Surface reaction mechanisms on Si(111)-(7 × 7) during silane UHV-CVD

Abstract We report an STM study of the Si(111)-(7 × 7) surface after silane adsorption in the temperature range 700–800 K. At these temperatures, we show that the decomposition of the adsorbed species and their subsequent diffusion lead to the etching of Si adatoms from the dimer adatom structure (DAS) and to the formation of hydrogenated silicon-atom clusters on the faulted part of the unit cell. We have also studied the steady state of the surface under static silane pressure. We conclude that hydrogen desorption occurs from these clusters, leading to a first-order desorption process.