Group III nitride LED with undoped cladding layer and multiple quantum well

The present invention is a semiconductor structure for light emitting devices that can emit in the red to ultraviolet portion of the electromagnetic spectrum. The structure includes a first n-type cladding layer of Al_xIn_yGa_1-x-yN, where 0x1 and 0y1 and (x+y)1; a second n-type cladding layer of Al_xIn_yGa_1-x-yN, where 0x1 and 0y1 and (x+y)1, wherein the second n-type cladding layer is further characterized by the substantial absence of magnesium; an active portion between the first and second cladding layers in the form of a multiple quantum well having a plurality of In_xGa_1-xN well layers where 0x1 separated by a corresponding plurality of Al_xIn_yGa_1-x-yN barrier layers where 0x1 and 0y1; a p-type layer of a Group III nitride, wherein the second n-type cladding layer is positioned between the p-type layer and the multiple quantum well; and wherein the first and second n-type cladding layers have respective bandgaps that are each larger than the bandgap of the well layers. In preferred embodiments, a Group III nitride superlattice supports the multiple quantum well.