Effect of annealing time on bias stress and light-induced instabilities in amorphous indium–gallium–zinc-oxide thin-film transistors

Abstract

Thermal post annealing was employed for amorphous indium–gallium–zinc-oxide (a-IGZO) thin-film transistors (TFTs) to optimize performance by a low-temperature process, in view of the envisaged role of a-IGZO in plastic electronics. The effect of annealing time at T = 250 and 280 °C on bias stress and light-induced instabilities was investigated. We find that long anneals are effective in reducing bias stress and light-induced instabilities, as well as hysteresis in the transfer characteristics. The time constant τ for positive bias stress and for negative bias stress increases after long anneal, attaining for positive bias stress the value of 1.05 × 106 s, the highest so far reported for these devices. The beneficial effect of long anneals appears to be because of a reorganization of the amorphous network, resulting in a more stable configuration.