Physical Internal Gain Mechanisms of ZnO-Based Nanorod Ultraviolet Photodetectors

Abstract

The structure of the ZnO-based p-ZnO:LiNO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> / i-ZnO/n-ZnO:In nanorod ultraviolet (UV) photodetectors was grown on sapphire substrates using the vapor cooling condensation system. To study the internal gain mechanisms of the photodetectors, the ZnO-based nanorods were photochemically passivated for different time and operated under various environments to vary the defect density resided on the sidewall surface of the ZnO-based nanorods. The mechanisms of the internal gain, which was attributed to the surface band bending effect of the ZnO-based nanorods induced from the sidewall surface defects and the absorbed oxygen molecules, were thus derived. The specific detectivity of 3.25×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> 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> was obtained for the ZnO-based nanorod UV photodetectors treated with the photoelectrochemical passivation process for 2 min.