Assessing Carrier Recombination Processes in Type-II SiGe/Si(001) Quantum Dots

• Authors: HACKL Florian; GRYDLIK Martyna; KLENOVSKÝ Petr; SCHAEFFLER Friedrich; FROMHERZ Thomas; BREHM Moritz
• Year of publication: 2019
• Type: Article in Periodical
• Magazine / Source: Annalen der Physik (Berlin)
• MU Faculty or unit: Faculty of Science
• Web: https://onlinelibrary.wiley.com/doi/epdf/10.1002/andp.201800259
• Doi: http://dx.doi.org/10.1002/andp.201800259
• Keywords: SiGe/Si;kvantove tecky;rekombinacni procesy;kp teorie
• Description: In this work, it is shown how different carrier recombination paths significantly broaden the photoluminescence (PL) emission bandwidth observed in type-II self-assembled SiGe/Si(001) quantum dots (QDs). QDs grown by molecular beam epitaxy with very homogeneous size distribution, onion-shaped composition profile, and Si capping layer thicknesses varying from 0 to 1100 nm are utilized to assess the optical carrier-recombination paths. By using high-energy photons for PL excitation, electron-hole pairs can be selectively generated either above or below the QD layer and, thus, clearly access two radiative carrier recombination channels. Fitting the charge carrier capture-, loss- and recombination-dynamics to PL time-decay curves measured for different experimental configurations allows to obtain quantitative information of carrier capture-, excitonic-emission-, and Auger-recombination rates in this type-II nano-system.

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