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

In this work, by coupling the pyroelectric effect, photoexcitation, and semiconductor properties, the pyrophototronic 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 pyrophototronic 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 mu m-Si/0.5 mu m-ZnO NWs heterojunction NIR PD exhibits superior detector performances, such as fast response speed with a rise time of 15 mu s and a fall time of 21 mu s, high photoresponsivity (164 mA/W) and perfect weak signal detection ability (D* = 8.78 x 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.