Low leakage a-Si:H thin film transistors deposited on glass substrates using hot-wire chemical vapor deposition

Stable, low leakage current hot-wire chemical vapor deposition (HWCVD) thin film transistors (TFTs) were fabricated using graphite filament on Corning 1737 glass substrates. TFTs were deposited using a bottom gate, inverted staggered, self-aligned, low temperature process with a molybdenum metal gate, a trilayer consisting of a HWCVD a-Si:Hi layer sandwiched between two plasma enhanced chemical vapor deposition (PECVD) a-SiNx:H layers, followed by a PECVD n+ a-Si:H Ohmic contact layer, and a final aluminum metal for source and drain contacts. Ion∕Ioff ratio exceeds 108 and the leakage current is less than 10−13A, while the field effect mobility is in the range of 0.13cm2∕Vs and the subthreshold slope is 0.6V∕decade. Time stress bias measurements show β of 0.156 for HW a-Si TFTs, showing superior stability compared to their fully PECVD counterparts.