S. Bouchoule

Polariton light-emitting diode in a GaAs-based microcavity

Cavity polaritons have been shown these last years to exhibit a rich variety of non-linear behaviors which could be used in new polariton based devices. Operation in the strong coupling regime under electrical injection remains a key step toward a practical polariton device. We report here on the realization of a polariton based light emitting diode using a GaAs microcavity with doped Bragg mirrors. Both photocurrent and electroluminescence spectra are governed by cavity polaritons up to 100 K.

Optical Bistability in a GaAs-Based Polariton Diode

We report on a new type of optical nonlinearity in a polariton p-i-n microcavity. Abrupt switching between the strong and weak coupling regime is induced by controlling the electric field within the cavity. As a consequence, bistable cycles are observed for low optical powers (2-3 orders of magnitude less than for Kerr induced bistability). Signatures of switching fronts propagating through the whole 300 x 300 microm2 mesa surface are evidenced.

Polariton lasing in a hybrid bulk ZnO microcavity

We demonstrate polariton lasing in a bulk ZnO planar microcavity under non-resonant optical pumping at a small negative detuning (δ ∼ −1/6 the 130 meV vacuum Rabi splitting) and a temperature of 120 K. The strong coupling regime is maintained at lasing threshold since the coherent nonlinear emission from the lower polariton branch occurs at zero in-plane wavevector well below the uncoupled cavity mode. The contribution of multiple localized polariton modes above threshold and the non-thermal polariton statistics show that the system is in a far-from-equilibrium regime, likely related to the moderate photon lifetime and in-plane photonic disorder in the cavity.

Investigations on GaInNAsSb quinary alloy for 1.5 μm laser emission on GaAs

GaInNAsSb quantum wells grown by molecular-beam epitaxy on GaAs substrates were investigated. Intricate incorporation mechanisms of the constituents in this quinary alloy were seen. In highly strained indium-rich alloys, antimony incorporation is strongly reduced, and a beneficial surfactant effect is observed. Due to this effect, high structural quality is preserved even for an uncompensated 2.67% strained multiquantum-well structure. Narrow luminescence linewidth (35 meV) could be achieved near 1.55 μm wavelength with these quantum wells. Laser emission is demonstrated at 1.50 μm with threshold current density of 3.5 kA/cm2.

Sidewall passivation assisted by a silicon coverplate during Cl2–H2 and HBr inductively coupled plasma etching of InP for photonic devices

Energy dispersive x-ray (EDX) spectroscopy coupled to transmission electron microscopy (TEM) is used to analyze the passivation layer deposited on the sidewall of InP submicron patterns etched in Cl2–H2 and HBr inductively coupled plasmas. It is shown that a thin Si-containing layer is deposited on the sidewalls of the etched patterns, resulting from the reaction of Cl2 or HBr with the Si wafer used as the sample tray. For Cl2-containing plasma, the deposition layer becomes thicker when hydrogen is added to the gas mixture, leading to highly anisotropic InP etching at an optimized H2 percentage. A similar effect is obtained in HBr plasma by increasing the ICP power. When O2 is added to the gas mixture, the deposited layer is changed from Si rich to more stoichiometric silicon oxide (SiO2) and the passivation effect is enhanced. EDX-TEM analysis has also been carried out on InP samples etched in Cl2–N2 plasma for comparison. A similar impact of the coverplate material on the sidewall profile is evidenced, ...

Incorporation and redistribution of impurities into silicon nanowires during metal-particle-assisted growth

The incorporation of metal atoms into silicon nanowires during metal-particle-assisted growth is a critical issue for various nanowire-based applications. Here we have been able to access directly the incorporation and redistribution of metal atoms into silicon nanowires produced by two different processes at growth rates ranging from 3 to 40 nm s(-1), by using laser-assisted atom probe tomography and scanning transmission electron microscopy. We find that the concentration of metal impurities in crystalline silicon nanowires increases with the growth rate and can reach a level of two orders of magnitude higher than that in their equilibrium solubility. Moreover, we demonstrate that the impurities are first incorporated into nanowire volume and then segregate at defects such as the twin planes. A dimer-atom-insertion kinetic model is proposed to account for the impurity incorporation into nanowires.

Continuous-wave operation of photonic band-edge laser near 1.55 μm on silicon wafer

We report on the continuous-wave operation of a band edge laser at room temperature near 1.55 μm in an InGaAs/InP photonic crystal. A flat dispersion band-edge photonic mode is used for surface normal operation. The photonic crystal slab is integrated onto a Silicon chip by means of Au/In bonding technology, which combines two advantages, efficient heat sinking and broad band reflectivity.

Optimization of a Cl2–H2 inductively coupled plasma etching process adapted to nonthermalized InP wafers for the realization of deep ridge heterostructures

Inductively coupled plasma etching using Cl2–H2 chemistry with no additive gas (CH4, Ar, or N2) is studied to realize deep (>5μm) ridges with smooth and vertical sidewalls. The process is optimized for nonthermalized InP wafers to avoid the use of thermal grease. Cleaning of the rear side of the wafer after etching is avoided, which is suitable for an industrial process or for critical subsequent steps such as epitaxial regrowth. The influence of the Cl2∕H2 ratio on the etching mechanism is investigated for both InP bulk layers and InGaAs∕InP or InGaAlAs∕InP heterostructures. The authors show that this ratio is the main parameter controlling the ridge profile, in a similar way for both bulk InP and InGa(Al)As∕InP samples. Smooth and vertical sidewalls with neither undercuts nor notches can be obtained in the 0.5–1mT pressure range for a hydrogen percentage of 35%–45% in the gas mixture. Etching rates from 900to1300nm∕min together with a selectivity over SiNx dielectric mask as high as 24:1–29:1 are measur...

Dynamic properties of InAs∕InP (311)B quantum dot Fabry–Perot lasers emitting at 1.52μm

Dynamic properties of truly three-dimensional-confined InAs∕InP quantum dot (QD) lasers obtained by molecular beam epitaxy growth on a (311)B oriented substrate are reported. The relative intensity noise and small signal modulation bandwidth experiments evidence maximum relaxation frequency of 3.8GHz with a clear relaxation oscillation peak, indicating less damping than InAs∕GaAs QD lasers. The Henry factor amounts to ∼1.8 below threshold and increases to ∼6 above threshold, which is attributed to band filling of the thick wetting layer.

UV polaritonic emission from a perovskite-based microcavity

We report on the realization of a molecule-based one-dimensional microcavity emitting in the near UV range at room temperature. The active material is a thin film of the two-dimensional perovskite (C6H5C2H4–NH3)2PbCl4, a molecular compound absorbing and emitting light around 3.6 eV. Angle-resolved reflectivity and photoluminescence measurements show that this microcavity works in the strong coupling regime. The emitting UV polariton is a mixed state between the photon cavity mode and the exciton of the perovskite-type semiconductor.