Insights into the pyro-phototronic effect in p-Si/n-ZnO nanowires heterojunction toward high-performance near-infrared photosensing

Abstract

In this work, by coupling the pyroelectric effect, photoexcitation, and semiconductor properties, the pyro-phototronic effect is used to turn/control the charges transport, and thus modulate the optoelectronic processes. The performances of fabricated three kinds of p-Si/n-ZnO nanowires (NWs) heterojunction with different Si thickness and ZnO NWs length are systematically investigated and explored toward high-performance pyro-phototronic NIR photosensor. It is interesting that the fabricated NIR PD with reduced Si thickness and shortened ZnO NW length show a better photoresponse performance. In our experiment, the 45 μm-Si/0.5 μm-ZnO NWs heterojunction NIR PD exhibits superior detector performances, such as fast response speed with a rise time of 15 μs and a fall time of 21 μs, high photoresponsivity (164 mA/W) and perfect weak signal detection ability (D* = 8.78 × 10 11 Jones). Moreover, the relationship between the dynamic response current and the chopper frequency is explored carefully to reveal the existence of resonance frequency and related working mechanism is proposed. This study not only provides an insight in the pyro-phototronic effect in p-Si/n-ZnO NWs heterojunction toward higher performance NIR photosensing, but also provides an effective design method to expand the application of NIR PDs. By adjusting the thickness of Si and the length of ZnO nanowires, the pyro-phototronic effect in p-Si/ZnO NW heterostructured near-infrared photosensor were systematically investigated. • The pyro-phototronic effect is introduced into p-Si/n-ZnO NWs heterojunction to achieve superior NIR detection capabilities. • The maximum responsivity and detectivity of the fabricated device reaches 14.7 mA/W and 7.9 × 10 11 Jones at zero bias. • The position of resonance frequency and the pyro-phototronic effect are impacted by the Si thickness and the ZnO NWs length.