Influência dos parâmetros de deposição nas propriedades óticas e elétricas de filmes finos de óxido de zinco gálio produzidos via pulverização catódica

Abstract

In this work a series of Gallium-doped Zinc Oxide (GZO) thin films was deposited via Radio Frequency Magnetron Sputtering technique. The sputtering target distributed power, work pressure, and working gas flux kept inside the deposition chamber during the process were varied in order to evaluate the influence of these parameters on the optical and electrical properties of GZO films. The gas used was Argon. The whole set of depositions was carried out onto clean glass substrates at ambient temperature. The films optical transmittance was measured by a UV-Visible spectrophotometer (Shimadzu UV-1800), the thickness by a tip profilometer (KLA Tencor D-100), and the electrical characteristics with a Hall Effect measurement system (Ecopia HMS 3000). A few samples were analyzed by X-Ray Diffraction (Bruker D8 Discover) and Scanning Electron Microscopy (Fei Quanta 250). The GZO films which presented the lowest and highest resistivity values in each parameter variation series were structurally analyzed, the samples presented preferred crystal orientation with respect to the [001] direction and showed a near constant crystallinity as the deposition parameters changed. All the samples exhibited a high transparency (higher than 80%) at visible electromagnetic spectrum, high transparency at near infrared (NIR) and a cutoff at UV wavelengths. The highest electrical resistivity obtained was 1.07x10-2 Ωcm at a deposition power of 180 W, work pressure of 0.08 mBar, and argon flux of 350 sccm. The lowest resistivity obtained was 1.98x10-3 Ωcm at a deposition power of 120 W, work pressure of 0.14 mBar, and argon flux of 300 sccm. The SEM images revealed GZO grain at the films surface of an irregular pattern and disperse sizes. The films electrical resistivity diminished as the grain size rose.