Temperature-dependent current-voltage characteristics of Pd/ZnO Schottky barrier diodes and the determination of the Richardson constant

摘要

We report on a systematic investigation of temperature dependent current-voltage (I-V)characteristics of Pd/ZnO Schottky barrier diodes in the 30-300 K temperature range. Theideality factor was observed to decrease with increase in temperature, whilst the barrierheight increases with increase in temperature. The observed trend has been attributed to barrierinhomogeneities, which results in a distribution of barrier heights at the interface. Usingthe dependence of saturation current values on temperature, we have calculated theRichardson constant (A*) which was investigated in the two distinct temperature regions:140–200 K and 210–300 K and values 3 x10-12 of and 3x10-9 A cm-2 K-2 were obtained,respectively. A mean barrier height of 0.97 eV was obtained in the 140-300 K temperaturerange. Applying the barrier height inhomogeneities correction, the value of A* was obtainedfrom the modified Richardson plots as 39.43 and 39.03 A cm-2 K-2 in the 140-200 K and210-300 K temperature range. The modified Richardson constant (A**) has proved to bestrongly affected by barrier inhomogeneities and dependent on contact quality.