Abstract
The enhancement of light extraction from light-emitting diodes (LEDs) grown on bulk c-plane gallium nitride (GaN) through chip shaping was investigated. Photolithography and diamond scribing determined the individual LED chip geometries (triangles, parallelograms, and rectangles). A light-absorbing material was applied to the sidewalls of individual LED dies systematically and measured in an integrating sphere to determine the amount of photon extraction from the sidewalls. The systematic use of the absorber was repeated in commercial ray tracing software yielding almost identical results and allowed the determination of the extraction efficiency for each chip geometry. The total extraction efficiencies were 47.7, 52.6, and 53.1% for the rectangle, parallelogram, and triangle, respectively.