Investigation of interface states in MIS-type Al-, Au- and Sn-GaAs Schottky barriers with a thin interfacial oxide layer

Abstract

Interface states in Al-, Au- and Sn-GaAs Schottky barriers were investigated by means of impedance measurements. From the deviation of the Mott-Schottky behaviour under forward bias, an interface-states parallel capacitance Cp' could be derived. For the dependence of Cp' versus forward voltage and Cp' versus frequency, simple laws were found. From Cp' the interface state density multiplied by the capture cross-section could be calculated. Large values were found for the reactive metals Al and Au and lower values for the rather inert metal Sn. In all GaAs Schottky barriers studied, only a thin ( approximately=2 nm) interfacial oxide layer was present, and the interface states were identified as metal-induced states.