ALLOY BROADENING IN PHOTOLUMINESCENCE SPECTRA OF GAXIN1-XASYP1-Y LATTICE-MATCHED TO INP

Low temperature photoluminescence measurements of GaxIn1-xAsyP1-y alloys nearly lattice matched to InP to study the line broadening of the observed band to band and near band gap transitions in these materials were performed. We find that the dominant broadening mechanism is alloy broadening that originates from the spatial fluctuations of the band gap energy due to random anion and cation distribution. A model that assumes that occupation of the group-III sites by Ga and In atoms and of the group-V sites by As and P atoms occurs randomly, is fitted to the photoluminescence spectra of our samples. This provides an excellent description of the experimental results.