Reduction of spontaneous surface segregation in (InP)(2)/(GaP)(2) quantum wells grown on tilted substrates

Abstract

We have studied the growth mechanism of (InP)(2)/(GaP)(2) short-period superlattices (SPS) and In(0.5)Gao(0.5)P quantum wells grown on tilted substrates using solid-source molecular beam epitaxy (SSMBE). Both the (InP)(2)/(GaP)(2) SPS and In0.5Ga0.5P quantum wells show blue shifts of photoluminescence (PL) wavelengths when the substrate's tilting angle is increased. The blue shift is more prominent in the SPS structure than in the In0.5Ga0.5P quantum wells. By comparing FL, polarized PL spectra and transmission electron micrographs, we confirm that the ordering effect exists in both the (InP)(2)/(GaP)(2) SPS and In0.5Ga0.5P quantum wells when the substrate tilt angle is small, and can be greatly reduced when the substrate lilt angle is increased. We believed that the height and density of steps on substrates with larger tilt angles repress the segregation of group III adatoms.