Graded strain-enhanced pyro-phototronic photodetector with a broad and plateau band

Self-powered broadband photodetectors (PDs) have important applications in the field of communication, sensing, imaging and Internet of thing. However, it is a great challenge to achieve high and plateau responsivity in ultra-wide band. Here, Mn graded doping is used as an effective strategy to design the graded p-Si/n-Zn1−xMnxO PD for UV–vis–NIR detecting based on sol-gel method. The graded strain caused by Mn graded doping leads to strong polarization field for further improving the pyro-phototronic effect for 300–1100 nm photon detection and pyroelectric effect for 1100–1700 nm photon detection. The graded p-Si/n-Zn1−xMnxO PD demonstrates a plateau responsivity band from 390 nm to 1100 nm with a high average responsivity of about 103 mA W-1, improving by two orders of magnify relative to those of the p-Si/n-ZnO PD. Particularly, the responsivity R is increased from 0.18 mA W-1 to 140 mA W-1 under the 900 nm quasi-monochromatic light illumination, showing an enhancement factor of 777 by the graded strain-induced polarization field. This work may supply an effective way to design the self-powered broadband PDs and promote their promising applications in real color imaging, smart sensing, environmental monitoring and Internet of things.