Schottky barrier studies on single crystal ZnTe and determination of interface index

Abstract

Detailed studies on metal-(111) p-ZnTe Schottky barriers have been carried out using In, Ag, Al, and Cu as barrier metals. Weak dependence of barrier height on metal work function was observed. The highest and lowest barrier heights of 0.99 and 0.80 eV were found for In and Cu respectively which had lowest and highest work functions. The ideality factor n was found to vary between 1.84 for In and 2.13 for Al contacts. The Fermi level was found to be pinned effectively by interface states, the density of which was calculated to be 4.7×1013 states/cm2/eV. From the current–voltage characteristics measured between 250 and 350 K, the effective Richardson constant A** was determined to be 72±6 A/cm2/K2. This agrees very well with the theoretically calculated value of A** for a hole effective mass mh*=0.6m0. The temperature variation of barrier height was also determined from the capacitance–voltage characteristics. The interface index a parameter used to describe the pinning strength of semiconductors was found to be 0.34 for ZnTe.