Collective Modes in the Luminescent Response of Si Nanodisk Chains with Embedded GeSi Quantum Dots
In this paper, we study the effects of GeSi quantum dot emission coupling with the collective
modes in the linear chains of Si disk resonators positioned on an SiO2 layer. The emission spectra
as a function of the chain period and disk radius were investigated using micro-photoluminescence
(micro-PL) spectroscopy. At optimal parameters of the disk chains, two narrow PL peaks, with quality
factors of around 190 and 340, were observed in the range of the quantum dot emission. A numerical
analysis of the mode composition allowed us to associate the observed peaks with two collective
modes with different electric field polarization relative to the chain line. The theoretical study
demonstrates the change of the far-field radiation pattern with increasing length of the disk chain.
The intensive out-of-plane emission was explained by the appearance of the dipole mode contribution.
The obtained results can be used for the development of Si-based near-infrared light sources.