Top-gate TFTs using 13.56 MHz PECVD microcrystalline silicon

Top-gate thin-film transistors (TFTs) with microcrystalline silicon (mu c-Si) channel layers deposited using standard 13.56 MHz plasma-enhanced chemical vapor deposition were fabricated at a maximum processing temperature of 250 degrees C. The TFTs employ amorphous silicon nitride (alpha-SiN) as the gate dielectric layer. The 80-nm-thick mu c-Si channel layer showed a dark conductivity of the order of 10(-7) S/cm and a crystalline volume fraction of over 80%., The mu c-Si TFTs showed a field effect mobility of 0.85 cm(2)/V (.) s, a threshold voltage of 4.8 V, a subthreshold slope of 1 V/dec, and an ON/OFF current ratio of similar to 10(7). More importantly, the TFTs were very stable under gate bias stress, offering promise for organic light-emitting display (OLED) applications.