Development of AlInGaN based blue–violet lasers on GaN and SiC substrates

We present a process for high quality InGaN laser diodes on free standing GaN substrates with high reproducibility. We demonstrate a self‐aligned process to contact lasers with ridge width <2 μm. The stability of the process allows us to optimize the epitaxial structure on GaN substrates and we achieve cw‐threshold current densities of 2.9 kA/cm 2 for 10 μm wide ridges and 4.7 kA/cm 2 for 1.5 μm wide ridges. Cw‐slope efficiencies of 1.0 W/A are achieved for both widths. Beside this we notice a reduction of the ideality factor and the forward bias linked to an improvement of the epitaxial interfaces. For maximum optical output we could achieve 3.4 W from one output facet at pulsed operation and a catastrophic optical mirror damage (COMD) level of 67 MW/cm 2 . Furthermore we observe a dependency of the COMD level from the pulse width corresponding to filament formation. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)