Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 2: GaN: devices

HL 2.2: Vortrag

Montag, 23. März 2009, 10:30–10:45, BEY 118

Wavelength Dependence of Optical Gain and Laser Threshold in InGaN MQW Lasers — •Jessica Schlegel¹, Jan-Robert van Look¹, Veit Hoffmann², Arne Knauer², Patrick Vogt¹, Markus Weyers², and Michael Kneissl^1,2 — ¹Institut für Festkörperphysik, TU-Berlin, Hardenbergstr. 36, EW6-1, 10623 Berlin — ²Ferdinand-Braun-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin

For InGaN quantum well (QW) laser diodes emitting in the blue and green spectral range indium contents of more than 20 % are required. To optimize the growth of InGaN QWs we have investigated the influence of the indium content on the gain characteristics and laser threshold. Optically pumped laser structures with emission wavelengths ranging between 395 nm and 450 nm were characterized. The laser heterostructures were grown by metalorganic vapor phase epitaxy (MOVPE) on (0001) sapphire substrates. The optical gain spectra were measured based on the variable stripe length method (VSLM). Laser structures with emission below 420 nm showed wavelength independent laser thresholds. A strong increase of the laser threshold and the width of the optical gain spectra was observed for longer wavelength and higher indium contents. This behaviour can be attributed to material inhomogeneities, defects and the quantum confined Stark effect (QCSE).