Photoluminescence spectroscopy of growth-interrupted GaAs/AlAs single quantum wells subjected to hydrogenation

Abstract

Photoluminescence excitation and emission spectroscopy (PLE and PL) have been used to investigate growth interrupted GaAs/AlAs single quantum wells (SQW). Evidence that growth interruption leads to smooth interfaces which vary in height by integer monolayer steps is provided by changes in the PLE and PL spectra from a broad single band for noninterrupted SQW to narrow multiple peak features for growth interrupted samples. However, growth interruption results in a dramatic reduction in the intensity of the photoluminescence signal above 30 K. Hydrogenation treatment has been found to recover the photoluminescence intensity in the growth-interrupted samples which we attribute to passivation of nonradiative centers incorporated during the growth interruption process. Similar, though less dramatic, effects have been observed for noninterrupted samples. Time-resolved photoluminescence spectroscopy and decay time measurements show that hydrogen passivates carbon acceptors also incorporated during interruption, and in addition, demonstrate the migration process of excitons from the narrower to the wider well widths in these SQW. This latter exciton kinetic information fully supports the view that growth interruption results in large lateral islands with monolayer fluctuations in well width.