Date

Place

Room F (Room 320)
53. Flexible/Transparent TFT and Circuitry
August 21, 2015 (Friday)
11:00 ~ 12:35

[53-3]
11:50 ~ 12:05
Title:How We Can Control Weakly-Bonded Oxygen Introduced by Sputtering Deposition for Amorphous In-Ga-Zn-O Thin-Film Transistor
Keisuke Ide (Tokyo Inst. of Tech., Japan), Mutsumi Kimura (Ryukoku Univ., Japan), Hidenori Hiramatsu, Hideya Kumomi, Hosono Hideo, and Toshio Kamiya (Tokyo Inst. of Tech., Japan)
Abstract: We previously reported that high temperature (��300oC) annealing in ozone (O3) atomosphere incorporates weakly-bonded oxygen to amorphous In-Ga-Zn-O (a-IGZO) films and causes large hysteresis on the operation of thin-film transistor (TFT) arising from bistable trap states. Here, we report that bistable trap states originating from weakly bonded oxygens are formed in unannealed a-IGZO channels deposited at room temperature (RT) if the oxygen flow ratio (RO2) during deposition is larger than the optimal value. It was found that the unannealed TFT deposited at, for example, RO2 = 10% showed a small turn-on voltage (Von) in the virgin curve while changed to large Von in the 2nd and 3rd measurements. Furthermore, it is seen that difference between the initial and 2nd Von (DVon) decreases with increasing annealing temperature (Tann). We also confirmed that TDS signal for various Tann. As a result, the total O2 desorption amount up to 400oC decreases with increasing Tann from 4.8��1018 cm-3 for the unannealed film to 3.8��1018 cm-3 for the 200oC-annealed film. More details including the relationship among RO2, DVon, hystresis DVth, O2 desorption, and subgap states will be discussed at the conference.
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