Schottky barriers of various metals on Al0.5Ga0.5As0.05Sb0.95 and the influence of hydrogen and sulfur treatments on their properties

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Abstract
Schottky barriers of Au, Al, and Sb on n- and p-type layers of Al0.5Ga0.5As0.05Sb0.95 have been studied. The Schottky barriers are high for Au (1.3 eV) and Al (1.2 eV) deposited on n-type material and very low for these metals on p-type layers. The behavior of Sb is unique with the barrier heights being 0.6–0.7 eV for both n- and p-type AlGaAsSb. The reason for the surface Fermi-level pinning for Au and Al could be related to a predominance of Ga-antisite–type native acceptors at the surface, which is not the case for Sb. Sulfur treatment of the surface is shown to decrease the barrier height for Au and to increase greatly the photosensitivity of Au Schottky diodes. The same effect is observed after treatment in a hydrogen plasma. In the latter case, changes in the Schottky barrier height are correlated with passivation of native acceptors in the bulk of the Al0.5Ga0.5As0.05Sb0.95.