Self-powered ultraviolet photodetector based on an n-ZnO:Ga microwire/p-Si heterojunction with the performance enhanced by a pyro-phototronic effect.

Abstract

In the present study, a heterojunction made of an individual ZnO microwire via Ga incorporation (ZnO:Ga MW) with a p-Si substrate was constructed to develop a self-powered ultraviolet photodetector. When operated under an illumination of 370 nm light with a power density of ∼ 0.5 mW/cm2, the device exhibited an excellent responsivity of 0.185 A/W, a large detectivity of 1.75×1012 Jones, and excellent stability and repeatability. The device also exhibited a high on/off photocurrent ratio up to 103, and a short rising and falling time of 499/412 μs. By integrating the pyro-phototronic effect, the maximum responsivity and detectivity increased significantly to 0.25 A/W and 2.30×1012 Jones, respectively. The response/recovery time was drastically reduced to 79/132 μs without an external power source. In addition, the effects of light wavelength, power density, and bias voltage on the photocurrent response mediated by the pyro-phototronic effect were systematically characterized and discussed. Our work not only provides an easy yet efficient procedure for constructing a self-powered ultraviolet photodetector but also broadens the application prospects for developing individual wire optoelectronic devices based on the photovoltaic-pyro-phototronic effect.