Dresden 2011 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 88: Lasers
HL 88.2: Vortrag
Freitag, 18. März 2011, 10:30–10:45, POT 151
Optical Gain, Thermal Resistance and Antiguiding Factor of GaN-based Laser Diodes from UV to Green — Wolfgang Scheibenzuber1, •Ulrich Schwarz1, Teresa Lermer2, Stephan Lutgen2, and Uwe Strauss2 — 1Fraunhofer IAF, Tullastrasse 72, D-79108 Freiburg, Germany — 2Osram Opto Semiconductors GmbH, Leibnizstrasse 4, D-93055 Regensburg, Germany
For highly efficient GaN-based laser diodes emitting from UV to green, suitable for projection applications or ultra short pulse generation, a detailed knowledge of the internal device properties optical gain, internal losses, thermal resistance and antiguiding factor is required. We measure these properties on state-of-the-art laser diodes emitting from UV to green. Optical gain and internal losses are determined from the modulation depth of the longitudinal modes in the electroluminescence spectrum below threshold using the Hakki-Paoli method. The measurements show an increase of the spectral width of the gain spectra towards longer laser wavelength, which is related to the larger inhomogeneous broadening and band-filling in InGaN quantum wells with high indium content. The thermal resistance of the devices is determined from the shift of the longitudinal modes above threshold. From the wavelength-shift of the longitudinal modes with increasing current at a constant device temperature we extract the charge carrier induced refractive index change and calculate the antiguiding factor of the laser diodes. All three examined samples have an antiguiding factor of 4 +- 0.5.