The geometric and electronic structure of metal adsorbates on cleaved GaAs(110) surfaces is studied with the scanning tunneling microscope. For the metals Sb and Bi, an ordered monolayer is formed, although in the case of Bi a series of misfit dislocations appear in the overlayer. In the case of Au, individual atoms are observed on the surface, forming clusters at higher metal coverage. Spectroscopic measurements reveal the presence of a state within the GaAs band gap. This state is observed near individual metal adsorbates (for Au and Sb), and near the edge of metal terraces (for Sb and Bi). The observed state is responsible for determining the position of the Fermi-level at the surface.
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Feenstra, R.M., Mårtensson, P. & Ludeke, R. Spectroscopy of Metal Adsorbates on the GaAs(110) Surface Studied with the Scanning Tunneling Microscope. MRS Online Proceedings Library 139, 15–24 (1988). https://doi.org/10.1557/PROC-139-15