Doping Concentration Influenced Pyro-Phototronic Effect in Self-Powered Photodetector Based on Ga-Incorporated ZnO Microwire/p+-GaN Heterojunction

Pyro-phototronic effect, a coupling of pyroelectric and photovoltaic effect, provides an effective method to improve the performance of self-powered photodetectors (PDs). Developing high-performance PDs, the influence of pyroelectric effect on photoelectric characteristics and coupling mechanism deserves further study. Herein, a self-powered PD made of Ga-incorporated ZnO microwire (ZnO:Ga MW) and p(+)-GaN layer is fabricated, and the performance influenced by pyro-phototronic effect is investigated systematically. Through varying Ga concentration in ZnO:Ga MWs, the pyroelectric current gradually dominates the photocurrent of PDs under ultraviolet illumination; while the photovoltaic current deteriorates rapidly. The enhanced pyroelectric responsivity can compensate the decreased photovoltaic responsivity, maintaining their high total responsivities (>5 mA W-1) under self-biased conditions. Furthermore, the decay time of pyroelectric current, representing the duration of pyroelectric effect, decreases markedly from 0.313 to 0.044 s by increasing Ga concentration. Associated with theoretical analysis, incorporating Ga dopant can not only increase the rate of photogenerated temperature variation, but also narrow depletion layer at ZnO:Ga/GaN heterojunction. Besides, the temperature variation can lead to a significant reduction of decay time. These findings give a deeper insight into the influence of pyroelectric effect on photoresponse and its coupling mechanism, providing a scheme to develop high-performance self-powered PDs.

Automated summary

The study investigates the effects of pyro-phototronic effect on self-powered photodetectors, showing that increasing Ga concentration in ZnO:Ga microwires can enhance pyroelectric responsivity, compensating for decreased photovoltaic responsivity and improving total responsivities of PDs. The findings also reveal that incorporating Ga dopant can increase the rate of photogenerated temperature variation, narrow depletion layer at ZnO:Ga/GaN heterojunction, and significantly reduce the decay time of pyroelectric current, providing insights into the development of high-performance self-powered PDs.