OXYGEN GAS-SENSING CHARACTERISTICS FOR ZNO(LI) SPUTTERED THIN-FILMS

The oxygen gas-sensing characteristics of ZnO sputtered thin films, undoped or Li doped, versus their working temperatures are reported in this paper. The Li content and the O/Zn ratio are obtained by measurements of nuclear reaction analysis (NRA) and Rutherford back-scattering (RBS), respectively. The structural properties of ZnO and ZnO(Li) films are studied by means of X-ray diffraction (XRD), the preferential orientation of the thin films is found to be (002). We have measured the variation of the electrical conductance for O2 concentrations between 100 and 2 x 10(5) ppm by means of absorption isotherms at temperatures varying from 400 to 550-degrees-C. The oxygen sensitivity and the response times for these ZnO thin films are reported here; the possible interaction mechanisms of gaseous O2 with the bulk of pure or Li-doped films will also be given.