Leakage current variation during two different modes of electrical stressing in undoped hydrogenated n-channel polysilicon thin film transistors (TFTs)

Leakage current evolution during two different modes of electrical stressin g in hydrogenated-undoped n-channel polysilicon thin film transistors (TFTs ) is studied in this work. On-state bias stress (high drain bias and positi ve gate bias) and off-state bias stress (high drain bias and negative gate bias) were performed in order to study the degradation of the leakage curre nt. It is found that during off-state bias stress the gate oxide is more se verely damaged than the SiO2-polySi interface. In contrast, during on-state bias stress, two different degradation mechanisms were detected which are analyzed. (C) 1999 Elsevier Science Ltd. All rights reserved.