CN-115332057-B - Epitaxial growth method for improving crystallization quality of boron nitride two-dimensional material

CN115332057BCN 115332057 BCN115332057 BCN 115332057BCN-115332057-B

Abstract

The invention discloses an epitaxial growth method for improving the crystallization quality of a boron nitride two-dimensional material, which is based on a material epitaxial growth mode such as Metal Organic Chemical Vapor Deposition (MOCVD), and the like, and by growing an aluminum nitride transition layer on the surface of a monocrystalline substrate, the surface catalytic activity of the substrate is improved, the activation energy required by the subsequent nucleation of the boron nitride two-dimensional material is reduced, a silicon nitride isolation layer is introduced, the impurity introduction of the boron nitride two-dimensional material from the substrate is reduced, an air flow zero transition process is introduced at the interface of the aluminum nitride transition layer/the boron nitride two-dimensional material, the disturbance of an interface temperature field and a flow field is reduced, the ordered nucleation of the boron nitride two-dimensional material is improved, and the crystallization quality is improved. The epitaxial growth method can realize the boron nitride two-dimensional material with flat surface and higher crystallization quality, and promote the improvement of the performances of novel devices such as boron nitride-based deep ultraviolet photoelectric devices, van der Waals heterojunction and the like.

Inventors

LI CHUANHAO
LI ZHONGHUI
PENG DAQING

Assignees

中国电子科技集团公司第五十五研究所

Dates

Publication Date: 20260505
Application Date: 20220824

Claims (2)

1. An epitaxial growth method for improving the crystallization quality of a boron nitride two-dimensional material is characterized by comprising the following steps: step 1, selecting a single crystal substrate, and placing the single crystal substrate on a base in MOCVD equipment; Step 2, setting the pressure of the reaction chamber to be 50-100 torr, introducing H 2 , heating to 1000-1100 ℃, baking the substrate for 5-15 minutes, and removing surface contamination of the substrate; Setting the pressure of the reaction chamber at 30-150 torr in the H 2 atmosphere, setting the temperature at 900-1300 ℃, introducing NH 3 , and maintaining for 1-20 minutes, and nitriding the surface of the substrate; Step 4, keeping the pressure and the temperature of the reaction chamber unchanged, closing NH 3 , simultaneously introducing an aluminum source for 5-25 seconds, then closing the aluminum source, simultaneously introducing NH 3 , continuously supplying ammonia for 5-25 seconds, repeating a pulse process of supplying the aluminum source and NH 3 in a time sharing way, growing an aluminum nitride transition layer with the thickness of 10-100 nm, closing the aluminum source, and adjusting the flow rates of NH 3 and the aluminum source during the growth of the aluminum nitride transition layer to enable the mole ratio of NH 3 to the aluminum source to reach N 1 ; Step 5, maintaining the pressure, temperature and gas flow of the reaction chamber unchanged, introducing a metal organic boron source, adjusting the flow of the boron source to enable the mole ratio of NH 3 to the boron source to reach N 2 , growing a 1-3 nm thick boron nitride two-dimensional material, and closing the boron source; step 6, cooling to room temperature under the protection of NH 3 atmosphere, and taking out the epitaxial material; step a, keeping the pressure, temperature and gas flow of the reaction chamber unchanged, introducing SiH 4 , growing a silicon nitride isolation layer with the thickness of 1-3 nm, and closing SiH 4 ; The aluminum nitride transition layer in the step 4, the silicon nitride isolation layer in the step5 and the boron nitride two-dimensional material in the step 6 have the same epitaxial growth pressure, temperature and gas flow, namely an air flow zero transition process is introduced at the interface of the aluminum nitride transition layer/the boron nitride two-dimensional material; In the step 4, the molar ratio N 1 of NH 3 to the aluminum source is 200-2000; In the step 5, the molar ratio N 2 of NH 3 to the boron source is 1000-5000.
2. The method for epitaxial growth of boron nitride two-dimensional material according to claim 1, wherein in step 1, the single crystal substrate is silicon carbide single crystal substrate or semi-insulating substrate suitable for epitaxial growth of V/III nitride.

Description

Epitaxial growth method for improving crystallization quality of boron nitride two-dimensional material Technical Field The invention belongs to the technical field of semiconductor epitaxial materials, and particularly relates to an epitaxial growth method for improving the crystallization quality of a boron nitride two-dimensional material. Background One key "neck" technology currently limiting the performance of deep ultraviolet optoelectronic devices is the low P-type doping efficiency of conventional V/III nitrides, which makes the implementation of the V/III nitride P-type heavily doped epitaxy process difficult. Researches show that compared with conventional V/III nitride materials, such as aluminum nitride, gallium nitride and the like, the activation energy required by magnesium doping in the boron nitride material is lower, namely the process of the P-type heavily-doped wide-forbidden-band boron nitride material is lower in implementation difficulty, so that the development of a high-performance deep ultraviolet photoelectric device is easy to realize based on the boron nitride material, boron nitride is similar to a graphene atomic structure, and lattice mismatch of the boron nitride and the graphene is only 1.7%, so that the boron nitride can be used as an ideal substrate for graphene growth, graphene mobility grown on the boron nitride substrate is reported to be 1.4 x 10 5cm2/(V.s), the boron nitride is highest so far, the boron nitride two-dimensional material has no dangling bond on the surface, can be used as a dielectric layer of a top gate-graphene field effect tube, can obviously reduce the concentration of traps and impurities of a dielectric interface, inhibit optical phonon scattering, greatly improve the device performance, and further, the van der heterojunction formed by combining the two-dimensional boron nitride material with the graphene and other two-dimensional materials has great application potential in room temperature superconductors, energy collectors, novel field tubes and the like. The application space of the boron nitride two-dimensional material is wide, the main technology for preparing the boron nitride two-dimensional material at present comprises ion beam sputtering deposition, CVD growth technology on a metal substrate with catalytic activity and the like, the material prepared by the technology has higher quality and process maturity, but the material size is lower than 1cm multiplied by 1cm, the boron nitride two-dimensional material is required to be transferred onto a semi-insulating substrate during the development of a device, pollution and fold are easily introduced during the transfer, and the quality and the device performance of the two-dimensional material are severely limited. Recently, research on developing a boron nitride two-dimensional material based on MOCVD technology is reported abroad, and the development of a 2-inch wafer-level material can be directly realized on a semi-insulating substrate, so that the problems of ion beam sputter deposition technology and metal substrate CVD growth technology are effectively overcome. However, due to the general lack of catalytic activity of the semi-insulating substrate, the boron nitride two-dimensional material has higher activation energy required for nucleation of the semi-insulating substrate, which results in difficult material nucleation and poor crystallization quality, and the migration rate of the surface of the metal boron atoms during MOCVD epitaxy is low, which results in difficult combination of the boron nitride material into a film and rough surface. Therefore, the development of the wafer-level high-crystallization-quality boron nitride two-dimensional material is realized on the semi-insulating substrate based on the MOCVD process through the improvement of an epitaxial technology and the process control, and the method has extremely important significance for the development of novel devices such as high-performance boron nitride-based deep ultraviolet photoelectric devices, van der Waals heterojunction and the like. The conventional epitaxial growth method of the boron nitride two-dimensional material adopted at present comprises the following steps: Selecting a 2 inch silicon carbide single crystal substrate, and placing the substrate on a base in MOCVD equipment; setting the pressure of the reaction chamber at 80torr, introducing H 2 with the flow of 100slm, heating the system to 1070 ℃, baking the substrate for 10 minutes, and removing the surface contamination of the substrate; setting the pressure of the reaction chamber to 50torr in the atmosphere with the flow rate of H 2 being 120slm, setting the temperature to 1100 ℃, introducing NH 3 with the flow rate of 8slm and keeping for 5 minutes, and nitriding the surface of the silicon carbide substrate; Setting the pressure of a reaction chamber to 30Torr, setting the flow rate of H 2 to 80slm, introducing triethylboron and NH 3