Electronic structure of lonsdaleite $\mathrm{Si}_{x}\mathrm{Ge}_{1-x}$ alloys
| Autor: | Christopher A. Broderick |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Photoluminescence
Materials science Silicon Condensed matter physics Band gap business.industry chemistry.chemical_element Lonsdaleite Diamond Germanium 02 engineering and technology Electronic structure engineering.material 021001 nanoscience & nanotechnology 01 natural sciences Condensed Matter::Materials Science chemistry Ab initio quantum chemistry methods 0103 physical sciences engineering Optoelectronics 010306 general physics 0210 nano-technology business |
| Zdroj: | 2020 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD). |
| DOI: | 10.1109/nusod49422.2020.9217637 |
| Popis: | Conventional diamond-structured silicon (Si) and germanium (Ge) possess indirect fundamental band gaps, limiting their potential for applications in light-emitting devices. However, $\mathrm{Si}_{x}\mathrm{Ge}_{1-x}$ alloys grown in the lonsdaleite (“hexagonal diamond”) phase have recently emerged as a promising direct-gap, Si-compatible material system, with experimental measurements demonstrating strong room temperature photoluminescence. When grown in the lonsdaleite phase, Ge possesses a narrow ( $\sim 0.3 \mathrm{eV}$ ) “pseudo-direct” fundamental band gap. Lonsdaleite Si is indirect-gap ( $\sim 0.8 \mathrm{eV}$ ), creating the possibility to achieve direct-gap lonsdaleite $\mathrm{Si}_{x}\mathrm{Ge}_{1-x}$ alloys across a Ge-rich composition range. We present a first principles analysis of the electronic and optical properties of lonsdaleite $\mathrm{Si}_{x}\mathrm{Ge}_{1-x}$ alloys, elucidate the electronic structure evolution and direct- to indirect-gap transition, and describe the impact of alloy band mixing effects on inter-band optical transition strengths. |
| Databáze: | OpenAIRE |
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