CMOS-compatible light emitters are intensely investigated for integrated active silicon photonic circuits. One of the approaches to achieve on-chip light emitters is the epitaxial growth of Ge(Si) QDs on silicon. Their broad emission in the 1.3-1.5 um range is attractive for the telecom applications.
We investigate optical properties of Ge(Si) QD multilayers, which are grown in a thin Si slab on an SOI wafer, by steady-state and time-resolved micro-photoluminescence. We identify Auger recombination as the governing mechanism of carrier dynamics in such heterostructures.
Then we demonstrate the possibility of light manipulation at the nanoscale by resonant nanostructures investigating Si nanodisks with embedded Ge(Si) QDs. We show that the Mie resonances of the disks govern the enhancement of the photoluminescent signal from the embedded QDs due to a good spatial overlap of the emitter position with the electric field of Mie modes. Furthermore, we engineer collective Mie-resonances in a nanodisk trimer resulting in an increased Q-factor and an up to 10-fold enhancement of the luminescent signal due to the excitation of anti-symmetric magnetic and electric dipole modes.
Using time-resolved measurements we show that the minima of the radiative lifetime coincide with the positions of the Mie resonances for a large variation of disk sizes confirming the impact of the Purcell effect on QD emission rate. Purcell factors at the different Mie-resonances are determined.
The dependence of photoluminescence spectra of SiGe/Si(001) structures with self-assembled islands on Ge deposition temperature was investigated. Due to inhibition of SiGe alloying and an increase of the Ge content in islands the photoluminescence peak from the islands significantly shifted to low energy with a lowering temperature. The maximum of the peak from the island grown at 600°C was observed at energies less than the energy of the bandgap for bulk Ge. As a result of holes localization in islands the photoluminescence peak from the islands was observed up to room temperature. Sufficient enhancement of the room-temperature intensity of the photoluminescence signal at 1.55 μm was obtained for structures with islands grown on pre-deposited Si1-xGex layer. It is associated with a more effective capturing of holes by densely packed islands in structures with a pre-deposited Si1-xGex layer.