ADSORPTION AND DECOMPOSITION OF DIETHYLGERMANE ON SI(111) 7X7

Germanium was deposited on Si(111) 7 x 7 by the adsorption and thermal decomposition of diethylgermane [(CH3CH2)2GeH2] (DEG). The DEG reaction products were CH2 = CH2 and H-2, which desorbed at 700 and 800 K, respectively, as observed by laser-induced thermal desorption and temperature programmed desorption techniques. The desorption of atomic Ge was also monitored at approximately 1200 K. The production of ethylene was consistent with a beta-hydride elimination mechanism for the surface ethyl groups, i.e., Ge-CH2CH3 --> GeH + CH2 = CH2. The initial sticking coefficient of DEG decreased with increasing surface temperature and a saturation coverage was obtained after exposures of E > 700 L at 200 K. This saturation behavior indicates that DEG may be useful for the controlled growth of Ge atomic layers on silicon surfaces.