Gas microsensors based on semiconductor thin films of Zno:Ga

Abstract

Four carbon monoxide microsensor based on semiconducting oxide Zn0:Ga has been developed. The results and analysis of the characterization in an atmosphere containing carbon monoxide (CO), are presented in this work. dilution CO is 50ppm. Zn0:Ga thin films were deposited at 450°C by the spray pyrolysis technique from a 0 . 2 M starting solution with a IGal/[ZnI= 3 at. YO. Microsensors with four different dimensions were designed: 20x20pm2, 20x40pm2, 20x60pm2 and 100x100pm2. Ohmic contacts were manufactured by thermal evaporation of aluminum on the top of the films. Both of gas microsensors and AI terminals were patterned by lift off. A surface resistance variation of several orders of magnitude was found in doped-gallium ZnO thin films when these were introduced into a camera with Oppm, lppm, 5ppm, 50ppm and lOOppm of CO. Thin films gas microsensors were tested at several temperatures and different CO concentrations.The measurement temperatures employed were 2OO0C, 250°C and 300°C. The surface of ZnO thin films doped with Ga was also characterized by AFM, showing a regular and uniform morpholgy.