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We report on the photoluminescence characterization of a metalorganic vapour phase epitaxy grown InP/InAlAs/InP structure. The energy band alignment of the InAlAs/InP interface is of type II. The PL arising from the first grown interface (InAlAs grown on InP) is clearly seen at 1.2 eV. The localization was possible by scanning the laser beam on a angle-bevelled sample whose bevel crosses all the layers of the InP/InAlAs/InP structure. For the second interface, called the inverse interface (InP grown on InAlAs), a different PL behaviour is observed. The energy of the observed PL peak is 1.3 eV. It is very sensitive to the excitation power. From this behaviour, the Auger depth profiling measurements and the wedge transmission electron microscopy performed on this sample we conclude that this recombination does not originate from a type II interface band structure but from an InAs x P 1- x layer located at the inverse interface. This intermediate layer originates from the higher incorporation coefficient of As compared to that of P.

A characterization study of GaAs layers grown by metal-organic chemical vapour deposition (MOCVD) on silicon substrates is presented, based on high resolution transmission electron microscopy, secondary ion mass spectroscopy, admittance technique measurements (current-voltage, capacitance-voltage, capacitance and photocapacitance spectroscopy, deep level transient spectroscopy (DLTS) and photoluminescence (PL) spectroscopy in the near band gap and near infrared region). We have analysed the initial stage of growth and the influence of growth parameters as GaAs/AlAs superlattices (SLs) at different distances from the GaAsSi heterointerface in the buffer layer or post-growth thermal annealing or selective epitaxy on the reduction of dislocation density, on the silicon distribution, on the deep defect levels and on the coplanar tensile strain in the active layer. This study shows an improvement of the material quality in the dislocation density decrease due to GaAs/AlAs SLs grown directly on the initial prelayer, or post-growth annealing or selective epitaxy. DLTS measurements reveal deep electron traps in the range 0.5–0.7 eV below the CB induced by dislocations due to the heteroepitaxy. For the first time we observe deep hole centres in the range 0.4–0.5 eV above the top of the valence band, which could be involved in the reduction of the minority carrier lifetime. We discuss their origins due to silicon incorporation in the GaAs layer on the basis of capacitance and photoluminescence experiments. PL shows the increase of strain with post-growth annealing. Finally the improvement in the quality of the layers is pointed out on the basis of double heterostructure (GaAlAs/ GaAs/GaAlAs) characteristics.

An adiabatic taper is proposed to couple light from a photonic crystal waveguide to a coupled-cavity waveguide. A Scanning Near-Field Optical Microscopy study is realized on these structures. This study permits to identify and to evaluate accurately the losses in the coupled-cavity waveguide.

The epitaxial growth and characterization of InAs surface quantum wells grown on InP by molecular beam epitaxy (MBE) are discussed. The structural properties of the InAs layers are described. Photoluminescence results are presented. This system shows practically no coupling between the confined states in the InAs quantum well and the InAs surface states. >

The key performances of optical filters requested by optical communications for wavelength-division multiplexing (WDM) systems are: (i) a high wavelength selectivity, enabling the selection of neighboring channels 1.6 nm apart with a crosstalk ratio of 20 dB, (ii) a continuous wavelength tuning range of about 30 nm around 1.55 /spl mu/m, with no degradation of the selectivity. We demonstrate the design and the fabrication of a vertical micromachined InP-air gap based Fabry-Perot filter, continuously tunable via electrostatic micromechanical actuation of the cavity air gap, which meets the WDM system requirements.

At a low MBE growth temperature (400°C), an anisotropic composition modulation has been observed by Transmission Electron Microscopy (TEM) on AIlnAs layers. Optical measurements have been performed on these samples and compared with classical AllnAs grown at 530°C. We show the clustering “organization” on the low temperature layers and we propose some hypothesis to explain the composition modulation effects on the AlInAs optical properties.