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III-N based short-wavelength LEDs, LUCO-LEDs and lasers

Kurzwellige LEDs, LUCO-LEDs und Laserdioden auf der Basis der Gruppe III-Nitride
: Sommer, F.; Stephan, T.; Vollrath, F.; Köhler, K.; Kunzer, M.; Müller, S.; Schlotter, P.; Pletschen, W.; Kaufmann, U.; Wagner, J.


Physica status solidi. A 201 (2004), Nr.12, S.2628-2634
ISSN: 0031-8965
ISSN: 1862-6300
ISSN: 1521-396X
ISSN: 1862-6319
Fraunhofer IAF ()
GaN; LED; light emitting diode; LUCO-LED; laser

Results are presented on the effect of using GaN templates with homogeneously reduced defect density on the performance of violet- und UV-emitting (AlGaIn)N LEDs, as well as on the use of such LED chips as pump light sources in three-phosphor white luminescence conversion LEDs (LUCO-LEDs). For LED chips emitting at 385 nm, an improvement in electroluminescence efficiency by a factor of two was found for growth on 8 x 10(exp 7) cm-2 defect density templates compared to direct growth on sapphire. Further we report on the fabrication and on-wafer testing of violet-emitting ridge waveguide (AlGaIn)N quantum well diode lasers with etched laser facets, grown on sapphire using conventional low-temperature GaN nucleation layer technology as well as on the above low defect density GaN templates. In on-wafer pulsed-mode operation a 35% reduction in threshold current density was achieved for the latter, resulting in a minimum injected power at threshold of 0.9 W of 500 µm x 2 µm ridge laser diodes with uncoated facets.