Electron Depleted ZnO Nanowalls-Based Broadband Photodetector

Abstract

Pristine ZnO has been extensively reported for high responsivity UV photodetectors based applications. However, in general, its photo-response in visible and NIR region is very poor. In this article, a simple and cost-effective technique of synthesizing pristine ZnO honeycomb nanostructure based high responsivity broadband (200 nm - 950 nm) photodetector is demonstrated. The dark current of the device was found to be as low as 5.6 pA at 10 V applied bias. The maximum photo-current to dark current ratio was $\sim 3.2 \times 10^{7}$ at 300 nm wavelength (measured at −10 V applied bias). The calculated linear dynamic range of the device is as high as 128.9 dB. The maximum specific photodetectivity, photoresponsivity and external quantum efficiency (@ 300 nm) calculated at −10 V bias was $2.07 \times 10^{15}$ cm $\cdot $ Hz $^{1/2} \cdot \text{W}^{-1}$ , 115 $\text{A}\cdot \text{W}^{-1}$ and 47,583% respectively, which is comparable to some of the existing commercial broadband photodetectors.