Publications by Benjamin Dwir | EPFL Graph Search

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We report on the growth and optical properties of dense arrays of single GaAs/AlGaAs quantum dot (QD) heterostructures with pitches as small as 300 nm. The samples were grown by organometallic chemical vapor deposition in dense inverted pyramids on {1 1 1}B GaAs substrate pre-patterned using electron beam lithography and wet chemical etching. The growth conditions such as deoxidation and growth temperatures, growth rates, and V/III ratio, had to be chosen quite differently from those employed with micron-si

We use polarization-resolved two-photon microscopy to investigate second harmonic generation (SHG) from individual assemblies of site-controlled nano-pyramidal recess templates covered with silver films. We demonstrate the effect of the surface plasmon pol ...

We demonstrate that the emission characteristics of site-controlled InGaAs/GaAs single quantum dots embedded in photonic crystal slab cavities correspond to single confined excitons coupled to cavity modes, unlike previous reports of similar systems based ...

The effect of surface passivation in BCl3/N-2 inductively coupled plasma reactive-ion etching of GaAs-based photonic crystals (PhCs) was investigated. It is shown that sidewall passivation is crucial for achieving cylindrical, vertical PhC holes, where the ...

We propose and investigate a new type of photonic crystal (PhC) cavity for integrated quantum photonics, which provides tailored optical modes with both confined and extended spatial components. The structures consist of elongated PhC cavities in which the ...

We report on the observation of negatively- and positively-charged excitons in the photoluminescence spectra of V-groove quantum wires. The. charged exciton binding energy increases with the strength of the quantum confinement. We demonstrate that fluctuat ...

Two site-controlled quantum dots (QDs) were integrated in a photonic crystal molecule (PCM) formed by L3 nanocavities. A statistical analysis of the coupled cavity modes demonstrated the formation of bonding and anti-bonding delocalized PCM states. Exciton ...

We demonstrate engineering of carrier states in the conduction band (CB) and valence band (VB) of site-controlled InGaAs/GaAs quantum dots (QDs) grown into pyramidal recesses, by controlling their shape, size, and composition. QDs with CB level separation ranging from ∼15 to 70 meV are obtained, useful in applications based on intraband transitions, e.g., QD photodetectors and QD cascade lasers. Moreover, by varying the aspect ratio and composition of the QDs we are able to switch the polarization of the do

Semiconductor quantum-dot (QD) systems offering perfect site control and tunable emission energy are essential for numerous nanophotonic device applications involving spatial and spectral matching of dots with optical cavities. Herein, the properties of ordered InGaAs/GaAs QDs grown by organometallic chemical vapor deposition on substrates patterned with pyramidal recesses are reported. The seeded growth of a single QD inside each pyramid results in near-perfect (

Precise positioning of single site-controlled inverted pyramidal InGaAs quantum dots (QDs) at the antinode of a GaAs photonic crystal cavity with nanometer-scale accuracy holds unique advantages compared to self-assembled QDs and offers great promise for p ...

The coupling of a prescribed number of site-controlled pyramidal quantum dots (QDs) with photonic crystal (PhC) cavities was studied by polarization and power-dependent photoluminescence measurements. The energy of the cavity mode could be readily tuned, m ...

Codeposition of hydrocarbons is a severe problem during focused electron beam writing of pure metal nanostructures. When using organometallic precursors, a low metal content carbonaceous matrix embedding and separating numerous nanosized metal clusters is formed. In this work, we present a new and easy approach to obtain high purity gold lines: the use of inorganic PF3AuCl as a precursor. Electrical resistivities as low as 22 µOhms cm at 295 K (ten times the bulk Au value) were obtained. This is to our know

Deterministic positioning single site-controlled high symmetric InGaAs quantum dots (QDs) in (111)B-oriented GaAs photonic crystal cavities with nanometer-scale accuracy provides an idea component for building integrated quantum photonic circuits. However, ...

Rectangular arrays of pyramidal recesses coated by silver film are investigated by means of polarization-resolved nonlinear microscopy at 900 nm fundamental wavelength, demonstrating strong dependence of the dipole-allowed SHG upon the lattice parameters. ...

We present a detailed study of biexciton complexes formed in single, site-controlled pyramidal GaInAs/GaAs quantum dots (QDs). By using power dependent measurements and photon correlation spectroscopy, we identify the excitonic transitions of a large numbe ...

Arrays of site-controlled, pyramidal InGaAs/GaAs quantum dots (QDs) grown by organo-metallic chemical vapour deposition with densities comparable to those of self-assembled QDs (5 x 109 cm(-2)) are demonstrated. The QDs exhibit high quality photoluminescen ...

We demonstrate selective optical coupling of multiple, site controlled semiconductor quantum dots (QDs) to photonic crystal waveguide structures. The impact of the exact position and emission spectrum of the QDs on the coupling efficiency is elucidated. Th ...

We report on transverse mode discrimination in long-wavelength wafer-fused vertical-cavity surface-emitting lasers (VCSELs) incorporating ring-shaped air gap patterns at the fused interface between the active region and the top distributed Bragg reflector (DBR). These 60-nm deep patterns were implemented with the aim of favoring the fundamental mode while preserving high output power. The VCSELs under consideration emit in the 1310-nm band and incorporate an AlGaInAs-based quantum well active region, a regr

Interactions of site-controlled quantum dots with a high-order cavity mode of an L7-type photonic crystal cavity are resolved spatially and spectrally. We observed a spatial avoided crossing in polarization-resolved optical emission of quantum dots. ...

The fabrication and characterization of site-controlled InGaAs/GaAs quantum dots (QDs) made by MOVPE using triethylgallium (TEGa) on patterned {111}B GaAs substrates are reported. Results are compared to more traditional pyramidal QD structures grown emplo ...

Benjamin Dwir

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Growth and Optical Characterization of Dense Arrays of Site-Controlled Quantum Dots Grown in Inverted Pyramids

Effects of surface plasmon polariton-mediated interactions on second harmonic generation from assemblies of pyramidal metallic nano-cavities

Phonon-Mediated Coupling of InGaAs/GaAs Quantum-Dot Excitons to Photonic Crystal Cavities

Effect of sidewall passivation in BCl3/N2 inductively coupled plasma etching of two-dimensional GaAs photonic crystals

Tilted-potential photonic crystal cavities for integrated quantum photonics

Charged excitons in modulation-doped quantum wires

Site-controlled quantum dots coupled to a photonic crystal molecule

Engineering conduction and valence band states in site-controlled pyramidal quantum dots

Site-Controlled InGaAs Quantum Dots with Tunable Emission Energy

Single site-controlled inverted pyramidal InGaAs QD-nanocavity operating at the onset of the strong coupling regime

Ordered systems of site-controlled pyramidal quantum dots incorporated in photonic crystal cavities

Focused electron beam induced deposition of gold

Exciton-polariton dynamics of the single site-controlled quantum dot-nanocavity in the coexisting strong-weak coupling regime

Non-centrosymmetric plasmonic crystals for second-harmonic generation with controlled anisotropy and enhancement

Bound and anti-bound biexciton in site-controlled pyramidal GaInAs/GaAs quantum dots

Dense arrays of pyramidal quantum dots with narrow linewidth photoluminescence spectra

Site-controlled quantum dots coupled to photonic crystal waveguides

Improved single-mode emission characteristics of long-wavelength wafer-fused vertical-cavity surface-emitting lasers by intra-cavity patterning

Spatial Avoided Crossing in Optical Emission of Site-Controlled Pyramidal Quantum Dots in Photonic Crystal Cavities

Site-controlled InGaAs/GaAs pyramidal quantum dots grown by MOVPE on patterned substrates using triethylgallium