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The possibility to tune the functional properties of nanomaterials is key to their technological applications. Superlattices, i.e., periodic repetitions of two or more materials in one or more dimensions, are being explored for their potential as materials with tailor-made properties. Meanwhile, nanowires offer a myriad of possibilities to engineer systems at the nanoscale, as well as to combine materials that cannot be put together in conventional heterostructures due to the lattice mismatch. In this work, we investigate GaAs/GaP superlattices embedded in GaP nanowires and demonstrate the tunability of their phononic and optoelectronic properties by inelastic light scattering experiments corroborated by ab initio calculations. We observe clear modifications in the dispersion relation for both acoustic and optical phonons in the superlattices nanowires. We find that by controlling the superlattice periodicity, we can achieve tunability of the phonon frequencies. We also performed wavelength-dependent Raman microscopy on GaAs/GaP superlattice nanowires, and our results indicate a reduction in the electronic bandgap in the superlattice compared to the bulk counterpart. All of our experimental results are rationalized with the help of ab initio density functional perturbation theory (DFPT) calculations. This work sheds fresh insights into how material engineering at the nanoscale can tailor phonon dispersion and open pathways for thermal engineering. [ABSTRACT FROM AUTHOR]

Hybrid integration of unconventional optical materials is arguably a promising way to substantially extend a range of chip functionalities on traditional silicon-based platforms. Especially, functional oxides are very promising because they exhibit many attractive properties, including superconductivity, piezoelectricity, ferroelectricity, and optical effects. In this article, we demonstrate hybrid photonic platform with an Erbium-doped (Er-doped) Yttria-Stabilized Zirconia (YSZ) thin film used as an active luminescent cladding on top of low-loss Silicon Nitride (SiN) waveguides. This active layer has been grown by a pulsed laser deposition (PLD) technique. Optical characterizations via photoluminescence (PL) measurements were performed in both normal and in-plane light incidence to demonstrate strong near-infrared (near-IR) emission of Er ions in the Er:YSZ thin film. Moreover, we also observed an intense in-plane guided PL emission in visible and near-IR wavelengths from hybrid Er:YSZ-on-SiNx waveguides. These results pave the way towards rare-earth-doped YSZ structures on silicon-based platforms, thereby affording required function versatility for future photonic integrated circuits. [ABSTRACT FROM AUTHOR]