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

摘要

Instability of amorphous InGaZnO thin-film transistors under pulsed gate voltage (V_g) stress with steep transitions was experimentally investigated. The device threshold voltage (Vth) 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 Vth 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.