OBSERVATION OF STRESS EFFECTS ON GAAS AT THE INTERFACE OF MOLECULAR-BEAM EPITAXY-GROWN ZNSE GAAS(100) HETEROSTRUCTURES/

We report the observation of stress effects on GaAs at the interface o f molecular beam epitaxy grown (MBE) ZnSe/GaAs, These effects were obs erved for samples with ZnSe epilayers thicker than their critical thic kness 0.17 mu m through the application of photoreflectance (PR) and r eflectance difference (RD) spectroscopy. Comparison between the first derivative of the RD spectra (DRD) and the PR spectra indicates that i n a sample 0.1 mu m thick, the PR is a normal bulk-like GaAs signal. T he same comparison indicates that for samples thicker than the critica l thickness, there are two components in the PR spectra: a bulk-like s ignal as for the thin sample, and a second signal coming from a strain ed region populated by dislocations. From the theory of PR spectra, we estimate that the observed strain is epsilon = 0.0010 +/- 0.0004 in t he GaAs at the heterostructure interface with a ZnSe layer 1.05 mu m i n thickness. (C) 1998 Elsevier Science B.V. All rights reserved.