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Low temperature gallium tin zinc oxide (GSZO) based thin film transistors fabricated on silicon has been investigated as a potential indium free transparent amorphous oxide semiconductor thin film transistor (TAOS TFT) with potential device applications on plastic substrates. A comprehensive and detailed study on the performance of GSZO TFTs has been carried out by studying the effects of processing parameters such as deposition temperature and annealing temperature/duration, as well as the channel thickness with all temperatures held below 150 °C. Variety of characterization techniques, namely Rutherford backscattering (RBS), x-ray photoelectron spectroscopy (XPS) and x-ray reflectivity (XRR) in addition to I-V and C-V measurements were employed to determine the effects of the above parameters on the composition and quality of the channel. Optimized TFT characteristics of ID=3×10-7 A, ION/OFF =2×106, VON ~ -2 V, SS ~ 1 V/dec and μFE = 0.14 cm2/V· s with a ΔVON of 3.3 V under 3 hours electrical stress were produced.

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 SiO 2 /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 10 6 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.