Electron Depleted ZnO Nanowalls-Based Broadband Photodetector

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 ~ 3.2 × 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 × 10
¹⁵
cm·Hz1/2·W
^-1
, 115 A·W
^-1
and 47,583% respectively, which is comparable to some of the existing commercial broadband photodetectors.