Stable Luminescent Silicon Nanocrystals and Porous Silicon Powders with Very High Quantum Yield Passivated by High-pressure Water Vapor Annealing

摘要

Silicon nanocrystals (SiNCs) have been fabricated using a high-frequency non-thermal plasma reactor.They have been considered for various applications such as photovoltaics, thermoelectricity, andoptoelectronic devices and materials. Here, we report a study of the luminescence of such SiNCs. Theas-prepared SiNCs were mostly spherical, hydrogen-terminated, and exhibited an average size of about 6nm. They did not exhibit visible luminescence as they were too large. In order to get visible luminescencefrom these SiNCs, their size had to be decreased. Oxidation is a convenient technique to achieve this goal,provided that the oxide quality can be good enough to give good surface passivation. However,low-temperature conventional thermal or chemical oxidation techniques generally induce significant defectdensities and do not lead to very stable SiNCs. Nevertheless, one such low-temperature oxidation techniquehas been shown to provide high-efficiency and very stable luminescent porous silicon layers: high-pressurewater vapor annealing (HWA).