Switching performance of high rate deposition processing a-Si:H TFTs

We studied the switching performance of thin film transistors fabricated using high deposition rate hydrogenated amorphous silicon deposited at high temperature. High field effect mobility was obtained with material deposited at rates close to 100 nm/min. The mobility decreased, the output characteristics showed current crowding, and capacitance-voltage (C-V) characteristics showed frequency dispersion and did not respond to high frequency when the hydrogenated amorphous silicon deposition rates were further increased. We also studied the performance of thin Nm transistors made using a 2-step deposition process for the hydrogenated amorphous silicon in an attempt to further increase the effective deposition rate. By using the 2-step process for hydrogenated amorphous silicon deposition, both static and dynamic mobility were improved and the charging of the pixel was not seriously affected for material deposited at close to similar to 200 nm/min.