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Electron-phonon coupling in n-type Ge two-dimensional systems

Ciano, C.; Persichetti, L.; Montanari, M.; Di Gaspare, L.; Capellini, G.; Baldassarre, L.; Ortolani, M.; Pashkin, O.; Helm, M.; Winnerl, S.; Virgilio, M.; de Seta, M.

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.

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Permalink: https://www.hzdr.de/publications/Publ-31751
Publ.-Id: 31751


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