Schottky barriers on anisotropic semiconductor GaTe

Abstract

Schottky barriers were studied on p-GaTe single crystals both normal and parallel to the layer planes. From the C-V characteristics the barrier heights qφ B normal to the layer planes were found to be 0.75, 0.63 and 0.485eV for Al, Ag and Au respectively dependent on the metal work functions. From the temperature dependence of the I-V characteristics of Al Schottky barriers, the effective Richardson constants A^∗ were determined to be 120 and 56.4 A cm-2 K-2 for current flow normal and parallel respectively to the layer planes, in excellent agreement with values obtained from the anisotropic hole effective masses. The corresponding ideality factors were 1.44 and 2.5 respectively at 300 K. The carrier concentration n increased while φ _B decreased with decrease in temperature owing to increased tunnelling and recombination currents. From the variation in φ _BP with φ _M the interface index S was found to be 0.30 as predicted by Kurtin, McGill and Mead in 1971 from electronegativity considerations.