Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 76: Nitride-based Green Lasers

HL 76.5: Talk

Thursday, March 17, 2011, 12:45–13:00, POT 51

Growth of AlGaN stripes with semipolar side facets as waveguide claddings for semipolar laser structures — •Robert Anton Richard Leute¹, Kamran Forghani¹, Frank Lipski¹, Ferdinand Scholz¹, Ingo Tischer², Benjamin Neuschl², and Klaus Thonke² — ¹Institut für Optoelektronik, Universität Ulm — ²Institut für Quantenmaterie / Gruppe Halbleiterphysik, Universität Ulm

Selective area growth of group III nitrides allows the epitaxy of semipolar facets with reduced piezoelectric field on 2-inch sapphire substrates. Additionally, the 3D growth of stripes, pyramids or the like enables us to manipulate the extraction and propagation of light by changing the surface topology. LEDs grown on GaN stripes with {1122} facets and GaN stripes with {1011} facets have been published. The fabrication of laser structures with resonators along the stripes depends critically on the controlled growth of a waveguide cladding for optical confinement, typically realized by AlGaN layers. However, the growth parameters of AlGaN are challenging for selective epitaxy. The high growth temperature promotes lateral growth, leading to the emergence of an undesirable c-plane facet, whereas the reduced selectivity of the mask material for Al atoms leads to polycrystalline growth on masked areas. We investigate the selective growth of AlGaN with Al contents up to 10% with structured SiO₂ and SiN_x masks. The influence of mask geometries (stripes ∥ m and ⊥ m, variable opening sizes and periods) on topology, material quality and Al incorporation is examined. Therefore, we present SEM investigations, spatially resolved cathodoluminescence as well as low temperature photoluminescence.