Effect of Oxygen on the Optical and the Electrical Properties of Amorphous InGaZnO Thin Films Prepared by RF Magnetron Sputtering
J. Korean Phy. Soc. 2008; 53: 2019~2023
Published online October 15, 2008 © 2008 The Korean Physical Society.

Abstract
To investigate the effect of oxygen on the optical and the electrical properties of amorphous InGaZnO (a-IGZO), we prepared thin films by RF magnetron sputtering in various oxygen atmospheres at room temperature and the thin-film transistors (TFTs) were evaluated. The oxygen concentration during the deposition process affected both the optical band-gap and the mobility of a-IGZO-based devices. As the oxygen concentration in the processing chamber during deposition was increased, the optical band-gap and the saturation mobility decreased concurrently. The highest optical band-gap and the best device performance were obtained from the a-IGZO film deposited in an atmosphere of 10 \% oxygen. The a-IGZO film deposited at this condition exhibited an optical band-gap of 3.29 eV and the transistors fabricated with this film revealed a saturation mobility of 2.6 cm$^2$/V$cdot$s, a subthreshold swing of 0.93 V/decade, an on-off current ratio of 10$^7$ and a threshold voltage of 13.9 V.
Keywords: Oxide semiconductor, Amorphous InGaZnO (a-IGZO), RF sputtering, Optical properties, Thin-film transistor, Electrical characteristics


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