| 摘要 |
PROBLEM TO BE SOLVED: To form p-n junctions before and after a current constricting layer and the p-n junction of an active layer at prescribed positions by suppressing the diffusion of a dopant from a cap layer, a second clad layer, or a third clad layer which is doped with the dopant at high concentrations by providing a diffusion preventing layer between the current constricting layer and third clad layer. SOLUTION: An n-type GaAs buffer layer 2 having a thickness of 0.2μm, a first clad layer 3, an active layer 4, a second clad layer 5, and a GaAs cap layer 6 are successively formed on an n-type GaAs substrate 1 by using an organometallic vapor growth method. Then a silicon oxide layer having a thickness of 0.04μm is formed on a wafer by using an electron beam vapor deposition method and another silicon oxide film having a thickness of 0.1μm is formed on the silicon oxide layer by using a sputtering method. Thereafter, a stripe-like silicon oxide mask 7 having a width of 3μm is formed by performing ordinary patterning. After the mask 7 is formed, the substrate 1 is taken out from a MOCVD device and a soft etching diffusion preventing layer 13 is formed by etching the upper part of a current constricting layer 8 with a phosphoric acid- based or iodine-based etchant.
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