Advanced Multilayer Amorphous Silicon Thin-Film Transistor Structure: Film Thickness Effect on Its Electrical Performance and Contact Resistance

Abstract

We report the intrinsic and extrinsic electrical characteristics of advanced multilayer amorphous silicon (a-Si:H) thin-film transistor (TFT) with dual amorphous silicon nitride (a-SiNX:H) and a-Si:H layers. The thickness effect of the high electronic quality a-Si:H film on the transistor's electrical property was investigated; with increasing film thickness, both field-effect mobility and subthreshold swing show improvement and the threshold voltage remain unchanged. However, the contact resistance increases with the a-Si:H film thickness. Using the two-step plasma enhanced chemical vapor deposition process, we fabricated TFT's with acceptable field-effect mobility (∼1 cm2 V-1 s-1) and threshold voltage (<1.5 V) with enhanced throughput.