利用反射各向异性谱(RAS)和反射谱在线监测了AlxGa1-xAs样品的金属有机化合物汽相淀积(MOCVD)外延生长过程。通过在线监测得到的RAS和反射谱可以敏感地反映出AlxGa1-xAs外延层组份发生的变化,从而优化外延生长工艺。实验表明,反射谱中的振荡周期可以在线计算组份和生长速率,利用反射谱中的振荡的第一个最小值与Al组份的线性关系,可以确定渐变组份初始值。通过在线计算得到的生长速率和组份与扫描电镜(SEM)和高分辨X射线衍射(HRXRD)测试得到的结果基本吻合。
AlxGa1-xAs sample were grown by metal-organic chemical vapor deposition(MOCVD) under the monitor of time resolved reflectance anisotropy spectroscopy(RAS) and normalized reflectance.During the growth,a significant dependence of the RAS and normalized reflectance signals on the aluminium composition has been found,which can be used to optimize the growth processes.The experimental results indicate that the period of normalized reflectance oscillation was directly related to the composition and growth rate.The first minimum of the normalized reflectance oscillation of AlxGa1-xAs almost linearly with aluminium composition and could be used to determine the starting value of graded aluminium composition.The compositions and growth rate of AlxGa1-xAs are calculated by normalized reflectance transient spectra,the value is in excellent agreement with the experimental data obtained by ex-situ scanning electron microscope(SEM) and high resolution X-ray diffraction(HRXRD).