Filtering of Defects in Semipolar (11−22) GaN Using 2-Steps Lateral Epitaxial Overgrowth

Good-quality (11−22) semipolar GaN sample was obtained using epitaxial lateral overgrowth. The growth conditions were chosen to enhance the growth rate along the [0001] inclined direction. Thus, the coalescence boundaries stop the propagation of basal stacking faults. The faults filtering and the improvement of the crystalline quality were attested by transmission electron microscopy and low temperature photoluminescence. The temperature dependence of the luminescence polarization under normal incidence was also studied

Cleaved-facet violet laser diodes with lattice-matched Al0.82In0.18N/GaN multilayers as n-cladding

Electrically injected, edge-emitting cleaved-facet violet laser diodes were realized using a 480 nm thick lattice matched Si doped Al0.82In0.18N/GaN multilayer as the cladding on the n-side of the waveguide. Far-field measurements verify strong mode confinement to the waveguide. An extra voltage is measured and investigated using separate mesa structures with a single AlInN insertion. This showed that the electron current has a small thermally activated shunt resistance with a barrier of 0.135 eV and a current which scales according to V-n, where n similar to 3 at current densities appropriate to laser operation. (C) 2011 American Institute of Physics. (doi:10.1063/1.3589974

Selective area growth of a- and c-plane GaN nanocolumns by molecular beam epitaxy using colloidal nanolithography

Selective area growth of a-plane GaN nanocolumns by molecular beam epitaxy was performed for the first time on a-plane GaN templates. Ti masks with 150 nm diameter nanoholes were fabricated by colloidal lithography, an easy, fast and cheap process capable to handle large areas. Even though colloidal lithography does not provide a perfect geometrical arrangement like e-beam lithography, it produces a very homogeneous mask in terms of nanohole diameter and density, and is used here for the first time for the selective area growth of GaN. Selective area growth of a-plane GaN nanocolumns is compared, in terms of anisotropic lateral and vertical growth rates, with GaN nanocolumns grown selectively on the c-plan

Ordered gan/ingan nanorods arrays grown by molecular beam epitaxy for phosphor-free white light emission

The basics of the self-assembled growth of GaN nanorods on Si(111) are reviewed. Morphology differences and optical properties are compared to those of GaN layers grown directly on Si(111). The effects of the growth temperature on the In incorporation in self-assembled InGaN nanorods grown on Si(111) is described. In addition, the inclusion of InGaN quantum disk structures into selfassembled GaN nanorods show clear confinement effects as a function of the quantum disk thickness. In order to overcome the properties dispersion and the intrinsic inhomogeneous nature of the self-assembled growth, the selective area growth of GaN nanorods on both, c-plane and a-plane GaN on sapphire templates, is addressed, with special emphasis on optical quality and morphology differences. The analysis of the optical emission from a single InGaN quantum disk is shown for both polar and non-polar nanorod orientation

Influence of substrate type and orientation on the morphology and optical properties of selective area growth of GaN and InGaN nanocolumns

A relevant issue concerning optoelectronic devices based on III-nitrides is the presence of strong polarization fields that may reduce efficiency

Band edge versus deep luminescence of InxGa1-xN layers grown by molecular beam epitaxy

InxGa1-xN (0<x<0.2) thin layers were grown on GaN-coated sapphire substrates by molecular beam epitaxy (MBE) using ammonia as the nitrogen source. Their optical properties have been investigated by low- and room-temperature photoluminescence (PL) and photothermal deflection spectroscopy. It is shown that high-quality InxGa1-xN layers with x similar to 0.1 can be grown by MBE using NH3. The PL linewidths are 48 and 80 meV at 9 and 300 K, respectively. A bowing parameter of 1 eV is deduced for the band-edge luminescence energy. On the other hand, when the growth conditions slightly move aside the optimum, the PL spectra exhibit broad and deep luminescence. The variation of the PL energy of this deep luminescence as a function of the In composition is then discussed. (C) 1998 American Institute of Physics

Plastic relaxation through buried cracks in AlGaN/GaN heterostructures

Due to high lattice mismatch, heterostructures of III-nitrides are subject to plastic relaxation. In this paper, we focus on the relaxation of AlGaN films grown on GaN. This relaxation is realised by cracking followed by the introduction of misfit dislocations. We describe those mechanisms and present a method to grow thick high quality crack-free AlGaN layers. This method uses jointly plastic relaxation and lateral growth

Impurity-defect interaction in polycrystalline silicon for photovoltaic applications. The role of hydrogen

An overview of the studies done by the authors on the physicochemical behaviour of some impurities (P, C, H) in silicon is given. Results concern : diffusion and segregation of impurities in mono and polycrystalline silicon, passivation of recombining defects by hydrogen, hydrogen-dopant interaction. A more focused interest is given on hydrogen diffusion and behaviour. The results are discussed, taking into account the existence of complex mechanisms of interaction between hydrogen and impurities or defects.Cet article résume les études effectuées par les auteurs sur le comportement physico-chimique de quelques impuretés (P, C, H) dans le silicium. Les résultats portent sur : la diffusion et la ségrégation d'impuretés dans le silicium mono et polycristallin, la passivation des défauts recombinants par l'hydrogène, les interactions hydrogène-dopants. Un accent particulier est mis sur le comportement et la diffusion de l'hydrogène. Les résultats sont discutés en tenant compte de l'existence de mécanismes complexes d'interactions entre l'hydrogène et les impuretés ou les défauts

Elaboration de diodes électroluminescentes et de miroirs sélectifs à base de nitrures d'éléments III pour diodes à cavité résonante

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