| 摘要 |
PURPOSE:To suppress leaking currents, by forming stripe shaped grooves in a crystal substrate and a cap layer along a laser axis in a semiconductor laser having a double heterostructure, and diffusing impurities in the approximately entire surface of the cap layer. CONSTITUTION:A stripe shaped groove in a specified shape is formed in an N-GaAs crystal substrate 6. An N-GaAlAs first clad 5, an I-GaAs active layer 4 and a P- GaAlAs second clad layer 3 are laminated so that the groove is buried and the upper surface becomes flat, and a double heterostructure is formed. An N-GaAs cap layer 2 is laminated. By using NH4OH-H2O, the layer 2 is selectively subjected to photoetching. Thus a stripe shaped groove 8 is selectively subjected to photoetching. Thus a stripe shaped groove 8 is formed in the direction of a laser light axis. The depth of the groove 8 is provided so that the layer 3 is exposed. The position of the groove 8 is approximately the same as that of the groove in the substrate. The groove 8 is narrower than the groove in the substrate. Then, P-type impurities such as Zn are diffused. A diffused cross section, which is shallow on the cap layer 2 and deep beneath the groove 8, is obtained. The current does not flow in the edge of the substrate, but flows in the narrow oscillating region and reaches the substrate 6. Therefore, leading currents are decreased. Since deep diffusion is not required, productivity is improved.
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