Abstract
In this paper we present a study of metal interfaces to vacuum and air cleaved (110) GaSb surfaces, formed at room temperature. Estimates of effective Schottky barrier heights of these diodes have been obtained using the current–voltage (I–V) measuring technique and the interfacial interactions were investigated using synchrotron radiation excited soft x-ray photoemission spectroscopy. For all the metals studied (Au, Ag, Al, Cr, Ni, Ga, Sb) nonideal diode characteristics were observed, with ideality factors close to 2 for both the clean and oxidized GaSb surfaces. These ideality factors suggest a large generation-recombination current. The effective barrier heights have been evaluated, using a curve fitting procedure. As previously found for n-type GaAs and InP gallium contacts yield the largest barrier height on GaSb, for the metals studied. In contrast the lowest barrier height observed was obtained for silver. In order to investigate reasons for the nonideal diode behavior the microscopic nature of the interfaces were studied and the results for Ag are described in detail. In contrast to its behavior on GaAs and InP, silver is found to chemically react with both types of GaSb surface, resulting in the selective removal of Sb from the interface. The thermodynamic aspects of these reactions are considered.
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