Assessing Carrier Recombination Processes in Type-II SiGe/Si(001) Quantum Dots
Sprache des Titels:
Englisch
Original Kurzfassung:
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.