High temperature growth of Ag phases on Ge(111)

Abstract

The growth of the (3 × 1) and (√3 × √3)R30° phases of Ag on Ge(111) on substrates at temperatures from 540 to 660 °C is characterized with low energy electron microscopy (LEEM) and low energy electron diffraction (LEED). From 540 °C to the Ag desorption temperature of 575 °C, LEEM images show that growth of the (3 × 1) phase begins at step edges. Upon completion of the (3 × 1) phase, the (√3 × √3)R30° phase is observed with a dendritic growth morphology that is not much affected by steps. For sufficiently high deposition rates, Ag accumulates on the sample above the desorption temperature. From 575 to 640 °C, the growth proceeded in a manner similar to that at lower temperatures, with growth of the (3 × 1) phase to completion, followed by growth of the (√3 × √3)R30° phase. Increasing the substrate temperature to 660 °C resulted in only (3 × 1) growth. In addition, for samples with Ag coverage less than 0.375ML, LEEM and LEED images were used to follow a reversible phase transformation near 575 °C, between a mixed high coverage phase of [(4 × 4) + (3 × 1)] and the high temperature, lower coverage (3 × 1) phase.