Photoluminescence and X-ray diffraction analysis of In 1− x− yGa xAl yAs/InP structures grown by molecular beam epitaxy

Abstract

We have investigated the effect of substrate temperature (T s varied from 410 to 560°C) on the crystalline and optical properties of In I− x− y Ga x Al y As layers grown on InP substrates by molecular beam epitaxy (MBE). The quaternary samples were analysed using double axis X-ray diffraction (XRD), :low temperature photoluminescence (PL) and energy dispersive X-ray spectroscopy (EDX). The crystalline quality and optical properties were found to be sensitive to the substrate temperature within the range investigated. The optimum substrate temperature range for the lowest XRD and PL full width at half maximum (FWHM) was found to be from 510 to 530°C. The PL FWHMs were lower than 20 meV for samples grown at 510°C, with the lowest value of 11.6 meV being recorded from the sample grown at 530°C. These values are comparable to the best values reported for this material system. From the PL spectra, the changeover from type I to type II transition was found to occur at an Al content exceeding 18%. The relationship between the normalised indium flux and lattice mismatch is presented.