Patent ID: 7508010

Claim:
A boron phosphide-based compound semiconductor device comprising a Group III nitride semiconductor light emitting layer, and a boron phosphide-based compound semiconductor upper cladding layer consisting of an amorphous layer and a polycrystal layer provided to join with the amorphous layer, wherein the Group-III nitride semiconductor layer as the light-emitting layer comprises a compound represented by the compositional formula Al α Ga β InγN (wherein 0≦α,β,γ≦1, α+β+γ=1) or Al α Ga β In γ N δ M 1−δ (wherein 0≦α,β,γ≦1, α+β+γ=1, 0<δ≦1, and M is a Group-V element except for nitrogen), and wherein the room-temperature bandgap of the boron phosphide-based compound semiconductor layer is from 3.0 eV to less than 4.2 eV and the polycrystal layer consists of cubic-zincblende crystal structure boron phosphide-based semiconductor.