Effects of post-annealing on Schottky contacts of Pt/ZnO films toward UV photodetector

The Schottky contact of Pt/ZnO was formed by depositing ZnO films oriented along c-axis by pulsed-laser deposition on Pt/Ti buffer layer supported by SiO2/Si substrate. Effects of the post-annealing on the crystallinity, uniformity and native defects of ZnO film as well as Schottky contacts of Pt/ZnO films were investigated. Results show that the annealing can improve the crystallinity of ZnO film, suppress the native defects, and enhance the performance of Pt/ZnO Schottky contacts dramatically. The best Schottky diode shows the largest barrier height of 0.8 eV with reverse leakage current of 1.5 × 10−5 A/cm2. The zero-biased photodetector based on the best Schottky diode possesses responsivity of 0.265 A/W at 378 nm, fast photo-response component with rise time of 10 ns and fall time of 17 ns. This report demonstrates possibility of ZnO films/Pt hetero-junction with large area Schottky contact, and establishes the potential of this material for use in UV photodetector devices.

► The novelty of proposed structure of Schottky diode.
► First systematic research on effects of post-annealing on Pt/ZnO Schottky contact.
► First the zero-biased Schottky photodetector was obtained.
► The performance of photodetector is comparable with the previous report.