Title :
Two-step Electrical Degradation Behavior in α-InGaZnO Thin-film Transistor Under Gate-bias Stress
Author :
Fa-Hsyang Chen ; Tung-Ming Pan ; Ching-Hung Chen ; Jiang-Hung Liu ; Wu-Hsiung Lin ; Po-Hsueh Chen
Author_Institution :
Dept. of Electron. Eng., Chang Gung Univ., Taoyuan, Taiwan
Abstract :
Investigated transfer characteristics on threshold voltage instability behavior in amorphous indium-gallium-zinc oxide thin-film transistor (α-IGZO TFT). A two-step electrical degradation behavior of α-IGZO TFT was found under gate-bias stress. A usual small positive shift followed by a special negative shift of threshold voltage is characterized in the α-IGZO TFT device. We suggest that the positive shift of the threshold voltage is due to the charge trapping in the gate dielectric and/or at the channel/dielectric interface, while the negative shift of threshold voltage is assigned to electric field-induced extra electron carriers from H2O molecules in the back channel protective layer. We conclude that the H2O molecules and the quality of passivation layer affect the degradation behavior of α-IGZO TFT devices.
Keywords :
amorphous semiconductors; circuit stability; gallium compounds; indium compounds; passivation; thin film transistors; α-IGZO TFT device; InGaZnO; amorphous indium-gallium-zinc oxide thin-film transistor; back channel protective layer; channel/dielectric interface; charge trapping; electric field-induced extra electron carrier; gate dielectric; gate-bias stress; negative shift; passivation layer; positive shift; threshold voltage instability behavior; transfer characteristics; two-step electrical degradation behavior; Charge carrier processes; Degradation; Logic gates; Stress; Thin film transistors; Threshold voltage; Amorphous indium-gallium-zinc oxide ($alpha$ -IGZO); gate-bias stress; reliability; thin-film transistor (TFT); two-step degradation;
Journal_Title :
Electron Device Letters, IEEE
DOI :
10.1109/LED.2013.2248115
