Origin of the spectral red-shift and polarization patterns of self-assembled InGaN nanostructures on GaN nanowires.

The luminescence of InGaN nanowires (NWs) is frequently reported with large red-shifts as compared to the theoretical value expected from the average In content. Both compositional fluctuations and radial built-in fields were considered accountable for this effect, depending on the size, structure, composition, and surrounding medium of the NWs. In the present work, the emission properties of InGaN/GaN NWs grown by plasma-assisted molecular beam epitaxy are investigated in a comprehensive study combining ultraviolet-Raman and photoluminescence spectroscopy (PL) on vertical arrays, polarization-dependent PL on bundles of a few NWs, scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, and calculations of the band profiles.

Temperature-Dependent Anisotropic Refractive Index in β-GaO: Application in Interferometric Thermometers.

An accurate knowledge of the optical properties of β-GaO is key to developing the full potential of this oxide for photonics applications. In particular, the dependence of these properties on temperature is still being studied. Optical micro- and nanocavities are promising for a wide range of applications.

Correlative analysis on InGaN/GaN nanowires: structural and optical properties of self-assembled short-period superlattices.

The influence of self-assembled short-period superlattices (SPSLs) on the structural and optical properties of InGaN/GaN nanowires (NWs) grown by PAMBE on Si (111) was investigated by STEM, EDXS, µ-PL analysis and k·p simulations. STEM analysis on single NWs indicates that in most of the studied nanostructures, SPSLs self-assemble during growth. The SPSLs display short-range ordering of In-rich and In-poor InGaN regions with a period of 2-3 nm that are covered by a GaN shell and that transition to a more homogenous InGaN core.

Wide Dynamic Range Thermometer Based on Luminescent Optical Cavities in Ga O :Cr Nanowires.

Remote temperature sensing at the micro- and nanoscale is key in fields such as photonics, electronics, energy, or biomedicine, with optical properties being one of the most used transducing mechanisms for such sensors. Ga O presents very high chemical and thermal stability, as well as high radiation resistance, becoming of great interest to be used under extreme conditions, for example, electrical and/or optical high-power devices and harsh environments. In this work, a luminescent and interferometric thermometer is proposed based on Fabry-Perot (FP) optical microcavities built on Cr-doped Ga O nanowires.

Near-UV optical cavities in GaO nanowires.

In this Letter, we report optical confinement in the near-ultraviolet (near-UV) range in nanowires (NWs) by distributed Bragg reflector (DBR) nanopatterned cavities. High-contrast DBRs, which act as the end mirrors of the cavities of the desired length, are designed and fabricated by focused ion beam etching. The resonant modes of the cavities are analyzed by micro-photoluminescence measurements, analytical models, and simulations, which show very good agreement between each other.

Direct observation of tunnelled intergrowth in SnO/GaO complex nanowires.

β-GaO intergrowths have been revealed in the SnO rutile structure when SnO/GaO complex nanostructures are grown by thermal evaporation with a catalyst-free basis method. The structure is formed by a GaO nanowire trunk, around which a rutile SnO particle is formed with [001] aligned to the [010] GaO trunk axis. Inside the SnO particle, β-GaO units occur separated periodically by hexagonal tunnels in the (210) rutile plane.

Shape Engineering Driven by Selective Growth of SnO on Doped GaO Nanowires.

Tailoring the shape of complex nanostructures requires control of the growth process. In this work, we report on the selective growth of nanostructured tin oxide on gallium oxide nanowires leading to the formation of SnO/GaO complex nanostructures. GaO nanowires decorated with either crossing SnO nanowires or SnO particles have been obtained in a single step treatment by thermal evaporation.