An Analytical Hot-Carrier Induced Degradation Model in Polysilicon TFTs

Hot-carrier effects in n-channel polysilicon thin-film transistors (TFTs), with channel width W=10 /spl mu/m and length L=10 /spl mu/m, are investigated. An analytical model predicting the post-stress performance is presented, by treating the channel of the stressed device as a series combination of a damaged region extended over a length /spl Delta/L beside the drain and a region of length L-/spl Delta/L having the properties of the unstressed device. The apparent channel mobility is derived considering that the mobility of the damaged region is described with the mobility of amorphous Si TFTs, whereas the mobility of the undamaged region is described with the mobility of the virgin device. From the evolution of the static characteristics during stress, the properties of the damaged region with stress time are investigated.