[12a-D419-1~12] 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」

▼ [12a-D419-11] Development of thin film transistor using an amorphous mixed-anion semiconductor a-ZnOS

〇(M2)Zhen Chen¹、Yasushi Hirose¹、Tetsuya Hasegawa¹ (1.Univ. of Tokyo)

キーワード：amorphous semiconductors, thin film transistors, mixed-anion compounds

Amorphous oxide semiconductors (AOSs) have been under intensive study during recent years. Because of their high electron mobility even under amorphous state, they have been widely used as key materials for flat panel displays and flexible electronics devices, especially as channel layers of thin film transistors (TFTs). Recently, it has been reported that an amorphous mixed-anion semiconductor consisting of only earth-abundant elements, zinc oxynitride (a-ZnON), shows high electron mobility and capability to TFT application. However, a-ZnON is unstable in air. To overcome this drawback, we synthesized another earth-abundant amorphous mixed-anion semiconductor, amorphous zinc oxysulfide (a-ZnOS), in thin film form and found that their electron mobility is comparable to those of conventional AOSs (~15 cm²V^-1s^-1), in addition to good chemical stability under ambient conditions. In this study, we fabricated a-ZnOS based TFTs and evaluated their performance. As a result, a-ZnOS thin films with S/(S+O) = ~0.30 shows obvious TFT performance and field effect ability increased with the decrease of S/(S+O). Annealing can also improve device performance and after the annealing under an optimal condition, a-ZnOS based TFT with S/(S+O) = ~0.17 exhibited an on/off ration over 10⁴, μ_FE of 11.3 cm²V⁻¹s⁻¹, V_th of 4.4 V and a subthreshold swing of 2.0 Vdec⁻¹.