We report the fabrication of a photonic platform consisting of single wire light-emitting diodes (LED) and photodetectors optically coupled by waveguides. MOVPE-grown (metal–organic vapor-phase ...epitaxy) InGaN/GaN p–n junction core–shell nanowires have been used for device fabrication. To achieve a good spectral matching between the emission wavelength and the detection range, different active regions containing either five narrow InGaN/GaN quantum wells or one wide InGaN segment were employed for the LED and the detector, respectively. The communication wavelength is ∼400 nm. The devices are realized by means of electron beam lithography on Si/SiO2 templates and connected by ∼100 μm long nonrectilinear SiN waveguides. The photodetector current trace shows signal variation correlated with the LED on/off switching with a fast transition time below 0.5 s.
We report the investigation of the photovoltaic properties of core–shell GaN/InGaN wires. The radial structure is grown on m-plane {11̅00} facets of self-assembled c̅-axis GaN wires elaborated by ...metal–organic vapor phase epitaxy (MOVPE) on sapphire substrates. The conversion efficiency of wires with radial shell composed of thick In0.1Ga0.9N layers and of 30× In0.18Ga0.82N/GaN quantum wells are compared. We also investigate the impact of the contact nature and layout on the carrier collection and photovoltaic performances. The contact optimization results in an improved conversion efficiency of 0.33% and a fill factor of 83% under 1 sun (AM1.5G) on single wires with a quantum well-based active region. Photocurrent spectroscopy demonstrates that the response ascribed to the absorption of InGaN/GaN quantum wells appears at wavelengths shorter than 440 nm.
Electronic or catalytic properties can be modified at the nanoscale level. Engineering efficient and specific nanomaterials requires the ability to study their complex structure–property ...relationships. Here, Bragg coherent diffraction imaging was used to measure the three‐dimensional shape and strain of platinum nanoparticles with a diameter smaller than 30 nm, i.e. significantly smaller than any previous study. This was made possible by the realization of the Extremely Brilliant Source of ESRF, The European Synchrotron. This work demonstrates the feasibility of imaging the complex structure of very small particles in three dimensions and paves the way towards the observation of realistic catalytic particles.
This work demonstrates three‐dimensional Bragg coherent diffraction imaging of single 20 nm Pt particles at the ID01‐EBS beamline of ESRF.
We report on the quantitative determination of the strain map in a strained silicon-on-insulator line with a 200×70 nm2 cross section. In order to study a single line as a function of time, we used ...an x-ray nanobeam with relaxed coherence properties as a compromise between beam size, coherence, and intensity. We demonstrate how it is possible to refine the line deformation map at the nanoscale, and follow its evolution as the line relaxes under the influence of the x-ray nanobeam. We find that the strained line flattens itself under irradiation but maintains the same linear strain (ε(zz) unchanged).
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