Anomalous downward band bending induced by selenium passivation of MBE-grown InAs(OO1) surfaces

In-situ synchrotron radiation photoelectron spectroscopy is used to study the surface chemical bonding structures on InAs(001) with and without Se passivation and to determine changes in the surface Fermi level (E,) position as a result of Se treatment. Analysis of the As 3d and In 4d core-levels for the epitaxially grown InAs and reflection high-energy electron diffraction pattern observations are found to be almost the same as those for GaAs(OOl)-(2 X 41, showing that a well-ordered InAs(OOl)-(2 X 4) surface is achieved. The results of As 3d and In 4d spectra for the Se-passivated InAs show that a Se-terminated surface is formed where the topmost Se atoms bond to In. Anomalous downward band bending, where the E, position is located at about 0.5 eV above the conduction band minimum, is observed for the first time at the Se-passivated InAs(OOl)-(2 X I), in contrast to the well-known results for Se-passivated GaAs.