Metastability of hot-wire amorphous-silicon thin-film transistors

Defect-state creation in hydrogenated amorphous-silicon causes a threshold- voltage shift in thin-film transistors (TFTs) after gate-voltage stress. We studied this metastable effect in transistors based on silicon deposited b y hat-wire chemical vapor deposition. Amorphous as well as heterogeneous si licon, incorporating some fraction of crystallites were used. We demonstrat e that such TFTs have a performance with a held-effect mobility of 1.4 cm(2 )/V s in an inverted-staggered structure. A threshold-voltage of 4.6 V was found for TFTs based on heterogeneous silicon deposited on silicon oxide. T he threshold-voltage shift in these TFTs could be fitted with the same func tion as for amorphous-silicon TFTs. All hot-wire TFTs had a stability bette r than that of state-of-the-art devices prepared by plasma-enhanced chemica l vapor deposition (PECVD). (C) 2000 Elsevier Science B.V. All rights reser ved.