The effect of various dopants on zno surface for gas sensor application

Abstract

One-dimensional (1-D) nanomaterials have drawn a lot of attention in last few decades because of their novel and unique properties and a wide range of applications. ZnO nanomaterials are among the most important 1-D nanomaterials due to their semi-conductive, piezoelectric, and biocompatible properties. With these unique characteristics, ZnO became one of the most important nanomaterials in scientific research and applications nowadays. ZnO is a member of group (II-VI) semiconducting compounds and exhibits n-type character so it can be easily doped by substituting Zn with group III elements (Al, Ge, In) and O with group VII elements (Chlorine, Iodine). Dopant effect can modify the electrical properties of ZnO which is an advancement for gas sensor. The large surface area of the ZnO 1-D nanostructures makes them attractive for gas sensing, as it can absorb as much of the target gas as possible particularly at low concentrations. Consequently, the electrical conductivity of ZnO significantly affected by the adsorption and desorption of gas species on their surface. In this work, simulation of pure and doped ZnO nanosheet are performed and the dopants effect on ZnO electronics, electrical and sensing properties are observed by using Quantum Wise simulation by ATK-VNL. The gas sensor based ZnO nano-structure are fabricated by the atomic scale simulation using Quantum Wise software VNL-ATK and examined with group III (Al) and group VII (F) effect on ZnO towards gas sensor applications. Pure ZnO found to be sensitive towards group III and Group VII elements (Aluminum, Fluorine) by substituting a single O and a single Zn atom respectively from the bulk. It was observed an increased on the Fermi energy level when introducing the dopants on the ZnO nano surface. The calculated Fermi levels were -3.4464 eV, -3.075495eV and -3.1921eV respectively for pure, F-doped and Al-doped ZnO. The sensitivity performance towards CO gas revealed, F-doped ZnO exhibits a 67% sensitivity. This value is higher compared to pure and Al-doped ZnO which were 28% and 56% respectively. This shows F-doped ZnO nanosheet can enhance the sensitivity towards CO gas sensing.