GaN-based violet-blue laser diodes

High power GaN-based laser diodes (LDs) are very desirable for various applications such as optical storage systems. We have obtained GaN films of low dislocation density using epitaxial lateral overgrowth technique and the raised- pressure metalorganic chemical vapor deposition technique. Dislocation density of the improved GaN is about 10 7 cm -2 . Optimized GaN-based LDs fabricated on the improved GaN films have operated up to 35 mW without any kink. The lifetime is more than 500 hours with a constant power of 20 mW at 25 degree(s)C under continuous wave conditions. Furthermore, we have introduced buried-ridge laser diode structure in order to control the optical transverse mode. The features of the far field patterns of LDs with AlGaN burying layers indicate their controllability.