GaAs on Si(111) with a layered structure GaSe buffer layer

Abstract

In this paper, we report the growth and characterization of 1 μm thick GaAs(111) films on GaSe(0001) films grown on As:Si(111) (As-passivated Si(111)) substrates, and compare these films to 1 μm thick GaAs(111) films grown directly on As:Si(111) using the same GaAs growth conditions. We used secondary electron microscopy (SEM) to look at the surface morphology, and we used reflection high-energy electron diffraction (RHEED), transmission electron microscopy (TEM) and X-ray diffraction to characterize the crystal quality and determine the nature of the crystalline defects in the films. In general, we find that the use of a GaSe(0001) buffer layer causes only a modest decrease in the overall crystalline quality. However, using the GaSe buffer layer reduced the effectiveness of thermal annealing as a means of reducing the defect density. We suggest that due to its layered structure, the GaSe effectively absorbs the thermal expansion mismatch strain during annealing, which reduces the driving force for defect motion during thermal annealing.