Anomalous current transport in Au/low-doped n-GaAs Schottky barrier diodes at low temperatures

Abstract

The current-voltage characteristics of Au=low doped n-GaAs Schottky diodes were determined at various temperatures in the range of 77-300 K. The estimated zero-bias barrier height and the ideality factor assuming thermionic emission (TE) show a temperature dependence of these parameters. While the ideality factor was found to show the T₀ effect, the zero-bias barrier height was found to exhibit two different trends in the temperature ranges of 77-160 K and 160-300 K. The variation in the flat-band barrier height with temperature was found to be -(4.7±0.2)× 10⁴ eVK^-1, approximately equal to that of the energy band gap. The value of the Richardson constant, A^∗∗, was found to be 0.27 Acm^-2K^-2 after considering the temperature dependence of the barrier height. The estimated value of this constant suggested the possibility of an interfacial oxide between the metal and the semiconductor. Investigations suggested the possibility of a thermionic field-emission-dominated current transport with a higher characteristic energy than that predicted by the theory. The observed variation in the zero-bias barrier height and the ideality factor could be explained in terms of barrier height inhomogenities in the Schottky diode.