Gas Microsensors Based on Semiconductor Thin Films of Zn0:Ga

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 450C 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, 250C and 300C. The surface of ZnO thin films doped with Ga was also characterized by AFM, showing a regular and uniform morpholgy.