ADSORPTION AND DECOMPOSITION OF DIETHYLSILANE AND DIETHYLDICHLOROSILANE BY SI(100)(2X1) AND SI(111)(1X1)

Electron energy loss spectroscopy (EELS) has been used to study the ad sorption and decomposition of diethylsilane (C2H5)(2)SiH2 (DES) and di ethyldichlorosilane (C2H5)(2)SiCl2 (DECS) on Si(100)(2 X 1) and Si(111 )(1 X 1). At 40 K DES and DECS adsorb molecularly. DES decomposes into ethyl groups and SiH after room temperature adsorption. At 600 K the ethyl groups undergo P-hydride elimination producing adsorbed ethylene and adsorbed hydrogen. Upon further heating the ethylene decomposes i nto surface CH-groups. Finally, at 800 K the CH-groups are dehydrogena ted, H desorbs and Si-C surface species are formed. The Si-C surface s pecies are stable up to 900 K, at which point they convert into a prel iminary stage of silicon carbide. Similar surface reactions are found after room temperature DECS adsorption on Si(100). In contrast to the results for Si(100) annealing the DECS exposed Si(111) surface leads t o a clean surface free from any contaminations.