Al0.83In0.17N lattice-matched to GaN used as an optical blocking layer in GaN-based edge emitting lasers

Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Quantum Electronics and Photonics, CH-1015 Lausanne, Switzerland
Applied Physics Letters (Impact Factor: 3.3). 06/2009; 94(19):193506 - 193506-3. DOI: 10.1063/1.3138136
Source: IEEE Xplore


Nitride-based blue laser diode structures with either Al 0.83 In 0.17 N / Al 0.07 Ga 0.93 N or Al 0.87 In 0.13 N bottom claddings have been fabricated and compared to standard structures including solely Al 0.07 Ga 0.93 N bottom claddings. Lasing emission at 415 nm is achieved in gain-guided structures at room temperature under pulsed current injection. Devices including the Al 0.83 In 0.17 N / Al 0.07 Ga 0.93 N bottom cladding exhibit superior device performance. This is a consequence of a better optical mode confinement, as expected from modeling.

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    • "In x Al 1 À x N can be grown lattice matched to GaN while maintaining a significant refractive index and spontaneous polarization difference with GaN [1] [2] [3] [4]. The refractive index contrast with GaN makes InAlN attractive as a thick, strain-free cladding layer in GaN based laser diodes and in distributed Bragg reflectors [5] [6]. High electron mobility transistors (HEMTs) take advantage of the large spontaneous polarization difference between In 0.18 Al 0.82 N and GaN to induce a high carrier density two dimensional electron gas (2DEG) [1] [2] [3] [4]. "
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    ABSTRACT: N-polar InAlN thin films were grown by plasma-assisted molecular beam epitaxy on freestanding GaN substrates under N-rich conditions. Indium and aluminum fluxes were varied independently at substrate temperatures below and above the onset of thermal desorption of indium. At low temperatures, the InAlN composition and growth rate are determined by the group-III fluxes. With increasing substrate temperature, the surface morphology transitions from quasi-3D to a smooth, 2D morphology at temperatures significantly above the onset of indium loss. At higher temperatures, we observe increased indium evaporation with higher indium fluxes and a suppression of indium evaporation with increased aluminum flux. The final optimized InAlN thin film results in step-flow morphology with rms roughness of 0.19 nm and high interfacial quality.
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    ABSTRACT: Inx Al1−x N alloys with low indium content (0.025 < x < 0.080) were grown on Si(111) substrates, with an AlN buffer layer, using gas source molecular beam epitaxy with ammonia under nitrogen-rich conditions. Composition was varied by changing the growth temperature from 580°C to 660°C. Growth temperature in excess of 580°C was found to be necessary to obtain compositional uniformity. As temperature was varied from 590°C to 660°C, both the growth rate and indium incorporation decreased substantially. Rising In content observed near the surface of each sample was attributed to native indium oxide formation.
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    ABSTRACT: InAlN thin films grown on GaN/Al2O3 (0001) templates by metal-organic vapor phase epitaxy were studied by transmission electron microscopy techniques. V-defects in the form of hexagonal inverted pyramids with {10-11} sidewalls were observed on the films’ surfaces linked to the termination of threading dislocations. Their origin is explained by the different surface atom mobility of In and Al and the built-in strain relaxation. Indium segregation in the films is influenced by the formation of V-defects, the edges and the apexes of which function as paths of migrating indium atoms diffusing along nanopipes formed at the open-core threading dislocations
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