Structure and electronic states ofInAs(001)−(2×4)surfaces

Abstract

We have performed a detailed study of the atomic and electronic structure of the $\mathrm{InAs}(001)\ensuremath{-}(2\ifmmode\times\else\texttimes\fi{}4)$ surfaces using ab inito pseudopotential calculations. Our results indicate that the surface atomic geometry of the $\mathrm{InAs}(001)\ensuremath{-}\ensuremath{\beta}2(2\ifmmode\times\else\texttimes\fi{}4)$ and $\mathrm{GaAs}(001)\ensuremath{-}\ensuremath{\beta}2(2\ifmmode\times\else\texttimes\fi{}4)$ surfaces are very similar, and our calculated geometrical results for $\mathrm{InAs}(001)\ensuremath{-}\ensuremath{\beta}2(2\ifmmode\times\else\texttimes\fi{}4)$ agree well with recent x-ray diffraction measurements. The equilibrium geometries of the equivalent surface atoms on the $\ensuremath{\alpha}(2\ifmmode\times\else\texttimes\fi{}4),$ $\ensuremath{\alpha}2(2\ifmmode\times\else\texttimes\fi{}4),$ and $\ensuremath{\beta}2(2\ifmmode\times\else\texttimes\fi{}4)$ reconstructions of the InAs(001) are very similar. Simulation of the desorption of an As dimer from the $\ensuremath{\beta}2(2\ifmmode\times\else\texttimes\fi{}4)$ reconstruction indicates that the $\ensuremath{\alpha}2(2\ifmmode\times\else\texttimes\fi{}4)$ reconstruction can easily take place for the InAs(001) surface, but not for the GaAs(001) surface, supporting earlier experimental observations. Our calculations further suggest that in the temperature range $600 \mathrm{K}--800 \mathrm{K}$ the desorption rate of the As dimer from the $\mathrm{InAs}(001)\ensuremath{-}\ensuremath{\beta}2(2\ifmmode\times\else\texttimes\fi{}4)$ is approximately 10 times that from the $\mathrm{GaAs}(001)\ensuremath{-}\ensuremath{\beta}2(2\ifmmode\times\else\texttimes\fi{}4)$ surface. For both $\ensuremath{\beta}2(2\ifmmode\times\else\texttimes\fi{}4)$ and $\ensuremath{\alpha}2(2\ifmmode\times\else\texttimes\fi{}4)$ reconstructions on GaAs(001) as well as on InAs(001) we observe four occupied surface states above the bulk continuum at the $\mathbf{K}$ point on the surface Brillouin zone.