Fabrication of Nanostructures in Group IV Semiconductors

摘要

The objectives of this work combine a study of the fundamental mechanisms oflight emission from porous silicon (PoSi) with the development of techniques for fabricating PoSi-based light emitting structures and devices. The incubation time of PoSi formation was found to have a strong dependence on the substrate doping type and concentration. Utilizing the incubation time difference and Ga+ FIB implantation a process was successfully developed to fabricate selective light emitting Si structures embedded in a conventional Si substrate. Sub-micron resolution was achieved for the first time. It was observed that a minimum level of crystallinity is required for PoSi layers to exhibit visible PL. A unique correlation exists between the level of crystallinity of the starting Si film and the presence of surface oxyhydrides and photoluminescence after stain-etching. Visible LED's using stain-etched PoSi have superior electrical characteristics and achieved the best ideality factor, the highest rectifying ratio and the lowest EL onset current reported to date. The stain-etch process is much simpler than anodization and can be used to form sub-micron luminescent PoSi patterns and to produce luminescing poly-PoSi films on quartz and glass. These results demonstrate a very promising technique for fabrication of PoSi-based LED's.