Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 2: GaN: devices

HL 2.3: Vortrag

Montag, 23. März 2009, 10:45–11:00, BEY 118

Optimization of InGaN multiple quantum wells for blue lasers — •J.R. van Look¹, J. Schlegel¹, V. Hoffmann², A. Knauer², S. Einfeldt², M. Weyers², P. Vogt¹, and M. Kneissl^1,2 — ¹Institut für Festkörperphysik, TU-Berlin, Hardenbergstr. 36, 10623 Berlin — ²Ferdinand-Braun-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin

Group III-nitride based lasers with emission targeted at the blue and green spectral region have attracted great interest in recent years. For the optimization of these indium-rich active regions, optically pumped as well as current-injection InGaN quantum well lasers with varying indium content and well width have been investigated. The laser heterostructures were grown by metalorganic vapor phase epitaxy (MOVPE) on (0001) sapphire substrates. The resulting structures with emission wavelengths ranging from 390 nm to 480 nm have been examined. In this talk we will present theoretical as well as experimental results on the characteristics of these indium rich InGaN multi quantum well (MQWs) lasers. The effect of well width in correlation with indium content on gain characteristics and laser threshold will be discussed. For optically pumped lasers with wells containing between 15% and 20% indium we observed a significant increase of the threshold excitation density to as much as 500 kW/cm2. In device structures for blue emitters with 480 nm luminescence observed under low excitation conditions, the laser emission strongly blue-shifted to 450 nm, which can be attributed to the compensation of the quantum confined stark effect (QCSE) under high excitation conditions.