Luminescence of silicon materials : chains, sheets, nanocrystals, nanowires, microcrystals, and porous silicon

Both nanocrystal silicon and porous silicon thin films show efficient visible luminescence at room temperature, thus suggesting the possibility of introducing some form of optically active, silicon-based material into integrated circuit processing. In this context, I discuss and analyze the responsible electronic quantum size effects and excited-state photophysics. In a broader context I discuss silicon optical and electronic properties as a function of dimensionality and surface chemistry. As one progresses from trans-polysilane (1D-Si) through puckered sheet polysilyne (2D-Si) to diamond lattice silicon (3D-Si), there is a systematic progression from direct to indirect gap behavior