ADSORPTION AND DISSOCIATION OF PH3 ON SiGe(100) (2 × 1) SURFACE

Abstract

The most stable structures for the adsorption and dissociation of phosphine ( PH 3) on SiGe (100) (2 × 1) surface have been investigated by relative total energy calculations based on density functional theory. According to the optimization calculations, PH 3 is adsorbed on the Si (down) and Ge (down) site of the Ge – Si and Ge – Ge dimers on SiGe surface, respectively. The PH 2 and H products have been found to be thermodynamically favored in the dissociation path of PH 3 on SiGe surface when the system is thermally activated. Although PH 3 is adsorbed on the Ge – Ge and Ge – Si dimers directly, it dissociates on the SiGe surface by passing through a transition state. The asymmetric Ge – Si and Ge – Ge dimers on SiGe surface are found to be approximately symmetric after the dissociation of PH 3 on the surface. The present work has showed that PH 2 prefers to be adsorbed on Ge site of the Ge – Si dimer. Therefore, the adsorption of PH 2 on Ge site of the Ge – Si dimer, while PH 3 being dissociated on the Si site, has indicated the migration of PH 2 on SiGe surface.