Abnormal behavior with hump characteristics in current stressed a-InGaZnO thin film transistors

• Published in: Solid-state electronics Vol. 137; pp. 22 - 28
• Main Authors: Kim, Woo-Sic, Cho, Yong-Jung, Lee, Yeol-Hyeong, Park, JeongKi, Kim, GeonTae, Kim, Ohyun
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-11-2017
• Subjects: Current stress; Hump; IGZO; Instability; Joule heating; Turn Around; IGZO; Instability; Hump; Turn Around; Current stress; Joule heating
• ISSN: 0038-1101; 1879-2405
• DOI: 10.1016/j.sse.2017.08.001

•Abnormal turn-around behavior with hump in I-V characteristics was found in current stressed a-IGZO TFTs.•Electric field causes degradation dominantly and Joule heating accelerates the degradation.•Mechanism of asymmetrical degradation was investigated.•Decomposition of I-V curve with hump shows close relationship between Turn-around behavior and acceptor-like states.
We investigated the degradation mechanism of a-InGaZnO TFTs under simultaneous gate and drain bias stress. Gate and drain bias of 20V were applied simultaneously to induce current stress, and abnormal turn-around behavior in transfer characteristics with a hump phenomenon were identified. Hump characteristics were interpreted in terms of parasitic current path, and the degradation itself was found to be caused dominantly by the electrical field and to be accelerated with current by Joule heating. The mechanism of asymmetrical degradation after current stress was also investigated. By decomposing the curves into two curves and measuring the relaxation behavior of the stressed TFTs, we also found that abnormal turn-around behavior in the transfer characteristics was related to acceptor-like states.