Investigating degradation behaviors induced by hot carriers in the etch stop layer in amorphous InGaZnO thin film transistors with different electrode materials and structures

This work investigates the hot carrier effect in via-contact type amorphous indium gallium zinc oxide thin film transistors with various source/drain materials and structures. According to previous research, the redundant drain electrode plays an important role in hot carrier stress-induced degradation, which leads to carrier-trapping in the etch stop layer between the active layer and the redundant drain electrode. Hot carrier stress has different influences on device characteristics, depending on materials and structure. Hot carrier stress causes more electron trapping in the etch stop layer below the redundant drain electrode in the presence of smaller source/drain metal work function or a longer redundant drain electrode. To further verify the mechanisms of the degradation behavior, the barrier height for Fowler-Nordheim-tunneling is extracted by a fitting charge trapping model. It is found that the barrier height for Fowler-Nordheim-tunneling is different for different source/drain materials.