Microstructural analysis of Ga-Zn Oxide thin films for gas sensing

Gallium oxide - zinc oxide (Ga-2(3)O-ZnO) metal oxide thin films have been prepared by the sol-gel process and their oxygen gas sensing performance has been investigated. These films were deposited on alumina transducers with interdigital electrodes for gas sensing measurements and on single crystal silicon substrates for microcharacterization. X-ray Photoelectron Spectroscopy showed that the actual concentrations in Ga-Zn oxide thin films differ from the nominal values in the prepared solutions as a function of annealing temperature. Furthermore, the concentration of Zn decreases with a rise of sample annealing temperature. It was found that by increasing the amount of ZnO in the thin film sensors, their operating temperature decreased as well as the base resistance. In addition, the sensors prepared with 40 at. % of Zn showed the largest response and preferred oxygen sensing at operating temperatures from 380 to 420C.