HYDROGEN ADSORPTION AND DESORPTION PROCESSES ON SI(100)

The hydrogen adsorption and desorption processes on the Si(100)(2 x 1) surface were investigated using in-situ infrared absorption spectrosc opy in the multiple internal reflection geometry. It is demonstrated t hat the distribution of hydride species (SiH, SiH2, and SiH3) signific antly changes during adsorption of atomic hydrogen and desorption of m olecular hydrogen. At the initial stages of hydrogen adsorption, the m onohydride Si (Si-H) and dihydride Si (Si-H-2) are populated, with Si- H being dominant. For higher hydrogen exposures the dihydride and trih ydride Si are formed. Thermal annealing causes hydrogen to desorb from the hydride species. For annealing temperature up to approximately 40 0 degrees C, the trihydride Si is etched away, producing a H-terminate d surface which consists of monohydride (SiH) and dihydride (SiH2) spe cies. We demonstrate that the conversion from the monohydride to the d ihydride phase occurs during thermal annealing. (C) 1998 Elsevier Scie nce B.V. All rights reserved.