Research On Key Issues Of Epitaxial Growth Of Single Crystal Diamond With MPCVD

Diamond is an ultra-wide bandgap semiconductor material with an energy gap of 5.5 eV.It has a high critical electric field strength（>10 MV/cm,30 times that of silicon）,high carrier mobility(～3000 cm²·V^-1·s^-1,twice that of silicon),enabling lower capacitor and drive resistance at the same voltage level.In addition,the thermal conductivity of diamond materials(～2200 W·m^-1·K^-1)is also much higher than that of silicon,gallium nitride,silicon carbide and gallium oxide materials,greatly reducing the heat dissipation requirements of the device.Therefore,diamond with a variety of excellent properties is recognized as an ideal power device material,and has great application prospects in electric vehicles,photovoltaic,military and other fields.To achieve industrial adoption,semiconductor materials require high purity,low defect density,high carrier concentration and mobility,and inch-level wafers.The growth of high-quality,large-area single crystal substrates remains a challenge for the commercialization of diamond materials.In order to avoid the formation of polycrystalline edges,the concave closed substrate is used to grow diamond single crystals by chemical vapor deposition.However,in the current literature,the absence of spatial position variables in the concave bottom bracket is the first problem to be solved.In addition,it is necessary to explore the high-speed growth conditions of diamond under multi-parameter coupling.In unloading stage,in-situ annealing process is used to suppress the stress.The broken diamond was repaired by in-situ setting.In addition,aiming at the original temperature detection requirements of diamond semiconductor devices under high temperature and high irradiation conditions,we designed a diamond diode temperature sensor and verified its detection performance in the range of 295～600 K.In order to solve the above problems,this paper studies the growth of single crystal diamond with closed substrate holder by using solid-state microwave plasma equipment.The specific innovations are as follows:（1）The spatial position of seeds in the concave closed scaffold was optimized,the influence on the growth mode of diamond was clarified,and the existence of single crystal growth zone was confirmed,which was conducive to the repeated growth of diamond.（2）Exploring the high-speed growth conditions of diamond under multi-parameter coupling can determine the change of growth rate under different parameters.These results are beneficial to obtain high-quality diamond single crystals with high growth ratio and smooth edges at the same time.（3）The stress state of the diamond with cracks is analyzed,and the in-situ annealing process is proposed to suppress the stress.The results show that high temperature annealing can effectively reduce the concentration of nitrogen impurities and improve the optical properties.（4）Repair the broken diamond by in-situ Mosaic method.The test results show that the repaired crystal quality is good,no stress deformation,and the risk of crack can be effectively eliminated.（5）Diamond temperature sensor was designed based on the Schottky-PN conjunctival diode,which presents a sensitivity of 5.31 mV/K at a relative low current density of 1×10^-3 A/cm^-2.