ADSORPTION AND DECOMPOSITION OF DIETHYLSILANE AND DIETHYLGERMANE ON SI(100) - SURFACE-REACTIONS FOR AN ATOMIC LAYER EPITAXIAL APPROACH TO COLUMN-IV EPITAXY

The room-temperature adsorption and desorption kinetics of diethylsila ne (DES) and diethylgermane (DEG) on the Si(100)-(2X1) surface were in vestigated under ultrahigh vacuum using temperature programmed desorpt ion, high resolution electron energy loss spectroscopy, and Auger elec tron spectroscopy. DES and DEG adsorb at room temperature in a self-li miting fashion, reaching saturation (0.4 and 0.3 monolayers, respectiv ely), at exposures above 30 and 350 L, respectively. Temperature progr ammed desorption of the DES-saturated and DEG-saturated surfaces revea led only two species, hydrogen and ethylene, desorbing from either sur face. In both systems, the hydrogen atoms desorbed primarily through t he recombinative desorption of monohydride species, while the ethyl gr oups decomposed via P-hydride elimination and subsequently desorbed as ethylene. The hydrogen desorption peak temperature was 794 K for the DES-saturated surface and 788 K for the DEG-saturated surface. The des orption peak temperature for ethylene was significantly lower in the D EG/Si(100) system (700 K) than in the DES/Si(100) system (730 K) becau se of a lower activation energy and higher pre-exponential factor for P-hydride elimination from DEG-dosed Si(100). High resolution electron energy loss spectra of the DEG-saturated surface support an adsorptio n mechanism in which the ethyl groups remain bonded to the incoming ge rmanium atom throughout the adsorption process. (C) 1995 American Vacu um Society.