The effect of lattice mismatch on the dynamical microstructure of III–V compound surfaces

The growth by molecular‐beam epitaxy on GaAs of InxGa1−xAs, x≤0.1, has been studied using reflection electron diffraction, Auger sputter profiling, and photoluminescence. Surface segregation of the In as a function of substrate temperature during growth has been observed. The effect of this segregation on optical properties was investigated by growing single quantum well structures and measuring the photoluminescence spectra. It was found that In segregation did not adversely affect the exciton recombination linewidth for most of the substrate temperatures examined; in fact anomalously high photoluminescence intensities were observed. This high luminescent efficiency is due to the formation of a long region of graded composition in the capping GaAs layer produced by the outdiffusion of In from the quantum well. The graded region increases the collection efficiency of the well by accelerating photogenerated electrons and holes into the well.