High Mobility and Stability of Thin-Film Transistors Using Silicon-Doped Amorphous Indium Tin Oxide Semiconductors

We report the fabrication of high-performance thin-film transistors (TFTs) with an amorphous silicon indium tin oxide ( a -SITO) channel, which was deposited by cosputtering a silicon dioxide and an indium tin oxide target. The effect of the silicon doping on the device performance and stability of the a -SITO TFTs was investigated. The field-effect mobility and stability under positive bias stress of the a -SITO TFTs with optimized Si content (0.22 at.% Si) dramatically improved to 28.7 cm 2 /Vs and 1.5 V shift of threshold voltage, respectively, compared with the values (0.72 cm 2 /Vs and 8.9 V shift) for a -SITO TFTs with 4.22 at.% Si. The role of silicon in a -SITO TFTs is discussed based on various physical and chemical analyses, including x-ray absorption spectroscopy, x-ray photoelectron spectroscopy, and spectroscopic ellipsometry measurements.