| 摘要 |
PURPOSE:To improve the optical confinement and to enable the laser operation by forming a double hetero structure and providing the GaAlAs buried layer of small refractive index in which the outside of an active region is made into mixed crystal by introduction of impurities. CONSTITUTION:At first on an N-type GaAs substrate 11, an N-type Ga1-xAlxAs layer 12, a P-type GaAs layer 13 of 0.2mum thick or under, an N-type Ga1-xAlxAs layer 14 and an N-type GaAs layer 15 are grown in order, after which an oxide film such as of SiO2 or a nitride film such as of Si3N4 is used as a mask and the region 16 except the stripe region is subjected to thermal diffusion of Zn or the like so far as it reaches the part of the N-type Ga1-xAlxAs layer 12. On the layer 15 and the diffusion region 16, an emitter electrode 17 and a base electrode 18 are formed and a collector electrode 19 is formed on a lower surface of the substrate 11. In the parts on right and left sides of the P-type GaAs layer 13 as an active layer, the change into P-type caused by the thermal diffusion of Zn as well as the change into mixed crystal in the boundary region 20 between the GaAs layer 13 and the Ga1-xAlxAs layer 12 and the boundary region 20 between the GaAs layer 13 and the N-type Ga1-xAlxAs layer 14 occurs to form the mixed crystal region 20 of Ga1-yAlyAs (0<=y<=x).
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