Amorphous Ge quantum dots embedded in crystalline Si -ab initioresults
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2015-09-24 |
| Journal | Journal of Physics Condensed Matter |
| Authors | M Laubscher, Sebastian KĆ¼fner, Peter Kroll, F. Bechstedt |
| Institutions | The University of Texas at Arlington, Friedrich Schiller University Jena |
| Citations | 17 |
Abstract
Section titled āAbstractāWe study amorphous Ge quantum dots embedded in a crystalline Si matrix through structure modeling and simulation using ab initio density functional theory including spin-orbit interaction and quasiparticle effects. Three models are generated by replacing a spherical region within diamond Si by Ge atoms and creating a disordered bond network with appropriate density inside the Ge quantum dot. After total-energy optimisations of the atomic geometry we compute the electronic and optical properties. We find three major effects: (i) the resulting nanostructures adopt a type-I heterostructure character; (ii) the lowest optical transitions occur only within the Ge quantum dots, and do not involve or cross the Ge-Si interface. (iii) for larger amorphous Ge quantum dots, with diameters of about 2.0 and 2.7 nm, absorption peaks appear in the mid-infrared spectral region. These are promising candidates for intense luminescence at photon energies below the gap energy of bulk Ge.