Porous silicon photoluminescence and quantum confinement

摘要

Images obtained from scanning tunnelling microscopy and atomic force microscopy reveal nanoscale features on hydrogen-passivated porous silicon surfaces. These surface features are altered by varying the chemical etching procedure, resulting in shifts in the wire size and consequent variations in the photoluminescence spectra. The morphology consists of wires with associated nodules. Consistent with the quantum confinement model, the widths of these features range from 1 to 7 nm, and the size distribution and photoluminescence peaks agree with theoretical predictions based on a second-neighbour, empirical tight-binding approximation. In tote, these observations demonstrate that such novel surface features are necessary for the photoluminescence of porous silicon and are consistent with the requirements of the quantum confinement model of porous silicon.