Si dangling bonds on Si(100) surface during gas-source molecular beam epitaxy with Si 2H 6

Abstract

During Si gas-source molecular beam epitaxy on Si(100) with Si 2H 6, dangling bonds responsible for Si 2H 6 dissociative adsorption on the surface were observed in situ at pressures up to 1×10 −5 Torr by ultraviolet photoelectron spectroscopy. The Arrhenius plot of the amount of dangling bonds was found to show two temperature regions in the surface-reaction rate-limited region, indicating a change in Si 2H 6 adsorption and H 2 desorption kinetics with lowering temperature. We suggested that Si 2H 6 dissociative adsorption becomes incomplete with lowering temperature, resulting in the appearance of higher-order hydrides in addition to monohydride, and such higher-order hydrides prevent isolated monohydrides from migrating and forming a paired monohydride on a dimer, from which H 2 desorbs easily. Furthermore, the amount of dangling bonds was observed to be a logarithmic function of Si 2H 6 pressure over a wide hydrogen coverage.