Electron accumulation layer on clean In-terminated InAs(0 0 1)(4×2)-c(8×2) surface

We have investigated clean In-terminated InAs(0 0 1)(4×2)-c(8×2) surface by LEED, STM and high-resolution core-level and valence band (VB) spectroscopies. The In4d and As3d core levels showed the presence of chemically shifted components. The decomposition of In4d core level exhibited a new surface component located close to that of free indium metal. This indicates that the origin of the electron emission at the Fermi level measured in the VB spectra is probably due to the free In charge. STM measurements showed a uniform distribution of charge on the In-rows, which are highly ordered over large areas of the surface.