| 摘要 |
PROBLEM TO BE SOLVED: To obtain a waveguide structure of low damages and high working accuracy by performing a reactive ion-etching as well as low damage etching for providing a overhung type waveguide. SOLUTION: A etching (RIE method) is performed halfway through a p-type InP ohmic layer 106 and a p-type InGaAsP clad layer 105 to provide a ridge-like waveguide 108. With phosphor based etchant, the p-type InGaAsP clad layer 105 comprising pn joint and a non-doped InGaAs light-absorbing layer 104 are etched sequentially. Since the ridge-like waveguide 108 is formed by RIE method with the configuration, a high-accuracy work is performed. Furthermore, the p-type InGaAs clad layer 105 and the InGaAs light-absorbing layer 104 are etched with a chemical liquid giving very little damage, since no joint is damaged for reduced leakage current.
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