Kinetic roughening during rare-gas homoepitaxy

Using an optical-reflectivity-difference technique, we monitored the growth of multilayer Xe films on a commensurate monolayer of Xe on Ni(111) from 3 5 to 60 K. A transition occurs near 40 K from rough growth at low temperatu re to quasi-layer-by-layer growth characterized by persistent oscillations in the reflectivity difference. We discuss this transition in terms of chan ges in the island formation process and the onset of second-layer nucleatio n. The Xe sticking coefficient at 40 K is obtained from the period of the o scillations in the reflectivity difference. We find that the sticking coeff icient decreases with increasing film thickness at fixed Xe pressure.