Patent ID: 8482027

Claim:
An epitaxial wafer for a light emitting diode, comprising a GaAs substrate, a pn junction-type light emitting unit provided on the GaAs substrate, and a strain adjustment layer provided on the light emitting unit, wherein the light emitting unit has a strained light emitting layer having a composition formula of (Al X Ga 1-X ) Y In 1-Y P (wherein X and Y are numerical values that satisfy 0≦X≦0.1 and 0.39≦Y≦0.45 respectively), the strain adjustment layer is transparent to an emission wavelength and has a lattice constant that is smaller than a lattice constant of the GaAs substrate, a thickness of the strained light emitting layer is within a range from 8 to 30 nm, a peak emission wavelength of the strained light emitting layer is within a range from 655 to 675 nm, and a thickness of the strain adjustment layer is within a range from 3 to 15 μm.