The influence of In composition on properties of In_xGa_(1-x)As/ GaAs structures grown by MOVPE and in situ monitored by spectral reflectance

摘要

Series of In_xGa_(1_x)As/GaAs structures with indium vapor composition ranging from 13 to 100%, denoted samples A, B, C and D, were grown by metalorganic vapor phase epitaxy (MOVPE) at 450 ℃ and in situ monitored by spectral reflectance (SR). In order to contribute to the enhancement of crystal quality and to understand growth kinetic of In_xGa_(1_x)As/GaAs structures, the dependence of structural and morphological properties on indium composition x was studied. Basing on high resolution x-ray diffraction (HRXRD) measurements, solid indium compositions x of samples A, B, C and D were determined. Also, the evolution of structural quality (dislocations density, grain size, etc.) as a function of indium composition x was quantified. Besides, morphological properties (hatching and islands formations, densities, sizes and uniformities, RMS surface roughness, etc.) and growth process (growth anisotropy, etc.) versus indium composition x were examined using atomic force microscopy (AFM) analysis. Also, reflectance three-dimensional plot as function of time and wavelength was recorded to quantify the evolution of reflectivity in the wavelength range from 400 to 1000 nm and to determine some growth parameters such as growth rates and thicknesses of In_xGa(1-x)As samples. A good correlation between experimental results issued from different characterizations tools was obtained.