Highly efficient, low cost, and stable self –powered UV photodetector based on Co2+:ZnO/Sn diluted magnetic semiconductor nanoparticles

Abstract

Abstract A low cost self-powered UV Schottky photosensor uses as photoactive layer a Co2+: ZnO diluted magnetic semiconductors nanoparticles (DMS) is presented in this paper. Herein, for the first time, a high-performance UV photosensor is elaborated using Co2+: ZnO nanoparticles based on a low-cost polyol method. In addition to the optical band gap of ZnO, Cobalt can yield another optical absorption band associated to the Co+2 d-d (tethrahedral symmetry) crystal field transitions, which could enhance the total optical absorption and produce a high responsivity. Several characterization techniques such as XRD, TEM, FTIR, PL and diffuse reflectance (DF) spectroscopy are used in this study. The performance of our devices was evaluated upon exposing to UV light of wavelength 375 nm and at zero bias voltage. The device exhibits a sensitivity of 209.7 and a high responsivity about 5.5 103 mA/W under intensity of 7.6 mW. The response times (the rise and recovery times) of our device are 0.62s and about 1.65 s without any external bias, respectively. Our self-powered PD shows higher detectivity about 1.3 1013 Jones, compared to the UV PD in other works. Such high responsivity and detectivity lead the Co2+: ZnO PD to have low noise spectral density of 10 − 24 A2/Hz and low noise equivalent power of 2.6E-11 W Hz−1/2. This study proposes an original process for the fabrication of low cost self-powered PDs with high performance and zero power consumption on a large-scale.