Department of Chemistry, Northwestern University, Evanston Illinois 60208, USA.
Nano Lett. 2012 Aug 8;12(8):4200-5. doi: 10.1021/nl301787g. Epub 2012 Jul 16.
A lack of consensus persists regarding the origin of photoluminescence in silicon nanocrystals. Here we report pressure-dependences of X-ray diffraction and photoluminescence from alkane-terminated colloidal particles. We determine the diamond-phase bulk modulus, observe multiple phase transitions, and importantly find a systematic photoluminescence red shift that matches the X(conduction)-to-Γ(valence) transition of bulk crystalline silicon. These results, reinforced by calculations, suggest that the efficient photoluminescence, frequently attributed to defects, arises instead from core-states that remain highly indirect despite quantum confinement.
硅纳米晶体的光致发光起源问题仍然缺乏共识。在这里，我们报告了烷烃封端胶体颗粒的 X 射线衍射和光致发光随压力的变化。我们确定了金刚石相的体弹性模量，观察到了多个相变，重要的是发现了一个系统的光致发光红移，与体结晶硅的 X(conduction)-to-Γ(valence)跃迁相匹配。这些结果得到了计算的支持，表明通常归因于缺陷的高效光致发光，实际上来自于尽管受到量子限制但仍保持高度间接的核心态。
