| 摘要 |
PROBLEM TO BE SOLVED: To restrain leakage current at reverse bias. SOLUTION: A ridge is formed by etching a semiconductor laminated structure formed by a first crystal growth. The ridge is sandwiched with N-type current block layers 31 by a second crystal growth. When third crystal growth is performed, by using a P-type contact layer 32, first doping concentration is set at 1.5×1018 cm-3, and doping concentration is changed to 3×1018 cm-3 in the way of crystal growth. The carrier concentration of a P-type contact layer 32a, which forms a PN junction together with the N-type current block layers 31, is turned into low carrier concentration. When a reverse bias voltage is applied, a depletion layer stretches sufficiently in a PN junction part of the N-type current block layer 31 and the P-type contact layer (low carrier concentration) 32a, even if crystal defects are formed in the case of crystal growth, so that the leakage current is hardly generated.
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