Li Q S, Zhang R Q, Lee S T, Niehaus T A, Frauenheim Th
Centre of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR, People's Republic of China.
J Chem Phys. 2008 Jun 28;128(24):244714. doi: 10.1063/1.2940735.
Surface functionalization is a critical step for Si nanocrystals being used as biological probes and sensors. Using density-functional tight-binding calculations, we systematically investigate the optical properties of silicon quantum dots (SiQDs) with various termination groups, including H, CH(3), NH(2), SH, and OH. Our calculations reveal that capping SiQDs with alkyl group (-Si-C-) induces minimal changes in the optical spectra, while covering the surface with NH(2), SH, and OH results in evident changes compared to hydrogenated SiQDs. The structural deformations and electronic property changes due to surface passivation were shown to be responsible for the above-described features. Interestingly, we find that the optical properties of SiQDs can be controlled by varying the S coverage on the surface. This tuning effect may have important implications in device fabrications.
表面功能化是硅纳米晶体用作生物探针和传感器的关键步骤。通过密度泛函紧束缚计算，我们系统地研究了具有各种端基（包括H、CH(3)、NH(2)、SH和OH）的硅量子点（SiQD）的光学性质。我们的计算表明，用烷基（-Si-C-）包覆SiQD会使光谱产生最小的变化，而与氢化SiQD相比，用NH(2)、SH和OH覆盖表面会导致明显的变化。表面钝化引起的结构变形和电子性质变化被证明是上述特征的原因。有趣的是，我们发现SiQD的光学性质可以通过改变表面的S覆盖率来控制。这种调谐效应可能在器件制造中具有重要意义。
