Journal
JOURNAL OF ALLOYS AND COMPOUNDS
Volume 862, Issue -, Pages -Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.jallcom.2020.158030
Keywords
IAZO thin film transistors; Dual-active-layer; Room temperature fabrication; Ta2O5 gate dielectric layer; RF magnetron sputtering
Categories
Funding
- Key Research and Development Program of Shandong Province, China [2017GGX201007]
- China Postdoctoral Science Foundation [2018T110685]
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This study focuses on the room temperature fabrication of high-performance amorphous oxide semiconductor thin film transistors (TFTs) with different structures and layer thicknesses, achieving excellent electrical performance and stability. The use of a room temperature-sputtered Ta2O5 gate insulator greatly improves the performance of the TFTs, especially in terms of mobility and subthreshold swing, while also exhibiting outstanding bias and illumination stabilities compared to traditional SiO2 insulators.
The room temperature fabrication of amorphous oxide semiconductor thin film transistors (TFTs) is essential for their applications in flexible electronics due to the low glass-transition temperatures of flexible substrates. High performance In-Al-Zn-O (IAZO) TFTs with a homogeneous dual-active-layer structure are successfully fabricated at room temperature. The electrical properties including bias and illumination stabilities of the as-fabricated devices are investigated. The sputtered bilayer IAZO films are firstly prepared on SiO2/p(+)-Si substrates with different bottom (low-oxygen)/top (high-oxygen) layer thicknesses. When the thicknesses of the bottom top layers are 20/10 nm, IAZO TFT exhibits the best overall performance and highest negative-bias-illumination stability, including a high saturation-mobility (12.05 cm(2) V-1 s(-1)) and a small threshold-voltage-shift (- 0.73 V). Then, in order to reduce the operating-voltage and meet the requirements of low temperature fabrication for flexible IAZO TFTs, a 70-nm-thick room-temperature-sputtered Ta2O5 film is employed to be the gate insulator. The performance of IAZO TFTs with Ta2O5 is greatly improved, especially the saturation-mobility (19.56 cm(2) V-1 s(-1)) and subthreshold-swing (81 mV dec(-1)). They also exhibit outstanding bias and illumination stabilities as compared to the IAZO TFTs using SiO2. The largest threshold-voltage-shifts under positive-bias-illumination (5 V) and laser-illumination (450 nm) stresses are only - 0.78 and 0.05 V, respectively. (C) 2020 Elsevier B.V. All rights reserved.
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