表面形貌对GaAs生长速率测量的影响

Influence of surface morphology on GaAs growth rate measurement

本文利用Reflection High Energy Electron Diffraction(RHEED)强度振荡测量GaAs同质外延生长,发现其生长速率随生长厚度按一定指数函数关系衰减.这种衰减与GaAs表面形貌的变化密切相关,表面台阶数量的增加使层状生长模式由2D成核模式逐渐转变为台阶流模式.由于RHEED强度振荡所测的生长速率与表面的粗糙程度密切相关,表面情况改变对生长速率会有一定的影响,导致测量的生长速率逐渐的衰减.根据生长速率随生长厚度的增加而衰减的拟合曲线,可以获得一个准确的生长速率.

In this paper,the Reflection High Energy Electron Diffraction(RHEED)intensity oscillation is used to measure the homoepitaxial growth of GaAs,and it is found that the growth rate decays according to a certain exponential function relationship with the growth thickness.This attenuation is closely related to the change of the GaAs surface morphology.The increase in the number of surface steps causes the layered growth mode to gradually change from the 2D nucleation mode to the step flow mode.Since the growth rate measured by RHEED intensity oscillation is closely related to the surface roughness,changes in surface conditions will have a certain impact on the growth rate,resulting in a gradual attenuation of the measured growth rate.According to the fitting curve of the attenuation of the growth rate with the increase of the growth thickness,an accurate growth rate can be obtained.