One Atomic Layer Heterointerface Fluctuations in GaAs-AlAs Quantum Well Structures and Their Suppression by Insertion of Smoothing Period in Molecular Beam Epitaxy

Photoluminescence spectra of GaAs-AlAs quantum wells are studied to evaluate the flatness of heterointerfaces prepared by molecular beam epitaxy. We examine the correlation of the interface roughness with the measured intensity oscillations of reflective high energy electron diffraction (RHEED) during the growth. The crystal surface is found to roughen after the growth of 10 or more atomic layers. The growth interruption of 10–100 seconds prior to the interface formation is effective in achieving an atomically flat interface, leading to sharp photoluminescence with the linewidth <30 Å at 77 K even when the quantum well width is reduced to 40 Å.