High‐power pure blue laser diodes

We successfully developed high‐power and long‐lived pure blue laser diodes (LDs) having an emission wavelength of 440–450 nm. The pure‐blue LDs were grown by metalorganic chemical vapor deposition (MOCVD) on GaN substrates. The dislocation density was successfully reduced to ∼106 cm–2 by optimizing the MOCVD growth conditions and the active layer structure. The vertical layer structure was designed to have an absorption loss of 4.9 cm–1 and an internal quantum efficiency of 91%. We also reduced the operating current density to 6 kA/cm2 under 750 mW continuous‐wave operation at 35 °C by optimizing the stripe width to 12 µm and the cavity length to 2000 µm. The half lifetimes in constant current mode are estimated to be longer than 10000 h. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)