The experimental investigations of hot carrier induced device degradation in IGZO thin film transistors under light illumination at elevated temperature have been performed. The degradations of threshold voltage and inverse subthreshold slope have been measured with stress time, stress temperature and light intensity. After hot carrier stress, the negative shift of transfer curves and the increased drain current are caused by the generation of a donor-like interface states at the interface between the channel region and the gate dielectric layer. The device degradation is increased with stress temperature and light intensity. Due to the positive temperature dependence of conduction current, the increased device degradation is attributed to the increased channel current at elevated temperature. The increased device degradation under light illumination is due to the increased channel current which is resulted from the photo-generated electron. The device degradation is the most significant at the stress condition of hot carrier stress combined with elevated temperature and light illumination. (c) 2012 Elsevier Ltd. All rights reserved.