Electrical Stability and Flicker Noise of Thin-Film Heterojunction FETs on Poly-Si Substrates

Electrical stability and flicker (1/f) noise of thin-film heterojunction field-effect transistors (HJFETs) comprised of hydrogenated amorphous Si (a-Si:H) gate and hydrogenated crystalline Si (c-Si:H) source and drain regions on small-grain poly-Si substrates are investigated and benchmarked against conventional thin-film transistors (TFTs). Despite the low growth temperature of a-Si:H and c-Si:H (~200°C), HJFETs are found to have higher stability and lower flicker noise than conventional TFTs. These results may be attributed partly to the device structure and partly to the high-quality gate heterojunction of the HJFETs.