AVS 59th Annual International Symposium and Exhibition
    Thin Film Wednesday Sessions
       Session TF+AS-WeA

Paper TF+AS-WeA10
Properties of Ytterium Doped Zinc Oxide Thin Films Deposited by r.f. Magnetron Sputtering

Wednesday, October 31, 2012, 5:00 pm, Room 11

Session: Thin Films: Growth and Characterization-I
Presenter: T.A. Gessert, National Renewable Energy Laboratory
Authors: K. VanSant, National Renewable Energy Laboratory
T. Barnes, National Renewable Energy Laboratory
J. Burst, National Renewable Energy Laboratory
J. Duenow, National Renewable Energy Laboratory
T.A. Gessert, National Renewable Energy Laboratory
Correspondent: Click to Email
Transparent conducting oxides (TCOs) based on zinc oxide (ZnO) and aluminum (Al) doped ZnO (AZO) are important for many large-scale commercial applications because they exhibit good optical and electrical properties. Further, their constituent elements are non-toxic and abundant, and high-quality thin-films can be deposited at room temperature using a variety of deposition processes. These characteristics make AZO appealing for use as part of the top contact in copper indium gallium diselenide (CIGS) PV modules. Although the present generation of ZnO-based TCOs meet many of the technical requirements of present-generation technologies, it is known that the material could be much more widely applied if some of its properties were more consistent with another important TCO, In2O3:Sn (i.e., ITO). In this comparison, the main properties requiring improvement include increasing the mobility from ~20 to ~50 cm2 V-1s-1 while maintaining carrier concentrations > 5x1020- cm-3 and improving the moisture-tolerance of the films. Earlier work has already shown that AZO with mobility approaching 50 cm2V-1s-1 can be achieved by careful control of the sputtering ambient and the dopant concentration. This study investigates the use of the Group IIIA material yttrium (Y) as a dopant, as well as the impact it has on the optical properties of ZnO. The Y-doped ZnO films are deposited on glass by r.f. magnetron sputtering using pressed powder targets, and the Y concentration is varied by simultaneous co-sputtering from a ZnO:Y target. The films will be analyzed using a combination of Hall measurements, UV-Vis-NIR spectrophotometry, spectroscopic ellipsometry, and Auger/X-ray photoelectron spectroscopy (XPS) and Secondary Ion Mass Spectrometry (SIMS). Based on prior research related to the addition of zirconium (Zr) to ITO, it is suspected that the addition of Y in ZnO may lead to similar changes in the optical properties of this material. Understanding the functionality of these changes could have significant implications for device applications requiring greater control of the dielectric properties of ZnO.