Correlation of the physical properties and the interface morphology of AlGaAs/GaAs heterostructures

Abstract

We have investigated the influence of interface roughness in GaAs/AlGaAs heterostructures on both the optical and the electronic properties by systematically varying the two growth parameters substrate temperature and growth interruption. We prove that the optimization of samples for optics and transport, respectively, requires different growth parameters. Whereas the optical properties are exclusively determined by the roughness of the two quantum well interfaces, the transport properties are additionally influenced by the ionized impurity scattering. The number of impurities increases during growth interruption and, consequently, in contrast to the optical samples, an optimization of the growth parameters is not as straightforward since it depends on the background impurities originating from the ultrahigh vacuum system. A direct correlation with information obtained from atomic force microscopy images is therefore only possible for the optical properties. At growth temperatures higher than 620 °C in addition to the usual terrace structure, a mesoscopic island structure appears and dominates the exciton luminescence linewidth.