Observation par photocapacité du dépiégeage au bord de la charge d'espace

Capacitance measurements have been made on Schottky diodes In/ZnTe. If the semiconductor surface has been damaged by an ion implantation the device shows trapping centres, whose electronic level is near the midgap. It is shown that the trapped electrons recombine with free holes at the edge of the space charge region within a temperature dependent length.La mesure de capacité de diodes Schottky In/ZnTe dans lesquelles la surface du semiconducteur a été endommagée par une implantation ionique montre un piégeage électronique dans des niveaux voisins du milieu de la bande interdite. Les électrons piégés se recombinent au bord de la charge d'espace par capture de trous libres sur une longueur dépendant de la température

Novel piezoelectric-barrier heterostructures for all-optical light modulation

We present preliminary new results on multiperiod piezoelectric-barrier all-optical modulators. It is shown first on single period structures that an incident beam of a few W/cm2 is able to create a space-charge field of approximately 20 kV/cm in the structure, inducing a 10 meV shift in the photoluminescence (PL) spectrum. We discuss then a multiperiod structure showing similar optically-driven PL shifts. Even though the multiperiod structure was not optimized for transmission modulation experiments, we observed a 12% transmission variation at 760 nm induced by a 10 W/cm2 optical beam

Laser emission in CdHgTe in the 2-3.5 µm range

Stimulated emission from HgCdTe separate confinement heterostructure waveguides embedding quantum wells as gain medium is studied. We explore the effect of composition grading in the barriers as well as that of using strained quantum wells on the temperature evolution of the laser threshold. The main effect of barrier grading is to suppress carrier trapping at low temperatures, leading to an improved excitation transfer from the barriers to the quantum wells, and to an intrinsic exponential dependence of the threshold on the temperature. For the strained quantum well structures, a two-fold reduction of the threshold is obtained, as compared with similar band gap unstrained structures. The threshold dependence on photon energy points out the importance of Auger type nonradiative recombinations. We determine the Auger constant in our structures, and compare them with published data. An exponential dependence of the Auger constants on the band gap, valid for type I heterostructures, is shown. A comparison of the published operating temperatures in competing devices is done. It appears that III–V type II and unipolar lasers are largely ahead of II–VI lasers. The future of HgCdTe could lie in vertical cavity, surface emitting lasers

Impurity identification and characterization by electrical optical and nuclear methods. The ZnTe : Au case

Gold is characterized in pure ZnTe by capacitance, luminescence and infrared absorption experiments. The position of gold in the lattice is analysed by channeling of charged particules. We show that gold is principally introduced in substitutional position (Au zn) and give a simple acceptor level at EV + 272 meV.L'or introduit par diffusion dans du tellurure de zinc de haute pureté a été caractérisé par des mesures de capacité, de luminescence et d'absorption infrarouge. La position de l'or dans le réseau est analysée par canalisation de particules chargées. II apparait que l'or se trouve principalement en site substitutionnel (Au Zn) et donne un accepteur simple à 272 meV de la bande de valence

Band gap engineering in II–VI based heterostructures

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