Enhanced Light Trapping in GaAs/TiO-Based Photocathodes for Hydrogen Production.

Photoelectrochemical cells (PEC) are appealing devices for the production of renewable energy carriers. In this context, III-V semiconductors such as GaAs are very promising materials due to their tunable band gaps, which can be appropriately adjusted for sunlight harvesting. Because of the high cost of these semiconductors, the nanostructuring of the photoactive layer can help to improve the device efficiency as well as drastically reduce the amount of material needed.

Background-Free Near-Infrared Biphoton Emission from Single GaAs Nanowires.

The generation of photon pairs from nanoscale structures with high rates is still a challenge for the integration of quantum devices, as it suffers from parasitic signals from the substrate. In this work, we report type-0 spontaneous parametric down-conversion at 1550 nm from individual bottom-up grown zinc-blende GaAs nanowires with lengths of up to 5 μm and diameters of up to 450 nm. The nanowires were deposited on a transparent ITO substrate, and we measured a background-free coincidence rate of 0.

Growing self-assisted GaAs nanowires up to 80m long by molecular beam epitaxy.

Ultralong GaAs nanowires were grown by molecular beam epitaxy using the vapor-liquid-solid method. In this ultralong regime we show the existence of two features concerning the growth kinetic and the structural properties. Firstly, we observed a non-classical growth mode, where the axial growth rate is attenuated.

Highly linear polarized emission at telecom bands in InAs/InP quantum dot-nanowires by geometry tailoring.

Nanowire (NW)-based opto-electronic devices require certain engineering in the NW geometry to realize polarized-dependent light sources and photodetectors. We present a growth procedure to produce InAs/InP quantum dot-nanowires (QD-NWs) with an elongated top-view cross-section relying on the vapor-liquid-solid method using molecular beam epitaxy. By interrupting the rotation of the sample during the radial growth sequence of the InP shell, hexagonal asymmetric (HA) NWs with long/short cross-section axes were obtained instead of the usual symmetrical shape.

InAs quantum dot in a needlelike tapered InP nanowire: a telecom band single photon source monolithically grown on silicon.

Realizing single photon sources emitting in the telecom band on silicon substrates is essential to reach complementary-metal-oxide-semiconductor (CMOS) compatible devices that secure communications over long distances. In this work, we propose the monolithic growth of needlelike tapered InAs/InP quantum dot-nanowires (QD-NWs) on silicon substrates with a small taper angle and a nanowire diameter tailored to support a single mode waveguide. Such a NW geometry is obtained by a controlled balance over axial and radial growths during the gold-catalyzed growth of the NWs by molecular beam epitaxy.

Impact of the Ga flux incidence angle on the growth kinetics of self-assisted GaAs nanowires on Si(111).

In this work we show that the incidence angle of group-III element fluxes plays a significant role in the diffusion-controlled growth of III-V nanowires (NWs) by molecular beam epitaxy (MBE). We present a thorough experimental study on the self-assisted growth of GaAs NWs by using a MBE reactor equipped with two Ga cells located at different incidence angles with respect to the surface normal of the substrate, so as to ascertain the impact of such a parameter on the NW growth kinetics. The as-obtained results show a dramatic influence of the Ga flux incidence angle on the NW length and diameter, as well as on the shape and size of the Ga droplets acting as catalysts.

Nanoscale investigation of a radial p-n junction in self-catalyzed GaAs nanowires grown on Si (111).

One obstacle for the development of nanowire (NW) solar cells is the challenge to assess and control their nanoscale electrical properties. In this work a top-cell made of p-n GaAs core/shell NWs grown on a Si(111) substrate by Molecular Beam Epitaxy (MBE) is investigated by high resolution charge collection microscopy. Electron Beam Induced Current (EBIC) analyses of single NWs have validated the formation of a homogeneous radial p-n junction over the entire length of the NWs.

Thermoelectric La-doped SrTiO epitaxial layers with single-crystal quality: from nano to micrometers.

High-quality thermoelectric LaSrTiO (LSTO) films, with thicknesses ranging from 20 nm to 0.7 μm, have been epitaxially grown on SrTiO(001) substrates by enhanced solid-source oxide molecular-beam epitaxy. All films are atomically flat (with rms roughness < 0.

Redshifted and blueshifted photoluminescence emission of InAs/InP quantum dots upon amorphization of phase change material.

We present the mechanisms underlying the redshifted and blueshifted photoluminescence (PL) of quantum dots (QDs) upon amorphization of phase change material (PCM). We calculated the stress and energy shift distribution induced by volume expansion using finite element method. Simulation result reveals that redshift is obtained beneath the flat part of amorphous mark, while blueshift is obtained beneath the edge region of amorphous mark.

10 Gbit/s all-optical NRZ-OOK to RZ-OOK format conversion in an ultra-small III-V-on-silicon microdisk fabricated in a CMOS pilot line.

We report the demonstration of an all-optical, bias free and error-free (bit-error-rate ~10(-12)), 10 Gbit/s non-return-to-zero (NRZ) to return-to-zero (RZ) data format conversion using a 7.5 µm diameter III-V-on-silicon microdisk resonator. The device is completely processed in a 200 mm CMOS pilot line.

Milliwatt-level fiber-coupled laser power from photonic crystal band-edge laser.

We report unprecedentedly high output powers measured from large area two-dimensional square-lattice photonic-crystal band-edge lasers (BELs), patterned by holographic lithography. In order to ensure mechanical rigidity, the BELs were fabricated in an InP-based epilayer bonded onto a fused silica substrate beforehand. The BEL devices, employing the surface-emitting Γ-point monopole band-edge mode, provide a fiber-coupled single mode output power as high as 2.

Subwavelength plasmonic lasing from a semiconductor nanodisk with silver nanopan cavity.

We report the experimental demonstration of an optically pumped silver-nanopan plasmonic laser with a subwavelength mode volume of 0.56(lambda/2n)(3). The lasing mode is clearly identified as a whispering-gallery plasmonic mode confined at the bottom of the silver nanopan from measurements of the spectrum, mode image, and polarization state, as well as agreement with numerical simulations.

Room temperature low-threshold InAs/InP quantum dot single mode photonic crystal microlasers at 1.5 microm using cavity-confined slow light.

We have designed, fabricated, and characterized an InP photonic crystal slab structure that supports a cavity-confined slow-light mode, i.e. a bandgap-confined valence band-edge mode.

Carrier-injection-based electro-optic modulator on silicon-on-insulator with a heterogeneously integrated III-V microdisk cavity.

A compact electro-optic modulator on silicon-on-insulator is presented. The structure consists of a III-V microdisk cavity heterogeneously integrated on a silicon-on-insulator wire waveguide. By modulating the loss of the active layer included in the cavity through carrier injection, the power of the transmitted light at the resonant wavelength is modulated; approximately 10 dB extinction ratio and 2.

Room-temperature InAs/InP Quantum Dots laser operation based on heterogeneous "2.5 D" Photonic Crystal.

The authors report on the design, fabrication and operation of heterogeneous and compact "2.5 D" Photonic Crystal microlaser with a single plane of InAs quantum dots as gain medium. The high quality factor photonic structures are tailored for vertical emission.