Surface structure transitions on InAs and GaAs (001) surfaces.

Abstract

Surface structure transitions on InAs and GaAs (001) surfaces are studied by using reflection high-energy electron diffraction (RHEED), scanning tunneling microscopy (STM), scanning electron microscopy (SEM), and Monte Carlo simulations. The RHEED study shows that the change in surface structure between As-stabilized (2\ifmmode\times\else\texttimes\fi{}4) and In-stabilized (4\ifmmode\times\else\texttimes\fi{}2) structures on InAs (001) is a discontinuous first-order phase transition with hysteresis, and that the discontinuous transition is not observed on GaAs surfaces. This phenomenon can be explained by a two-dimensional lattice gas model assuming lateral interaction between surface species, and it is suggested that the lateral interaction is stronger with InAs than GaAs. STM observation indicates that this strong lateral interaction between surface species causes a thermally stable dimer vacancy row structure on the InAs (2\ifmmode\times\else\texttimes\fi{}4) surface. RHEED, STM, and SEM observation for misoriented InAs surfaces clarify the role of steps on the phase transition. The metastability of the InAs surface is shown to be reduced by monomolecular steps due to the finite size effects on the phase transition.