Probing the IZO thin films for application as gas sensor and antibacterial agents

Abstract

Among various extensively investigated transparent conducting oxides (TCOs), ZnO is a versatile one [1]. ZnO is a key technological material for various optoelectronic applications, because it has exceptional optical, electrical and mechanical properties [2]. It is an n-type wide band gap semiconductor with high chemical and mechanical stability. Because of good electrical conductivity and optical transmittance in the visible region, it can also be used as transparent electrodes [3]. It is a multipurpose material for different industrial application due to the abundance of the raw material and low toxicity. It is also an important metal oxide used for gas sensor and biological applications. Particle size and surface morphology plays an important role for these applications. newlineZnO nanostructures with different morphologies like nanorods, nanobelts, nanowires, nanotubes and nanoparticles are expansively studied in recent times for gas sensor applications, because of its high sensitivity to toxic and combustible gases like methanol, ethanol, acetone, LPG and H2S etc [4]. However, thin films of ZnO are more suitable, because the gas-sensing properties are related to the surface of the material where the gases are adsorbed and the surface reactions occur. As a result of which, concentration of charge carriers in the material are modulated leading to the change in its electrical resistance which is taken as the measurement for the detection of test gas. newlineUndoped ZnO thin films have certain limitations for application in various fields. In order to obtain desired structural, optical and electrical properties, these materials are doped with various dopant materials such as Sn, Cu, Fe, In, Ga etc [5][6]. When ZnO is doped with higher valence electrons such as In3+, Fe3+ and Sn4+ atoms, these dopants substitute Zn atoms to release free electrons and increase the carrier concentration to obtain good conductivity. Doping with In is done by many researchers to obtain high transparency and conductivity. It also enhances the gas