Semiconductor LED flip-chip having low refractive index underfill

摘要

In accordance with the invention, a difference in index of refraction is created at the mesa wall of a III-nitride flip chip light emitting device. The step in index of refraction reflects much of the light incident on the mesa wall back into the device where it can be usefully extracted. In some embodiments, a solder wall on the submount or a high index gel coating the light emitting device and the submount creates a sealed gap between the light emitting device and the submount. The gap is filled with a material having a low index of refraction. In other embodiments, a high index material covers the substrate of the light emitting device, and a low index material fills the gap between the submount and the light emitting device.