Selenium- and tellurium-terminated GaAs(100) surfaces observed by scanning tunneling microscopy.

Abstract

GaAs(100) surfaces with adsorbed Se or Te have been studied using scanning tunneling microscopy (STM), x-ray-photoemission spectroscopy (XPS), and electron diffraction. STM reveals uniform dimerization which is consistent with the 2\ifmmode\times\else\texttimes\fi{}1 symmetry of the electron diffraction. XPS shows an initial single-monolayer coverage of Se followed by a slow Se uptake which predominantly replaces As. Narrow single- and double-bilayer high islands, which are long in the [011] direction of dimer rows, are generally observed as well as terrace edges which show related kink anisotropy. Possible surface structures are discussed.