| 摘要 |
PROBLEM TO BE SOLVED: To enable soft switching of the reverse recovery characteristics and reduce negative temp. dependence of a forward voltage or make it positive, by providing an n-barrier layer having a higher impurity concn. than that of an n-drift layer between a p-anode layer and the n-drift layer. SOLUTION: An n+ cathode layer 3 is formed on a surface layer of one main surface of a high resistivity n-drift layer 1, an n+ barrier layer 9 is formed on a surface layer of the other main surface, and a p-anode layer 2 is formed adjacent to it. A cathode electrode 6 is provided in contact with the cathode layer 3 and an anode electrode 5 is provided in contact with the surface of anode layer 2. As to, e.g. a diode of class 2500 V, the impurity concn. of the drift layer 1 is about 4×1013/cm3 and its thickness is 30μm. Each layer is formed by ion implantation and diffusion with a high temp. drive-in and the barrier layer 9 has a surface impurity concn. of about 2×1016/cm3 and a thickness of 10μm.
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