Structural, electric and humidity sensitivity properties of Zn-doped LPFO thin films deposited by rf magnetron sputtering

Abstract

Lanthanum perovskite LaFeO3 (LFO) is a semi-conducting oxide and it has been extensively studied with reference to several potential applications, such as gas sensors, humidity sensors and catalysts. This oxide crystallizes in an orthorhombic perovskite structure. This work is dedicated to the study of the structural, electric and humidity sensitivity properties of some thin films obtained through rf magnetron sputtering using as targets La0.8Pb0.2FeO3 (LPFO) perovskites in which Fe-ions were partially substituted by Zn-ions. The effects of substitutions, substrate (quartz and alumina) and its temperature during deposition, as well as of working gas composition (O2/(O2 + Ar)) and subsequent heat treatments have been investigated.Electrical behavior of the deposited layers is that of a p-type semiconductor. Thermal activation energy (Ea) is around 0.5 eV and increases to 0.62 eV with the increase of zinc ions content (from 0 to 0.2) in LPFO target.The influence of the environmental humidity on the electric resistivity of the obtained films was determined within the 0%–98% RH interval. By increasing the amount of zinc ions which substitute the iron in LPFO target, films much more sensitive to humidity between 53% and 98% RH were obtained.