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

Abstract

We report on a systematic investigation of temperature dependent current–voltage (I–V) characteristics of Pd/ZnO Schottky barrier diodes in the 30–300K 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: 140–200K and 210–300K and values of 3×10−12 and 3×10−9Acm−2K−2 were obtained, respectively. A mean barrier height of 0.97eV was obtained in the 140–300K temperature range. Applying the barrier height inhomogeneities correction, the value of A⁎ was obtained from the modified Richardson plots as 39.43 and 39.03Acm−2K−2 in the 140–200K and 210–300K temperature range. The modified Richardson constant (A⁎⁎) has proved to be strongly affected by barrier inhomogeneities and dependent on contact quality.