From pseudo-direct hexagonal germanium to direct silicon-germanium alloys
| Autor: | Silvana Botti, Friedhelm Bechstedt, Pedro Borlido, Claudia Rödl, Jens Renè Suckert, Jürgen Furthmüller |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Condensed Matter - Materials Science
Materials science Physics and Astronomy (miscellaneous) Condensed matter physics Band gap Oscillator strength Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences Lonsdaleite chemistry.chemical_element Germanium 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Silicon-germanium chemistry.chemical_compound Lattice constant chemistry Ab initio quantum chemistry methods 0103 physical sciences General Materials Science Direct and indirect band gaps 010306 general physics 0210 nano-technology |
| Zdroj: | Physical Review Materials. 5 |
| ISSN: | 2475-9953 |
| DOI: | 10.1103/physrevmaterials.5.114604 |
| Popis: | We present ab initio calculations of the electronic and optical properties of hexagonal SiGe alloys in the lonsdaleite structure. Lattice constants and electronic band structures in excellent agreement with experiment are obtained using density-functional theory. Hexagonal Si has an indirect band gap, while hexagonal Ge has a pseudo-direct gap, i.e. the optical transitions at the minimum direct band gap are very weak. The pseudo-direct character of pure hexagonal Ge is efficiently lifted by alloying. Already for a small admixture of Si, symmetry reduction enhances the oscillator strength of the lowest direct optical transitions. The band gap is direct for a Si content below 45 %. We validate lonsdaleite group-IV alloys to be efficient optical emitters, suitable for integrated optoelectronic applications. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|