Electronic structure of Sb overlayers on GaAs(110).

Abstract

Sb overlayers deposited at 300 K on GaAs(110) surfaces cleaved in ultrahigh vacuum have been investigated by ultraviolet and x-ray photoemission and ellipsometric spectroscopies. For the strongly chemisorbed, well-ordered first monolayer of Sb (1\ifmmode\times\else\texttimes\fi{}1 as determined by low-energy electron diffraction) information about electronic interface states and optical transitions between them is obtained. On top of this first Sb layer a semiconducting Sb species is deposited. The metallic character of the film, revealed by a sharp Fermi edge in the ultraviolet photoemission spectra, occurs not before evaporation of about 20 monolayers of Sb. Simultaneous measurement of the work function gives further information about electronic states in the Sb overlayer. The results can also be explained consistently with respect to the recently measured Schottky barriers on GaAs(110)-Sb.