Amorphous Ge quantum dots embedded in crystalline Si: ab initio results
M Laubscher1, S Küfner, P Kroll
1Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany.
Journal of Physics. Condensed Matter : an Institute of Physics Journal
|September 25, 2015
Summary
We simulated amorphous germanium (Ge) quantum dots in silicon (Si) using advanced computational methods. Our findings show these Ge quantum dots exhibit unique electronic properties and potential for mid-infrared light emission.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Computational Nanoscience
Background:
- Quantum dots (QDs) are crucial for advanced electronic and optical applications.
- Understanding the behavior of amorphous germanium (a-Ge) QDs within a silicon (Si) matrix is key to novel device design.
Purpose of the Study:
- To investigate the structural, electronic, and optical properties of amorphous Ge quantum dots embedded in crystalline Si.
- To explore the potential of these nanostructures for optoelectronic applications.
Main Methods:
- Ab initio density functional theory (DFT) calculations.
- Inclusion of spin-orbit interaction and quasiparticle effects.
- Total-energy optimization of atomic geometry for three distinct models.
Main Results:
- The nanostructures exhibit a type-I heterostructure character.
- Lowest optical transitions are confined within the a-Ge QDs, not crossing the Ge-Si interface.
- Larger a-Ge QDs (2.0-2.7 nm) show mid-infrared absorption peaks.
Conclusions:
- Amorphous Ge quantum dots in Si form type-I heterostructures.
- These QDs are promising for mid-infrared light emission below the bulk Ge band gap energy.
