P. Viktorovitch

Group velocity and propagation losses measurement in a single-line photonic-crystal waveguide on InP membranes

Single-line photonic-crystal waveguides are investigated. Photoluminescence experiments and three-dimensional calculation are performed and allow a clear identification of the guided modes. The propagation properties of the latter (group velocity, losses) are extracted from photoluminescence spectra obtained on closed waveguides which act as linear cavities.

Highly selective and widely tunable 1.55-μm InP/air-gap micromachined Fabry-Perot filter for optical communications

The authors report, for the first time, a highly selective and widely tunable optical filter at 1.55 /spl mu/m using a Fabry-Perot resonator with micromachined InP/air-gap distributed Bragg reflectors. The minimum resonance full-width at half-maximum (FWHM), as measured by microreflectivity experiments, is close to 0.4 mm (around 1.55 /spl mu/m) and is compatible with wavelength-division multiplexing specifications of optical telecommunications. The tuning range is 62 nm for a tuning voltage of 14 V. The FWHM is kept below 1 nm over a 40 nm tuning range.

Surface-emitting microlaser combining two-dimensional photonic crystal membrane and vertical Bragg mirror

We report on the design and fabrication of heterogeneous and compact surface-emitting microlasers, optically pumped and operating at 1.5μm at room-temperature. A very low threshold, below 15μW, is achieved. The devices consists of a top two-dimensional InP photonic crystal slab, including four InAsP quantum wells, a SiO2 bonding layer, and a bottom high index contrast Si∕SiO2 Bragg mirror deposited on a Si wafer. The graphitelike photonic crystal lattice is tailored for vertical emission. We theoretically and experimentally demonstrate that the Bragg reflector can strongly enhance the quality factor of the photonic crystal resonant mode, leading to a drastic decrease of the lasing threshold.

Heterogeneous integration of microdisk lasers on silicon strip waveguides for optical interconnects

A new approach is proposed to realize an optical link for intrachip optical interconnects. This link includes III-V compound-based laser sources and photodetectors, and silicon-on-insulator-based strip waveguides. The heterogeneous integration of an InP-based microdisk laser with a silicon waveguide using SiO/sub 2/-SiO/sub 2/ molecular bonding and nanofabrication procedures is emphasized. The technological procedure is described and first experimental results show that, with an adequate configuration, 35% of light could be coupled from the optically pumped microlaser to the waveguide, as a result of the vertical evanescent coupling.

Two-dimensional hexagonal-shaped microcavities formed in a two-dimensional photonic crystal on an InP membrane

We present simulation and experimental results on hexagonal-shaped microcavities formed in two-dimensional (2D) photonic crystals (PC’s). The PC structures, realized with InP-based materials, are studied in two configurations : Air-suspended membranes (A type) and membranes supported by silica (S type). The optical properties of these microcavities are analyzed through photoluminescence experiments. Plane-wave expansion method calculations provide simulation results that are consistent with experimental data. The influence on spectral properties of various parameters, such as cavity size or air filling factor (f), is thoroughly analyzed, and their effect on resonator loss mechanisms is extracted, to give guidance for further PC laser improvement, e.g., threshold reduction.

Fabrication of InP-based freestanding microstructures by selective surface micromachining

InP-based microstructuring methods are presented with a view to develop micro opto electro mechanical systems (MOEMS). Fabrication parameters and dimensions of the freestanding structures are determined for specific technological constraints (etching selectivities, anisotropy, sticking phenomena). thick InGaAs deformable cantilevers, bridges and membranes have been fabricated by elimination of around -thick InAlAs sacrificial layers. Showing high aspect ratio, smooth surfaces and high accuracy in thicknesses, these microstructures are perfectly suitable for optical applications.

New native oxide of InP with improved electrical interface properties

The electrical properties of InP insulator interface were improved by using a new native oxide between gate insulator and the semiconductor. This phosphorus‐rich oxide identified as In(PO3)y polyphosphate was grown anodically. Capacitance‐voltage measurements on this metal‐insulator‐semiconductor structure yielded an interface state density as low as 4×1010 cm−2 eV−1 and were nearly free of hysteresis in the depletion and accumulation region.

IMPROVED ELECTRONIC PROPERTIES OF GAAS SURFACES STABILIZED WITH PHOSPHORUS

We report on a new passivation procedure of the GaAs surface based on a thermal treatment under a PH3 overpressure. This treatment results, by As/P exchange, in the formation of a thin superficial GaP layer which prevents the formation of an arsenic oxide, as observed by x‐ray photoelectron spectroscopy analysis. Subsequent increase of the photoluminescence signal indicates improved electronic properties of GaAs surfaces as a result of this passivation procedure.

Reduction of fast interface states and suppression of drift phenomena in arsenic‐stabilized metal‐insulator‐InP structures

A significant improvement of the electronical properties of metal‐Al2O3‐InP structures is obtained after treating InP substrates at 500u2009°C in an As overpressure (10−6 Torr). The density of fast interface states near the conduction‐band edge is markedly reduced and drift phenomena are greatly suppressed, as compared to results obtained with chemically etched reference substrates. An interpretation of these effects is given based on the compensation of phosphorus vacancies by As atoms more strongly attached to the InP surface than P atoms.

Electrical characterization of metal-oxide-InP tunnel diodes based on current-voltage, admittance and low frequency noise measurements

Abstract Electrical properties of metal-oxide-InP tunnel diodes, based on combined d.c. transport, admittance and low frequency noise measurements, are reported. They appear to be strongly dominated by interfacial nonuniformities, which are related to a nonuniform distribution of trapping centers across the contact area. It is demonstrated that low frequency noise measurements give details on the spatial distribution of interfacial defect traps within the oxide thickness and across the diode section, and therefore can provide an effective qualification of the uniformity of the passivation of the semiconductor surface.