Mobility and Stability Enhancement of Amorphous In-Ga-Zn-O TFTs With Atomic Layer Deposited Al₂O₃/SiO₂ Stacked Insulators

• Main Authors: Li-Li Zheng, Shi-Bing Qian, You-Hang Wang, Wen-Jun Liu, Shi-Jin Ding
• Format: Article
• Language: English
• Published: IEEE 2016-01-01
• Series: IEEE Journal of the Electron Devices Society
• Subjects: Amorphous In-Ga-Zn-O; thin-film transistor; SiO2 buffer layer; negative gate bias stress
• Online Access: https://ieeexplore.ieee.org/document/7482673/

Amorphous In-Ga-Zn-O (a-IGZO) thin film transistors (TFTs) were fabricated with an atomic-layer-deposited (ALD) SiO₂ buffer layer between the a-IGZO channel and the Al₂O₃ dielectric. Compared with the TFTs with a single Al₂O₃ dielectric, the a-IGZO TFTs with the Al₂O₃/SiO₂ stacked insulator demonstrated improved performance. That is, the field-effect mobility increased from 12.3 to 16.2 cm²V^-1s^-1, the threshold voltage (Vth) and subthreshold swing (SS) decreased from 1.14 to 0.72 V and from 0.48 to 0.30 V/dec, respectively. Furthermore, the Al₂O₃/SiO₂ device also exhibited better electrical stability under negative gate bias stress and negative bias illumination stress than the Al₂O₃ device. These are mainly attributed to improved interfacial properties between IGZO and SiO₂. Such a buffer layer of ALD SiO₂ in a-IGZO TFTs is very promising for practical applications.