Enhanced radiative transition inSinGemnanoclusters

2003/04/01 by Ming Yu, C. S. Jayanthi, D. A. Drabold +3
Materials Science · Physics and Astronomy · #Carbon and Quantum Dots Applications #Quantum Dots Synthesis And Properties #Silicon Nanostructures and Photoluminescence #cond-mat.mtrl-sci

paper · pdf · doi:10.1103/physrevb.68.035404

6 figures

arxiv created 2003/04/01 · openalex publication_date 2003/07/01 · arxiv updated 2009/11/30 · openalex created_date 2016/10/28 · openalex updated_date 2026/07/28

Abstract

Using an ab initio molecular-dynamics scheme (the ``fireball'' scheme), we determined the equilibrium structure of intermediate-size Si_nGe_m(n+m=71) nanoclusters with and without hydrogen passivation on the surface. Due to the strong surface distortion, defect states are found to permeate the energy gap of Si_nGe_m clusters. However, the defect states are removed by adding H atoms on the surface of Si_nGe_m clusters, and the gap opens up to a few eV, indicating a blueshift for photoluminescence. It is also found that the radiative transition between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) states is enhanced by one to two orders of magnitude for Si_nGe_m nanoclusters with respect to the corresponding pure Si clusters. This significant increase of the emission probability is attributed to the strong overlap of HOMO and LUMO wave functions centered mostly on the Ge atoms.

Citations

• New Method for Calculating the One-Particle Green's Function with Application to the Electron-Gas Problem
• Electron-hole excitations and optical spectra from first principles
• Self-interaction correction to density-functional approximations for many-electron systems