AVS 50th International Symposium
    Thin Films Wednesday Sessions
       Session TF-WeP

Paper TF-WeP14
Amorphous Transparent Conductive Oxide Films of In@sub 2@O@sub 3@-ZnO with Additional Al@sub 2@O@sub 3@ Impurities

Wednesday, November 5, 2003, 11:00 am, Room Hall A-C

Session: Poster Session
Presenter: K. Tominaga, Tokushima University, Japan
Authors: K. Tominaga, Tokushima University, Japan
H. Fukumoto, Tokushima University, Japan
Y. Hayashi, Tokushima University, Japan
K. Murai, Tokushima University, Japan
T. Moriga, Tokushima University, Japan
I. Nakabayashi, Tokushima University, Japan
Correspondent: Click to Email
In@sub 2@O@sub 3@-ZnO films were deposited by facing target sputtering system of ZnO:Al and In@sub2@O@sub3@ targets. Two targets were sputtered simultaneously in Ar gas at 1 mTorr, and electric current ratio @ganma@=I@sub Zn@/(I@sub Zn@+I@sub In@) was adopted as a deposition parameter to change film composition. Discharge current of each target was changed from 0 to 80 mA in order to change the contents of Zn and In in the film. Compositional ratios of Zn/(Zn+In) in films were nearly equal to @ganna@ value according to the data estimated by X-ray fluorescence analysis. Five ZnO:Al targets containing 0,1,2,3 and 4 wt% Al@sub 2@O@sub 3@ were used for Al adding in the films. In@sub 2@O@sub 3@-ZnO films in amorphous phase were deposited between Zn/Zn+In=0.2-0.6. The lowest resistivity of 1.5x10@super -4@ @ohm@cm was attained in amorphous phase films deposited from In@sub 2@O@sub3@ and ZnO:Al (Al@sub 2@O@sub 3@=2 wt %). Carrier mobility did not depend on Al@sub 2@O@sub 3@ content in ZnO:Al target. Carrier concentrations at the lowest resistivity in amorphous In@sub 2@O@sub 3@-ZnO had the highest value for 2 wt% Al@sub 2@O@sub 3@ content, but decreased at above 3 and 4 wt%. Optical bandgap energy shifted to higher energy side for the film of 4 wt% Al@sub 2@O@sub 3@ content. These results indicate that the energy shift of optical bandgap for amorphous phase film is not ascribed to Burstein-Moss shift. The role of Al in amorphous films is different with that of donors in crystalline In@sub 2@O@sub 3@:Sb and ZnO:Al. On the other hand, Al@sub2@O@sub3@ doping in homologous phase of In@sub 2@O@sub 3@ film decreased carrier concentration, independent on the levels of Al@sub 2@O@sub 3@ doping. This indicates that Al did not act as donor impurities in homologous Zn@sub k@In@sub 2@O@sub k+3@ crystalline films.