Size control of Si nanocrystal with visible Photoluminescence in a-Si:H/nc-Si multilayer structures

We report strong visible photoluminescence at room temperature in a-Si:H/nc-Si multilayer structures. The peak emission energy was controlled by the thickness of the nc-Si layer. The peak energy decreases as the nc-Si thickness was increased from 5 nm to 30 nm, indicating quantum size effects. The structures show photoluminescence at visible to near-infrared, from radiative recombination at the interface between the nc-Si and a-Si:H layers. Thicker layer structures exhibit persistent photoconductivity from carriers trapped at interface states. These nanocrystalline-amorphous Si superlattices offer a pathway for synthesizing embedded Si nanocrystals with controlled sizes and can be integrated with electronic and photonic devices.