Polarization doping in nitride based diodes

摘要

A light emitting device comprising a three-dimensional polarization-graded (3DPG) structure that improves lateral current spreading within the device without introducing additional dopant impurities in the epitaxial structures. The 3DPG structure can include a repeatable stack unit that may be repeated several times within the 3DPG. The stack unit includes a compositionally graded layer and a silicon (Si) delta-doped layer. The graded layer is compositionally graded over a distance from a first material to a second material, introducing a polarization-induced bulk charge into the structure. The Si delta-doped layer compensates for back-depletion of the electron gas at the interface of the graded layers and adjacent layers. The 3DPG facilitates lateral current spreading so that current is injected into the entire active region, increasing the number of radiative recombination events in the active region and improving the external quantum efficiency and the wall-plug efficiency of the device.