Room temperature distributed-feedback (DFB) laser operation is demonstrated with emission wavelengths ranging from 389 to 399 nm. Second-order DFB gratings were defined by electron beam lithography and reactive ion etching in the top GaN barrier layer of a GaInN/GaN double heterostructure grown by metalorganic vapor phase epitaxy. Our data allow a precise determination of the effective refractive index neff(λ) over the whole emission range. neff(λ) is compared with previously published values for GaN and GaInN.

The dependence of the In-incorporation efficiency and the optical properties of MOVPE-grown GaInN/GaN-heterostructures on various growth parameters has been investigated. A significant improvement of the In-incorporation rate could be obtained by increasing the growth rate and reducing the H 2 -partial pressure in the MOVPE reactor. However, GaInN layers with a high In-content typically show an additional low energy photoluminescence peak, whose distance to the band-edge increases with increasing In-content. For GaInN/GaN quantum wells with an In-content of approximately 12%, an increase of the well thickness is accompanied by a significant line broadening and a large increase of the Stokes shift between the emission peak and the band edge determined by photothermal deflection spectroscopy. With a further increase of the thickness of the GaInN layer, a second GaInN-correlated emission peak emerges. To elucidate the nature of these optical transitions, power-dependent as well as time-resolved photoluminescence measurements have been performed and compared to the results of scanning transmission electron microscopy.

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