PHOTO-ASSISTED MBE GROWTH OF ZNSE ON GAAS SUBSTRATES

ZnSe epilayers have been grown by photo-assisted MBE on GaAs substrates at various substrate temperatures and under various molecular beam intensity ratios of group VI to group III element. A He-Cd laser with 441.6 nm wavelength was used as a light source. From the temperature dependence of the photo-desorption rate constants, the activation energies of photo-desorption of Zn and Se adatoms from the physical adsorption state (E(Zn)P, E(Ss)P) and from the chemical adsorption state (E(C)) are obtained, that is E(Zn)P = 7.8 kcal/mol, E(Se)P = 6.7 kcal/mol and E(C) = 16.1 kcal/mol. Thus, the photo-desorption observed in photo-enhanced "thermal" desorption. ZnSe epilayers have been successfully grown at a temperature as low as 150-degrees-C. A sharp and strong free-excition emission is observed in photoluminescence spectra at 11 K in the low-temperature grown samples, which shows that the crystallinity is almost comparable with that of the unirradiated epilayer grown at 340-degrees-C (the optimum growth temperature without irradiation).