A device and method for laser-induced surface doping of single-crystal diamond

Abstract

The present invention belongs to the technical field of semiconductor materials, and discloses a device and method for laser-induced surface doping of single-crystal diamond. The present invention uses an ultrashort pulse laser to excite and ionize a doping solution containing a doping element to generate doped particles, and uses an ultrashort pulse laser to inject the doped particles into the surface of the diamond, thereby inducing the generation of a doped conductive layer on the surface of the diamond. The present invention can prepare a diamond doping layer with good electrical conductivity, and can also flexibly select the doping area and doping concentration to prepare a heavily doped area, and can achieve the preparation of diamond semiconductor materials with excellent performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor materials, and more specifically, relates to a device and method for laser-induced surface doping of single-crystal diamond. Background Art

[0002] Diamond material has the characteristics of large bandgap width (5.5eV), high thermal conductivity, high sound transmission speed, small dielectric constant, etc. It combines excellent mechanical, electrical, thermal, acoustic, optical and corrosion resistance properties, and is one of the most promising wide bandgap semiconductor materials. It is reported that the current operating temperature of diamond Schottky diodes can reach 1000℃. The operating temperature range of diamond semiconductors is greatly improved compared with ordinary semiconductors, and its operating frequency range is also wider than that of ordinary semiconductors.

[0003] Diamond itself is an insulator, but if it is doped with elements (boron, phosphorus, arsenic, etc.), the properties of diamond can be changed to make it a semiconductor material with excellent properties. At present, there are many problems with diamond doping, such as the generally low concentration of doped atoms and low carrier concentration. In particular, for the preparation of n-type diamond, phosphorus atom doping is usually used. However, since phosphorus atoms are large, it is difficult for them to enter the diamond lattice, resulting in a low carrier concentration. The doped diamond usually needs to be annealed at high temperature. This process may cause the diamond to graphitize, which has a significant impact on its conductivity. In addition, in order to form a good ohmic contact, it is usually necessary to prepare a heavily doped area on the surface of the doped diamond, but conventional doping equipment and methods make it difficult to select and prepare the heavily doped area, which results in a more complicated diamond ohmic contact preparation process, and due to the low conductivity, it affects the application in semiconductor devices. Summary of the invention

[0004] The present invention solves the problems of complex diamond doping process and low conductivity in the prior art by providing a device and method for laser-induced single crystal diamond surface doping.

[0005] The present invention provides a method for laser-induced surface doping of single-crystal diamond, which uses an ultrashort pulse laser to excite and ionize a doping solution containing a doping element to generate doped particles, and uses the ultrashort pulse laser to inject the doped particles into the surface of the diamond to induce a doped conductive layer on the surface of the diamond.

[0006] Preferably, based on single-source laser induced doping, a first laser source and a first optical parametric amplifier connected thereto are used to generate a first ultrashort pulse laser, wherein the ultrashort pulse laser includes the first ultrashort pulse laser; the wavelength range of the first ultrashort pulse laser matches the chemical bond resonance range in diamond;

[0007] Alternatively, induced doping is performed based on dual-source lasers, a first ultrashort pulse laser is generated by a first laser source and a first optical parametric amplifier connected thereto, and a second ultrashort pulse laser is generated by a second laser source and a second optical parametric amplifier connected thereto, wherein the ultrashort pulse laser includes the first ultrashort pulse laser and the second ultrashort pulse laser; the wavelength range of the first ultrashort pulse laser matches the chemical bond resonance range in diamond, and the wavelength range of the second ultrashort pulse laser matches the chemical bond resonance range in the doping solution.

[0008] Preferably, when the doped particles are injected into the surface of the diamond using an ultrashort pulse laser, the pulse time of the ultrashort pulse laser is 250-350 ps and the energy density is 3.8-4.2 J / cm 2 , the laser repetition frequency is 1-5Hz, and the number of irradiations is 500-600 times.

[0009] Preferably, when diamond is n-doped, the doping solution is phosphoric acid or a first mixed acid; the acid containing phosphorus in the first mixed acid accounts for 30% to 90% of the mixed acid; when diamond is p-doped, the doping solution is boric acid or a second mixed acid; the acid containing boron in the second mixed acid accounts for 30% to 90% of the mixed acid.

[0010] Preferably, the surface of the diamond is covered with a mask, the mask comprising a microlens array and a cavity, the microlens array is used to focus the ultrashort pulse laser, the cavity is used to form a sealed cavity between the mask and the surface of the diamond, and the doping solution is contained in the sealed cavity.

[0011] Preferably, the method for laser-induced surface doping of single-crystal diamond comprises the following steps:

[0012] Step 1: pre-treating the diamond, wherein the pre-treatment includes surface polishing;

[0013] Step 2: injecting the doping solution into a cavity, wherein a hot and cold stage is provided in the cavity; placing the surface-polished diamond on the hot and cold stage, and immersing the diamond in the doping solution; controlling the temperature of the hot and cold stage to reach a preset temperature, controlling the vacuum degree, gas pressure and gas atmosphere in the cavity to reach preset conditions, controlling the boiling time of the doping solution to reach a preset time, and performing acid treatment on the diamond;

[0014] Step 3: removing the acid-treated diamond from the doping solution, brushing the doping solution on the surface of the diamond, brushing the doping solution in the cavity of the mask, and then covering the surface of the diamond with the mask, so that the sealed cavity formed between the mask and the surface of the diamond contains the doping solution;

[0015] Step 4: The diamond covered with the mask is still located in the cavity, and the temperature of the hot and cold stage and the vacuum degree, gas pressure and gas atmosphere in the cavity are controlled in the same manner as in step 2; a single-source laser or a dual-source laser is used to generate an ultrashort pulse laser, and the ultrashort pulse laser reaches the surface of the diamond after being focused by the mask to induce doping on the diamond surface.

[0016] Preferably, an XYZ three-axis translation stage is installed in the cavity, the hot and cold stage is installed on the XYZ three-axis translation stage, and a temperature sensor is installed on the hot and cold stage; the XYZ three-axis translation stage is used to perform Z-axis translation to immerse the diamond in or remove the doping solution, and to adjust the focus of the ultrashort pulse laser on the diamond surface; the XYZ three-axis translation stage is used to perform X-axis and Y-axis translation to perform doping treatment on different areas of the diamond surface.

[0017] Preferably, an illumination light source is used to illuminate the internal environment of the cavity, a CCD camera is used to observe the focusing condition of the ultrashort pulse laser, and the ultrashort pulse laser is accurately focused on the surface of the diamond in combination with the XYZ three-axis translation stage.

[0018] In another aspect, the present invention provides a device for laser-induced surface doping of single-crystal diamond, comprising:

[0019] A laser source, wherein the laser source comprises a first laser source and a first optical parametric amplifier, or the laser source comprises the first laser source, the first optical parametric amplifier, the second laser source and the second optical parametric amplifier; the laser source is used to generate an ultrashort pulse laser to excite and ionize a doping solution to generate doping particles, and to inject the doping particles into the surface of the diamond;

[0020] A mask, wherein the mask comprises a microlens array and a cavity, wherein the microlens array is used to focus the ultrashort pulse laser, and the cavity is used to form a sealed cavity between the mask and the surface of the diamond, wherein the doping solution is contained in the sealed cavity;

[0021] A hot and cold stage, which is used to adjust the temperature at which diamond is doped;

[0022] A vacuum system, wherein the vacuum system is used to adjust the vacuum degree in the cavity;

[0023] A gas circuit system, the gas circuit system is used to adjust the gas pressure and gas atmosphere in the cavity;

[0024] The device for laser-induced single-crystal diamond surface doping is used to implement the steps in the above-mentioned method for laser-induced single-crystal diamond surface doping.

[0025] Preferably, the laser-induced single crystal diamond surface doping device further comprises:

[0026] An XYZ three-axis translation stage, wherein the XYZ three-axis translation stage is used to make the diamond immersed in or removed from the doping solution by Z-axis translation, and to adjust the focus of the ultrashort pulse laser on the diamond surface; the XYZ three-axis translation stage is used to perform X-axis and Y-axis translation to adjust different areas of the diamond surface undergoing doping treatment;

[0027] A temperature sensor, the temperature sensor is used to monitor the temperature of the hot and cold stage or the doping solution;

[0028] A CCD camera, wherein the CCD camera is used to observe the focusing condition of the ultrashort pulse laser;

[0029] An illumination light source, the illumination light source is used to illuminate the internal environment of the cavity;

[0030] The device for laser-induced single-crystal diamond surface doping is used to implement the steps in the above-mentioned method for laser-induced single-crystal diamond surface doping.

[0031] One or more technical solutions provided in the present invention have at least the following technical effects or advantages:

[0032] In the present invention, the ultrashort pulse laser has extremely high instantaneous power and can transfer high energy to the dielectric material in a short time. The ultrashort pulse laser is used to excite and ionize the doping solution containing the doping element to generate doped particles, and the ultrashort pulse laser is used to inject the doped particles into the surface of the diamond to induce the generation of a doped conductive layer on the surface of the diamond. The present invention can prepare a diamond doping layer with good electrical conductivity, and can also flexibly select the doping area and doping concentration to prepare a heavily doped area, and can achieve the preparation of diamond semiconductor materials with excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the structure of a device for laser-induced single-crystal diamond surface doping provided by the present invention;

[0034] Figure 2 is a graph showing the relationship between the number of irradiation times and the conductivity of doped diamond;

[0035] Figure 3 This is a comparison chart of the Raman spectra of irradiated diamond and intrinsic diamond;

[0036] Figure 4 A front view of a mask in a device for laser-induced single-crystal diamond surface doping provided by the present invention;

[0037] Figure 5A top view of a mask in a device for laser-induced single-crystal diamond surface doping provided by the present invention;

[0038] Figure 6 The left side view of the mask in the device for laser-induced single-crystal diamond surface doping provided by the present invention.

[0039] Among them, 1-first laser source, 2-first optical parametric amplifier, 3-second laser source, 4-second optical parametric amplifier, 5-first dichroic mirror, 6-optical lens, 7-quartz window, 8-illumination light source, 9-mask, 10-single-channel gas valve control, 11-gas flow meter, 12-gas cylinder, 13-temperature sensor, 14-doping solution, 15-diamond, 16-hot and cold stage, 17-XYZ three-axis translation stage, 18-butterfly control valve, 19-gas pressure sensor, 20-mechanical pump, 21-cavity, 22-CCD camera, 23-second dichroic mirror, 24-third dichroic mirror. DETAILED DESCRIPTION

[0040] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0041] Embodiment 1:

[0042] Embodiment 1 provides a method for laser-induced surface doping of single-crystal diamond, which uses an ultrashort pulse laser to excite and ionize a doping solution containing a doping element to generate doped particles, and uses an ultrashort pulse laser to inject the doped particles into the surface of the diamond, thereby inducing the generation of a doped conductive layer on the surface of the diamond.

[0043] Wherein, induced doping can be performed based on a single-source laser, and a first laser source and a first optical parametric amplifier connected thereto are used to generate a first ultrashort pulse laser, and the ultrashort pulse laser includes the first ultrashort pulse laser; the wavelength range of the first ultrashort pulse laser matches the chemical bond resonance range in diamond. Induced doping can also be performed based on a dual-source laser, and a first laser source and a first optical parametric amplifier connected thereto are used to generate a first ultrashort pulse laser, and a second laser source and a second optical parametric amplifier connected thereto are used to generate a second ultrashort pulse laser, and the ultrashort pulse laser includes the first ultrashort pulse laser and the second ultrashort pulse laser; the wavelength range of the first ultrashort pulse laser matches the chemical bond resonance range in diamond, and the wavelength range of the second ultrashort pulse laser matches the chemical bond resonance range in the doping solution.

[0044] When the doped particles are injected into the surface of the diamond using an ultrashort pulse laser, the pulse time of the ultrashort pulse laser is 250-350 ps and the energy density is 3.8-4.2 J / cm 2, the laser repetition frequency is 1-5Hz, and the number of irradiations is 500-600 times.

[0045] When diamond is n-doped, the doping solution is phosphoric acid or a first mixed acid; the acid containing phosphorus in the first mixed acid accounts for 30% to 90% of the mixed acid; when diamond is p-doped, the doping solution is boric acid or a second mixed acid; the acid containing boron in the second mixed acid accounts for 30% to 90% of the mixed acid.

[0046] Specifically, a mask may be covered on the surface of the diamond, the mask comprising a microlens array and a cavity, the microlens array being used to focus the ultrashort pulse laser, the cavity being used to form a sealed cavity between the mask and the surface of the diamond, the sealed cavity containing the doping solution.

[0047] The following is a description of the specific steps of the method of the present invention in combination with parameters and operation methods.

[0048] The present invention provides a method for laser-induced surface doping of single-crystal diamond, comprising the following steps:

[0049] Step 1: Pre-treating the diamond, including surface polishing.

[0050] Specifically, a HTHP (High-temperature and High-pressure) or MPCVD (Microwave Plasma Chemical Vapor Deposition) diamond substrate with a smaller crystal plane curvature is selected for surface polishing.

[0051] Step 2: injecting the doping solution into a cavity, wherein a hot and cold stage is provided in the cavity; placing the surface-polished diamond on the hot and cold stage, and immersing the diamond in the doping solution; controlling the temperature of the hot and cold stage to reach a preset temperature, controlling the vacuum degree, gas pressure and gas atmosphere in the cavity to reach preset conditions, controlling the boiling time of the doping solution to reach a preset time, and performing acid treatment on the diamond.

[0052] Among them, acid treatment can remove surface impurities of diamond, and the doping solution used in the acid treatment is the same as the doping solution in step 3. After the acid treatment, the surface of the diamond will be covered with a doping layer, and some doping atoms will enter the surface of the diamond, which can improve the doping effect.

[0053] For example, during acid treatment, the temperature range of the hot and cold stages is controlled to be 170° C.-230° C., the gas pressure in the cavity is controlled to be around normal pressure, the atmosphere is an inert atmosphere, and the boiling time is 30 min-90 min.

[0054] For example, an XYZ three-axis translation stage is installed in the cavity, the hot and cold stage is installed on the XYZ three-axis translation stage, and a temperature sensor is installed on the hot and cold stage; the XYZ three-axis translation stage is used to perform Z-axis translation to immerse the diamond in the doping solution.

[0055] Step 3: Remove the acid-treated diamond from the doping solution, brush the doping solution on the surface of the diamond, brush the doping solution in the cavity of the mask, and then cover the surface of the diamond with the mask so that the sealed cavity formed between the mask and the surface of the diamond is filled with the doping solution.

[0056] For example, the XYZ three-axis translation stage is used to perform Z-axis translation to move the diamond out of the doping solution.

[0057] Step 4: The diamond covered with the mask is still located in the cavity, and the temperature of the hot and cold stage and the vacuum degree, gas pressure and gas atmosphere in the cavity are controlled in the same manner as in step 2; a single-source laser or a dual-source laser is used to generate an ultrashort pulse laser, and the ultrashort pulse laser reaches the surface of the diamond after being focused by the mask to induce doping on the diamond surface.

[0058] Specifically, according to the wavelength or frequency of the selected ultrashort pulse laser and the focal length of the selected mask, the XYZ three-axis translation stage is controlled to move along the Z axis for optical focusing. That is, the XYZ three-axis translation stage is used to perform Z-axis translation to adjust the focus of the ultrashort pulse laser on the diamond surface. In addition, the XYZ three-axis translation stage can also be used to perform X-axis and Y-axis translation to perform doping treatment on different areas of the diamond surface.

[0059] The internal environment of the cavity is illuminated by an illumination light source, and the focusing condition of the ultrashort pulse laser is observed by a CCD camera, so as to facilitate the operation of the diamond in the cavity. In combination with the XYZ three-axis translation stage, the ultrashort pulse laser is accurately focused on the surface of the diamond.

[0060] If dual-source laser is used, in step 4, the first laser source, the second laser source, the first optical parametric amplifier and the second optical parametric amplifier are turned on. The frequency range of the dual-source laser should include the resonance frequency of the solute chemical bond in the doping solution and the resonance frequency range of the diamond chemical bond, the pulse time is 250-350ps, and the energy density is 3.8-4.2J / cm 2, the laser repetition frequency is 1-5Hz, and the irradiation is 500-600 times. After processing an area, the XYZ three-axis translation stage is used to translate the X-axis and Y-axis, and another area is laser-induced doping until all areas are doped. If a single-source laser is used, the first laser source and the first optical parametric amplifier are turned on, and the frequency range of the ultrashort pulse laser matches the chemical bond resonance range in diamond.

[0061] Specifically, the IV measurement and analysis of the doped diamond obtained by the method of the present invention can be used to obtain the above-mentioned preferred parameters of the pulsed laser. When the wavelength range of the two pulsed lasers is close to the resonance range of the chemical bonds in the solution and the chemical bonds in the diamond, the doping efficiency is the highest, the doping effect is the best, and the diamond semiconductor conductivity is the highest. The relationship between the number of irradiations and the conductivity of the doped diamond is shown in the figure below: Figure 2 shown.

[0062] In addition, in order to verify the doping effect, the following steps may also be included:

[0063] Step 5: Take out the doped diamond and perform Raman spectroscopy analysis.

[0064] Specifically, the process includes shutting down the laser source, the CCD camera, and the illumination light source, controlling the vacuum system and the gas system to restore the air pressure in the cavity to a normal state, shutting down the hot and cold stages, removing the mask, obtaining the doped diamond, washing and draining the diamond with pure water, and performing Raman spectroscopy analysis on the diamond produced by doping.

[0065] See also Figure 3 When the doped diamond obtained by the method of the present invention is subjected to Raman spectroscopy analysis, the main peak of the Raman spectra of the irradiated diamond and the unirradiated diamond is at 1333 cm -1 The half-width of the Raman peak of the irradiated diamond is almost the same as that of the unirradiated diamond, indicating that the crystal quality of the induced doped diamond is almost the same as that of the undoped diamond, and the incorporation of doping atoms into the diamond matrix by laser irradiation will not deteriorate the crystal quality.

[0066] The method provided by the present invention is described below in conjunction with the corresponding device.

[0067] The device for implementing this method can be found in Figure 1 , the method of realizing diamond surface doping by using the device includes:

[0068] (1) The single crystal diamond 15 to be doped is fixed on the hot and cold stage 16, and the doping solution 14 is injected into the cavity 21. The substrate temperature of the diamond 15 is adjusted by the hot and cold stage 16, and the gas atmosphere and pressure of the cavity 21 are adjusted by the vacuum system and the gas path system.

[0069] If an n-type semiconductor is required, the (hkl)-surface diamond 15 (such as (100)-surface, (110)-surface, (111)-surface diamond) is immersed in an n-type doping solution 14, such as phosphoric acid, and boiled at normal pressure; if a p-type semiconductor is required, the diamond 15 is immersed in a p-type doping solution 14, such as boric acid, and boiled at normal pressure.

[0070] (2) After the boiling treatment is completed, the diamond 15 is taken out, and then a thin layer of doping solution 14 is coated on the surface of the diamond 15, and the mask 9 is covered. The diamond 15 covered with the mask 9 is placed in the cavity 21, and the substrate temperature of the diamond 15 and the gas atmosphere and pressure of the cavity 21 are adjusted again.

[0071] When adjusting the gas atmosphere and pressure of the cavity 21, the single-channel gas valve control 10 is opened, the gas flow in the gas circuit is adjusted by the gas flow meter 11, and the required atmosphere gas is filled into the gas cylinder 12, while the mechanical pump 20 is always open, and the gas pressure in the cavity 21 is controlled by adjusting the opening and closing of the butterfly control valve 18. The mask 9 is provided with a layer of gaps, and the gaps have a certain height. A layer of doping solution 14 can be brushed on one side of the gap of the mask 9, and then a layer of doping liquid can be brushed on the surface of the diamond 15 to facilitate its full doping. The material of the mask 9 can be quartz, glass, sapphire, resin and other optically transparent materials.

[0072] (3) Perform laser irradiation treatment. First, the diamond 15 is irradiated with the illumination light source 8, the XYZ three-axis translation stage 17 is adjusted for focusing, and the CCD camera 22 is used for imaging. Then, the surface of the diamond 15 is irradiated with a laser. At this time, the first laser source 1 or the second laser source 3 can work independently, or the first laser source 1 can select a resonance wavelength that matches the doping solution 14, and the second laser source 3 can select a wavelength range that has a high transmittance to the doping solution 14 and is more easily absorbed by the diamond 15 material. When performing laser irradiation treatment, the mask 9 covers the entire or partial area of ​​the surface of the diamond 15, and the focal length of the incident laser is adjusted by manipulating the XYZ three-axis translation stage 17. The ultrashort pulse laser reaches the surface of the diamond 15 after being focused by the mask 9, and induces doping on the surface of the diamond 15.

[0073] If the laser source selects a dual-beam laser source, the first laser source 1, the second laser source 3, the first optical parametric amplifier 2 and the second optical parametric amplifier 4 are turned on, the laser emitted by the first laser source 1 and the illumination light of the illumination light source 8 are merged through the first dichroic mirror 5, and then pass through the second dichroic mirror 23 together with the laser emitted by the second laser source 3, pass through the third dichroic mirror 24, the optical lens 6 and the quartz glass 7, and then through the mask 9 to focus on the diamond 15. If the laser source selects a single-beam laser source, the first laser source 1 and the first optical parametric amplifier 2 are turned on, the laser emitted by the first laser source 1 and the illumination light of the illumination light source 8 pass through the first dichroic mirror 5, the second dichroic mirror 23, the third dichroic mirror 24, the optical lens 6 and the quartz glass 7, and then are focused by the mask 9 and finally reach the diamond 15.

[0074] Embodiment 2:

[0075] Embodiment 2 provides a device for laser-induced surface doping of single-crystal diamond, see Figure 1 ,include:

[0076] A laser source, the laser source includes a first laser source 1 and a first optical parametric amplifier 2, or the laser source includes a first laser source 1, a first optical parametric amplifier 2, a second laser source 3 and a second optical parametric amplifier 4; the laser source is used to generate an ultrashort pulse laser, so that the doping solution 14 is excited and ionized to generate doping particles, and the doping particles are injected into the surface of the diamond 15. That is, the laser source includes an ultrashort pulse laser emitter and an optical parametric amplifier, the laser source can emit pulsed laser, the pulsed laser is used for doping the surface of the diamond 15, and the optical parametric amplifier can be one of the existing technologies. When the laser source is a dual-beam laser, the wavelengths of the two laser beams can be continuously adjusted within the range of 200nm-2000nm through the optical parametric amplifier, the dual-beam lasers can work independently, or they can work together after optical path coupling, and the diamond 15 is radiated, so that the doping of the diamond 15 can be achieved more effectively.

[0077] The mask 9 includes a microlens array and a cavity, wherein the microlens array is used to focus the ultrashort pulse laser, and the cavity is used to form a sealed cavity between the mask 9 and the surface of the diamond 15, wherein the doping solution 14 is contained in the sealed cavity. For details, see Figure 4 , Figure 5 , Figure 6The height of the mask is H, the width is W, and the length is L. It contains a cavity inside. The height of the cavity is h, and the distance between the cavity and the outer edge of the mask side is d. The cavity is filled with a layer of doping solution. The focal length of the microlens array determines the irradiation area and irradiation depth of the laser. By changing the focal length of the lens, the depth of focus can be changed, thereby affecting the depth and intensity of laser irradiation. The focal length of the lens can be changed by replacing masks with different focal lengths, thereby changing the depth of focus, and performing doping at different depths. The focal length of the lens is generally between 1-10mm.

[0078] The hot and cold stage 16 is used to adjust the temperature of the diamond 15 for doping. Specifically, the hot and cold stage 16 achieves the purpose of heating or cooling by resistance wire heating and liquid nitrogen cooling. The hot and cold stage 16 can be installed on the XYZ three-axis translation stage 17 as an accessory, and the temperature control range of the hot and cold stage 16 is -196°C-1200°C.

[0079] The vacuum system is used to adjust the vacuum degree in the cavity 21. Specifically, it includes the cavity 21, the gas pressure sensor 19, the butterfly control valve 18, and the mechanical pump 20. The mechanical pump 20 is used to evacuate the cavity, and the vacuum degree of the cavity can reach 1 Pa. The gas pressure in the cavity 21 can be preset, and the butterfly control valve 18 can be automatically adjusted according to the gas pressure value fed back by the gas pressure sensor 19, so that the gas pressure in the cavity 21 can be maintained at the preset value.

[0080] The gas circuit system is used to adjust the gas pressure and gas atmosphere in the cavity 21. Specifically, it includes a gas cylinder 12, a gas flow meter 11, and a single-channel gas valve control 10. Through the gas circuit system, inert gas, reducing gas, or oxidizing gas can be filled into the cavity 21, thereby changing the atmosphere of the environment in which the diamond 15 is located. For example, filling with inert gas can eliminate the influence of impurity gas and improve the quality of doping in the radiation area. By adjusting the gas flow meter 11 and the butterfly control valve 18 in the vacuum system, the gas pressure in the cavity 21 can be adjusted.

[0081] The XYZ three-axis translation stage 17 is used to immerse the diamond 15 in or out of the doping solution 14 through Z-axis translation, and adjust the focus of the ultrashort pulse laser on the surface of the diamond 15; the XYZ three-axis translation stage 17 is used to perform X-axis and Y-axis translation to adjust different areas of the surface of the diamond 15 undergoing doping treatment.

[0082] The temperature sensor 13 is used to monitor the temperature of the hot / cold stage 16 or the doping solution 14 .

[0083] The CCD camera 22 is used to observe the focusing condition of the ultrashort pulse laser. The CCD camera 22 can monitor the doping condition of the diamond 15 in the cavity 21, so as to perform corresponding operations on the diamond 15 in the cavity 21.

[0084] The illumination light source 8 is used to illuminate the internal environment of the cavity 21. The illumination light source 8 can be a white light source.

[0085] In addition, the device may further include: a first dichroic mirror 5, a second dichroic mirror 23, a third dichroic mirror 24, an optical lens 6, and a quartz window 7. The ultrashort pulse laser is beam-combined through a plurality of dichroic mirrors, and is focused on the surface of the diamond 15 after passing through the optical lens 6 and the quartz window 7. The optical components of the device may be connected by a sleeve at the periphery of the optical path, or optical signals may be coupled and then transmitted by optical fiber, or may be exposed to a gas environment or a vacuum without connection. In addition, the device may further include a controller, and the controller controls the normal operation of the entire device.

[0086] The laser-induced single-crystal diamond surface doping device provided in Example 2 is used to implement the steps in the method provided in Example 1. The specific functions of the device can be found in the description of Example 1 and will not be repeated here.

[0087] The device and method for laser-induced surface doping of single-crystal diamond provided by the embodiments of the present invention include at least the following technical effects:

[0088] (1) The present invention uses a single-source laser or a dual-source laser to dope the surface of diamond with elements to improve the electrical conductivity of diamond, and forms a crystal structure with atomic doping on the surface of diamond, so that it can be used as a semiconductor material suitable for high frequency and high power in the field of microelectronics. The present invention provides a new diamond doping method to obtain n-type and p-type diamond semiconductor materials. Compared with the traditional method, the present method uses nanosecond, picosecond or femtosecond pulse lasers, which can directly inject boron ions and phosphorus ions into the surface of diamond, avoid excessive thermal effects on the surface of diamond, and reduce the probability of diamond graphitization. And the effect of using a dual-source laser is better than that of a single-source laser. When a dual-source laser is used, the energy density of each laser source can be lower, the probability of diamond carbonization will be smaller, and the doping atoms can better enter the diamond, so the doping effect is better. When the wavelength range of the ultrashort pulse laser in the present invention is close to the resonance range of the chemical bonds in the doping solution and the chemical bonds in the diamond, a resonance effect will be generated, making it easier for the doping elements to enter the diamond, and a better quality diamond semiconductor will be obtained.

[0089] (2) The present invention covers the surface of diamond with a mask, the mask includes a microlens array and a cavity, the microlens array is used to focus the ultrashort pulse laser, and the cavity is used to form a sealed cavity between the mask and the surface of the diamond, and the sealed cavity is filled with a doping solution. The mask can reduce the dissipation of doping, reduce the adverse effects of the doping environment, and provide doping atoms to avoid insufficient doping atoms, thereby improving the doping quality of the diamond surface.

[0090] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for laser-induced surface doping of single-crystal diamond, characterized in that: Using an ultrashort pulse laser to excite and ionize a doping solution containing a doping element to generate doping particles, and using the ultrashort pulse laser to inject the doping particles into the surface of the diamond to induce a doped conductive layer on the surface of the diamond; Wherein, a mask is covered on the surface of the diamond, the mask comprises a microlens array and a cavity, the microlens array is used to focus the ultrashort pulse laser, the cavity is used to form a sealed cavity between the mask and the surface of the diamond, and the doping solution is contained in the sealed cavity; The method for laser-induced single crystal diamond surface doping comprises the following steps: Step 1: pre-treating the diamond, wherein the pre-treatment includes surface polishing; Step 2: injecting the doping solution into a cavity, wherein a hot and cold stage is provided in the cavity; placing the surface-polished diamond on the hot and cold stage, and immersing the diamond in the doping solution; controlling the temperature of the hot and cold stage to reach a preset temperature, controlling the vacuum degree, gas pressure and gas atmosphere in the cavity to reach preset conditions, controlling the boiling time of the doping solution to reach a preset time, and performing acid treatment on the diamond; Step 3: removing the acid-treated diamond from the doping solution, brushing the doping solution on the surface of the diamond, brushing the doping solution in the cavity of the mask, and then covering the surface of the diamond with the mask, so that the sealed cavity formed between the mask and the surface of the diamond contains the doping solution; Step 4: The diamond covered with the mask is still located in the cavity, and the temperature of the hot and cold stage and the vacuum degree, gas pressure and gas atmosphere in the cavity are controlled in the same manner as in step 2; a single-source laser or a dual-source laser is used to generate an ultrashort pulse laser, and the ultrashort pulse laser reaches the surface of the diamond after being focused by the mask to induce doping on the diamond surface.

2. The method for laser-induced surface doping of single-crystal diamond according to claim 1, characterized in that: Based on single-source laser induction doping, a first ultrashort pulse laser is generated by using a first laser source and a first optical parametric amplifier connected thereto, wherein the ultrashort pulse laser includes the first ultrashort pulse laser; the wavelength range of the first ultrashort pulse laser matches the chemical bond resonance range in diamond; Alternatively, induced doping is performed based on dual-source lasers, a first ultrashort pulse laser is generated by a first laser source and a first optical parametric amplifier connected thereto, and a second ultrashort pulse laser is generated by a second laser source and a second optical parametric amplifier connected thereto, wherein the ultrashort pulse laser includes the first ultrashort pulse laser and the second ultrashort pulse laser; the wavelength range of the first ultrashort pulse laser matches the chemical bond resonance range in diamond, and the wavelength range of the second ultrashort pulse laser matches the chemical bond resonance range in the doping solution.

3. The method for laser-induced surface doping of single-crystal diamond according to claim 1, characterized in that: When the doped particles are injected into the surface of the diamond using an ultrashort pulse laser, the pulse time of the ultrashort pulse laser is 250-350 ps and the energy density is 3.8-4.2 J / cm 2 , the laser repetition frequency is 1-5Hz, and the number of irradiations is 500-600 times.

4. The method for laser-induced surface doping of single-crystal diamond according to claim 1, characterized in that: When diamond is n-doped, the doping solution is phosphoric acid or a first mixed acid; the acid containing phosphorus in the first mixed acid accounts for 30% to 90% of the mixed acid; when diamond is p-doped, the doping solution is boric acid or a second mixed acid; the acid containing boron in the second mixed acid accounts for 30% to 90% of the mixed acid.

5. The method for laser-induced surface doping of single-crystal diamond according to claim 1, characterized in that: An XYZ three-axis translation stage is installed in the cavity, the hot and cold stage is installed on the XYZ three-axis translation stage, and a temperature sensor is installed on the hot and cold stage; the XYZ three-axis translation stage is used to perform Z-axis translation to immerse the diamond in or remove the doping solution, and to adjust the focus of the ultrashort pulse laser on the diamond surface; The XYZ three-axis translation stage is used to perform X-axis and Y-axis translation to perform doping treatment on different areas of the diamond surface.

6. The method for laser-induced surface doping of single-crystal diamond according to claim 5, characterized in that: The internal environment of the cavity is illuminated by an illumination light source, the focusing condition of the ultrashort pulse laser is observed by a CCD camera, and the ultrashort pulse laser is precisely focused on the surface of the diamond in combination with the XYZ three-axis translation stage.

7. A device for laser-induced surface doping of single-crystal diamond, characterized in that: include: A laser source, wherein the laser source comprises a first laser source and a first optical parametric amplifier, or the laser source comprises the first laser source, the first optical parametric amplifier, the second laser source and the second optical parametric amplifier; the laser source is used to generate an ultrashort pulse laser to excite and ionize a doping solution to generate doping particles, and to inject the doping particles into the surface of the diamond; A mask, wherein the mask comprises a microlens array and a cavity, wherein the microlens array is used to focus the ultrashort pulse laser, and the cavity is used to form a sealed cavity between the mask and the surface of the diamond, wherein the doping solution is contained in the sealed cavity; A hot and cold stage, which is used to adjust the temperature at which diamond is doped; A vacuum system, wherein the vacuum system is used to adjust the vacuum degree in the cavity; A gas circuit system, the gas circuit system is used to adjust the gas pressure and gas atmosphere in the cavity; The device for laser-induced single-crystal diamond surface doping is used to implement the steps in the method for laser-induced single-crystal diamond surface doping as claimed in any one of claims 1 to 4.

8. The device for laser-induced surface doping of single-crystal diamond according to claim 7, characterized in that: Also includes: An XYZ three-axis translation stage, wherein the XYZ three-axis translation stage is used to make the diamond immersed in or removed from the doping solution by Z-axis translation, and to adjust the focus of the ultrashort pulse laser on the diamond surface; the XYZ three-axis translation stage is used to perform X-axis and Y-axis translation to adjust different areas of the diamond surface undergoing doping treatment; A temperature sensor, the temperature sensor is used to monitor the temperature of the hot and cold stage or the doping solution; A CCD camera, wherein the CCD camera is used to observe the focusing condition of the ultrashort pulse laser; An illumination light source, the illumination light source is used to illuminate the internal environment of the cavity; The device for laser-induced single-crystal diamond surface doping is used to implement the steps in the method for laser-induced single-crystal diamond surface doping as claimed in any one of claims 1 to 6.

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