Performance and degradation of continuous-wave InGaN multiple-quantum-well laser diodes on epitaxially laterally overgrown GaN substrates

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Abstract
The performance and degradation characteristics of continuous-wave (cw) InGaN multiple-quantum-well laser diodes are reported. A cw threshold current as low as 62 mA was obtained for ridge-waveguide laser diodes on epitaxially laterally overgrown GaN on sapphire substrates grown by metalorganic chemical vapor deposition. Transmission electron microscopy reveals a defect density <5×107 cm−2 in the active region. The emission wavelength was near 400 nm with output powers greater than 20 mW per facet. Under cw conditions, laser oscillation was observed up to 70 °C. The room-temperature cw operation lifetimes, measured at a constant output power of 2 mW, exceeded 15 h. From the temperature dependence of the laser diode lifetimes, an activation energy of 0.50 eV±0.05 eV was determined.