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Focus of this work is the optimization of growth to achieve high quality laser material for emission at 1.3 mm and beyond. GaAs/GaAsN/InGaAsN heterostructures were grown by solid source molecular beam epitaxy. To achieve optimum crystal quality of InGaAsN heterostructures, growth was followed by a high temperature treatment at about 7008C. The high optical quality of our annealed material is attested by large exciton recombination lifetimes (more than 2 ns). Consequently, a decrease of single quantum well transparency current density down to 100 A/cm 2 is found and SWQ lasers with threshold current densities as low as 350 A/cm 2 have been made. This represents clearly the lowest laser thresholds reported so far for emission around 1.3 mm from the InGaAsN material system.

Abstract. We report on the growth and properties of InGaAsN/GaAs heterostructures and on their applications for lasers emitting at X -1.3 jIm. Structures are grown by molecular beam epitaxy using an RF plasma-source. Broad area and ridge waveguide laser structures based on such QWs exhibit performance that can compete with those of 1.3 /m InGaAsP lasers. In particular, we have achieved 300 K operation of broad area lasers at 1.3 /Im with threshold current density down to 400 A/cm 2 and 650 A/cm 2 for single and triple QW structures. Similar structures with heatsinking at 10'C yield maximum output powers of 2.4 W (cw) and 4 W (pulsed). Ridge waveguide lasers have thresholds down to 16 mA and show cw operation up to 10"C with a To of up to 110 K.

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The combination of wafer soldering using metal layers and the introduction of buried micro-reflector structures has proven to be a promising approach to fabricate high brightness, substrate-less LEDs in the AlGaInP material system. In addition to the enhanced light output, the scalability of this approach has been predicted as a major advantage. In contrast to other approaches, larger area LEDs can be fabricated without altering the epitaxial structure and thickness of layers simply by offering a larger area for light generation. First samples of amber (λ = 615 nm) buried micro-reflector LEDs with side-length up to 1000 µm have been realized. Devices mounted in packages with improved heat sinks are capable of low voltage CW operation with currents as high as 600 mA (V fw ≤ 2,8 V) without significant thermal flattening of the light-current characteristics. The maximum luminous flux achieved at these operating conditions is 46 lumen. Already these first experiments demonstrate the potential of the concept of buried micro-reflector LEDs not only for high-brightness but also for high-current operation. The results are among the best values of high-flux LEDs in this wavelength range.

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