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

Abstract

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 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 for 500 μm x 2 μm ridge laser diodes with uncoated facets.