Roles of Gate Voltage and Stress Power in Self-Heating Degradation of a-InGaZnO Thin-Film Transistors

Roles of gate voltage (V
_G
) and stress power in self-heating (SH) degradation of amorphous InGaZnO thin-film transistors have been clarified. Normally observed positive threshold voltage (V
_th
) shift is attributed to the electron trapping mechanism, which is enhanced by both the effective V
_G
and stress power. The effective V
_G
plays a dominant role in most cases, while stress power takes control only if it is high enough. Following the positive V
_th
shift, a second-stage negative V
_th
backshift is also observed and is attributed to the water-related positive charges generation mechanism. It is enhanced by both stress power and effective V
_G
for which stress power is found to be the dominant factor.