Electrical characterization of Ni/n-ZnO/p-Si/Al heterostructure fabricated by pulsed laser deposition technique

The ZnO thin films are grown on the p-Si for the heterojunction fabrication by pulsed laser deposition method. X-ray diffraction study showed that the texture of the film is hexagonal with a strong (0 0 2) plane as preferred direction. High purity vacuum evaporated nickel and aluminum metals were used to make contacts to the n-ZnO and p-Si, respectively. The current-voltage characteristics of Ni/n-ZnO/p-Si(1 0 0)/Al hetero structure measured over the temperature range 80-300 K have been studied on the basis of thermionic emission diffusion mechanism. The equivalent Schottky barrier height and diode ideality factor are determined by fitting of measured current-voltage data in to thermionic diffusion equation. It is observed that the barrier height decreases and the ideality factor increases with decrease of temperature and the activation energy plot exhibit non-linear behavior. These characteristics are attributed to the Gaussian distribution of barrier heights. The capacitance-voltage characteristics of Ni/n-ZnO/p-Si(1 0 0)/Al heterojunction diode are also studied over wide temperature range. From the measured capacitance-voltage data the built in voltage and impurity concentration in n-type ZnO is estimated.