A new a-Si TFT(Thin Film '&insistor) with an A1 gate electrode and an A1 0 / SiN double-layered gate insulater has been developed, and this TFT has been successfully applied to the 10.4-inch diagonal multicolor display panel. A1 is a low resistivity metal and it is also possible to form Alz O 3 by anodic oxidation.These features contribute greatly to decreasing the number of defects in the panel and are indispensable for manufacturing large -size display. The Al. which is used as a gate electrode, can also be used as a gate bus-line metal. As a result, the gate bus -line resistance of the panel can be reduced to about 2 KQ and this is quite effective to improve the image quality of the panel.