High-Performance Blue InGaN Laser Diodes With Single-Quantum-Well Active Layers (original) (raw)
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ABSTRACTThe performance characteristics are reported for continuous-wave (cw) InGaN multiple-quantum-well laser diodes grown on epitaxially laterally overgrown GaN on sapphire substrates by metalorganic chemical vapor deposition. Room-temperature cw threshold currents as low as 41mA with operating voltages of 6.0V were obtained. 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 90°C. A significant reduction in thermal resistance was observed for laser diodes transferred from sapphire onto Cu substrates by excimer laser lift-off, resulting in increased cw output power of more than 100mW.
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The performance characteristics of green InGaN multi-quantum well laser diode structures emitting at 500 nm to 510 nm were investigated numerically. A threshold current of 87.2 mA corresponding to the threshold current density of 4.84 kA/cm 2 and a threshold voltage of 8.837 V were achieved for a basic structure emitting at 504.31 nm output emission wavelength. The effects of well numbers, well thickness, barrier thickness, and barrier doping on performance characteristics such as output power, threshold current, slope efficiency, and differential quantum efficiency were studied. The basic structure and material parameters used in the model were extracted based on the newest literatures and experimental works. Simulation results indicated that lowest threshold current, highest output power, differential quantum efficiency and slope efficiency are observed when the number of well layers is one and well thickness is between 3 and 4 nm. Significant changes in output power, threshold current, and slope efficiency were observed with the variations in barrier thickness and doping.
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We report on the characteristics of blue superluminescent light emitting diodes based on the emission of InGaN quantum wells. Narrow ridgewaveguide devices realized by standard processing techniques and with extremely low facet reflectivity show single lateral mode emission and continuous-wave output powers >35 mW with a typical spectral bandwidth of 4-5 nm. Tuning the composition of the active region, superluminescent light emitting diodes spanning all the spectral range between 410 and 445 nm could be realized. The light output is highly directional and results in a coupling efficiency into single mode fibers >50%. The device temperature behavior is also discussed.
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