CHARACTERISTICS OF POLYCRYSTALLINE-SI THIN-FILM TRANSISTORS FABRICATED BY EXCIMER-LASER ANNEALING METHOD

The electrical characteristics of excimer laser annealed (ELA) polycry stalline-Si thin film transistors (poly-Si TFT's) were investigated. T hese results were compared to those of poly-Si TFT fabricated by solid phase crystallization (SPC). From the temperature dependence of the d rain current, the activation energies of n-type poly-Si TFT's were obt ained. The activation energies have negative values under the gate vol tage from 0 to 5 V. The negative activation energy together with small threshold voltage (V(th)) are the main characteristics of ELA poly-Si TFT. Temperature dependencies of V(th) and field effect mobility are very similar to those of SPC. From these results, it is concluded that the trap state density of ELA poly-Si TFT is very small and the elect rical characteristics can be explained by the band tail states localiz ed at the grain boundary.