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采用标准的液晶显示屏基板制备工艺制备出铟镓锌氧薄膜晶体管(IGZO-TFT),通过调节IGZO薄膜工艺中氧分压,研究不同氧分压对TFT器件电学性能的影响。实验结果表明,所有器件都展现出良好的电学特性,随着氧分压从10%增加到50%,TFT的阈值电压由0.5V增加到2.2V,而亚阈值摆幅没有发生变化。在栅极施加30V偏压3 600s后,随着氧分压的增加,阈值电压向正向的漂移量由1V增加到9V。经过分析得出高氧分压的IGZO-TFT器件中载流子浓度低,建立相同导电能力的沟道时所需要栅极电压会更大,阈值电压会增加。而在金属-绝缘层-半导体(MIS)结构中低载流子浓度会导致有源层能带弯曲的部分包含更多与电子陷阱相同的能态,栅介质层(GI)会俘获更多的电子,造成阈值电压漂移量较大的现象。
Indium gallium zinc oxide thin film transistor (IGZO-TFT) is prepared by a standard liquid crystal display substrate preparation process. The influence of different oxygen partial pressure on the electrical properties of the TFT device is investigated by adjusting the oxygen partial pressure in the IGZO thin film process. The experimental results show that all devices exhibit good electrical characteristics. With the increase of oxygen partial pressure from 10% to 50%, the threshold voltage of TFT increases from 0.5V to 2.2V, while the subthreshold swing has not changed. After the gate is applied with 30V bias for 3 600s, the threshold voltage shifts forward from 1V to 9V as the oxygen partial pressure increases. After analyzing the IGZO-TFT devices with high partial pressure of oxygen, the gate voltage will be larger and the threshold voltage will increase when the carrier concentration is low and the channel with the same conductivity is established. Whereas, the low carrier concentration in a MIS structure results in more energy band bending in the active layer containing the same energy states as the electron traps, and the gate dielectric layer (GI) captures more Electrons, resulting in a larger threshold voltage drift phenomenon.