Vacancy migration, adatom motion, and atomic bistability on the GaAs(110) surface studied by scanning tunneling microscopy

Abstract

[[abstract]]In this article scanning tunneling microscopy studies of atomic motion of defects on the GaAs (110) surface at room temperature are reported. The slow dynamic behavior of vacancies and As adatoms can be resolved within a time scale of about one minute. The vacancies and As adatoms are observed to move preferably along the [110BAR] direction, corresponding to a large anisotropy in the two-dimensional diffusion coefficients. We attribute such a large anisotropy to the energetics of atom migration in the presence of the GaAs(110) surface zigzag chain structure. Observations of As adatoms also indicate that they form linear chains along the zigzag chain. Finally, the fast dynamic behavior of atomic flip-flop action at a dual divacancy is discussed. The characteristic flip-flop time is estimated from the scanning speed and sampling frequency to be on the order of milliseconds.[[fileno]]2010109010004[[department]]物理