Light Emission from Porous Silicon Photoetched in Aqueous Alkali Salt Solutions

概要

論文の詳細を見る
An interband-transition model was applied to explain the emission mechanism in porous silicon (PSi) fabricated by photoetching in aqueous HF and salt (NaF and KF) solutions. The HF-formed samples show a yellow photoluminescence band at ${\sim}2$ eV. The salt-formed samples, on the other hand, show an ultraviolet (UV) emission peak at ${\sim}3.3$ eV with a spectral width of ${\sim}0.1$ eV, together with a broad emission band at ${\sim}2.7$ eV. The broad emission bands at ${\sim}2$ and ${\sim}2.7$ eV can be explained by the quantum-mechanical confinement effect, i.e., a relaxation of the momentum conservation at and above the indirect-absorption edge (supra-$E_{\text{g}}^{\text{ID}}$ emission). This effect may also lead to a change in the $E_{1}$ critical point (CP) from the two-dimensional M0 to the zero-dimensional CP with decreasing nanocrystalline size. The change in the $E_{1}$-CP dimensionality makes possible an emission in the UV region with a narrow spectral width.
2007-07-15