Patent ID: 8212268

Claim:
An epitaxial wafer, comprising: a semiconductor substrate; a light-emitting portion including an active layer provided between a first cladding layer of a first conductivity type and a second cladding layer of a second conductivity type different from the first conductivity type; a reflective portion which is provided between the semiconductor substrate and the light-emitting portion and which reflects a light emitted from the active layer; and a current dispersing layer provided on an opposite side of the reflective portion in relation to the light-emitting portion, and including first and second current dispersing layers having different carrier densities and impurity densities from each other, wherein the reflective portion includes plural pairs of layers each including a first semiconductor layer and a second semiconductor layer different from the first semiconductor layer, wherein the first semiconductor layer has a thickness of T A defined by Equation (1), T A = λ p 4 ⁢ n A ⁢ 1 - ( n In ⁢ sin ⁢ ⁢ θ n A ) 2 ( 1 ) wherein λ p is a wavelength at a peak of the light emitted from the active layer, n A is a refractive index of the first semiconductor layer, n B is a refractive index of the second semiconductor layer, n In is a refractive index of the first cladding layer and θ is an incident angle to the second semiconductor layer, wherein the second semiconductor layer has a thickness of T B defined by Equation (2), T B = λ p 4 ⁢ n B ⁢ 1 - ( n In ⁢ sin ⁢ ⁢ θ n B ) 2 ( 2 ) wherein the second current dispersing layer has a higher carrier density than the first current dispersing layer or has a higher impurity density than the first current dispersing layer, and the second current dispersing layer is provided with a convexoconcave portion on the surface.