Regensburg 2007 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 46: Poster 2
HL 46.17: Poster
Donnerstag, 29. März 2007, 15:00–17:30, Poster A
Gain measurements of 405 nm (In, Al)GaN laser diodes using the Hakki-Paoli Method — •Tobias Meyer1, Harald Braun1, Ulrich T. Schwarz1, Marc Schillgalies2, Christoph Eichler2, Stephan Lutgen2, and Uwe Strauss2 — 1Naturwissenschaftliche Fakultät II - Physik, Universität Regensburg — 2Osram Opto Semiconductors GmbH, Leibnizstr. 2, 93055 Regensburg
We use a high spectral resolution setup to measure the electroluminescence (EL) spectra of 405 nm (In, Al)GaN quantum well laser diodes. The Hakki-Paoli method is employed to estimate the optical gain spectrum by analyzing the modulation of the Fabry-Perot modes of the laser resonator below lasing threshold. To obtain the internal loss of the waveguide, the gain spectrum is evaluated at energies below peak gain. We use a theoretical model to simulate the gain spectrum, using the homogeneous and inhomogeneous broadening as fitting parameters. By measuring EL spectra for different carrier densities, we get the differential gain, and the shift of the longitudinal modes leads to the carrier-induced change of the refractive index. We use these parameters to calculate the antiguiding factor. Furthermore, the high spectral resolution allows us to study the mode spectrum evolution at and above the threshold. In addition, we compare our results for diodes with different composition and structure.