By using MOVPE at atmospheric pressure, double heterostructure InP/GaInAs with a GaAs top layer has been grown in the same reactor without generating any limitation in device performance. Thickness and composition uniformity all over 2 inch wafers are in the range of ±3% and 0.1%, respectively. Excellent planar photodiodes with very low leakage current of 2 × 10-7 A/cm2 have been prepared. GaAs MESFETS integrated with photodiodes have been achieved with performances (transconductance = 120 mS/mm for 1 μm gate length) similar to those observed for the standard process on GaAs substrates.

Dectectors integrated with optical circuits are expected to play an important role as key devices in optical telecommunications. The paper focuses on PIN GaInAs detectors monolithically integrated on InP based photonic circuits. Examples of such circuits include coherent receiver and access switch for a high speed local area network. Various detector structures and integrated strategies (butt-joint coupling and evanescent coupling) are reviewed and critically compared. Despite its weaker coupling to the waveguide, it is shown that evanescent field coupled structure is very attractive because of its relative ease of fabrication, good electrical characteristics and flexibility. The most recent results on evanescent field coupled detectors are reported. This includes PIN detectors fabricated on both n+ and semi-insulating InP substrates. To achieve a full compatibility between high speed detector and an active device such as for instance an optical switch, a two step epitaxial process is used. Typical results for detectors fabricated on semi-insulating substrate are 95% detector/waveguide coupling efficiency, dark current of 0.1 nA at -10 V, capacitance of 0.3 pF at - 10 V and bandwidth in excess of 5 GHz.

We have studied MOCVD-grown InxAl1−xAs films, with x close to 0.52 (lattice matched to InP), by means of low temperature photoluminescence and Resonant Raman (RR) scattering. Besides the E0 emission at ≈ 1.49 eV, we observe a weak photoluminescence band, B, ∼ 50 meV above the fundamental one. In the Raman spectra, we identify the InAs-like and AlAs-like LO phonons and their overtones and combinations. An enhancement of the Raman efficiency for any of these phonons is observed at photon energies close to the B luminescence band. The resonance maximum red shifts with increasing In composition, according to the In-composition dependence of the E0-gap. We suggest that the B luminescence originates from electronic transitions, due either to composition fluctuations through formation of macroscopic clusters or to the presence of resonant impurity states above the fundamental gap.

Reports on the achievement of high performance submicron gate Al 0.48In0.52As/Ga0.47In0.53As HEMT's both on atmospheric pressure MOCVD and on MBE grown heterostructures. Very high density and high mobility modulation doped heterostructures have been successfully grown by AP-MOCVD. FET's, having gate lengths of 0.6 μm show transconductances as high as 680 mS/mm on MOCVD grown layers. A current gain cut-off frequency as high as 56 GHz and a maximum stable gain (MSG) value of about 12 dB at 26 GHz were extracted from the RF measurements on MBE grown layers

AbstractWe have measured the noise performance of GaInAs PIN photodiodes in the microwave frequency range. We show that the frequency response of the photodetectors can be deduced from their photocurrent shot noise spectra. The noise level has been measured using a setup which is based on heterodyne microwave mixing.

Atmospheric pressure organometallic vapor phase epitaxy is used for the growth of GaInP-AlGaInP lattice matched to GaAs substrate. The investigation of the GaInP/GaAs heterostructure has been carried out and mobility as high as 75 000 cm2 V-1s-1 for a sheet carrier concentration of 7.5 1011 cm-2 has been measured by Shubnikov-de Haas at 4 K. Red and yellow LED's have been obtained with emission wavelength of 670 nm and 576 nm respectively. Oxide stripe laser emitting at 660 nm in pulsed mode have been performed and present a threshold current density of 5 kA cm-2. Three ridge waveguide laser diode arrays with maximum output power of 108 mW have also been achieved.

The microwave performance of short-gate JFETs, made on GaInAs lattice matched on InP, realized by n-type ion implantation and zinc diffusion, is reported. A typical structure consists of an undoped 0.4- mu m-thick GaInAs layer grown on an 0.1- mu m-thick InP buffer layer using trichloride vapor-phase epitaxy. The n-type doping is obtained by Si ion implantation. The p-n junction is obtained by zin...

A computer program based on the Takagi-Taupin differential equations for X-ray propagation in distorted crystals has been developed in order to simulate dislocation images in the Bragg case. The program is valid both for thin and thick crystals. Simulated images of misfit dislocations formed either in a thin epilayer or in a thick substrate are compared with experimental images obtained by synchrotron-radiation plane-wave topography. The influence of the various strain components on the image features is discussed.

The extremely parallel and monochromatic beam (divergence ∼ 0·3″, spectral width Δλ/λ ∼ 7 × 10−6) extracted from the white synchrotron-radiation X-ray beam by a multiple reflection single-crystal monochromator has been used to record plane-wave reflection topographs. Separate images of a quaternary epilayer, Ga0.7Al0.3As1-yPy and a GaAs substrate building up a nearly matched heterostructure have been obtained. Typical thin-crystal features are observed in the epilayer. Differences in the interface dislocation contrast and strain field are revealed between the layer and substrate. By increasing the local departure from Bragg incidence (weak-beam condition), images as narrow as 1 μm can be obtained.

Boundary conditions in the numerical integration of the Takagi-Taupin equations are investigated in both Laue and Bragg reflections. They show how an incident spherical or plane wave may be simulated, and they discuss the accuracy of the calculation. In the Laue case the conclusion is that a spherical incident plane wave is well simulated lightening one elementary source, and a plane wave lightening more than 30 elementary sources. In the Bragg case it is shown that the accuracy of the numerical integration depends upon the distribution of sources and the thickness of the crystal. On a étudié l'influence des conditions aux limites dans l'intégration numérique des équations de Takagi-Taupin pour la réflexion de Laue comme celle de Bragg. On montre comment on peut simuler de façon satisfaisante une onde incidente plane ou sphérique. Dans le cas de Laue il suffit d'un point source pour simuler une onde incidente sphérique; par contre il faut au moins une trentaine de points pour obtenir une onde incidente plane. Dans le cas de Bragg la précision de l'intégration numérique dépend de la distribution de sources élémentaires mais aussi de l'épaisseur du cristal.