Department of Mechanical and Control Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan.
Langmuir. 2013 Feb 12;29(6):1802-7. doi: 10.1021/la3042082. Epub 2013 Jan 28.
We investigate the size-dependent optical extinction properties of colloidal silicon nanocrystals (Si NCs) from the near infrared (NIR) to the ultraviolet (UV). Experimental results are compared to the Mie solution to Maxwell's equations using the same refractive index as bulk Si to evaluate the deviation from bulk properties. We find that the energy for the lowest direct transition (E(1)) continuously blueshifts from near bulk-like at ~3.4 eV in large NCs (16 nm) to ~3.6 eV for small NCs (3.9 nm), contrary to the Mie solution. The extinction cross-section of NCs on a per atom basis was found to be independent of the NC size, within our experimental resolution. The results suggest that quantum confinement effects strongly influence excitons associated with the E(1) transition.
我们研究了胶体硅纳米晶体（Si NCs）的尺寸依赖性光消光特性，范围从近红外（NIR）到紫外（UV）。将实验结果与麦克斯韦方程的米氏解进行比较，使用与体硅相同的折射率来评估与体硅性质的偏差。我们发现，最低直接跃迁（E（1））的能量连续蓝移，从大 NCs（16nm）中的近体硅样的3.4eV 到小 NCs（3.9nm）中的3.6eV，这与米氏解相反。我们发现，在我们的实验分辨率内，每原子的 NC 消光截面与 NC 尺寸无关。结果表明，量子限制效应强烈影响与 E（1）跃迁相关的激子。
