Ga adatom migration over a nonplanar substrate during molecular beam epitaxial growth of GaAs/AlGaAs heterostructures

Abstract

Thickness variations in GaAs/AlGaAs quantum wells grown on patterned substrates by molecular beam epitaxy have been analyzed by spatially and spectrally resolved low-temperature cathodoluminescence. For the lower and upper (100) facets joined by an angled (311)A facet, relative increases in quantum well thicknesses up to ≅6% and 20% are observed, respectively, in the vicinity of the intersection of the facets. Following an exponential behavior, the Ga adatom migration length is found to be in the range of 1-2 μm on both the lower and upper (100) facets and is independent of quantum well thickness. This migration length is orders of magnitude greater than previously reported for Ga adatoms during molecular beam epitaxy growth.