 30 minutes, and the NV-center-containing diamond semiconductor layer was formed on the first diamond semiconductor layer. After that, the metal mask was removed by acid cleaning.

[0083] The nitrogen concentration in the NV-center-containing diamond semiconductor layer measured by the SIMS analyzer was 1×10 18 cm -3 It was. Also, the thickness of the NV-center-containing diamond semiconductor layer measured by the SIMS analyzer was 1 μm.

[0084] <Electrode> Next, in the same manner as in Example 1, electrodes (a laminated electrode of Au(100 nm) / Pt(30 nm) / Ti(30 nm)) were formed on the surfaces of the second diamond semiconductor layer and the third diamond semiconductor layer.

[0085] The diamond semiconductor device according to Example 2 was manufactured through the above process. Figure 9 shows an optical microscope image of the diamond semiconductor device according to Example 2, taken from above. In the diamond semiconductor device according to Example 2, the thickness of the NV-containing centrifugal diamond semiconductor layer is greater than that of the second and third diamond semiconductor layers compared to the diamond semiconductor device 20 shown in Figure 4, and the structure is such that each side edge of the NV-containing centrifugal diamond semiconductor layer is in contact with the electrode. The NV-containing centrifugal diamond semiconductor layer is a layer with a low concentration of nitrogen, which is also an n-type impurity (i(n - The diamond semiconductor layer is configured to act as an insulating layer within the operating voltage range and does not provide a current path between the second diamond semiconductor layer and the third diamond semiconductor layer. The structure of the diamond semiconductor device according to Example 2 is schematically shown in Figure 10.

[0086] <Current-voltage characteristics> The current-voltage characteristics of the diamond semiconductor device according to Example 2 were measured using the same method as described in Example 1. As a result, current-voltage characteristics similar to those of the diamond semiconductor device according to Example 1 were obtained, and it was confirmed that the diamond semiconductor device according to Example 2 also had clean rectification characteristics. In other words, it was confirmed that the lateral PIN diode was formed correctly. Specifically, when a forward voltage of 5V or greater is applied, the diode turns ON, and at voltages below this magnitude, the diode turns OFF. Furthermore, electroluminescent emission was observed when the device was in the ON state.

[0087] (Luminous properties) The luminescence characteristics of the diamond semiconductor device according to Example 2 were analyzed using the same method as described in Example 1. The first diamond semiconductor layer (i(n) near the center of the lateral PIN diode structure -The two-dimensional mapping image of the light emission of the NV center-containing diamond semiconductor layer observed from the

[0088] As shown in Fig. 11, bright spots are also confirmed in the electroluminescence image of the diamond semiconductor device according to Example 2, just as in that of the diamond semiconductor device according to Example 1. Also, these bright spots are confirmed to have the same light emission pattern as the photoluminescence image and are bright spots at the same positions as those in the photoluminescence image. Therefore, it is confirmed that electrical excitation and EL emission occur at a single said NV center.

[0089] Fig. 12 shows the light emission spectra of photoluminescence (PL) and electroluminescence (EL). From the spectral shapes shown in Fig. 12, the zero phonon line at 637 nm and the phonon sideband, which are typical for the said NV - can be confirmed, and it is confirmed that the bright spots are light emissions derived from the said NV - That is, in the diamond semiconductor device according to Example 2 as well, successful single photon emission was obtained from the negatively charged said NV - <00,00568>

[0090] (Example 3) A diamond semiconductor device according to Example 3 was manufactured according to the configuration shown in Fig. 1. In Example 3, the method for forming the NV center-containing diamond semiconductor layer was changed from the ion implantation method in Example 1 to the CVD method to form the NV center-containing diamond semiconductor layer. Also, the said NV center layer in Example 3, unlike Example 2, is formed by being embedded in the - diamond semiconductor layer (i(n The following will be specifically described.

[0091] <First diamond semiconductor layer: i(n - ) layer, and formation of NV center-containing diamond semiconductor layer: CVD method>​​ First, a diamond substrate (TISNCM, Type Ib substrate) was prepared, which was offset at a slight angle and whose main surface was designated as the (111) plane. When the off-angle and off-direction of the diamond substrate were measured by X-ray diffraction, the off-angle was found to be 3.2°, and the off-direction was a direction shifted by -5° from <-1-12>.

[0092] Next, the plasma vapor deposition apparatus is used to deposit i(n) as a first diamond semiconductor layer on the diamond substrate. - A diamond semiconductor layer of type ) and a nitrogen-doped diamond layer containing the NV centers as the NV-centered diamond semiconductor layer were formed in a continuous manner as follows.

[0093] First, hydrogen gas, methane gas, and phosphine gas to impart n-type conductivity were used as raw materials. The hydrogen gas flow rate was 996 sccm, the methane gas flow rate was 4 sccm, and the hydrogen-diluted phosphine gas (phosphine content: 0.1 volume%) flow rate was 5 sccm, respectively, and these were introduced into the plasma vapor deposition apparatus. The deposition conditions of the plasma vapor deposition apparatus were set to a plasma input power of 3,600 W, a pressure of 150 Torr, and a deposition time of 5 hours to form the first diamond semiconductor layer on the diamond substrate.

[0094] Furthermore, the phosphorus concentration in the first diamond semiconductor layer, as measured by the SIMS analyzer, was 1 × 10⁻⁶ 17 cm -3 Other impurities, hydrogen and nitrogen, were below the background level of SIMS analysis, and boron was below the detection limit. Furthermore, the thickness of the first diamond semiconductor layer, as measured by the SIMS analyzer, was 20 μm. Furthermore, the surface of the first diamond semiconductor layer had a shape in which terrace surfaces and step surfaces were alternately formed in one direction, following the surface shape of the diamond substrate. In addition, the terrace surfaces had (111) planes, following the surface shape of the diamond substrate.

[0095] Next, hydrogen gas, methane gas, and nitrogen gas for forming the NV centers were introduced into the plasma vapor deposition apparatus at a flow rate of 999 sccm for hydrogen gas, 1 sccm for methane gas, and 0.05 sccm for nitrogen gas. The deposition conditions of the plasma vapor deposition apparatus were set to a plasma input power of 3,500 W, a pressure of 120 Torr, and a deposition time of 15 minutes to form the NV-centered diamond semiconductor layer on the first diamond semiconductor layer.

[0096] Furthermore, the nitrogen concentration in the NV-containing diamond semiconductor layer, as measured by the SIMS analyzer, was 1 × 10⁻⁶. 18 cm -3 That was the case. Furthermore, the thickness of the NV-containing diamond semiconductor layer, as measured by the SIMS analyzer, was 0.5 μm.

[0097] Next, using hydrogen gas, methane gas, and phosphine gas as raw materials again, the hydrogen gas flow rate was set to 996 sccm, the methane gas flow rate to 4 sccm, and the hydrogen-diluted phosphine gas (phosphine content: 0.1 volume%) flow rate to 5 sccm, respectively, and these were introduced into the plasma vapor deposition apparatus. The deposition conditions of the plasma vapor deposition apparatus were set to a plasma input power of 3,600 W, a pressure of 150 Torr, and a deposition time of 30 minutes, and the first diamond semiconductor layer was grown on the NV-containing diamond semiconductor layer. A diamond semiconductor structure was fabricated in which the NV-containing diamond semiconductor layer was embedded in the first diamond semiconductor layer, sandwiched between the first diamond semiconductor layer formed earlier and the first diamond semiconductor layer formed later.

[0098] Furthermore, the phosphorus concentration in the first diamond semiconductor layer related to the additional growth, as measured by the SIMS analyzer, is 1 × 10⁻⁶ 17 cm -3 That was the case. Furthermore, the thickness of the first diamond semiconductor layer related to the additional growth, as measured by the SIMS analyzer, was 1.5 μm. Furthermore, the surface of the first diamond semiconductor layer (follow-up growth) had a shape in which terrace surfaces and step surfaces were alternately formed in one direction, following the surface shape of the diamond substrate. In addition, the terrace surfaces had (111) planes, following the surface shape of the diamond substrate.

[0099] <Second diamond semiconductor layer: n + Layer> Next, the second diamond semiconductor layer was selectively grown on the first diamond semiconductor layer using the metal mask, in the same manner as in Example 1, except that the film deposition pressure conditions were changed from 75 Torr to 25 Torr.

[0100] Furthermore, the phosphorus concentration in the second diamond semiconductor layer, as measured by the SIMS analyzer, was 3 × 10⁻⁶. 20 cm -3 That was the case. Furthermore, the thickness of the second diamond semiconductor layer, as measured by the SIMS analyzer, was 0.18 μm.

[0101] <Third diamond semiconductor layer: p + Layer> Next, the third diamond semiconductor layer was selectively grown on the first diamond semiconductor layer using the metal mask, in the same manner as in Example 1. The boron concentration and thickness of the third diamond semiconductor layer, as measured by the SIMS analyzer, were the same as in Example 1.

[0102] <Electrode> Next, the electrodes (Au(100nm) / Pt(30nm) / Ti(30nm) stacked electrodes) were formed on the surfaces of the second diamond semiconductor layer and the third diamond semiconductor layer, respectively, in the same manner as in Example 1.

[0103] The diamond semiconductor device according to Example 3 was manufactured through the above process.

[0104] <Current-voltage characteristics> The current-voltage characteristics of the diamond semiconductor device according to Example 3 were measured using the same method as described in Example 1. As a result, current-voltage characteristics similar to those of the diamond semiconductor device according to Example 1 were obtained, and it was confirmed that the diamond semiconductor device according to Example 3 also had clean rectification characteristics. In other words, it was confirmed that the lateral PIN diode was formed correctly. Specifically, when a forward voltage of 5V or greater is applied, the diode turns ON, and at voltages below this magnitude, the diode turns OFF. Furthermore, electroluminescent emission was observed when the device was in the ON state.

[0105] (Luminous properties) The luminescence characteristics of the diamond semiconductor device according to Example 3 were analyzed using the same method as described in Example 1. The first diamond semiconductor layer (i(n) near the center of the lateral PIN diode structure - Figure 13 shows a two-dimensional mapping image of the electroluminescence of the NV-containing diamond semiconductor layer observed from the ) layer.

[0106] As shown in Figure 13, the electroluminescent image of the diamond semiconductor device according to Example 3 also shows the same negatively charged NV as that of the diamond semiconductor devices according to Examples 1 and 2. - We succeeded in obtaining single-photon emission from it.

[0107] Furthermore, Figure 14 shows the relationship between the voltage applied to the lateral PIN diode structure in the diamond semiconductor device according to Example 3 and the light emission intensity of the electroluminescence. As explained earlier, the amount of current flowing through the horizontal PIN diode increases with the application of voltage (see Figure 7), and as shown in Figure 14, it can be seen that the electroluminescence intensity also increases as the applied voltage increases. That is, the NV -The intensity of the EL light emitted from the device can be controlled by the applied voltage value (injection current).

[0108] (Example 4) A diamond semiconductor device according to Example 4 was manufactured in accordance with the configuration shown in Figure 5. In the diamond semiconductor device according to Example 4, the number of NV-containing diamond semiconductor layers embedded in the first diamond semiconductor layer in Example 3 is changed from 1 layer to 5 layers. The following provides a detailed explanation.

[0109] First, a diamond substrate (Sumitomo Electric Industries, Type Ib substrate) was prepared, which was offset at a slight angle and whose main surface was designated as the (111) plane. When the off-angle and off-direction of the diamond substrate were measured by X-ray diffraction, the off-angle was found to be 2.3°, and the off-direction was a direction shifted by +5° from <-1-12>.

[0110] Next, the first diamond semiconductor layer (bottom layer) was formed on the diamond substrate in the same manner as in Example 3, except that the flow rate of the hydrogen dilution gas of phosphine (phosphine content: 0.1 volume%) was changed from 5 sccm to 8 sccm and the film deposition time was changed from 5 hours to 2 hours.

[0111] Furthermore, the phosphorus concentration in the first diamond semiconductor layer (bottom layer), as measured by the SIMS analyzer, was 1.5 × 10⁻⁶. 17 cm -3 Other impurities, hydrogen and nitrogen, were below the background level of SIMS analysis, and boron was below the detection limit. Furthermore, the thickness of the first diamond semiconductor layer (bottom layer), as measured by the SIMS analyzer, was 10 μm. Furthermore, the surface of the first diamond semiconductor layer (bottommost layer) had a shape in which terrace surfaces and step surfaces were alternately formed in one direction, following the surface shape of the diamond substrate. In addition, the terrace surfaces had (111) planes, following the surface shape of the diamond substrate.

[0112] Next, the NV-containing diamond semiconductor layer was formed on the first diamond semiconductor layer (bottom layer) in the same manner as in Example 3, except that the film deposition time was changed from 15 minutes to 3 minutes.

[0113] Next, the first diamond semiconductor layer (post-growth layer) was formed on the NV-containing diamond semiconductor layer in the same manner as in Example 3, except that the flow rate of the hydrogen dilution gas of phosphine (phosphine content: 0.1 volume%) was changed from 5 sccm to 8 sccm.

[0114] Furthermore, the growth formation of the NV-containing diamond semiconductor layer and the first diamond semiconductor layer (follow-up growth layer) was repeated four times alternately in the order described above under the conditions described above, thereby creating a structure in which a total of five NV-containing diamond semiconductor layers were embedded in the first diamond semiconductor layer. Furthermore, the phosphorus concentration in each of the first diamond semiconductor layers related to the additional growth, as measured by the SIMS analyzer, was 1.5 × 10⁻⁶. 17 cm -3 That was the case. Furthermore, the total thickness of the NV-containing diamond semiconductor layer and the first diamond semiconductor layer, including the additional growth, as measured by the SIMS analyzer, was 17 μm. The nitrogen concentration in the NV-containing diamond semiconductor layer, as measured by the SIMS analyzer, is approximately 1 × 10⁻⁶. 17 cm -3 Furthermore, the nitrogen concentration in the other regions (the first diamond semiconductor layer related to the growth) was below the background level of the SIMS analysis. Furthermore, the thickness of the NV-containing diamond semiconductor layer, as measured by the SIMS analyzer, was 0.1 μm. As evidence, Figure 15 shows the SIMS analysis results of a structure in which five layers of the NV-containing diamond semiconductor layer are embedded in the first diamond semiconductor layer.

[0115] <Second diamond semiconductor layer: n+ Layer, third diamond semiconductor layer: p + Layers, electrodes> Next, the second diamond semiconductor layer, the third diamond semiconductor layer, and the electrode (a stacked electrode of Au(100nm) / Pt(30nm) / Ti(30nm)) were formed on the sample on which the first diamond semiconductor layer, which is the outermost layer and represents the growth portion, was formed, in the same manner as in Example 3.

[0116] The diamond semiconductor device according to Example 4 was manufactured through the above process. As shown in the manufacturing example of the diamond semiconductor device according to this embodiment 4, the diamond semiconductor device of the present invention can be obtained by alternately growing the first diamond semiconductor layer and the NV-containing diamond semiconductor layer in a continuous manner, depending on the selection of a raw material gas, and a plurality of the NV-containing diamond semiconductor layers can be embedded and formed within the first diamond semiconductor layer. [Explanation of symbols]

[0117] 10, 20, 30, 100 Diamond semiconductor equipment 11,21,31 Diamond substrate 12,22,32 First diamond semiconductor layer 13,23,33a,33b,33c NV-centered diamond semiconductor layer 14,24,34 Second diamond semiconductor layer 15, 25, 35 Third diamond semiconductor layer 16 Antenna Circuit

Claims

1. A first diamond semiconductor layer doped with phosphorus, A second diamond semiconductor layer is disposed on the surface of the first diamond semiconductor layer, and is doped with n-type impurities at a higher concentration than the phosphorus concentration in the first diamond semiconductor layer, so that its conductivity is n-type. A third diamond semiconductor layer is disposed on the surface of the first diamond semiconductor layer, spaced apart from the second diamond semiconductor layer, and is doped with p-type impurities at a higher concentration than the phosphorus concentration in the first diamond semiconductor layer, thereby having a p-type conductivity. An NV-centered diamond semiconductor layer having NV centers formed in its crystal structure, disposed on the surface of the first diamond semiconductor layer sandwiched between the second diamond semiconductor layer and the third diamond semiconductor layer, or disposed on the back surface of the first diamond semiconductor layer facing the surface of the first diamond semiconductor layer at the position sandwiched between the second diamond semiconductor layer and the third diamond semiconductor layer, A diamond semiconductor device characterized by containing [a specific component].

2. The diamond semiconductor device according to claim 1, wherein the NV axis at at least one NV center and the path of the current flowing in the in-layer direction of the first diamond semiconductor layer from the third diamond semiconductor layer toward the second diamond semiconductor layer are orthogonal to each other.

3. The diamond semiconductor device according to claim 1 or 2, wherein the surface of the first diamond semiconductor layer is a (111) plane.

4. The phosphorus concentration in the first diamond semiconductor layer is 1 × 10⁻⁶ １５ cm －３ ~1 x 10 １８ cm －３ The diamond semiconductor device according to claim 1 or 2.

5. The diamond semiconductor device according to claim 1 or 2, wherein the thickness of the first diamond semiconductor layer is 0.1 μm to 50 μm.

6. The concentration of NV centers in the NV-centered diamond semiconductor layer is 1 × 10⁻¹⁶ １９ cm －３ The diamond semiconductor device according to claim 1 or 2, wherein the following applies:

7. The diamond semiconductor device according to claim 1 or 2, wherein the product of the phosphorus concentration in the first diamond semiconductor layer and the thickness of the first diamond semiconductor layer is greater than the product of the concentration of NV centers in the NV-centered diamond semiconductor layer and the thickness of the NV-centered diamond semiconductor layer.

8. The diamond semiconductor device according to claim 1 or 2, wherein multiple NV-centered diamond semiconductor layers are arranged.

9. The diamond semiconductor device according to claim 1 or 2, wherein the distance between the second diamond semiconductor layer and the third diamond semiconductor layer is 0.1 μm to 50 μm.

10. The diamond semiconductor device according to claim 1 or 2, wherein the second diamond semiconductor layer has hopping conductivity.

11. The diamond semiconductor device according to claim 1 or 2, wherein the third diamond semiconductor layer has hopping conductivity.

Images