Efficient Light-Emitting Diodes with Radial Outcoupling Taper at 980 and 630 nm Emission Wavelength

摘要

We have investigated efficient light outcoupling from light-emitting diodes (LEDs) by introducing lateral tapers. The concept is based on light generation in the very central area of a circularly symmetric structure. After propagating between two highly reflecting mirrors light is outcoupled in a tapered mesa region. By proper processing we achieve quantum efficiencies of almost 40 % for outcoupling via a planar surface or quantum and wallplug efficiencies of 52 % and 48 %, respectively, for encapsulated devices. Neglecting reabsorption, approximative equations yield optimum design parameters.