Light emitting diode of improved current blocking and light extraction structure

Abstract

Structures for light emitting diodes are disclosed, which include improved current blocking and light extraction structures. The diodes typically include a substrate formed on a first electrode, a first confining layer of a first conductivity type formed on the substrate, an active region formed on the first confining layer, a second confining layer of a second conductivity type formed on the active region, and a window layer of the second conductivity type formed on the second confining layer. A contact layer of the second conductivity type is formed on the window layer for making ohmic contact, a conductive oxide layer is formed on the contact layer, and a second electrode is formed on the conductive oxide layer. The conductive oxide layer typically includes a central portion located below the second top electrode, which extends into the LED structure, typically beyond the contact layer and into the window layer, or even beyond the window layer, such as into the second confining layer. The improved LED structures preferably include a higher resistive or reverse biased pattern, typically built on or within the substrate, approximately below the second electrode, to further assist the current blocking function. The light emitting diodes preferably include one or more holes which are defined in the conductive oxide layer, or within both the conductive oxide layer and the contact layer, to promote the transmission of light from the upper surface of the light emitting diode. A Distributed Bragg Reflector is also preferably provided between the lower substrate and the first confining layer, to reduce light absorption within the substrate, and to promote efficient light extraction from the top of the LED structure.