GaN-based light-emitting diode structure with monolithically integrated sidewall deflectors for enhanced surface emission

To improve the overall surface emission efficiency, the structure of a standard GaN light-emitting diode (LED) was modified; the mesa sidewalls were etched at an angle, and deep enough to reach the sapphire substrate. Photoexcitation experiments, including photoluminescence and near- and far-field emission patterns, were performed on LED-like test devices, and results indicated that the angled sidewalls efficiently deflect photons that are initially guided laterally within the GaN epilayer in the off-surface direction. For a sidewall angle of 30deg, the total surface emission strength was improved by a factor exceeding three. Computer simulations produced results consistent with the experimental observations