ملخص: Hot carrier effects owing to bias stress are studied in two types of polysilicon TFTs: classical in-situ doped drain TFTs and lightly in-situ doped drain TFTs. Two types of bias stress are applied: a negative bias stress corresponding to a negative gate to drain voltage and a positive bias stress corresponding to a positive gate to drain voltage. The positive bias stress induces hot-hole injection into the gate oxide leading to a decrease of the leakage (off state) current and of the threshold voltage, and to an increase of the transconductance in classical in-situ doped drain TFTs. On the other hand, due to a lower local electric field in the drain junction, no significant change is observed in LDD TFTs. However, by stressing TFTs with a negative bias stress, a very large hot-carrier degradation occurs in lightly in-situ doped drain TFTs due to hot electron injection into the gate oxide.

لغة: إنجليزية