Godefroo S, Hayne M, Jivanescu M, Stesmans A, Zacharias M, Lebedev O I, Van Tendeloo G, Moshchalkov V V
INPAC-Institute for Nanoscale Physics and Chemistry, Pulsed Field Group, KU Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium.
Nat Nanotechnol. 2008 Mar;3(3):174-8. doi: 10.1038/nnano.2008.7. Epub 2008 Mar 2.
Silicon dominates the electronics industry, but its poor optical properties mean that III-V compound semiconductors are preferred for photonics applications. Photoluminescence at visible wavelengths was observed from porous Si at room temperature in 1990, but the origin of these photons (do they arise from highly localized defect states or quantum confinement effects?) has been the subject of intense debate ever since. Attention has subsequently shifted from porous Si to Si nanocrystals, but the same fundamental question about the origin of the photoluminescence has remained. Here we show, based on measurements in high magnetic fields, that defects are the dominant source of light from Si nanocrystals. Moreover, we show that it is possible to control the origin of the photoluminescence in a single sample: passivation with hydrogen removes the defects, resulting in photoluminescence from quantum-confined states, but subsequent ultraviolet illumination reintroduces the defects, making them the origin of the light again.
硅在电子工业中占据主导地位，但其光学性能不佳意味着III-V族化合物半导体更适合用于光子学应用。1990年在室温下从多孔硅中观测到了可见波长的光致发光现象，但自那时起，这些光子的起源（它们是源于高度局域化的缺陷态还是量子限制效应？）一直是激烈争论的主题。随后，注意力从多孔硅转移到了硅纳米晶体上，但关于光致发光起源的同一个基本问题依然存在。在此我们基于在强磁场中的测量结果表明，缺陷是硅纳米晶体发光的主要来源。此外，我们还表明在单个样品中有可能控制光致发光的起源：用氢进行钝化会去除缺陷，从而产生源于量子限制态的光致发光，但随后的紫外线照射会再次引入缺陷，使其再次成为发光的起源。
