Mixed Si-Ge nanoparticle quantum dots: a density functional theory study
| Autor: | Shaun C. Hendy, B. G. Walker, Richard D. Tilley |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Materials science
Absorption spectroscopy Solid-state physics Condensed matter physics business.industry chemistry.chemical_element Nanoparticle Germanium Time-dependent density functional theory Condensed Matter Physics Molecular physics Electronic Optical and Magnetic Materials Semiconductor chemistry Quantum dot Physics::Atomic and Molecular Clusters Density functional theory business |
| Zdroj: | The European Physical Journal B. 72:193-201 |
| ISSN: | 1434-6036 1434-6028 |
| Popis: | We present a systematic study of small mixed composition Si and Ge nanoparticle quantum dots performed using density functional theory (DFT) and time-dependent density functional theory (TDDFT) with real space grids and norm-conserving pseudopotentials. Quantum dot models are obtained by distributing Si and Ge atoms within basic models containing a specified number of atomic sites, tetrahedrally-coordinated about a central site, with H atoms added to terminate the surfaces. We consider models containing up to 35 semiconductor atoms, and a number of subsets of the total number of possible configurations (e.g. alternating elements in successive shells). Following calculation of structural and energetic properties, the optical absorption spectra are determined using time-dependent DFT within Casida's linear-response approach. With respect to Si, the inclusion of Ge moves spectral weight to lower energies. We observe that the relative fractions of Si and Ge have stronger effects on the absorption spectra than the structural distribution of those atoms within the nanoparticle, which tends to have quite small effects. |
| Databáze: | OpenAIRE |
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