Electrical characterization of ZnO and ZnO Schottky barrier diodes

Abstract

The electrical properties of ZnO and Schottky contacts to ZnO have been investigated using different techniques. Good rectifying Schottky contact has been fabricated on ZnO, after treating the samples with boiling hydrogen peroxide. Electrical properties of these Schottky contacts have been investigated using current-voltage (IV) and capacitance-voltage (CV) measurements in the temperature range (20-350 K). Schottky barrier heights (SBHs) determined using temperature-dependent IV measurements have been observed to increase with temperature and this has been explained as an effect of the barrier inhomogeities. The Schottky contacts have indicated the dominance of predominantly thermionic emission at room temperature and the existence of other current transport mechanisms at lower temperatures. Palladium Schottky barrier diodes on melt grown n-ZnO were irradiated with alpha-particles from a Van de Graaff accelerator. To determine the effect of these changes on the electrical characteristics of Schottky contacts several techniques were used. The CV measurements showed a decrease in the free carrier concentration with increase in fluence. Deep level transient spectroscopy (DLTS) was used to determine the concentrations, capture cross-sections, introduction rate and energy level in the bandgap of deep level defects introduced during the alpha-particles irradiation.