Atomic-Resolution STM Study of a Structural Phase Transition of Steps on Vicinal As/Ge(100)

Scanning tunneling microscope images of arsenic-exposed vicinal Ge(100) surfaces show that most As/Ge steps are reconstructed and that a variety of different step structures exist. The entire family of reconstructed As/Ge steps can be divided into two types, which we have chosen to call “single-row” (SR) steps and “double-row” (DR) steps. By changing the sample preparation conditions, we are able to consistently change the ratio of SR/DR steps. In other words, we have observed a structural phase transition in the reconstruction of As/Ge steps at atomic resolution.