Optical characterization of [111]B InGaAs layers

Abstract

Strain assessment of [111]B InGaAs/GaAs layers, of several compositions and variable thicknesses, has been performed by photoluminescence and Raman spectroscopies. Both the gap energy and GaAs-like LO frequency undergo a blue shift proportional to the residual strain, which can be thus determined. The critical layer thickness for [111]B orientation is found to be three times larger than for [001] layers grown simultaneously. In addition, two kinds of inhomogeneities in the relaxation are found: strain domains, demonstrated by the spectral and spatial resolution of photoluminescence excitation, micro-photoluminescence and micro-Raman experiments; and a change in the strain release with layer depth, obtained by Raman at different excitation energies.