STUDIES OF MG OVERLAYER ON GAAS(100) SURFACE-TREATED BY CH3CSNH2

A new sulfur passivation method for GaAs, CH3CSNH2 treatment, has been developed. By Synchrotron Radiation Photoemission Spectroscopy (SRPES ), the chemical states and electronic aspects of the passivated surfac es are investigated. It is found that the oxide layer of the GaAs is e ffectively removed, and Sulfur atoms bond both to Ga and As atom at ro om temperature. In addition, the behavior of Mg deposited on the passi vated surfaces with and without annealing has been investigated. It is found that Ga atoms can be exchanged from Ga-S bond, and diffuse into Mg overlayer, but the sulfur atoms remain at the interfaces. At highe r Mg coverage, a MgGa alloy may be formed due to excess Mg atoms react ing with Ga atoms at the overlayer.