GaN LEDs with improved output coupling efficiency

Abstract

An LED having a higher light coupling efficiency than prior art devices, particularly those based on GaN. An LED according to the present invention includes a substrate having a top surface, a first layer of a semiconducting material deposited on the top surface of the substrate, a light generation region deposited on the first layer, and a second layer of semiconducting material deposited on the first layer. Electrical contacts are connected to the first and second layers. In one embodiment, the top surface of the substrate includes protrusions and/or depressions for scattering light generated by the light generation region. In a second embodiment, the surface of the second layer that is not in contact with the first layer includes a plurality of protrusions having facets positioned such that at least a portion of the light generated by light generation layer strikes the facets and exits the surface of the second layer. In a third embodiment, the second layer includes a plurality of channels extending from the surface of the second layer that is not in contact with the light generation layer. The channels are filled with a material having an index of refraction less that that of the semiconducting material.

Dependencies are inferred from the claim text.