PERFORMANCE IMPROVEMENT OF AMORPHOUS-SILICON THIN-FILM TRANSISTORS WITH SIO2 GATE INSULATOR BY N-2 PLASMA TREATMENT

We studied the performance improvement of hydrogenated amorphous silic on (a-Si:H) thin-film transistor (TFT) using atmospheric pressure chem ical vapor deposition (APCVD) SiO2 as a gate insulator. The threshold voltage and the subthreshold swing decrease remarkably by N-2 plasma t reatment on the APCVD SiO2 surface even though the field effect mobili ty changes little, indicating that the interface state density around the Fermi level is reduced significantly by N-2 plasma treatment. We o btained the high performance a-Si:H TFT with the field effect mobility of 1.25 cm(2)/V s, the threshold voltage of 3.5 V and the subthreshol d swing of 0.45 V/dec.