Highly Visible-Blind ZnO Photodetector by Customizing Nanostructures With Controlled Defects
Jitesh Agrawal, Tejendra Dixit, I. A. Palani, Vipul Singh
Abstract
In this work, a highly visible-blind UV photodetector with a large photo-responsivity using ZnO nanostructures is demonstrated. A large photoconductive gain of 2050 and external quantum efficiency of 2.05 x 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> % at 350 nm (illumination intensity of 1 mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2)</sup> incident radiation has been successfully achieved by morphological transition engineering i.e. growth of nanoplates around the nanorods. Further, by suppression of intrinsic defect states during the growth of nanostructures, high UV to visible rejection ratio of 4.78 x 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> and photoresponsivity of 578 A/W has been accomplished. The device has demonstrated high selectivity for UV-A radiations, with a sharp responsivity peak at 350 nm of 60 nm FWHM. Moreover, the specific photo-detectivity was calculated to be as high as 2.15 x 1015 cmHz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . The proposed device has the capability to establish ZnO as a potential candidate for the variety of commercial applications, where high responsivity along with large UV to visible rejection ratio are the major requirements.