基于MOCVD三步生长的GaAs/Si外延技术EI北大核心CSCD

在硅(Si)上外延生长高质量的砷化镓(GaAs)薄膜是实现硅基光源单片集成的关键因素。但是,Si材料与GaAs材料之间较大的晶格失配、热失配等问题对获得高质量的GaAs薄膜造成了严重影响。本文利用金属有机化学气相沉积(MOCVD)技术开展Si基GaAs生长研究。通过采用三步生长法,运用低温成核层、高温GaAs层与循环热退火等结合的方式,进一步降低Si基GaAs材料的表面粗糙度和穿透位错密度。并利用X射线衍射(XRD)ω-2θ扫描追踪采用不同方法生长的样品中残余应力的变化。最终,在GaAs低温成核层生长时间62 min(生长厚度约25 nm)时,采用三步生长、循环热退火等结合的方式获得GaAs(004)XRD摇摆曲线峰值半高宽(FWHM)为401″、缺陷密度为6.8×10^(7) cm^(-2)、5μm×5μm区域表面粗糙度为6.71 nm的GaAs外延材料,在材料中表现出张应力。

Three-step Epitaxial Growth of GaAs on Si by MOCVD Technology

Epitaxial growth of high-quality gallium arsenide(GaAs)films on silicon(Si)is the key factor to realize the monolithic integration of silicon-based light sources.However,the large lattice mismatch and thermal mismatch between Si and GaAs have a serious impact on the quality of GaAs films obtained by epitaxial growth.The growth of GaAs on Si was studied by metal-organic chemical vapor deposition(MOCVD).In this paper,the three-step growth method was used to further reduce the surface roughness and threading dislocation density of GaAs on Si by combining low temperature GaAs nucleation layer,high temperature GaAs layer and thermal cycle annealing.And the changes of residual stress in samples grown by different methods were tracked by X-ray diffraction(XRD)ω-2θscan.Finally,when the growth time of GaAs low-temperature nucleation layer was 62 min(the growth thickness was about 25 nm),the full width at half maximum(FWHM)of GaAs epitaxial material exhibiting tensile stress with GaAs(004)rocking curve measured by XRD was 401″,threading dislocation density was 6.8×10⁷ cm^-2 and surface roughness over 5μm×5μm scan areas of 6.71 nm was obtained by means of three-step growth and cyclic annealing.