High current stress effects in amorphous-InGaZnO4 thin-film transistors

Abstract

Amorphous-InGaZnO4 (a-IGZO) thin-film transistors (TFTs) on glass undergo large positive threshold voltage shifts (ΔVTH) under high current stress (HCS)—a consequence of Joule heating of the active-layer. Here, we show that when the active layer is split into smaller parts, HCS induces negligible ΔVTH. When the active layer heats up during HCS, conducting electrons in the channel gain enough energy to surmount the energy barrier at the active-layer/gate-insulator interface and become trapped into deep states inside the gate-insulator. Splitting the active-layer into smaller parts increases the surface area for heat dissipation, resulting in the elimination of these self-heating effects.