Method for increasing hole concentration in p-type iii-nitride material and applications thereof

Abstract

This invention discloses a method for increasing the hole concentration in p-type group III nitride materials and its application. The method includes: during and / or after the growth of the p-type group III nitride material, reacting the p-type group III nitride material with halogen-based active atoms and / or halogen-based active groups to remove some group III atoms from the p-type group III nitride material, thereby generating cation vacancies in the p-type group III nitride material; and activating acceptor impurities in the p-type group III nitride material containing the cation vacancies. This invention provides a method for increasing the hole concentration in AlGaN semiconductor materials, overcoming the limitations of traditional p-type AlGaN materials such as low acceptor Mg atom incorporation efficiency and severe self-compensation effects. It can utilize group III cation vacancies to significantly increase the concentration of Mg acceptor impurities at group III atom lattice sites, thereby significantly increasing the hole concentration in the p-type AlGaN material.

Description

Technical Field

[0001] This invention specifically relates to a method for increasing the hole concentration in p-type III nitride materials and its application, belonging to the field of semiconductor technology. Background Technology

[0002] AlGaN semiconductors are direct, wide-bandgap semiconductors with a bandgap that is continuously adjustable between 3.4 eV and 6.2 eV. Their wavelength range covers the near-ultraviolet to deep ultraviolet bands, making them ideal materials for the fabrication of ultraviolet optoelectronic devices such as LEDs, lasers, and detectors. They also have broad application prospects in general lighting, ultraviolet sterilization and disinfection, and solar blindness detection.

[0003] For PN junction devices such as AlGaN-based LEDs, lasers, and PiN detectors, high-quality, low-resistivity ohmic contacts are essential for improving device performance and reliability. However, fabricating ohmic contacts in p-type AlGaN is extremely difficult because p-type AlGaN has a large bandgap and a high work function (above 7.5 eV), while the highest work function of naturally occurring Pt metal is only 5.65 eV. Therefore, the lack of a high work function metal to match p-type AlGaN results in a very high potential barrier at the metal-p-type AlGaN contact, requiring a very high electric field to excite hole carriers to pass through. Increasing the hole concentration in p-type AlGaN can reduce the width of the metal / p-type AlGaN contact barrier and enhance hole tunneling, which is beneficial for reducing ohmic contact resistance. However, the large bandgap, high Mg acceptor ionization energy, and low Mg acceptor ionization rate (less than 10%) of p-type AlGaN often result in a low hole concentration (generally around 10). 17 cm -3 This directly leads to an increase in the width of the depletion region of metal / p-type AlGaN and a decrease in the probability of hole tunneling, resulting in a very high ohmic contact resistance. The high ohmic contact resistance and series resistance of p-type AlGaN materials result in high device operating voltage and high heat dissipation, leading to a very high device operating junction temperature, which seriously affects the performance and reliability of the device. Therefore, the development of ohmic contact technology for p-type AlGaN materials has become an urgent need for the development of AlGaN-based deep ultraviolet materials and devices.

[0004] To prepare ohmic contacts for p-type AlGaN materials, it is necessary to maximize the hole concentration near the surface to reduce the depletion region of the gold / semi-contact and enhance hole tunneling.

[0005] However, due to the large bandgap and high ionization energy of Mg acceptors (above 150 meV, far exceeding the thermal energy of 26 meV at room temperature), the hole concentration in p-type AlGaN semiconductor materials is often low (generally around 10). 17 cm-3 The electron concentration is 1-2 orders of magnitude lower than the electron concentration, and the hole mobility is 1-2 orders of magnitude lower than the electron mobility. This directly leads to: 1) Asymmetric transport of electrons and holes, resulting in low device quantum efficiency. Due to the low hole mobility and high electron mobility, electron-hole recombination mainly occurs in the quantum well near the p-side, resulting in low recombination efficiency. Simultaneously, because the electron concentration is 1-2 orders of magnitude higher than the hole concentration, excess, unrecombined hot electrons easily overflow the quantum well and overshoot into p-type AlGaN, where they are trapped by material defects, generating a large amount of heat, leading to a sharp decrease in device quantum efficiency and reduced reliability; 2) High bulk resistivity and large series resistance in p-type AlGaN materials. For high-Al content AlGaN materials, the above problems become more severe due to the larger bandgap and further increased ionization energy of Mg acceptors. Higher series resistance leads to higher device operating voltage and greater heat generation, resulting in a very high device junction temperature, severely affecting device performance and reliability.

[0006] Traditional methods of increasing hole concentration in p-type AlGaN by heavily doping with Mg atoms have significant limitations. On one hand, with increasing Al content, the activation energy of Mg acceptor impurities increases significantly, leading to a substantial decrease in acceptor activation efficiency, making it difficult to significantly improve hole concentration even with heavy Mg doping. On the other hand, Mg atoms have low solid solubility in group III nitride semiconductors; excessive doping will result in a large number of Mg atoms occupying interstitial sites and nitrogen antisites, forming Mg-derived complexes. These interstitial Mg atoms (Mg... i ), nitrogen antisite Mg atom (Mg N ) and derived complexes often exhibit donor-type defects, with Mg acceptors occupying group III atomic lattice sites (Mg III Self-compensation occurs, making it difficult to significantly increase the hole concentration in p-type AlGaN materials.

[0007] Another common method to increase the hole concentration in p-type AlGaN materials is polarization-induced doping, as illustrated in patent CN108365069A. The physical idea behind this method is to induce a continuous polarization electric field within the material by varying the Al composition. This polarization electric field activates acceptor impurities / vacancies in the material, thereby increasing the hole concentration. While this method can increase the hole concentration to some extent, it suffers from several problems: 1) Changes in alloy composition alter the band structure, affecting photon and carrier transport. For example, for gallium-polarized AlGaN-based deep ultraviolet optoelectronic devices, the Al composition needs to be reduced along the growth direction to achieve polarization doping. However, reducing the Al composition leads to a smaller band gap, increasing internal absorption of deep ultraviolet light and severely impacting light extraction efficiency; 2) The hole concentration is highly dependent on the intensity of the polarization electric field induced by changes in alloy composition, resulting in poor stability and controllability; 3) It cannot be applied to increase the hole concentration in binary alloy materials such as GaN.

[0008] Other known methods, such as uniformly doped superlattices and modulated doped superlattices, can increase the hole concentration within the superlattice structure by utilizing the tail state, but they also have multiple heterojunction barriers in the longitudinal transport direction of holes, resulting in a relatively large series resistance in actual devices. Moreover, these methods have low production efficiency, high cost, and very limited effectiveness.

[0009] By intentionally introducing cation vacancies V into p-type AlGaN III Increasing the hole carrier concentration is an innovative approach. For AlGaN materials, the conventional method for generating cation vacancies V is... III The main methods include dry etching and thermal decomposition. One method to increase cation vacancies by dry etching p-type AlGaN materials is illustrated in the paper IEEE Transactions on Electron Devices 57,42 (2009). This method utilizes high-energy Cl-based ions to bombard the AlGaN surface and induce a chemical reaction, thereby removing Al and Ga atoms and generating a large number of acceptor-type cation vacancies. III However, due to the bombardment of high-energy ions, nitrogen atoms preferentially leave the material surface, resulting in a large number of nitrogen vacancies (V1) on the surface. N V N In nitride semiconductor materials, defects manifest as shallow-level donors (levels located close to the conduction band), thereby compensating for acceptor defects—cation vacancies V—in p-type AlGaN materials. III and Mg III Acceptance, on the contrary, reduces the hole concentration in the material. Thermal decomposition can also break bonds and create vacancies in AlGaN materials, but this is often accompanied by the simultaneous desorption of Al / Ga and N atoms. Although N atom desorption can be suppressed by extremely high pressure and NH3 protection (V...N This increases the concentration of cation vacancies, but it is costly, time-consuming, and the results are not satisfactory. Summary of the Invention

[0010] The main objective of this invention is to provide a method for increasing the hole concentration in p-type III nitride materials and its application, so as to overcome the shortcomings of the prior art.

[0011] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0012] This invention provides a method for increasing the hole concentration in p-type group III nitride materials, comprising:

[0013] During and / or after the growth of the p-type III nitride material, the p-type III nitride material is brought into contact with halogen-based active atoms and / or halogen-based active groups to remove some of the III atoms in the p-type III nitride material, thereby generating cation vacancies in the p-type III nitride material; and

[0014] Activate acceptor impurities in p-type group III nitride materials containing the cation vacancies.

[0015] This invention also provides a method for preparing an ohmic contact of a p-type group III nitride semiconductor material, comprising:

[0016] The method described above can be used to increase the hole concentration in p-type III nitride materials;

[0017] An electrode is fabricated, and the electrode is made to form an ohmic contact with the p-type III nitride material.

[0018] This invention also provides a method for fabricating an ultraviolet optoelectronic device, comprising:

[0019] The first step in fabricating the main structure of an ultraviolet optoelectronic device, and

[0020] The second step is to fabricate electrodes that mate with the main structure.

[0021] Furthermore, the first step also includes: increasing the hole concentration of the p-type III nitride material using the method described above.

[0022] Compared with the prior art, the advantages of the present invention include:

[0023] 1) The present invention provides a method for increasing the hole concentration in AlGaN semiconductor materials, which overcomes the limitations of traditional p-type AlGaN materials such as low acceptor Mg atom incorporation efficiency and severe self-compensation effect. It can utilize group III cation vacancies to significantly increase the Mg acceptor impurity concentration at group III atom lattice sites, thereby significantly increasing the hole concentration in p-type AlGaN materials.

[0024] 2) The method for increasing the hole concentration of AlGaN semiconductor material provided by the present invention does not reduce the band gap of p-type AlGaN material and does not cause internal photon absorption in AlGaN deep ultraviolet optoelectronic devices.

[0025] 3) The present invention provides a method for preparing ohmic contacts of p-type group III nitride semiconductor materials, which can overcome the donor-type V-type defects caused by traditional dry etching and other methods. N High concentration and other drawbacks; selective removal of some group III atoms to generate cation vacancies V III This significantly increases the hole concentration on the p-type AlGaN surface and reduces the ohmic contact resistance;

[0026] 4) The present invention provides a method for preparing ohmic contacts of p-type group III nitride semiconductor materials, which can avoid the problem of "Mg acceptor activation of buried p-type AlGaN materials" faced by tunnel junction technology;

[0027] 5) The present invention provides a method for preparing ohmic contacts of p-type group III nitride semiconductor materials. The process is simple, repeatable and controllable, and is fully suitable for large-scale production. Attached Figure Description

[0028] Figure 1 This is an unintentionally doped Al solution provided in Embodiment 1 of the present invention. 0.6 G a0.4 A schematic diagram of the N-layer structure;

[0029] Figure 2 This is a method provided in Embodiment 1 of the present invention for enhancing the Mg acceptor (Mg) by utilizing halogen-based active atoms / groups. Ga A schematic diagram of the structure of p-type AlGaN material with a concentration of 1000000.

[0030] Figure 3 This is a schematic cross-sectional view of the Hall test structure after the p-type ohmic contact electrode is prepared in Embodiment 1 of the present invention;

[0031] Figure 4 This is a schematic diagram of the AlGaN electron blocking layer in Embodiment 2 of the present invention without treatment of halogen-based active atoms / groups;

[0032] Figure 5This is a schematic diagram of the AlGaN electron blocking layer grown by cyclic processing and growth of halogen-based active atoms / groups in Example 2 of the present invention;

[0033] Figure 6 This is a schematic diagram of the ultraviolet LED epitaxial structure after the p-type AlGaN hole injection layer has been grown in Embodiment 2 of the present invention;

[0034] Figure 7 This is a schematic diagram of the AlGaN-based ultraviolet LED device structure after the preparation of p-type and n-type ohmic contact electrodes in Embodiment 2 of the present invention;

[0035] Figure 8 This is a schematic diagram of the AlGaN-based ultraviolet LED epitaxial structure used in Embodiment 3 of the present invention;

[0036] Figure 9 This is a schematic diagram of the structure of the p-type AlGaN material surface treated with halogen-based active atoms / groups in Example 3 of the present invention to form a cation vacancy layer;

[0037] Figure 10 This is a schematic diagram of the AlGaN-based ultraviolet LED device structure after the preparation of p-type and n-type ohmic contact electrodes in Embodiment 3 of the present invention.

[0038] Figure 11 This is a schematic diagram of the epitaxial structure of a GaN laser without halogen-based active atoms / groups in Embodiment 4 of the present invention;

[0039] Figure 12 This is a schematic diagram of the GaN laser structure after treating the p-type GaN surface with halogen-based active atoms / groups in Embodiment 4 of the present invention;

[0040] Figure 13 This is a schematic diagram of the GaN laser structure in Embodiment 4 of the present invention, in which p-type ohmic contact metal is deposited and etched to expose the nGaN mesa.

[0041] Figure 14 This is a schematic diagram of the GaN laser structure after etching the ridge structure and depositing the n-type ohmic contact metal in Embodiment 4 of the present invention.

[0042] Figure reference numerals: 100 - Substrate for epitaxial growth; 101 - Nucleation layer; 102 - Buffer layer; 103 - Underlayer; 104 - p-type AlGaN layer; 105 - Ohmic contact electrode of p-type AlGaN material; 200 - Substrate for epitaxial growth; 201 - Buffer layer; 202 - n-type AlGaN layer; 203 - Light-emitting active region; Typical - Quantum well structure; 204 - p-type AlGaN electron blocking layer; 205 - Cation vacancy layer formed after treatment with halogen-based active atoms / groups; 206 - p-type AlGaN hole injection layer; 207 - Ohmic contact electrode of p-type AlGaN material; 208 - Ohmic contact electrode of n-type AlGaN material;

[0043] 300 - Substrate for epitaxial growth; 301 - Buffer layer; 302 - n-type AlGaN layer; 303 - Light-emitting active region, typically - quantum well structure; 304 - p-type AlGaN layer; 305 - Cation vacancy layer formed on the surface of p-type AlGaN by treating with halogen-based active atoms / groups; 306 - Ohmic contact electrode of p-type AlGaN material; 307 - Ohmic contact electrode of n-type AlGaN material; 400 - Self-supporting GaN substrate; 401 - Lower optical field confinement layer; 402 - Lower waveguide; 403 - Quantum well active region; 404 - Upper waveguide; 405 - Electron blocking layer; 406 - Upper optical field confinement layer; 407 - p-type GaN contact layer; 408 - Cation vacancy layer formed on the surface of p-type GaN by treating with halogen-based active atoms / groups; 409 - Ohmic contact metal of p-type GaN; 410 - Ohmic contact electrode of n-type GaN. Detailed Implementation

[0044] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0045] This invention is based on increasing the cation vacancy V III Based on the physical principle of enhancing hole carrier concentration through concentration, this invention proposes a practical scheme for increasing the hole concentration in p-type group III nitride materials such as p-type AlGaN and for preparing ohmic contacts in p-type group III nitride materials. During and / or after the growth of p-type AlGaN p-type group III nitride materials, halogen-based active atoms / groups are introduced in situ. Utilizing the low activation energy (chemical decomposition process) of the chemical reaction between the halogen-based active atoms / groups and group III nitride semiconductor materials, group III atoms such as Al and Ga are efficiently and selectively removed, thereby generating a large number of cation vacancies V. IIITypically, the actual reaction process primarily involves the removal of Ga atoms. This is because the Al-N bond energy is significantly stronger than the Ga-N bond energy. By controlling a suitable chemical reaction temperature, Ga-N bonds can be broken while Al-N bonds remain largely intact, thereby removing some Ga atoms from the AlGaN material and generating a large number of cation vacancies (V) in situ. III .

[0046] On the one hand, cation vacancy V III The energy level is located near the valence band of p-type group III nitride materials such as p-type AlGaN, and acts as an acceptor, which can utilize these cation vacancies V III Hole carriers are generated by ionization of the acceptor level near the valence band of p-type group III nitride materials such as p-type AlGaN, thereby increasing the hole concentration near the surface and enhancing the ohmic contact of p-type group III nitride materials such as p-type AlGaN. On the other hand, these cation vacancies provide more group III atomic lattice sites for the subsequent incorporation of Mg impurities, and these cation vacancies can be utilized for V III This provides more group III atomic lattice sites for Mg impurity incorporation, thereby increasing the concentration of Mg acceptor impurities at group III atomic lattice substitution sites (Mg only acts as an acceptor when occupying group III atomic sites), and suppressing donor-type interstitial sites (Mg). i ), nitrogen transsite (Mg N The incorporation of Mg atoms suppresses the donor-acceptor self-compensation effect, significantly increases hole concentration, and enhances the ohmic contact of p-type AlGaN materials.

[0047] The process of this invention is simple, cost-effective, and completely repeatable and controllable, making it very suitable for the large-scale preparation of p-type AlGaN materials with high hole concentration.

[0048] This invention provides a method for increasing the hole concentration in p-type group III nitride materials, comprising:

[0049] During and / or after the growth of the p-type III nitride material, the p-type III nitride material is brought into contact with halogen-based active atoms and / or halogen-based active groups to remove some of the III atoms in the p-type III nitride material, thereby generating cation vacancies in the p-type III nitride material; and

[0050] Activate acceptor impurities in p-type group III nitride materials containing the cation vacancies.

[0051] In one specific implementation, the method includes:

[0052] When growing p-type III nitride materials in a reaction chamber, a halogen source is introduced into the reaction chamber. The halogen source can form halogen-based active atoms and / or halogen-based active groups at the growth temperature of the p-type III nitride material, and cause the p-type III nitride material to contact and react with the halogen-based active atoms and / or halogen-based active groups to remove some of the III atoms in the p-type III nitride material, thereby generating cation vacancies in the p-type III nitride material.

[0053] In one specific embodiment, the method further includes:

[0054] The p-type group III nitride material containing the cation vacancies is removed from the reaction chamber, and the acceptor impurities therein are then activated.

[0055] In one specific implementation, the method includes:

[0056] A halogen source is introduced into a reaction chamber containing a p-type group III nitride material, and the halogen source is used to form halogen-based active atoms and / or halogen-based active groups. The surface of the p-type group III nitride material is brought into contact with the halogen-based active atoms and / or halogen-based active groups to remove some group III atoms near the surface of the p-type group III nitride material, thereby forming a thin layer of cation vacancy near the surface of the p-type group III nitride material. The thin layer of cation vacancy contains multiple cation vacancies.

[0057] In one specific implementation, the method specifically includes:

[0058] S1. A group III metal source, an acceptor impurity source, and a nitrogen source are introduced into the reaction chamber to grow and form a p-type group III nitride material.

[0059] S2. Stop feeding the group III metal source and acceptor impurity source into the reaction chamber, and feed a halogen source into the reaction chamber, and make the halogen source form the halogen active atom and / or halogen active group. Then, make the surface of the p-type group III nitride material contact and react with the halogen active atom and / or halogen active group to remove some group III atoms near the surface of the p-type group III nitride material, thereby forming a thin cation vacancy layer near the surface of the p-type group III nitride material.

[0060] S3. Repeat steps S1-S3 once or more until a p-type III nitride material layer of the required thickness is obtained.

[0061] S4. Activate the acceptor impurities in the p-type III nitride material layer finally obtained in step S3.

[0062] In one specific embodiment, the method further includes:

[0063] S2x: After completing step S2, an acceptor impurity source is introduced and maintained for 0-60s to promote the acceptor impurity to fully occupy the group III cation vacancy, and then step S3 is performed; specifically, after the group III cation vacancy is generated, the acceptor impurity source can be introduced for only a few seconds to allow the impurity atoms to fully occupy the lattice sites of the group III cation vacancy, thereby increasing the concentration of acceptor-type impurities. It should be noted that acceptor impurity atoms only behave as acceptors when they occupy group III cation lattice sites, and do not behave as acceptors when they occupy interstitial sites and group V lattice sites.

[0064] In one specific embodiment, the method further includes:

[0065] S3x: After completing step S3, continue to grow a semiconductor material layer or a non-semiconductor material layer on the p-type III nitride material layer, and then proceed to step S4; for example, the semiconductor material layer or the non-semiconductor material layer can be a dielectric layer, a passivation layer, etc.

[0066] In one specific embodiment, the method includes: continuously performing steps S1-S4 in the same reaction chamber to avoid contamination caused by epitaxial wafer transfer.

[0067] In one specific embodiment, the material of the p-type group III nitride material layer includes a multi-component group III nitride.

[0068] In one specific embodiment, the multi-component group III nitride includes In x Al y Ga 1-x-y N, B x Al 1-x N or B x Al y Ga 1-x-y N, 0≤x≤1, 0≤y≤1.

[0069] In one specific embodiment, the halogen source includes, but is not limited to, any one of elemental halogens, organic compounds containing halogens, and inorganic compounds containing halogens.

[0070] In one specific embodiment, the halogen source includes any one or a combination of two or more of tert-butyl chloride, hydrogen chloride, chlorine, and tetrachloromethane, but is not limited thereto.

[0071] In one specific embodiment, the acceptor impurity includes any one or more combinations of Mg, Zn, Be, and C.

[0072] This invention also provides a method for preparing an ohmic contact of a p-type group III nitride semiconductor material, comprising:

[0073] The method described above can be used to increase the hole concentration in p-type III nitride materials;

[0074] An electrode is fabricated, and the electrode is made to form an ohmic contact with the p-type III nitride material.

[0075] This invention also provides a method for fabricating an ultraviolet optoelectronic device, comprising:

[0076] The first step in fabricating the main structure of an ultraviolet optoelectronic device, and

[0077] The second step is to fabricate electrodes that mate with the main structure.

[0078] Furthermore, the first step also includes: increasing the hole concentration of the p-type III nitride material using the method described above.

[0079] In some more specific implementations, a method for increasing the hole concentration of p-type group III nitride materials involves introducing halogen-based active atoms and / or halogen-based active groups during the epitaxial growth of p-type AlGaN materials, and preparing high-hole-concentration p-type AlGaN materials using an "etch-while-growing" approach. The specific steps include:

[0080] 1) A p-type AlGaN thin film of a certain thickness is epitaxially grown using methods such as metal-organic chemical vapor deposition (MOCVD). The equipment and growth conditions such as growth temperature and pressure used for epitaxial growth are known to those skilled in the art.

[0081] During the growth process, a halogen-based source is introduced into the reaction chamber for growing p-type AlGaN material. The halogen-based source can form halogen-based active atoms and / or halogen-based active groups at the growth temperature of the p-type AlGaN material, and cause the p-type AlGaN material to contact and react with the halogen-based active atoms and / or halogen-based active groups, so as to efficiently remove some group III atoms in the p-type AlGaN material and generate cation vacancies, thereby providing more group III atom lattice sites for Mg atom incorporation and increasing the Mg impurity concentration of acceptor type.

[0082] 2) Stop the supply of halogen source and cool the reaction chamber to room temperature, then remove the p-type AlGaN epitaxial wafer obtained by epitaxial growth; activate the Mg acceptors in the p-type AlGaN material by high-temperature annealing or electron beam irradiation;

[0083] 3) P-type ohmic contact electrodes were prepared and annealed. Hall effect tests showed that the hole concentration of the obtained p-type AlGaN epitaxial wafer was significantly improved compared with that of traditional p-type AlGaN.

[0084] In some more specific implementations, a method for increasing the hole concentration of p-type group III nitride materials involves introducing halogen-based active atoms and / or halogen-based active groups onto the surface of the p-type AlGaN material after its growth. This generates a large number of cation vacancies in situ near the surface of the p-type AlGaN material. The p-type AlGaN material is then grown again, and this process can be repeated multiple times. This "etch-re-growth" method is used to prepare p-type AlGaN materials with high hole concentrations. The specific steps include:

[0085] 1) Introduce Al, Ga, and Mg metal sources into the reaction chamber and use metal-organic chemical vapor deposition (MOCVD) to epitaxially grow a certain thickness of p-type AlGaN material inside and outside the reaction chamber.

[0086] 2) Stop the supply of Al, Ga, and Mg metal sources, adjust the pressure in the reaction chamber to 5-500 mbar, the temperature to 500-1300℃, and the NH3 flow rate to 0-200 slm. Preferably, adjust the pressure in the reaction chamber to 50-200 mbar, the temperature to 750-900℃, and the NH3 flow rate to 0.1-20 slm.

[0087] 3) A halogen-based source is introduced into the reaction chamber for 0.1-60 min to perform in-situ treatment on the p-type AlGaN material, forming a thin cation vacancy layer near the surface of the p-type AlGaN material. The concentration of group III cation vacancies in this cation vacancy layer is significantly increased compared to other regions. Preferably, the halogen-based source is introduced for 0.1-10 min.

[0088] 4) Stop the supply of halogen base source, adjust the pressure of the reaction chamber to 10-500 mbar, the temperature to 500-1300℃, and the NH3 flow rate to 0.1-100 slm; preferably, adjust the pressure of the reaction chamber to 100-200 mbar and the temperature to 950-1100℃.

[0089] 5) Re-introduce Al, Ga, and Mg metal sources into the reaction chamber and epitaxially grow a certain thickness of p-type AlGaN material on the side surface of the p-type AlGaN material with a cation vacancy layer.

[0090] 6) Repeat steps 2 to 5 in sequence to obtain a thicker p-type AlGaN epitaxial wafer;

[0091] 7) Stop the supply of halogen source, cool the reaction chamber to room temperature, remove the p-type AlGaN epitaxial wafer, and activate the Mg acceptor in the p-type AlGaN material by high-temperature annealing or electron beam irradiation.

[0092] 8) P-type ohmic contact electrodes were prepared and annealed. Hall effect tests showed that the hole concentration of the obtained p-type AlGaN epitaxial wafer was significantly improved compared with that of traditional p-type AlGaN.

[0093] In some more specific embodiments, a method for preparing ohmic contacts of p-type group III nitride semiconductor materials directly utilizes halogen-based active atoms and / or halogen-based active groups to etch and generate group III cation vacancies V. III Ionization generates hole carriers to enhance the p-type ohmic contact, specifically including the following steps:

[0094] 1) First, Al, Ga, and Mg metal sources are introduced into the reaction chamber, and p-type AlGaN material of a certain thickness is epitaxially grown inside and outside the reaction chamber using methods such as metal-organic chemical vapor deposition (MOCVD).

[0095] 2) Stop supplying Al, Ga, and Mg metal sources to the reaction chamber, adjust the pressure of the reaction chamber to 5-500 mbar, the temperature to 500-1300℃, and the NH3 flow rate to 0-200 slm; preferably, adjust the pressure of the reaction chamber to 50-200 mbar, the temperature to 750-900℃, and the NH3 flow rate to 0.1-20 slm.

[0096] 3) Introduce a halogen source into the reaction chamber for 0.1-60 min, preferably 0.1-10 min, to perform in-situ treatment on the surface of the p-type AlGaN material, forming a thin cation vacancy layer near the surface of the p-type AlGaN material. The concentration of group III cation vacancies in this cation vacancy layer is significantly increased compared to other regions in the bulk, thereby obtaining an epitaxial wafer.

[0097] 4) Stop the supply of halogen source, cool the reaction chamber to room temperature, and remove the epitaxial wafer. Optionally, activate the Mg acceptor in the p-type AlGaN material by high-temperature annealing or electron beam irradiation.

[0098] 5) The p-type ohmic contact electrode was prepared and annealed. The test results showed that the specific contact resistivity of the p-type AlGaN prepared by this method was significantly reduced compared with that prepared by the traditional method.

[0099] In some more specific embodiments, a method for preparing ohmic contacts of p-type group III nitride semiconductor materials involves etching group III cation vacancies (V) using halogen-based active atoms and / or halogen-based active groups. IIIThis increases the concentration of Mg acceptor impurities at group III atomic lattice substitution sites near the surface, thereby enhancing the ohmic contact of p-type AlGaN materials. Specifically, the steps include:

[0100] 1) First, Al, Ga, and Mg metal sources are introduced into the reaction chamber, and p-type AlGaN material of a certain thickness is epitaxially grown inside and outside the reaction chamber using methods such as metal-organic chemical vapor deposition (MOCVD).

[0101] 2) Stop the supply of Al, Ga, and Mg metal sources, adjust the pressure in the reaction chamber to 5-500 mbar, the temperature to 500-1300℃, and the NH3 flow rate to 0-200 slm; preferably, adjust the pressure in the reaction chamber to 50-200 mbar, the temperature to 750-900℃, and the NH3 flow rate to 0.1-20 slm.

[0102] 3) Introduce a halogen source into the reaction chamber for 0.1-60 min, preferably 0.1-10 min, to perform in-situ treatment on the surface of the p-type AlGaN material, forming a thin cation vacancy layer near the surface of the p-type AlGaN material. The concentration of group III cation vacancies in this cation vacancy layer is significantly increased compared to other regions in the bulk.

[0103] 4) Stop the supply of halogen source, adjust the pressure in the reaction chamber to 5-300 mbar, the temperature to 800-1300℃, and the NH3 flow rate to 0-200 slm. Introduce Al, Ga, and Mg metal sources into the reaction chamber and continue to grow a p-type (Al)GaN contact layer of a certain thickness. This allows a large number of Mg atoms to occupy the group III cation vacancies generated by the halogen source treatment, forming a high concentration of acceptor-state Mg doping, thereby obtaining an epitaxial wafer. Preferably, a p-type (Al)GaN contact layer of 5-10 nm thickness is grown.

[0104] 5) Turn off the halogen source supply, cool the reaction chamber to room temperature, remove the epitaxial wafer, and activate the Mg acceptor in the p-type AlGaN material by high-temperature annealing or electron beam irradiation.

[0105] 6) P-type ohmic contact electrodes were prepared and annealed. Tests showed that compared with p-type (Al)GaN prepared by traditional methods, the specific contact resistivity of p-type (Al)GaN prepared by this method was significantly reduced, which is beneficial to significantly reduce the operating voltage of the device.

[0106] The following will further explain the technical solution, its implementation process and principle in conjunction with the accompanying drawings and specific implementation examples. Unless otherwise specified, the equipment and process parameters used in the epitaxial growth, annealing, electron irradiation, testing and other processes adopted in the embodiments of the present invention can all be implemented using processes and equipment known to those skilled in the art, and no special limitations are made here.

[0107] Example 1: Please refer to Figures 1-3 In p-type Al 0.5 Ga 0.5 During the epitaxial growth of N-type materials, tert-butyl chloride (TBCl) is introduced, and in-situ etching generates cation vacancies, promoting Mg acceptor incorporation and enhancing p-type Al. 0.5 Ga 0.5 The hole concentration of N is determined by the following steps:

[0108] S1: 1μm AlN and 700nm AlN / AlN / AlN were sequentially epitaxially grown on a silicon carbide substrate using MOCVD. 0.7 Ga 0.3 N-type superlattice buffer layer, 1μm thick unintentionally doped Al 0.6 Ga 0.4 N is the base layer;

[0109] S2: Turn off the n-type doping source SiH4, introduce magnesia-ceramic (CP2Mg) into the reaction chamber for acceptor doping, and simultaneously introduce a 50 sccm tert-butyl chloride (TBCl) organic source to epitaxially grow a 200 nm thick p-type Al. 0.5 Ga 0.5 In the N thin film, during growth, TBCl undergoes thermal decomposition to generate Cl radicals, which react with Ga and Al atoms at lattice sites. This preferentially consumes Ga atoms, creating numerous group III atom vacancies, providing more acceptor lattice sites for Mg atom incorporation and increasing the number of acceptor Mg impurities (Mg). Ga )concentration;

[0110] S3: Stop the supply of tert-butyl chloride organic source, cool the reaction chamber to room temperature, remove the epitaxial wafer, and use a rapid annealing furnace to anneal at 750°C under N2 for 120 seconds to activate the Mg acceptors in the epitaxial wafer material.

[0111] S4: Using photolithography, etching, electron beam evaporation and other processes, 50nm / 150nm Ni / Au ohmic contact electrodes are prepared and annealed to form good ohmic contact electrodes;

[0112] p-type Al prepared in Example 1 0.5 Ga 0.5 N, as shown by room temperature Hall effect testing, has a hole concentration of 8 × 10⁻⁶. 17 cm -3Hole mobility 12.6cm 2 / V·s, compared with traditional p-type Al without TBCl treatment 0.5 Ga 0.5 Compared to N, the sheet resistance is reduced to 1 / 3 of the original, only 310 Ω / □; further, the high hole concentration p-type Al prepared by this method... 0.5 Ga 0.5 N-film was used to fabricate deep ultraviolet LED devices. Current-voltage tests showed that the operating voltage of the deep ultraviolet LED devices dropped to 4.8V at 100mA, significantly improving reliability.

[0113] Example 2: Please refer to Figures 4-7 p-type Al was treated by multiple cycles of tert-butyl chloride. 0.8 Ga 0.2 An N-electron blocking layer is used to increase hole concentration, reduce device series resistance, and improve hole injection efficiency in AlGaN deep ultraviolet LEDs. The specific steps include:

[0114] S1: 1μm AlN and 500nm AlN were sequentially epitaxially grown on a flat sapphire substrate using MOCVD. 0.9 Ga 0.1 N-buffer layer, 300nm Al 0.7 Ga 0.3 N-buffer layer, 1μm n-type Al 0.6 Ga 0.4 N-electron injection layer, 5-cycle Al 0.45 Ga 0.65 N / Al 0.55 Ga 0.55 N-quantum well active region light-emitting layer (well barrier thicknesses of 2nm / 10nm), 5nm thick p-type Al 0.8 Ga 0.2 N-electron blocking layer (EBL);

[0115] S2: Stop the flow of trimethylaluminum (TMAl), trimethylgallium (TMGa), and magnesium pyrocene (CP2Mg) organic sources, adjust the pressure in the reaction chamber to 100 mbar, the temperature to 850 °C, and the NH3 flow rate to 15 slm;

[0116] S3: Introduce a tert-butyl chloride (TBCl) source into the reaction chamber to react with p-type Al. 0.8 Ga 0.2 In-situ treatment of the N-electron blocking layer surface for 2 minutes resulted in the formation of a thin AlGaN cation vacancy layer near the surface, which serves as a foundation for subsequent p-type Al... 0.8 Ga 0.2 During the growth of the N electron blocking layer, Mg atoms provide more acceptor lattice sites.

[0117] S4: Stop the TBCl source supply, adjust the pressure in the reaction chamber to 100 mbar, the temperature to 1060℃, and the NH3 flow rate to 15 slm. Re-introduce the TMAl, TMGa, and Cp2Mg metal sources into the reaction chamber and continue the epitaxial growth of a 5 nm thick p-type Al. 0.8 Ga 0.2 N-film;

[0118] S5: Repeat steps S2-S4 twice to obtain the acceptor Mg. Ga The concentration of p-type Al increased significantly 0.8 Ga 0.2 The N-electron blocking layer has a total thickness of approximately 20 nm.

[0119] S6: Continue epitaxial growth of a 100nm thick p-type Al 0.6 Ga 0.4 An N-hole injection layer and a 5nm p-type GaN contact layer were then formed. H2 carrier gas and NH3 were then turned off, the temperature was lowered to 800℃, and the MOCVD chamber was annealed for 25 min to activate the incorporated Mg acceptors.

[0120] S7: Cool the reaction chamber to room temperature, remove the epitaxial wafer, and use photolithography, etching, and electron beam evaporation processes to deposit epitaxial wafers on n-type and p-type Al₂O₃ substrates, respectively. 0.5 Ga 0.5 The cathode and anode metals are prepared on the N surface, and finally annealed to form a good ohmic contact electrode.

[0121] The AlGaN deep ultraviolet LED prepared in Example 2, as shown by room temperature current-voltage (IV) testing, exhibited an emission wavelength of approximately 278 nm at an injection current of 100 mA and an operating voltage of approximately 5.1 V. Compared to conventional devices of the same type, the voltage drop was approximately 1 V, indicating that this multilayered cation vacancy layer can significantly improve the p-type Al... 0.7 Ga 0.3 The N-electron blocking layer reduces hole concentration and lowers series resistance. Meanwhile, optical power testing shows that the device outputs approximately 30mW of optical power at 100mA and has an external quantum efficiency of approximately 6%, reaching the international advanced level.

[0122] Example 3: Please refer to Figures 8-10 p-type Al was etched in situ using tert-butyl chloride. 0.6 Ga 0.4 N surface generates cation vacancies V III To increase the surface hole concentration, significantly enhance the p-type ohmic contact of AlGaN deep ultraviolet LEDs, and reduce the operating voltage of the device, the following steps are included:

[0123] S1: 2μm AlN and 500nm AlN / AlN / AlN were sequentially epitaxially grown on a nanopatterned sapphire substrate using MOCVD. 0.7 Ga 0.3 N-superlattice buffer layer, 1μm n-type Al 0.6 Ga 0.4 N-electron injection layer, 5-cycle Al 0.5 Ga 0.5 N / Al 0.6 Ga 0.4 N-quantum well active region light-emitting layer (well barrier thicknesses of 2nm / 10nm), 20nm thick p-type Al 0.8 Ga 0.2 N-electron blocking layer, 90nm thick p-type Al 0.6 Ga 0.4 N-hole injection layer;

[0124] S2: Stop the flow of trimethylaluminum (TMAl), trimethylgallium (TMGa), and magnesium pyrocene (CP2Mg) organic sources, adjust the pressure in the reaction chamber to 200 mbar, adjust the temperature to 900℃, and adjust the NH3 flow rate to 20 slm;

[0125] S3: Introduce a tert-butyl chloride (TBCl) source into the reaction chamber to react with p-type Al. 0.6 Ga 0.4 In-situ treatment of the N thin film surface for 10 min resulted in the formation of a thin AlGaN vacancy defect layer near the surface, which showed a significant increase in the concentration of group III cation vacancies compared to the bulk layer.

[0126] S4: Stop the TBCl source supply, cool to room temperature, remove the epitaxial wafer, and perform high-temperature annealing at 750℃ and N2 environment to activate the Mg acceptors in the p-type AlGaN material;

[0127] S5: Using photolithography, etching, electron beam evaporation, and other processes, respectively, on n-type and p-type Al... 0.6 Ga 0.4 The cathode and anode metals are prepared on the N surface, and finally annealed to form a good ohmic contact electrode.

[0128] The AlGaN deep ultraviolet LED prepared in Example 3 showed that the room temperature current-voltage (IV) test showed that the device emitted a wavelength of about 265 nm at an injection current of 100 mA and had an operating voltage of only 5.1 V, which is about 1-2 V lower than the voltage of traditional devices without cation vacancy layers. At the same time, the optical power test showed that the device had an output optical power of up to 46 mW at 100 mA and an external quantum efficiency of about 9%, which is among the top international levels.

[0129] Example 4: Please refer to Figures 11-14In-situ etching of the p-type GaN surface of a GaN-based laser using tert-butyl chloride generates cation vacancies, providing more group III atom lattice sites for Mg atom incorporation. This enhances the formation of acceptors at the Mg atom incorporation sites, thereby suppressing donor-type interstitial sites (Mg). i ), nitrogen transsite (Mg N The incorporation of Mg atoms increases the hole concentration and reduces the p-type ohmic contact resistance, ultimately lowering the laser's operating voltage. This process includes the following steps:

[0130] S1: 500 nm thick n-type Al atoms were epitaxially grown sequentially on a self-supporting GaN substrate using the MOCVD method. 0.07 Ga 0.93 N-field confinement layer, 120nm thick In 0.02 Ga 0.98 N-waveguide layer, 3-period In 0.12 Ga 0.88 The active region light-emitting layer of the N / GaN quantum well (with well barrier thicknesses of 2.5 nm and 12 nm, respectively), and the 90 nm thick In... 0.02 Ga 0.98 N-waveguide layer, 20nm thick p-type Al 0.2 Ga 0.8 N-electron blocking layer, 600nm thick p-type Al 0.08 Ga 0.92 The N-type GaN has an optical field confinement layer and a 50nm thick p-type GaN contact layer.

[0131] S2: Stop the flow of trimethylgallium (TMGa) and magnesium pyrocene (CP2Mg) organic sources, adjust the pressure in the reaction chamber to 100 mbar, adjust the temperature to 750℃, and adjust the NH3 flow rate to 15 slm;

[0132] S3: Introduce tert-butyl chloride (TBCl) source to treat the surface of p-type GaN contact layer in situ for 5 min, forming a thin cation vacancy layer near the surface, the cation vacancy concentration of which is significantly increased compared to the in vivo concentration.

[0133] S4: Stop the TBCl source supply, adjust the reaction chamber pressure to 200 mbar, adjust the temperature to 920℃, adjust the NH3 flow rate to 20 slm, introduce Ga and Mg sources, grow 5 nm heavily doped p-type GaN, so that a large number of Mg atoms occupy the group III cation vacancies generated by the halogen-based source treatment, forming a high concentration of acceptor state Mg doping.

[0134] S5: Cool to room temperature and remove the epitaxial wafer. Activate the Mg acceptors in the p-type AlGaN material using methods such as high-temperature annealing or electron beam irradiation;

[0135] S6: Using magnetron sputtering equipment, Pd / Pt / Au ohmic contact electrodes are prepared on the p-type GaN surface with a cation vacancy layer, and rapid thermal annealing is performed to form a good ohmic contact;

[0136] S7: Photolithography, using ion beam etching to fabricate ridge waveguide structures;

[0137] S8: An n-type ohmic contact electrode is fabricated on the back side of a self-supporting GaN and then annealed to form a good ohmic contact;

[0138] S9: Slice and cleave the laser cavity surface to form laser bars, with ten laser devices on each bar.

[0139] The GaN-based violet laser prepared in Example 4, as shown by room temperature current-voltage (IV) testing, has a threshold voltage of only 3.7V, which is about 0.8V lower than that of conventional lasers. This indicates that the cation vacancy layer can significantly increase the hole concentration of p-type GaN and reduce the ohmic contact resistance. At the same time, aging tests show that the continuous operating life of the device has increased significantly from 2000 hours to 4500 hours, and the reliability has been greatly improved.

[0140] It should be noted that the halogen source used in the in-situ treatment of the embodiments of the present invention includes, but is not limited to, various chlorine-containing elements and compounds such as tert-butyl chloride (TBCl), hydrogen chloride (HCl), chlorine (Cl2), tetrachloromethane (CCl4), and gallium chloride (GaCl3), as well as various fluorinated and brominated derivatives, and any combination thereof. It should be particularly pointed out that the halogen source can be introduced into the reaction chamber in a manner including, but not limited to, continuous introduction, pulsed introduction, and intermittent introduction.

[0141] It should be specifically noted that the semiconductor material used for processing includes, but is not limited to, AlGaN material, where the Al composition x ranges from 0 ≤ x ≤ 1; it can also be In. x Al y Ga 1-x-y N-ary nitride semiconductor material, 0≤x≤1, 0≤y≤1; can also be B-ary nitride semiconductor material. x Al 1-x For N and Al components, the range of x is 0 ≤ x ≤ 1; it can also be B. x Al y Ga 1-x-y Materials such as N, 0≤x≤1, 0≤y≤1; and when treating the material surface with halogen-based active atoms / groups, a reaction chamber can be introduced either during the material growth process (as in Example 1) or after the material growth process (as in Example 2); the growth process can be performed in a single treatment or in multiple cycles.

[0142] In addition, the doping atoms used for p-type doping include, but are not limited to, atoms such as Mg, Zn, Be, and C; preferably, Mg doping is used; the metal used to prepare the ohmic contact of the p-type AlGaN material can be any one or a combination of two or more of the following materials: Ni, Ti, Pd, Pt, Au, Al, Ag, Rh, Cr, Mo, Ru, Zn, In, Sn, TiN, ITO (indium tin oxide), and IGZO (indium gallium zinc oxide); the substrate used for epitaxial AlGaN includes, but is not limited to, sapphire, silicon, self-supporting AlN single crystal, self-supporting GaN single crystal, silicon carbide, and diamond substrates; the methods for epitaxially growing AlGaN materials include, but are not limited to, metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), hydride vapor phase epitaxy (HVPE), and pulsed laser deposition (PLD); preferably, the MOCVD method is used.

[0143] This invention provides a method for increasing the hole concentration in AlGaN semiconductor materials. This method involves in-situ introduction of highly chemically active halogen atoms / groups. Leveraging the low activation energy of the chemical reaction between these halogen atoms / groups and AlGaN materials, the method specifically removes group III atoms (Al and Ga), thereby generating a large number of cation vacancies (V). III These group III cation vacancies have two beneficial effects: 1) they can ionize to generate a large number of hole carriers; 2) they can provide more group III atomic lattice sites for subsequent Mg impurity incorporation, further increasing the concentration of acceptor Mg impurities at group III atomic lattice substitution sites, thereby significantly increasing the hole concentration inside p-type AlGaN materials.

[0144] This invention provides a method for increasing the hole concentration in AlGaN semiconductor materials. It utilizes halogen-based active atoms / groups to in-situ treat the AlGaN surface, generating a large number of cation vacancies. This enhances the incorporation of acceptor Mg impurities at group III atomic lattice substitution sites, thereby significantly increasing the hole concentration. This method overcomes the limitations of traditional p-type AlGaN, such as low acceptor Mg atom incorporation efficiency and severe self-compensation effects. It utilizes the chemical reaction between halogen-based active atoms / groups and AlGaN materials to generate a large number of cation vacancies in situ. It effectively utilizes group III cation vacancies to generate a large number of hole carriers, while simultaneously enhancing the incorporation of acceptor Mg atoms at group III atomic lattice substitution sites, suppressing the self-compensation effect, and significantly increasing the hole concentration in p-type AlGaN materials.

[0145] This invention provides a method for preparing ohmic contacts of p-type group III nitride semiconductor materials. It involves in-situ introduction of highly chemically active halogen-based atoms / groups into a reaction chamber. Utilizing the low activation energy of the chemical reaction between the halogen-based active atoms / groups and AlGaN materials, group III atoms Al and Ga are efficiently and selectively removed, thereby generating a large number of cation vacancies V. III These group III cation vacancies have two beneficial effects: 1) they can generate a large number of hole carriers and reduce ohmic contact resistance; 2) they can provide more group III atomic lattice sites for Mg impurity incorporation, further increasing the concentration of acceptor Mg impurities at group III atomic lattice substitution sites, increasing the concentration of hole carriers generated by their ionization, and enhancing the ohmic contact of p-type AlGaN materials.

[0146] This invention provides a method for preparing ohmic contacts in p-type group III nitride semiconductor materials. It utilizes halogen-based active atoms / groups to in-situ treat the p-type AlGaN surface, generating cation vacancies to increase hole concentration and reduce the ohmic contact resistance of the p-type material. This method overcomes the limitations of traditional dry etching methods that result in surface donor-type V-type ohmic contacts. N The high concentration also avoids the problem of "Mg acceptor activation of buried p-type AlGaN material" faced by tunnel junction technology. It effectively utilizes the inherent chemical bond properties of (Al)GaN material. By introducing halogen-based active atoms / groups, AlGaN material can be repeatedly and controllably etched to generate group III cation vacancies, thereby significantly increasing the hole concentration near the p-type AlGaN surface and reducing the ohmic contact resistance.

[0147] It should be noted that this invention can also be used to enhance the ohmic contact of binary alloys such as p-type GaN (as in Example 2). Unlike AlGaN-based ternary and quaternary alloys, for binary alloys such as GaN, InN, and AlN, the high density of dangling bonds and the ease of chemical reaction near the dislocation "core" can be utilized. By introducing chemically active halogen atoms / groups and controlling the temperature of the reaction chamber, some group III atoms in the region surrounding the dislocation can be preferentially removed, thereby generating a large number of acceptor cation vacancies near the surface of binary alloys such as GaN. These cation vacancies can also enhance the incorporation of acceptor Mg atoms at the group III atom lattice substitution sites, increasing the hole concentration in the overall material and enhancing the ohmic contact of binary alloys such as p-type GaN.

[0148] This invention provides a method for increasing the hole concentration in AlGaN semiconductor materials, which overcomes the limitations of traditional p-type AlGaN materials, such as low acceptor Mg atom incorporation efficiency and severe self-compensation effect. It can utilize group III cation vacancies to significantly increase the concentration of Mg acceptor impurities at group III atom lattice sites, thereby significantly increasing the hole concentration in p-type AlGaN materials.

[0149] The present invention provides a method for preparing ohmic contacts of p-type group III nitride semiconductor materials, which can overcome the disadvantages of high donor VN concentration caused by traditional dry etching and other methods. It selectively removes some group III atoms to generate cation vacancies VIII, which significantly increases the hole concentration on the p-type AlGaN surface and reduces the ohmic contact resistance.

[0150] As mentioned earlier, when the surface of p-type AlGaN material is treated by methods such as dry etching, the nitrogen atoms preferentially leave the surface due to high-energy ion bombardment, resulting in a large number of donor-type nitrogen vacancy (VN) defects on the p-type AlGaN material surface. Therefore, the AlGaN material surface exhibits high resistance characteristics, which is not conducive to the preparation of p-type ohmic contacts. This invention introduces halogen-based active atoms / groups in situ to efficiently and selectively remove group III atoms such as Al and Ga, thereby generating a large number of cation vacancies VN. III On the one hand, these cation vacancies V III The energy level is located near the valence band of AlGaN material, acting as an acceptor and capable of ionizing to generate hole carriers; on the other hand, these cation vacancies V III This provides more group III atom lattice sites for the subsequent incorporation of Mg impurities, which is beneficial to increasing the concentration of Mg acceptor impurities at group III atom lattice substitution sites (Mg only acts as an acceptor when it occupies a group III atom site), thereby reducing the number of donor Mg atoms at interstitial sites and nitrogen antisites, suppressing the self-compensation effect, and significantly increasing the hole concentration.

[0151] The present invention provides a method for increasing the hole concentration of AlGaN semiconductor material without reducing the band gap of p-type AlGaN material and without causing internal photon absorption in AlGaN deep ultraviolet optoelectronic devices.

[0152] The present invention provides a method for preparing ohmic contacts of p-type group III nitride semiconductor materials, which does not reduce the band gap of p-type AlGaN materials and does not cause internal photon absorption in AlGaN deep ultraviolet optoelectronic devices.

[0153] This invention utilizes the reaction of halogen-based active atoms / groups with AlGaN materials. By controlling an appropriate chemical reaction temperature, it efficiently and selectively removes group III atoms (Al and Ga), thereby generating a large number of cation vacancies (V). IIIIn fact, removing even trace amounts of group III atoms can produce a considerable vacancy concentration, as seen in GaN materials (atomic density 8.9 × 10⁻⁶). 22 cm -3 For example, removing 1 / 10000 of the Ga atoms can produce 10 18 cm -3 The removal of trace amounts of group III atoms from AlGaN alloys is far from affecting the alloy composition, and therefore has almost no impact on the bandgap of AlGaN materials. Consequently, it does not cause internal absorption of photons emitted in the active region, and has virtually no impact on the external quantum efficiency of deep ultraviolet devices.

[0154] The present invention provides a method for increasing the hole concentration of AlGaN semiconductor material. The process is simple, repeatable and controllable, and is fully suitable for large-scale production.

[0155] The halogen source used in this invention is fully compatible with equipment such as MOCVD. When growing p-type AlGaN materials, only the halogen source needs to be introduced in situ. By controlling the source flow rate, reaction chamber pressure, temperature and other conditions, a large number of cation vacancies can be generated on the surface of p-type AlGaN materials. The operation is practical and feasible, and the cost is greatly reduced. It is very suitable for the large-scale production of high-quality p-type AlGaN materials with high hole concentration.

[0156] The present invention provides a method for preparing ohmic contacts of p-type group III nitride semiconductor materials, which can avoid the problem of "Mg acceptor activation of buried p-type AlGaN materials" faced by tunnel junction technology.

[0157] This invention provides a method for preparing ohmic contacts in p-type group III nitride semiconductor materials. It primarily utilizes the significant difference in bond energies between Al-N and Ga-N bonds to selectively remove some Ga atoms in situ during epitaxial growth, generating a large number of cation vacancies. These cation vacancies are then ionized to generate hole carriers, significantly increasing the hole concentration in the p-type AlGaN material. Therefore, this invention does not involve growing n-type semiconductor materials on p-type AlGaN, thus avoiding the Mg acceptor activation problem of buried p-type AlGaN in traditional tunnel junction schemes.

[0158] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for increasing the hole concentration in p-type III nitride materials, characterized in that, include: During and / or after the growth of the p-type III nitride material, the p-type III nitride material is brought into contact with halogen-based active atoms and / or halogen-based active groups to remove some of the III atoms in the p-type III nitride material, thereby generating cation vacancies in the p-type III nitride material; and Activate acceptor impurities in p-type group III nitride materials containing the cation vacancies.

2. The method according to claim 1, characterized in that, include: When growing p-type III nitride materials in a reaction chamber, a halogen source is introduced into the reaction chamber. The halogen source can form halogen-based active atoms and / or halogen-based active groups at the growth temperature of the p-type III nitride material, and cause the p-type III nitride material to contact and react with the halogen-based active atoms and / or halogen-based active groups to remove some of the III atoms in the p-type III nitride material, thereby generating cation vacancies in the p-type III nitride material.

3. The method according to claim 2, characterized in that, It also includes: removing the p-type group III nitride material containing the cation vacancy from the reaction chamber and then activating the acceptor impurity therein.

4. The method according to claim 1, characterized in that, include: A halogen source is introduced into a reaction chamber containing a p-type group III nitride material, and the halogen source is used to form halogen-based active atoms and / or halogen-based active groups. The surface of the p-type group III nitride material is brought into contact with the halogen-based active atoms and / or halogen-based active groups to remove some group III atoms near the surface of the p-type group III nitride material, thereby forming a thin layer of cation vacancy near the surface of the p-type group III nitride material. The thin layer of cation vacancy contains multiple cation vacancies.

5. The method according to claim 4, characterized in that, Specifically, it includes: S1. A group III metal source, an acceptor impurity source, and a nitrogen source are introduced into the reaction chamber to grow and form a p-type group III nitride material. S2. Stop feeding the group III metal source and acceptor impurity source into the reaction chamber, and feed a halogen source into the reaction chamber, and make the halogen source form the halogen active atom and / or halogen active group. Then, make the surface of the p-type group III nitride material contact and react with the halogen active atom and / or halogen active group to remove some group III atoms near the surface of the p-type group III nitride material, thereby forming a thin cation vacancy layer near the surface of the p-type group III nitride material. S3. Repeat steps S1-S3 once or more until a p-type III nitride material layer of the required thickness is obtained. S4. Activate the acceptor impurities in the p-type III nitride material layer finally obtained in step S3.

6. The method according to claim 5, characterized in that, Also includes: S2x: After completing step S2, introduce an acceptor impurity source and maintain it for 0-60s to promote the acceptor impurity to fully occupy the group III cation vacancy, and then proceed to step S3.

7. The method according to claim 6, characterized in that, The method further includes: S3x: After completing step S3, continue to grow a semiconductor material layer or a non-semiconductor material layer on the p-type III nitride material layer, and then proceed to step S4.

8. The method according to claim 5, 6, or 7, characterized in that, include: The operations of steps S1-S4 are performed continuously in the same reaction chamber.

9. The method according to claim 1, characterized in that: The material of the p-type group III nitride material layer includes a multi-component group III nitride.

10. The method according to claim 9, characterized in that: The multi-component group III nitrides include In x Al y Ga 1-x- y N, B x Al 1-x N or B x Al y Ga 1-x-y N, 0≤x≤1, 0≤y≤1.

11. The method according to claim 2, characterized in that: The halogen source includes any one of the following: elemental halogens, organic compounds containing halogens, and inorganic compounds containing halogens.

12. The method according to claim 11, characterized in that: The halogen source includes any one or a combination of two or more of tert-butyl chloride, hydrogen chloride, chlorine, and tetrachloromethane.

13. The method according to claim 1, characterized in that: The acceptor impurity includes any one or more combinations of Mg, Zn, Be, and C.

14. A method for preparing ohmic contacts of p-type group III nitride semiconductor materials, characterized in that, include: The hole concentration of p-type group III nitride materials can be increased by the method described in any one of claims 1-13; An electrode is fabricated, and the electrode is made to form an ohmic contact with the p-type III nitride material.

15. A method for fabricating an ultraviolet optoelectronic device, comprising: The first step in fabricating the main structure of an ultraviolet optoelectronic device, and The second step is to fabricate electrodes that mate with the main structure. The first step is characterized by further comprising: The hole concentration of p-type group III nitride materials can be increased by using the method described in any one of claims 1-13.

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