The chemistry, structure and stability of CH3CSNH2 passivated GaAs(100) surfaces

An organic sulfide, CH3CSNH2 treated sulfur-passivated GaAs(100), has been studied using synchrotron radiation photo-emission spectroscopy (SRPES), Au ger electron spectroscopy (AES) and low energy electron diffraction (LEED). The SRPES and AES measurements show that the treatment removes the GaAs su rface oxide layer and forms sulfides of Ga and As on the surface. The therm al stability and surface structure of the passivated samples at different t emperatures have also been studied. We found that the surface sulfides are also gradually removed and a clean, ordered and thus Fermi level unpinning surface can finally be achieved. Surface restructuring can be observed from the GaAs(100)-S (2x1) pattern between 260 and 450 degrees C to the (4x1) p attern without S between 460 and 550 degrees C. (C) 1999 Elsevier Science B .V. All rights reserved.