Low frequency noise in polysilicon thin film transistors: effect of the laser annealing of the active layer

Abstract

International audienceLow-frequency noise is studied in N-channel polysilicon TFTs issued from two (low temperature '600°C) technologies: fur-nace solid phase crystallized (FSPC) and laser solid phase crystallized (LSPC) TFTs. The distribution of the trap states (DOS) into the polysilicon bandgap determined for devices biased in the weak inversion is one decade lower for LSPC devices. The high range values 'Α' of the measured macroscopic noise parameter, defined according to the Hooge empirical re-lationship, are explained by the drain current crowding due to structural defects within the active layer. The higher values of Α for the LSPC TFTs are attributed to a better structural quality of the active layer

Optimization of charge pumping technique in polysilicon TFTs for geometric effect elimination and trap state density extraction

“…Fig.8 is the semi-log plot of the energy distribution obtained by Eq.5 and Eq.6. This dual exponential distribution has a small slope of 0.597 eV-1 for deep states and a large slope of 5.039 eV-1 for tail states, agreeing with the typical energy distribution of D t determined from other measurements [14,15]. The current result obtained by using optimized CP technique is in contrast to that in some previous CP studies for polysilicon TFTs, where irregular or distorted energy distribution of D t was obtained [5,6].…”