1. Electron-phonon coupling in n-type Ge two-dimensional systems
- Author
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Chiara Ciano, M. De Seta, Michele Virgilio, Michele Montanari, Leonetta Baldassarre, Giovanni Capellini, Alexej Pashkin, S. Winnerl, L. Di Gaspare, Manfred Helm, Michele Ortolani, Luca Persichetti, Ciano, C., Persichetti, L., Montanari, M., Di Gaspare, L., Capellini, G., Baldassarre, L., Ortolani, M., Pashkin, A., Helm, M., Winnerl, S., Virgilio, M., and De Seta, M.
- Subjects
Coupling ,Materials science ,Settore FIS/03 ,Condensed matter physics ,Phonon ,intersubband ,Heterojunction ,02 engineering and technology ,FLASH ,021001 nanoscience & nanotechnology ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,01 natural sciences ,Symmetry (physics) ,Condensed Matter::Materials Science ,quantum wells ,QCL ,0103 physical sciences ,Transmittance ,Relaxation (physics) ,010306 general physics ,0210 nano-technology ,Spectroscopy ,Electron-Phonon Coupling ,Realization (systems) - Abstract
Electron-optical phonon interaction is the dominant energy-loss mechanism in low-dimensional Ge/SiGe heterostructures and represents a key parameter for the design and realization of electronic and optoelectronic devices based on this material system compatible with the mainstream Si complementary metal-oxide semiconductor technology. Here we investigate the intersubband relaxation dynamics of $n$-type Ge/SiGe multiquantum wells with different symmetry and design by means of single-color pump-probe spectroscopy. By comparing the experimental differential transmittance data as a function of the pump-probe delay with numerical calculations based on an energy-balance rate-equation model, we could quantify an effective value for the optical phonon deformation potential describing the electron-phonon coupling in two-dimensional Ge-based systems. We found nonradiative relaxation times longer than 20 ps even in samples having intersubband energy separations larger than the optical phonon energy, evidencing the presence of a less effective electron-phonon coupling with respect to that estimated in bulk Ge.
- Published
- 2020