Highly efficient resonant-cavity light-emitting diodes for compact color projectors

An overview of red-green-blue highly efficient resonant-cavity light-emitting diodes is presented. First, the main parameters of dipole emission in planar cavities are reviewed. From these, we derive design rules to improve the device external efficiency. We point out some guidelines for comparison of light-emitting diodes, and use these to review the different device structures in different material systems and at different wavelengths.