Hydrogenated amorphous silicon thin film transistor fabricated on plasma treated silicon nitride

We have demonstrated that the performance of the inverted staggered, hydrogenated amorphous silicon thin film transistor (a-Si:H TFT) is improved by a He, H/sub 2/, NH/sub 3/ or N/sub 2/ plasma treatment for a short time on the surface of silicon nitride (SiN/sub x/) before a-Si:H deposition. With increasing plasma exposure time, the field-effect mobility increase at first and then decrease, but the threshold voltage changes little. The a-Si:H TFT with a 6-min N/sub 2/ plasma treatment on SiN/sub x/ exhibited a field effect mobility of 1.37 cm/sup 2//Vs, a threshold voltage of 4.2 V and a subthreshold slope of 0.34 V/dec. It is found that surface roughness of SiN/sub x/ is decreased and N concentration in the SiN/sub x/ at the surface region decreases using the plasma treatment.