A light-emitting diode or laser diode comprises a sapphire substrate and, grown on the substrate, a GaN buffer layer, an n-doped GaN contact layer, an n-doped (AlGa)N cladding layer, a Zn-doped (InGa)N active layer, a p-doped (AlGa)N cladding layer and a p-doped GaN contact layer. Graded layers are introduced...http://www.google.com/patents/US6695913?utm_source=gb-gplus-sharePatent US6695913 - III-Nitride optoelectronic semiconductor device containing lattice mismatched III-Nitride semiconductor materials
