High-power blue-violet lasers grown on 3-inch sapphire and GaN substrate.

This report presents a high-power blue-violet laser grown on a 3-inch sapphire substrate. The laser has a low threshold current of 27.5 mA, achieved by reducing the internal loss to 13.6 cm(-1), and an Al(0.18)gGaN electron-blocking layer inserted at an appropriate distance from the active layer reduces the absorption loss of the Mg-doped cladding layer while maintaining the internal quantum efficiency (0.94). The lifetime of these lasers is improved by employing an epitaxial lateral overgrown (ELO) substrate with low dislocation density of 3 x 10(6) cm(-2). The very low dislocation density was found to be essential to achieve stable operation for more than 5,000 h under 30 mW continuous wave operation at 60degreesC. Lasers grown on GaN substrates are also discussed, and the lifetime of lasers with dislocation density of below 1 x 10(6) cm(-2) is estimated to exceed 100,000 h.