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

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 estim ated zero-bias barrier height and the ideality factor assuming thermionic e mission (TE) show a temperature dependence of these parameters. While the i deality factor was found to show the To effect, the zero-bias barrier heigh t was found to exhibit two different trends in the temperature ranges of 77 -160 K and 160-300 K, The variation in the Bat-band barrier height with tem perature was found to be -(4.7 +/- 0.2) x 10(4) eVK(-1), approximately equa l to that of the energy band gap, The value of the Richardson constant, A** , was found to be 0.27 A cm(-2) K-2 after considering the temperature depen dence of the barrier height. The estimated value of this constant suggested the possibility of an interfacial oxide between the metal and the semicond uctor. Investigations suggested the possibility of a thermionic field-emiss ion-dominated current transport with a higher characteristic energy than th at predicted by the theory, The observed variation in the zero-bias barrier height and the ideality factor could be explained in terms of barrier heig ht inhomogenities in the Schottky diode.