Growth-mode-induced surface morphology and its relation to optical properties of GaAs single quantum wells

Abstract

Quantum wells with short period superlattice barriers are grown by molecular beam epitaxy in growth modes which range from two-dimensional island nucleation to step flow. These different growth modes result in different surface morphologies as imaged by atomic force microscopy. Micro-photoluminescence of the quantum wells and of their barriers reveal spectra with a rich fine structure. These narrow lines in the micro-photoluminescence spectra are attributed to exciton localization by potential fluctuations at the interface. The formation of a pronounced roughening of step edges for samples grown either at high As 4 -partial pressure or on misoriented substrates with As-terminated steps is observed, which is accompanied by the appearance of a pronounced fine structure in photoluminescence and a broadening of its distribution.