| 摘要 |
PURPOSE:To entrap intensive light while improving the carrier injecting efficiency, by constituting at least one of optical guide layers by overlaying alternately two specific types of AlGaAs layers such that the an optical refractive index thereof is increased progressively toward the outside. CONSTITUTION:A clad layer of N-type AlGaAs (x=0.7) 22, a GRIN guide layer of non-doped AlAs/GaAs superlattice 23, a quantum well active layer of non-doped AlGaAs (x=0.2) 24, a GRIN guide layer of non-doped A As/GaAs superlattice 25, a clad layer of P-type AlGaAs (x=0.7) 26, a cap layer of P-type GaAs 27 and a current blocking layer of N-type AlGaAs 28 are grown on an N-type GaAs substrate 21 sequentially in that order. an average of crystal mixing ratios, xeff=LB/(LB+LZ) of a superlattice in which the AlAs layers 26 having a thickness LB and the GaAs layers 28 having a thickness LZ are overlaid alternately is fixed, and the crystal mixing ratio xeff is increased progressively from the region contacted with the active layer toward the outside so as to increase the optical refractive index according thereto. Laser beams are thereby entrapped and, at the same time therewith, the carrier injecting efficiency can be improved.
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