THE EFFECTS OF DEPOSITION RATE ON THE STRUCTURAL AND ELECTRICAL-PROPERTIES OF ZNO-AL FILMS DEPOSITED ON (1120) ORIENTED SAPPHIRE SUBSTRATES

Aluminum doped zinc oxide (ZnO:Al) films were deposited on (1120BAR) oriented sapphire substrates heated to 200-degrees-C with a radio-frequency (rf) power ranging from 25 to 170 W for a deposition rate in the range 0.7-27.4 nm min-1 by rf-magnetron sputtering from a ZnO target mixed with Al2O3 of 2 wt. %. All of the films deposited were (0001) oriented single-crystalline films with an internal stress. The stress was increased and degraded the crystallinity of the epitaxial film as a deposition rate was increased, and thus the Hall mobility and the resistivity of the film were, respectively, decreased and increased. However, the resistivities obtained were in the range about 1.4-3.0 x 10(-4) OMEGA cm, the values comparable to those for indium tin oxide film presently used as a transparent electrode.