The realization of group III--nitride laser diodes with a vertical current path on a n-conducting SiC substrate is described. The vertical current path and the possibility of cleaved laser facets result in a simpler process technology. Gain spectra measured by the Hakki-Paoli method show a modulation of the modal gain due to parasitic modes in the SiC substrate. As up to now no defect reduction technique was successfully transfered to GaN on SiC,
degradation is the major issue. We discuss the impact of degradation on the gain spectra, facet degradation, and rule out formation of cracks during degradation. We show that the high heat conductivity of SiC may give an advantage with respect to degradation as it results in a only moderate temperature rise of the active region.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.