M. Hack et al., PHYSICAL MODELS FOR DEGRADATION EFFECTS IN POLYSILICON THIN-FILM TRANSISTORS, I.E.E.E. transactions on electron devices, 40(5), 1993, pp. 890-897
In this paper we present experimental data showing the degradation in
performance of polysilicon Thin-Film Transistors (TFT's) under a varie
ty of bias stress conditions. We propose a model to explain these degr
adation effects whereby device performance degrades due to changes in
the effective density of defect states in the material. Unlike single-
crystal devices which degrade from hot-carrier effects, we believe tha
t poly-Si TFT's degrade primarily due to the presence of high carrier
densities in the channel. We present good agreement between our comput
er simulations of the device characteristics and experimental data. Fi
nally, we show that stressing under transient conditions leads to a mo
re severe performance degradation than stressing under comparable stea
dy-state conditions.