Dynamic degradation of a-InGaZnO thin-film transistors under pulsed gate voltage stress

Instability of amorphous InGaZnO thin-film transistors under pulsed gate voltage (V-g) stress with steep transitions was experimentally investigated. The device threshold voltage (V-th) shifts positively depending on the number of pulse repetitions of the applied V-g pulses. For steeper pulse falling time (t(f)), more degradation occurs. In addition, for different base voltages of the V-g pulses, the maximum V-th degradation occurs under the condition that V-g pulses are symmetric about the flat band voltage. Such dynamic degradation is attributed to hot-carrier induced charge injection into the gate insulator and/or trapping at the interface near the source/drain regions during the t(f) transients. (C) 2015 AIP Publishing LLC.