Subband Optical Transitions in a-Si:H Quantum Well Structures

The hydrogenated amorphous silicon (a-Si:H)/silicon carbide (a-SiC_x:H) quantum well (QW) and superlattice structures were fabricated by glow discharge deposition. Wavelength differential absorption spectroscopy has been applied to study the subband transition in a-Si:H/a-SiC_x:H Q W, and derivative spectra change clearly from a linear to a step-like form when a-Si:H well-layer thickness has decreased below 40Å. These results indicate that three-dimensional parabolic band transition is turned into subband transition in the a-Si:H QW.