Simulation Research On The Cavity Structure Of GaN Growth By Hydride Vapor Phase Epitaxy

Gallium Nitride（GaN）materials shine brightly in the field of semiconductor applications in the past 20 years,and together with Silicon Carbide（Si C）,they rank among the the frontiers and hot spots in the research and development of the third-generation wide-bandgap semiconductor devices in the world today.Not only the realization form of GaN technology evolves towards Mini/Micro LED display under the dual drive of technology and production capacity on the basis of traditional LED lighting and blue-green LD,but also shines in the fields of smart grid,5G communication,new energy vehicles,and consumer-grade power supplies based on its high-power,high-frequency and high-efficiency performance in power and RF devices.The rapid development of GaN-based devices puts forward higher requirements on the quality of GaN substrates.Homoepitaxial growth can avoid defects caused by lattice mismatch and thermal mismatch.Hydride Vapor Phase Epitaxy（HVPE）is the mainstream method for preparing GaN single crystal substrates currently.This subject conducts two-dimensional simulation research on the core structure of GaN grown in the horizontal HVPE reaction chamber based on computational fluid dynamics（CFD）and finite volume analysis method（FVM）,and a 3D simulation study of the vertical HVPE reaction system is introduced as a reference.The optimal growth process for growing high-quality GaN single crystals is sought based on the above simulation experiments.The main research work and results of the dissertation are as follows:The effects of the three-dimensional structural changes of the distance between the Ga Cl gas inlet and the substrate,the tilt angle of the substrate,and the height of the substrate on the GaN growth distribution and growth rate were explored.When the temperature of each gas inlet is fixed at1123.15K,the outlet temperature is 1073.15K,the temperature in the reaction zone of the substrate is1323.15K;the total velocity of the mixed gas of Ga Cl and N₂ is 0.0106m/s,in which the mole fraction of Ga Cl is 0.3;the total velocity of the mixed gas of NH₃ and N₂ is 0.0084m/s,in which the mole fraction of NH₃ is 0.3;1 atm.We chose a distance of 32mm between the Ga Cl inlet and the substrate,a height difference of 10mm between the front and rear of the substrate,and a substrate height of29mm.At this time,the growth uniformity and growth rate of GaN are in an optimal ideal state:when the average growth rate reaches 107μm/h,the growth relative inhomogeneity is only 5.93%.We also found that increasing the substrate rotation speed can improve the crystal quality of the GaN film effectively due to the optimization of the flow field under the condition of ensuring a certain growth rate and uniformity in the 3D simulation research work of the vertical HVPE system,which brings new inspiration to the optimization direction of the HVPE cavity structure.The results of the simulation experiments above provide a theoretical basis for the adjustment and optimization of the parameters of the GaN growth system in the actual production process,which also has certain guiding significance for the industrialized preparation of GaN substrates.