p-(001)NiO/n-(0001)ZnO Heterostructures based Ultraviolet Photodetectors

TL;DR

This paper demonstrates the development of epitaxial NiO/ZnO heterostructure ultraviolet photodetectors with high responsivity, fast response times, and stability, tunable by bias voltage, suitable for UV-A detection.

Contribution

It introduces a novel epitaxial NiO/ZnO heterostructure device with tunable response time and high stability for UV photodetection, advancing the field of self-powered UV sensors.

Findings

Achieved responsivity up to 5mA/W at zero bias

Response time as short as 400 microseconds in self-powered mode

Device stability over repeated illumination cycles

Abstract

We investigate the potential of epitaxial (001)p-NiO/(0001)n-ZnO heterostructures grown on (0001)sapphire substrates by pulsed laser deposition technique for ultraviolet photodetector application. Our study reveals that in the self-powered mode, these devices can serve as effective photodetectors for the UV-A band (320-400 nm) with response time as short as 400 microseconds. Peak responsivity as high as 5mA/W at zero bias condition have been achieved. These devices also show a very high level of stability under repeated on/off illumination cycles over a long period of time. Furthermore, we find that the response time of these detectors can be controlled from several microseconds to thousands of seconds by applying bias both in the forward and the reverse directions. This persistent photoconductivity effect has been explained in terms of the field induced change in the capture barrier height associated with certain traps located at the junction.