Assessing Carrier Recombination Processes in Type‐II SiGe/Si(001) Quantum Dots. Issue 6 (11th January 2019)

• Record Type: Journal Article
• Authors: Hackl, Florian; Grydlik, Martyna; Klenovský, Petr; Schäffler, Friedrich; Fromherz, Thomas; Brehm, Moritz
• Other Names: Ruffenach Sandra guestEditor.; Tchernycheva Maria guestEditor.
• Is Part Of: Annalen der Physik. Volume 531:Issue 6(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-01-11
• Subjects: molecular beam epitaxy -- photoluminescence -- quantum dots -- silicon‐germanium -- time‐resolved spectroscopy; Physics -- Periodicals; Chemistry -- Periodicals; 530.05
• DOI: 10.1002/andp.201800259
• Languages: English
• ISSNs: 0003-3804

Abstract

Abstract: 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. Abstract : It is demonstrated that type‐II self‐assembled quantum dots are affected by a significant broadening of their photoluminescence emission bandwidth caused by different carrier recombination paths. These recombination channels are assessed by selective generation of electron‐hole pairs either above or below the quantum dots. From time‐resolved spectroscopy, pair‐ and Auger‐recombination rates of different transitions are determined quantitatively.