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

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. The ideality factor was observed to decrease with increase in temperature, whilst the barrier height increases with increase in temperature. The observed trend has been attributed to barrier inhomogeneities, which results in a distribution of barrier heights at the interface. Using the dependence of saturation current values on temperature, we have calculated the Richardson constant (A⁎) which was investigated in the two distinct temperature regions: 140–200 K and 210–300 K and values of 3×10−12 and 3×10−9 A cm−2 K−2 were obtained, respectively. A mean barrier height of 0.97 eV was obtained in the 140–300 K temperature range. Applying the barrier height inhomogeneities correction, the value of A⁎ was obtained from the modified Richardson plots as 39.43 and 39.03 A cm−2 K−2 in the 140–200 K and 210–300 K temperature range. The modified Richardson constant (A⁎⁎) has proved to be strongly affected by barrier inhomogeneities and dependent on contact quality.