| 摘要 |
PROBLEM TO BE SOLVED: To reduce a forward voltage drop and its variation, to improve the trade-off of the forward voltage drop and reverse recovery loss, and to make a current softly recovered. SOLUTION: On an n-cathode layer 1 in which antimony is doped, an epitaxial growth layer 20 is formed while doping phosphorous, and a impurity concentration in the epitaxial growth layer 20 is gradually increased from an n<SP>+</SP>-layer 1 side to a central part (Xp) and gradually decreased from the central part (Xp) toward the surface of the epitaxial growth layer 20. A p-anode layer 3 is formed in the surface layer of the epitaxial growth layer 20, and an n<SP>+</SP>-layer 4 is formed by introducing As of 1×10<SP>18</SP>cm<SP>-3</SP>or higher in a surface concentration in the surface layer of the n-cathode layer 1. An ohmic contact between the cathode electrode 6 and the cathode layer 1 is ensured by forming the n<SP>+</SP>-layer 4, thereby reducing an ON voltage (a forward voltage drop) and its variation. Also the trade-off of the forward voltage drop and the reverse recovery loss can be improved. Moreover, the current can be softly recovered by enhancing the concentration in the central part Xp of the n-drift layer. COPYRIGHT: (C)2004,JPO
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