Study of p-n Heterojunction Thin Films for Reducing Gas Sensing Application Fabricated by Thermal Evaporation Technique

Abstract

Gas sensors have been widely implemented to solve concerns of air pollution, monitor human health, and crop yields. Because of its high sensitivity, quick response time, and short recovery time, metal oxide semiconductor (MOS) gas sensors have become a significant topic of research in the field of gas sensing. In the recent decade, many researchers are work on the different types of pure and doped MOS for improve gas sensor response. The present research work deals with the fabrication of p-n heterojunction thin films on alumina substrate by using thermal evaporation technique for reducing gas sensing application. In the current research work, ZnO is used as a functional material and MgO as a dopant. The structural, electrical, and gas sensing properties of fabricated p-n (CuO-ZnO) heterojunction thin films were studied. The resistivity of p-n heterojunction thin films was found to be 23.461Ω/m. The found to be negative to p-n heterojunction thin films. The morphological, elemental and structural characterization of fabricated CuO-ZnO heterojunction thin films were analyzed by using , EDAX and XRD standard tools respectively. By using Scherer’s formula the crystallite size of CuO-ZnO heterojunction thin films was found as 36.83 nm. The fabricated CuO-ZnO heterojunction thin films were exposed to reducing gases such as Liquefied petroleum (LPG), Ammonia (NH3), Ethanol (C2H5OH), and Dichlorofluoromethane (R12) to determine gas response and selectivity. Fabricated CuO-ZnO heterojunction thin films shows maximum response to LPG gas as compare to other gases. The maximum sensitivity has to be found 89.23% to LPG gas of concentration 300 ppm. Fabricated MgO-ZnO thin films also show fast response and recovery time in seconds.