In this work the performance of bottom gate thin film transistors (TFTs) with transparent amorphous gallium tin zinc oxide (GSZO) active layers fabricated by radio frequency sputter deposition using a single GSZO target on SiO₂/Si wafers will be presented. Trap density and its energetic distribution, and oxygen chemisorption were found to play a critical role in determining the operational characteristics of the device, all of which can be controlled by the oxygen incorporation and substrate temperature during deposition, along with the post-deposition annealing. In addition device instability, with respect to the electrical stress and optical illumination, can be suppressed by suitably tailoring these parameters. TFTs exhibiting a drain current (I_D) of 10^-6 A and on/off current ratio (I_on/off ) of 10⁶ was achieved. A stable TFT has been achieved under electrical stress for 2% oxygen flow exhibiting ΔV_T as low as ~0.5 V for 3hr stress under a gate bias of 1.2 and 12 V, with good optical stability.

Date Published: 18 March 2013
PDF: 10 pages
Proc. SPIE 8626, Oxide-based Materials and Devices IV, 862615 (18 March 2013); doi: 10.1117/12.2013277

Published in SPIE Proceedings Vol. 8626:
Oxide-based Materials and Devices IV
Ferechteh Hosseini Teherani; David C. Look; David J. Rogers, Editor(s)