Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 76: Nitride-based Green Lasers

HL 76.3: Talk

Thursday, March 17, 2011, 12:15–12:30, POT 51

Growth and characterization of AlInN for cladding layers in long wavelength GaN based laser structures — •Ernst Ronald Buß¹, Heiko Bremers¹, Uwe Rossow¹, Egidijus Sakalauskas², Rüdiger Goldhahn³, and Andreas Hangleiter¹ — ¹Institute of Applied Physics, TU Braunschweig, Mendelssohnstraße 2, Braunschweig — ²Institute of Physics, TU Ilmenau, Weimarer Straße 32, Ilmenau — ³Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Universitätsplatz 2, Magdeburg

Cladding layers in actual GaN based laser structures usually consist of AlGaN, or AlGaN/GaN superlattices. Alloying GaN with AlN does always lead to strain in the whole compositional range, and the difference of the refractive indices of GaN and AlGaN is very small. In contrast AlInN can be grown matched to the a-lattice constant of GaN, so the stress in these structures can be minimized. Furthermore, the refractive index contrast is about 0.08 at 530 nm resulting in a better optical confinement in green laser structures.

The samples are grown by low pressure MOVPE. To optimize growth conditions parameters like temperature, reactor pressure and source fluxes has been varied. HRXRD measurements on samples with x_In≈0.179 show pseudomorphic growth and lattice matching for 845^∘C and 50mbar. Investigations by AFM exhibit smooth surfaces with low RMS roughnesses built up of small domains surrounding pits generated by crystal defects. The refractive index and the band gap energy are obtained from spectroscopic ellipsometry. Optical gain has already been shown and first laser structures are realized.