Investigation of Trapezoidal Well for Improving the Light Efficiency in AlGaInP-Based Light-Emitting Diodes.

We investigated high-brightness light emitting diodes appropriate for general lighting applications in terms of their optical behaviors and device performances according to the insertion of the sloped barrier between the well and the barrier and changing the sloped barrier thickness. As the sloped barrier thickness was increased from 0 to 5 nm, radiative recombination efficiency and device performances significantly improved, due to the suppression of carrier overflow by the stronger capture of carriers and the shortening of the carrier lifetime in the active region owing to the built-in quasi-electric field. At a further increase in the sloped barrier thickness to 10 nm, however, the optical and device performances started to degrade because of the loosening of the quantum confinement effect in the active region and due to the saturation of the improvement of the carrier capture by the sloped barrier region.