MULTILAYERED AMORPHOUS SILICON STRUCTURES

Abstract
Ultra-thin multiple layered structures which consist of hydrogenated amorphous silicon (a-Si:H) and silicon nitride (a-Si_1-XN_X:H) have been systematically studied as a new class of semiconductor superlattices. The layer thickness can be controlled on an atomic scale, and hence the optical and electrical properties have been interpreted by assuming the quantized states in the potential well layers, as in the case of crystalline semiconductor superlattices. The existence of the quantized levels in the a-Si:H well layer has been directly demonstrated by observing the resonant tunneling current through a-Si:H/a-Si₃N₄:H double barrier structures. Novel thin film transistors (TFTs) in which the a-Si:H/a-Si_1-XN_X:H multilayer is employed as an active region have been designed and fabricated.