As-rich reconstruction stability observed by high temperature scanning tunnelling microscopy

Atomic resolution scanning tunnelling microscopy (STM) has been used to study in-situ the As-terminated reconstructions formed on GaAs(0 0 1) surfaces in the presence of an As4 flux. The reconstructions c(4×4), (2×4) and (3×1) are long established for GaAs(0 0 1) between 400 and 600 °C for varying Ga and As flux, however the stoichiometry of incommensurate transient reconstructions is still uncertain. By performing high temperature STM on an initial (2×4) surface between 250 and 450 °C in the absence of an As flux, small domains with varying reconstruction are observed in a similar manner to the InAs/GaAs(0 0 1) wetting layer. The local storage of excess Ga in Ga-rich domains could provide insight into sub ML homo- and hetero-epitaxial growth.