The effect of gas atmospheres on resistivity of indium tin oxide films at high temperature

Abstract

The effects of heat treatment in Q₂, O₂ and N₂, and Ar gases on the high temperature (500‡ C) electrical resistivity of indium tin oxide (ITO) film 52 nm thick prepared by chemical spray pyrolysis method were studied. The partial oxygen pressure effect on the resistivity was found to be$P_{{\text{O}}_{\text{2}} }^{1/5}$ to$P_{{\text{O}}_{\text{2}} }^{1/3.5}$. The resistivity changes for cyclic exchange of O₂ by Ar gas at 500‡ C. These lead to the conclusion that chemisorption of oxygen atoms in the film surface is dominant for this thin film, for thicker films such as 640 nm oxygen diffusion is found to occur. The Langmuir model of the monolayer isothermal adsorption of oxygen atoms in the surface is applicable to the rapid change of resistivity.