Coverage dependence of the Fe-induced Fermi-level shift and the two-dimensional electron gas on InAs(110)

The coverage dependence of the Fe-induced Fermi-level shift on p- and n-InAs(110) was investigated by angle-resolved photoelectron spectroscopy at 300 K. The Fermi-level position was found to be coverage dependent, exhibiting a maximum at 300 meV above the conduction-band minimum. The coverage dependence is explained by the surface doping model, if inhomogeneities in the Fe-adatom distribution and the resulting ionization probabilities are taken into account. The Fe-adatom distribution is determined by scanning tunneling microscopy. Photoemission spectra provided direct evidence of a two-dimensional electron gas at the Fe-covered surface.