Two dimensional simulation and modeling of the electrical behavior in nanocrystalline silicon thin-film transistors

Abstract

Nanocrystalline silicon thin-film transistors present technological interest in that they combine many of the advantages of amorphous with those of polycrystalline Si structures. Progress in practical implementation of this technology is hampered by limited understanding of the conduction mechanisms in these structures and of the underlying relationship between device behavior and process manufacturing parameters. These mechanisms are explored through detailed simulation that includes model calibration and correlation with experimental results, as well as parametric sensitivity evaluation of this class of devices over the entire range of applied voltage. Through fitting of the tests results, a unique set of density of states was identified that characterizes the particular technology used. The leakage current was attributed to the band to band tunneling and thermal generation-recombination mechanisms. For devices with channel length of less than 20μm, the kink effect was observed in the output characteristics for high drain voltages and the impact ionization coefficient was determined.