Theory of alkyl-terminated silicon quantum dots
Theory of alkyl-terminated silicon quantum dots
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DOI：
10.1021/jp0462254
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发表时间：
2005-01-27
影响因子：
3.3
通讯作者：
Galli, G
中科院分区：
文献类型：
--
作者：
Reboredo, FA;Galli, G
我们进行了一系列从头计算来研究Si量子点的光学性质随表面钝化的变化。特别地，我们比较了氢钝化点和表面有烷基基团的点。我们发现，虽然在具有重构表面的团簇上完全的烷基钝化是可能的，但空间排斥力阻止了具有非重构表面的Si点的完全钝化。此外，我们的计算表明，位阻斥力可能在决定烷基钝化簇的表面结构和最终稳定性方面起主导作用，其结果取决于碳链的长度。烷基钝化对硅量子点的光学间隙影响较弱，但会显著降低其电离势和电子亲和力，影响其激发态性质。在我们的研究结果的基础上，我们提出烷基端部量子点可以选择尺寸，利用电离势的变化作为簇大小的函数。
We have carried out a series of ab initio calculations to investigate changes in the optical properties of Si quantum dots as a function of surface passivation. In particular, we have compared hydrogen-passivated dots with those having alkyl groups at the surface. We find that, while on clusters with reconstructed surfaces complete alkyl passivation is possible, steric repulsion prevents full passivation of Si dots with unreconstructed surfaces. In addition, our calculations show that steric repulsion may have a dominant effect in determining the surface structure and eventually the stability of alkyl-passivated clusters, with results dependent on the length of the carbon chain. Alkyl passivation weakly affects optical gaps of silicon quantum dots, while it substantially decreases ionization potentials and electron affinities and affects their excited state properties. On the basis of our results, we propose that alkyl-terminated quantum dots may be size selected, taking advantage of the change in ionization potential as a function of the cluster size.