Epitaxial growth of Bi thin films on Ge(111)

We investigated Bi thin film growth on Ge(1 1 1) by using low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM). In the submonolayer regime, adsorbed Bi atoms form patches of the ( 2 × 1 ) structure. However, the structure does not grow to a long-range order. Following the formation of a ( 1 × 1 ) monolayer (ML) film, two-dimensional (1 1 0)-orientated Bi islands grow. The film orientation changes from (1 1 0) to (1 1 1) at 6–10 ML. The (1 1 0)-oriented Bi film shows a six-domain LEED pattern with missing spots, associated with a glide-line symmetry. The hexagonal (1 1 1) film at 14 ML has a lattice constant 2% smaller than bulk Bi(1 1 1).