The epitaxial reflector 304 may comprise multiple layers of Group III-V semiconductor materials having different compositions. The epitaxial reflector 304 may comprise repetitions of a first layer 306 and a second layer 308. In an example, the first layer 306 may comprise AlInN and the second layer 308 may comprise GaN. The first layer 306 may have a concentration of Al_0.82In_0.18N. The first layer 306 may have a thickness of approximately 42 nm and the second layer 308 may have a thickness of approximately 55 nm. The first layer 306 and the second layer 308 may have different refractive indices and thicknesses optimized to maximize reflectivity at the wavelength and main emission angle of the EL emission. The epitaxial reflector 304 may comprise approximately 35 repetitions of the first layer 306 and the second layer 308. The refractive index of the first layer 306 and the second 308 layer may differ in their as-grown state due to differences in their in alloy composition or doping concentration. The additional epitaxial layers may not form a good reflector in the as-grown state, but may be grown with differences in doping and/or alloy composition that affect their chemical reactivity in post-growth processing. Post growth-processing may transform the layers into an effective reflector, as described below.

In another example, the first layer 306 may comprise AlGaIn and the second layer 308 may comprise AlGaN. In this example, the first layer 306 may have a concentration of Al_0.80Ga_0.03In_0.17 and the second layer 308 may have a composition of Al_0.02Ga_0.98N.