Effect of O₂ Fraction in the Sputter Gas on the Electrical Properties of Amorphous In-Zn-O and the Thin Film Transistor Performance

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• 作者：Austin S. Reed ; David C. Paine ; Sunghwan Lee
• 关键词：Amorphous oxides ; In ; Zn ; O (IZO) ; thin film transistor (TFT) ; carrier density ; threshold voltage
• 刊名：Journal of Electronic Materials
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：45
• 期：12
• 页码：6310-6316
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Optical and Electronic Materials; Characterization and Evaluation of Materials; Electronics and Microelectronics, Instrumentation; Solid State Physics;
• 出版者：Springer US
• ISSN：1543-186X
• 卷排序：45

文摘

Amorphous oxide semiconductors (AOSs) exhibiting high mobility in the range of 10–30 cm2/Vs have received significant attention for their application in flexible and transparent electronics such as next-generation displays. Here, we report on how the oxygen volume fraction (vol.%) in the O₂/Ar sputter gas affects both the electrical properties of sputtered amorphous In-Zn-O (a-IZO) and the threshold voltage of a-IZO thin film transistor (TFT) devices. As the oxygen fraction increases during sputter deposition, the carrier density in a-IZO is adjusted from the heavily-doped regime of >1020/cm3 to the semiconducting regime of <1017/cm3. A series of bottom-gated TFT devices were fabricated through depositing the channel a-IZO films as a function of O₂ vol.%. All the TFTs manufactured operate in depletion mode and the threshold voltage is found to shift positively with the increasing presence of O₂ in the sputter gas. These results are attributed to both a decrease in oxygen vacancy defects, which donate two free carriers per vacancy, and a subsequent reduction in the a-IZO channel’s carrier density.