A model of size-dependent photoluminescence in amorphous silicon nanostructures: Comparison with observations of porous silicon

We present calculations using a simple model of radiative recombination in 2D slabs, 1D wires, and OD spheres of hydrogenated amorphous silicon (a-Si:H) showing a significant size dependence of the photoluminescence. Room-temperature peak emission energies >1.8 eV and efficiencies near unity are possible in a-Si:H spheres with diameters <20 Angstrom. Broad homogeneous linewidths >0.25 eV are also predicted for these highly confined structures. While the effects are similar to those predicted from quantum confinement, these results are caused by the statistics of spatial confinement. We suggest that these results provide insights into nanostructured a-Si:H structures and porous silicon. (C) 1996 American Institute of Physics.