An investigation was made of the effect of (001)GaAs substrate preparation upon the first stages of ZnSe hetero-epitaxial growth via molecular beam epitaxy. It was shown that 3 different GaAs reconstructions occurred, depending upon the substrate preparation, the Se residual pressure in the growth chamber and the temperature. After deoxidation, an epi-ready substrate led to a (2 x 1) reconstructed surface at about 600C. This turned into a non-reconstructed surface during cooling to the growth temperature of 280C. Etched substrates instead exhibited a (2 x 3) or (4 x 3) reconstruction; depending upon the temperature that was attained during deoxidation. Both reconstructions were stable during cooling to the growth temperature. The direct nucleation of ZnSe on such deoxidized substrates led to 3-dimensional, quasi 2-dimensional and purely 2-dimensional growth modes on the non-reconstructed (2 x 3) and (4 x 3) reconstructed surfaces, respectively. Marked oscillations of the reflection high-energy electron diffraction intensity were observed during nucleation on the (4 x 3) surface. Excellent agreement was found, between simulated and experimentally observed X-ray rocking curves, for pseudomorphic layers that were grown on a (4 x 3) starting surface. In addition, their low-temperature photoluminescence spectra were dominated by free exciton recombination, with no defect-related line. Overall, the results indicated a substantial improvement in ZnSe hetero-epitaxy on bare GaAs substrates.

V.Bousquet, C.Ongaretto, M.Laügt, M.Behringer, E.Tournié, J.P.Faurie: Journal of Applied Physics, 1997, 81[10], 7012-7