HIGH FIELD-EFFECT-MOBILITY A-SI-H TFT BASED ON HIGH DEPOSITION-RATE PECVD MATERIALS

The hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFT 's) having a field-effect mobility of 1.45 +/- 0.05 cm(2)/V . s and th reshold voltage of 2.0 +/- 0.2 V have been fabricated from the high de position-rate plasma-enhanced chemical vapor deposited (PECVD) materia ls, For this TFT, the deposition rates of a-Si:H and N-rich hydrogenat ed amorphous silicon nitride (a-SiN1.5:H) are about 50 and 190 nm/min, respectively, The TFT has a very high ON/OFF-current ratio (of more t han 10(7)), sharp subthreshold slope (0.3 +/- 0.03 V/decade), and very low source-drain current activation energy (50 +/- 5 meV), All these parameters are consistent with a high mobility value obtained for our a-Si:H TFT structures. To our best knowledge, this is the highest fiel d-effect mobility ever reported for an a-Si:H TFT fabricated from high deposition-rate PECVD materials.