2022年第69回応用物理学会春季学術講演会

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21 合同セッションK「ワイドギャップ酸化物半導体材料・デバイス」 » 21.1 合同セッションK 「ワイドギャップ酸化物半導体材料・デバイス」

[25p-E202-1~15] 21.1 合同セッションK 「ワイドギャップ酸化物半導体材料・デバイス」

2022年3月25日(金) 13:30 〜 17:30 E202 (E202)

富樫 理恵(上智大)、曲 勇作(島根大)

13:30 〜 13:45

[25p-E202-1] Off-current reduction of InSnZnOx thin film transistors by Ga-addition

〇(D)Hui Yang1,2、Xiqing Zhang1 (1.Beijing Jiaotong Univ.、2.RIES-Hokkaido Univ.)

キーワード:transparent amorphous oxide semiconductor, thin film transistor, InSnZnO

Transparent amorphous oxide semiconductor (TAOS, a-InGaZnO4 is the representative) based thin-film transistors (TFTs) have widely commercialized as the backplane of OLEDs and LCDs in recent years from the points TAOS-TFTs exhibit rather high field-effect mobility (μFE ~10 cm2 V−1 s−1) as compared to that of a-Si TFTs (μFE ~0.5 cm2 V−1 s−1). In order to improve the resolution of OLEDs and LCDs, TAOS-TFTs that exhibits higher μFE are required. Among many TAOSs, we focus on an amorphous In-Zn-Sn-O (a-IZTO) system as a promising active TFT material that can satisfy the increasing demands for future displays because a-IZTO-TFTs show higher μFE (~30 cm2 V−1 s−1). However, a-IZTO TFTs are not stable due to that oxygen vacancies are easily formed. In order to overcome this issue, we added Ga to a-IZTO. Because the introduction of Ga improves the stability of the electrical properties of n-type TAOS. Further, strong Ga−O bonding suppresses oxygen vacancy formation. We fabricated the a-IZTO: Ga TFTs with the bottom-gate structure on SiO2/Si substrates by RF magnetron sputtering. The off current of the a-IZTO: Ga-TFT is hundred fA range, which is more than two orders of magnitude smaller than that of a-IZTO-TFT. The a-IZTO: Ga-TFT showed excellent device performance: μSAT of 36 cm2 V−1 s−1, VTH of 1.0 V, subthreshold swing S.S. of 420 mV decade−1, and on-to-off current ratio ION/IOFF of 3.8 × 109. These results reveal that Ga addition to the IZTO channel layer is effective to improve the transistor characteristics of a-IZTO-TFTs.