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 recombinatio n in 2D slabs, 1D wires, and OD spheres of hydrogenated amorphous sili con (a-Si:H) showing a significant size dependence of the photolumines cence. Room-temperature peak emission energies >1.8 eV and efficiencie s near unity are possible in a-Si:H spheres with diameters <20 Angstro m. Broad homogeneous linewidths >0.25 eV are also predicted for these highly confined structures. While the effects are similar to those pre dicted from quantum confinement, these results are caused by the stati stics of spatial confinement. We suggest that these results provide in sights into nanostructured a-Si:H structures and porous silicon. (C) 1 996 American Institute of Physics.