Yellow-red emission from (Ga,In)N heterostructures

(Ga,In)N-based light emitting devices are very efficient in producing blue light and to a lesser extent green. Extending their spectral range to longer wavelengths while maintaining high efficiency is a challenge due to material and physical issues related to high-In content (Ga,In)N alloys. We review the current status of yellow and red emitters (light emitting diodes and laser diodes) based on this material system. We also describe the state-of-the-art of devices mixing blue-yellow or red-blue-green coloured light, such as monolithic phosphor-free white light emitting diodes and full-colour micro-displays.