APPLICATION OF PULSED-LASER DEPOSITION TECHNIQUE FOR CLEANING A GAAS SURFACE AND FOR EPITAXIAL ZNSE FILM GROWTH

A new method is described whereby a pulsed ArF excimer laser can be us ed to clean GaAs substrates prior to thin film deposition by pulsed-la ser deposition (PLD). The laser is used to create excited hydrogen, wh ich effectively removes contaminants from the GaAs surface. The cleani ng process involves hydrogen, photoelectrons, and photons, and is term ed HEP to reflect the involvement of these three types of particles. Z nSe films have been epitaxically deposited by PLD on GaAs substrates c leaned by the HEP process. X-ray diffraction data show that GaAs subst rates treated by excited hydrogen are very good for epitaxial growth o f ZnSe. ZnSe films were synthesized at 320 degrees C under different A r pressures to understand the effects of ambient gas pressure on film quality and morphology. Introduction of an ambient gas (Ar) improved f ilm duality and morphology. The full width at half maximum of the x-ra y theta rocking for the (004)-ZnSe peak for the best film grown, at 20 mTorr and 320 degrees C, was 0.04 degrees. X-ray and atomic force mic roscopy results are reported for several ZnSe films deposited on GaAs substrates cleaned by the HEP process. The results are compared with t hose of ZnSe films synthesized on GaAs substrates that were thermally treated, but were not treated by the HEP process. (C) 1998 American Va cuum Society. [S0734-2101 (98)03805-6].