STATE-SPECIFIC STUDY OF HYDROGEN DESORPTION FROM SI(100)-(2X1) - COMPARISON OF DISILANE AND HYDROGEN ADSORPTION

The desorption of hydrogen from the monohydride species on Si(100) has been studied state specifically using (2 + 1) resonance-enhanced multiphoton ionization. The monohydride phase was prepared by dosing the surface with either disilane (Si2H6) or atomic hydrogen. Adsorption of disilane with subsequent desorption of H-2 leads to the growth of an epitaxial silicon film, based on evidence obtained with scanning electron microscopy and low energy electron diffraction. We report that the rovibrational-state distribution for hydrogen desorbed from Si(100) is the same after both disilane and atomic-H adsorption. Hydrogen desorbs with low average rotational energy but with a population in the nu = 1 state enhanced by roughly 20 times over a thermal distribution at the temperature of the surface. The agreement between internal-state distributions for both adsorption schemes indicates that the desorption of hydrogen during epitaxial growth of Si after Si2H6 adsorption proceeds in the same manner as that for a hydrogen-prepared Si(100)-(2 X 1):H surface.