US Patent 8742396 III nitride epitaxial substrate and deep ultraviolet light emitting device using the same

A III nitride epitaxial substrate which makes it possible to obtain a deep ultraviolet light emitting device with improved light output power is provided. A III nitride epitaxial substrate includes a substrate, an AlN buffer layer, a first superlattice laminate, a second superlattice laminate and a III nitride laminate in this order. The III nitride laminate includes an active layer including an AlαGa1-αN (0.03≦α) layer. The first superlattice laminate includes AlaGa1-aN layers and AlbGa1-bN (0.9<b≦1) layers which are alternately stacked, where α(alpha)<a and a<b. The second superlattice laminate includes repeated layer sets each having an AlxGa1-xN layer, an AlyGa1-yN layer, and an AlzGa1-zN (0.9<z≦1) layer, where α(alpha)<x and x<y<z.