IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Thin Films Tuesday Sessions
       Session TF-TuM

Paper TF-TuM1
Influence of Processing Conditions on Sputter Deposited ZnO:Al Thin Films

Tuesday, October 30, 2001, 8:20 am, Room 123

Session: Optical Thin Films
Presenter: L.W. Rieth, University of Florida
Authors: L.W. Rieth, University of Florida
P.H. Holloway, University of Florida
Correspondent: Click to Email
Thin films of zinc oxide (ZnO) are useful in many applications including transparent conductors, gas sensors, RF filters, varistors, and Cu(In,Ga)Se@sub 2@ (CIGS) based thin film solar cells. Thin films of Al doped ZnO are deposited from a ceramic target of ZnO:Al@sub 2@O@sub 3@ (98wt%:2wt%) using an 8 inch RF diode source onto cleaned soda-lime glass substrates with no intentional heating. RF power and process pressure are varied over the ranges of 250 - 1000 watts and 5 - 50 mTorr, respectively. As deposited and modestly heat treated films (400°C for 1 hour) are characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), four point probe, Hall measurements, and spectrophotometry. AFM micropgraphs indicate the films are polycrystalline with grain sizes between 10 and 100nm. XRD results indicate the films have the wurtzite structure with a strong basal texture (0001). XPS spectra reveal the films have the proper stoichiometry, and a chemisorbed surface oxide species that is sensitive in particular to the gas ambient during the modest heat treatments. Electrical data show that the films have a large range of resistivities, which improve with heat treatment to as low as 10@sup -3@ @ohm@-cm, while maintaining transmission greater than 80% across the visible range. The properties were sensitive to location on the substrate relative to the sputter deposition source, exhibiting the lowest resistivity for off axis deposited films These results are discussed with respect to the hypothesis that negative ion resputtering (NIR) strongly influences the properties of the deposited films.