Epitaxial wafer device including an active layer having a two-phase structure and light-emitting device using the wafer

Claim 2

An epitaxial wafer for a light-emitting device that includes a double hetero-structure, said epitaxial wafer comprising: a single-crystal substrate, a lower cladding layer of Al.sub.α Ga.sub.β N (0≦α, β≦1, α+β=1) grown on the substrate, an active layer grown on the lower cladding layer, said active layer having a two-phase structure comprised of a matrix of Al x Ga y In z N (wherein 0≦x, y, z≦1, x+y+z=1) and crystallets of Al a Ga b In c N (wherein 0≦a, b<1, 0<c<1, and a+b+c=1), and an upper cladding layer of Al.sub.α Ga.sub.β N (0≦α, β≦1, α+β=1) grown on the active layer.

Claim 3

An epitaxial wafer according to claim 1, wherein the crystallets are substantially spherical crystals with a diameter of not less than 1 nm and not more than 30 nm or are mesa-shaped crystals with a lateral width of not less than 1 nm and not more than 30 nm.

Claim 4

An epitaxial wafer according to claim 1, wherein the active layer has a thickness of not less than 1 nm and not more than 300 nm and a crystallet density of not less than 1×10 12 cm -3 and not more than 2×10 18 cm -3 .

Claim 5

An epitaxial wafer according to claim 3, wherein the active layer has a thickness of not more than 20 nm and a relationship between crystallet density d and active layer thickness t of d (crystallets/cm 3 )≦5.0×10 23 ×t.

Claim 6

A light-emitting device comprising: a single-crystal substrate, a lower cladding layer of Al.sub.α Ga.sub.β N (0≦α, β≦1, α+β=1) grown on the substrate, an active layer grown on the lower cladding layer, said active layer having a two-phase structure comprised of a matrix of Al x Ga y In z N (wherein 0≦x, y, z≦1, x+y+z=1) and crystallets of Al a Ga b In c N (wherein 0≦a, b<1, 0<c<1, and a+b+c=1), an upper cladding layer of Al.sub.α Ga.sub.β N (0≦α, β≦1, α+β=1) grown on the active layer, a GaN contact layer grown on the upper cladding, an electrode of a first conductivity type provided on a surface of the lower cladding layer, and an electrode of a second conductivity type provided on a surface of the contact layer.

Claim 7

A light-emitting device comprising: a single-crystal substrate, a lower cladding layer of Al.sub.α Ga.sub.β N (0≦α, β≦1, α+β=1) grown on the substrate, an active layer grown on the lower cladding layer, said active layer having a two-phase structure comprised of a matrix of Al x Ga y In z N (wherein 0≦x, y, z≦1, x+y+z=1) and crystallets of Al a Ga b In c N (wherein 0≦a, b<1, 0<c<1, and a+b+c=1), an upper cladding layer of Al.sub.α Ga.sub.β N (0≦α, β≦1, α+β=1) grown on the active layer, a GaN contact layer grown on the upper cladding, an electrode of a first conductivity type provided on a surface of the lower cladding layer, and an electrode of a second conductivity type provided on a surface of the contact layer.

Claim 8

A light-emitting device according to claim 5, wherein the crystallets are substantially spherical crystals with a diameter of not less than 1 nm and not more than 30 nm or are mesa-shaped crystals with a lateral width of not less than 1 nm and not more than 30 nm.

Claim 9

An epitaxial wafer according to claim 5, wherein the active layer has a thickness of not less than 1 nm and not more than 300 nm and a crystallet density of not less than 1×10 12 cm -3 and not more than 2×10 18 cm -3 .

Claim 10

An epitaxial wafer according to claim 7, wherein the active layer has a thickness of not more than 20 nm and a relationship between crystallet density d and active layer thickness t of d (crystallets/cm 3 )≦5.0×10 23 ×t.