Abnormal Subthreshold Swing Decrease in a-InGaZnO Thin-Film Transistor After Self-Heating Stress

This study investigates abnormal decreased subthreshold swing (S.S.) and increased
${I}_{ \mathrm{\scriptscriptstyle ON}}$
in back-channel etch (BCE) InGaZnO (IGZO) thin-film transistors (TFTs) under self-heating stress (SHS) operation. With confirmation of the energy band diagram via gate-to-source (
${C}_{\text {GS}}$
) and gate-to-drain capacitance (
${C}_{\text {GD}}$
) measurements of the capacitance–voltage (
${C}$
–
${V}$
) curve, the degradation mechanism is further inferred. The degradation arises from uneven trapped charges by the thermal field. To illustrate the mechanism, the device with uneven trapped charges and the double-gate device with different values of
${V}_{\text {TH}}$
are simulated by SILVACO-TCAD.