Effect of GaAs surface treatments using HCl or (NH4)2Sx solutions on the interfacial bonding states induced by deposition of Au

The chemical bonding nature of the Au/GaAs interface has been investigated using monochromatic X-ray photoelectron spectroscopy (WS), with an initially different GaAs surface obtained by HCl cleaning or S-passivation. The composition, chemical bonding state, and thickness of the interface were obviously dependent on the preparation of GaAs surface prior to Au-deposition. The interface region of Au/S-passivated GaAs was more uniform than Au/HCl-cleaned GaAs. In particular, surface bonding states such as As-O and As-S prior to Au-deposition were changed to Ga-O and Ga-S banding due to the energy released from the deposition of Au, resulting in a combination of resultant As and Au. These bonding transitions were observed to occur at As-O/GaAs and As-S/GaAs interfaces. The bonding-layer distributions of the interfaces induced from non-destructive angle-resolved XPS measurements were Au/Au,As-O/As-Au/Ga-O/Ga-As in the Au/HCl-cleaned GaAs, and Au/As-Au/As-S,Ga-S/GaAs in the Au/S-passivated GaAs. (C) 1998 Elsevier Science S.A. All rights reserved.