Temperature analysis of polysilicon thin-film transistors made by excimer laser crystallization

摘要

The transfer and output electrical characteristics of polysilicon thin film transistors have been measured in the temperature range from 400 to 80 K. The devices, with the active layer made by excimer laser crystallization of amorphous silicon, show high field-effect mobility values (>200 cm~2/Vs), even at low temperature. The electrical characteristics have been analyzed using a uniformly distributed density of states (DOS) model. Using the DOS derived from the values of the conductance at various temperatures, we have calculated the transfer characteristics and the threshold voltage versus temperature, obtaining a very good agreement with experimental data. The output characteristics show for all temperatures the anomalous current increase, commonly referred to as the 'kink effect', that appears at lower V_(ds) as the temperature is decreased. This temperature dependence is related to the threshold voltage variation with temperature