Patent ID: 8513643

Claim:
A semiconductor light emitting device, comprising: an Al 2 O 3 substrate; a planar In k Al x Ga 1-x-k N template layer formed over said substrate, said template layer having threading dislocations originating at said substrate and propagating substantially in a direction perpendicular to the plane of said template layer; a defect redirection region formed over said template layer, said template layer having threading dislocations transmitted from said template layer which are bent by said defect redirection region so as to propagate within said defect redirection region substantially in a direction other than perpendicular to the plane of said template layer; an active region having a composition In z Al y Ga 1-y-z N, formed over said defect redirection region said active region having threading dislocations transmitted from said defect redirection region, said threading dislocations propagating both in a direction perpendicular to the plane of said template layer and in a direction other than perpendicular to the plane of said template layer, the number of said threading dislocations propagating in a direction perpendicular to the plane of said template layer in said active region being substantially less than the number of threading dislocations propagating in a direction perpendicular to the plane of said template layer in said template layer; and wherein said defect redirection region comprises a plurality of groups of layer pairs, a first of said layer pairs comprising In r Al s Ga 1-s-r N, and a second of said layer pairs comprising In q Al t Ga 1-t-q N, and wherein each group has an average aluminum concentration, the average aluminum concentration of the group proximate the template layer approaching or equal to x, and the average aluminum concentration of the group proximate the active region approaching or equal to y.