In this work we report on the elaboration and characterization of Ge1−xSnx nanowires synthetized by chemical vapor deposition (CVD) via vapor–liquid–solid (VLS) mechanism using GeH4 and SnCl4 as precursors. We have investigated tin incorporation in Ge as a function of experimental growth conditions such as growth temperature and Sn precursor partial pressure (PSnCl4/PGeH4 ratio). We have demonstrated Ge1−xSnx nanowires with Sn incorporation around 1 at.% in the core with a thin Sn‐rich shell with up to 10 at.% Sn well beyond the equilibrium solubility of Sn in bulk Ge.

The lateral oxidation of thick AlGaAs layers (>500 nm) is studied. An uncommon shape of the oxide tip is evidenced and attributed to the embedded stress distribution, inherent to the oxidation reaction. Experimental and numerical studies of the internal strain in oxidized AlxGa1−xAs/GaAs structures were carried out by dark-field electron holography and finite element methods. A mapping of the strain distribution around the AlGaAs/oxide interface demonstrates the main role of internal stress on the shaping of the oxide front. These results demonstrate the high relevance of strain in oxide-confined III-V devices, in particular, with over-500-nm thick AlOx confinement layers.

Strain from oxidation-induced volume shrinkage is studied by micro-photoluminescence. An InGaAs/GaAs quantum well (QW) placed at the vicinity of the selectively oxidized AlAs layer is used to probe the spatial distribution of the strain with a resolution of 1 µm. A QW wavelength shift of 1 nm imputed to the embedded strain is observed in agreement with finite element calculations. With this method, an overstrained zone is highlighted where the counter-propagative oxidation fronts merge.

We report the effect of the aluminum oxide substrate on the emission of monolithic AlGaAs-on-insulator nonlinear nanoantennas. By coupling nonlinear optical measurements with electron diffraction and microscopy observations, we find that the oxidation-induced stress causes negligible crystal deformation in the AlGaAs nanostructures and only plays a minor role in the polarization state of the harmonic field. This result highlights the reliability of the wet oxidation of thick AlGaAs optical substrates and further confirms the bulk χ(2) origin of second harmonic generation at 1.55 μm in these nanoantennas, paving the way for the development of AlGaAs-on-insulator monolithic metasurfaces.

International audienceThe optical absorption and thermal conductivity of GaAsPN absorbers are investigated by means of optical absorption spectroscopy and photo-thermal deflection spectroscopy (PDS) for different 100 nm-thick GaAsNP/GaP samples under different growth conditions and various post-growth annealing temperatures. It is first shown that the As content strongly modifies the optical absorption spectrum of the GaAsPN: with a maximum absorption coefficient of 38,000 cm À 1 below the GaP bandgap energy. The optical absorption and thermal conductivities of the samples are then evaluated for various growth and annealing conditions using PDS: the results showing overall agreement with optical absorption spec-troscopy measurements. A significant improvement in optical absorption and thermal conductivity after annealing is demonstrated. The best thermal conductivity measured is equal to 4 W/m K. These results are promising for the development of absorbers in multijunction solar-cell architecture

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We propose an original approach of lateral confinement through oxidation of buried AlGaAs layers and epitaxial regrowth. The buried AlGaAs layer is selectively oxidized from the surface thanks to an array of sub‐micron holes defined by electron beam lithography and etched in the GaAs/AlGaAs epitaxial structure. Oxidation spreads laterally into the Al‐rich ternary surrounding the holes until the adjacent oxide fronts coalesce. Finally, epitaxial regrowth is used to stack further epitaxial layers above the partially oxidized structure. This technology enables free engineering of localized buried oxide areas through standard lithography techniques, unlike the standard process of lateral oxidation on mesas with size of a few decamicrons for which the oxide aperture is circumcised by the initial mesa shape. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

This work focuses on the nanopatterning of sub-10 nm InGaAs fins by inductively coupled plasma reactive ion etching for advanced IIIÀV n-fin field effect transistors (n-FinFETs) on silicon. First, different chlorine chemistries have been investigated and compared in order to select the most adequate one for the FinFETs process. Following this analysis, the BCl 3 /SiCl 4 /Ar mixture was selected for the remaining of the work. Thus, a systematic study of the etching process based on this chemistry has been carried out, and the effects of the experimental conditions on the etching kinetics and the sidewalls quality have been revealed. The optimized results depict 8 nm width fins with smooth (line edge roughness %2 nm) and almost vertical (85 6 1) sidewalls, opening the way for sub-10 nm width InGaAs FinFETs on silicon. V