The Effect of the Active Layer Thickness on the Negative Bias Stress-Induced Instability in Amorphous InGaZnO Thin-Film Transistors

• Published in: IEEE electron device letters Vol. 32; no. 10; pp. 1388 - 1390
• Main Authors: Kong, Dongsik, Jung, Hyun-Kwang, Kim, Yongsik, Bae, Minkyung, Jeon, Yong Woo, Kim, Sungchul, Kim, Dong Myong, Kim, Dae Hwan
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.10.2011; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Active layer thickness; amorphous InGaZnO (a-IGZO) TFTs; Applied sciences; Bias; Computer simulation; density-of-states (DOS); Disk operating system (DOS); Electronics; Exact sciences and technology; Hysteresis; Instability; Lighting; Logic gates; negative bias stress (NBS)-induced instability; NIST; Semiconductor devices; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Solvents; Stress; Thin film transistors; Transistors; Surface field; Voltage threshold; Amorphous material; Density of states; density-of-states (DOS); negative bias stress (NBS)-induced instability; Electric stress; Active layer; Active layer thickness; amorphous InGaZnO (a-IGZO) TFTs; Electric field; Stress effects; Thin film transistor
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2011.2161746

The effect of the active layer thickness ( T IGZO ) on the negative bias stress (NBS)-induced threshold voltage shift (Δ VT ) in amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) is investigated and explained by using a subgap density-of-states (DOS) model. The NBS-induced negative Δ VT in a-IGZO TFT with a thinner T IGZO is larger than that with a thicker T IGZO . Based on the simulation result with the subgap DOS model, it is concluded that the T IGZO -dependent Δ VT is originated from the accelerated creation of shallow donor states due to a higher surface electric field in a-IGZO TFTs with a thinner T IGZO .