A semiconductor device comprising: a semiconductor base body having the structure where a first semiconductor layer of a first conductive type and a second semiconductor layer of a first conductive type containing an impurity of a first conductive type at a concentration lower than a concentration of the impurity of the first conductive type contained in the first semiconductor layer are laminated to each other in this order; a high concentration diffusion region of a second conductive type selectively formed on the surface of the second semiconductor layer opposite to the first semiconductor layer, and containing an impurity of a second conductive type opposite to the conductive type of the impurity of the first conductive type at a concentration higher than a concentration of the impurity of the first conductive type which the second semiconductor layer contains; and a barrier metal layer formed on said surface of the second semiconductor layer and a surface of the high concentration diffusion region, forming a Schottky junction between the barrier metal layer and the second semiconductor layer, and forming an ohmic junction between the barrier metal layer and the high concentration diffusion region, wherein heavy metal is diffused into the semiconductor base body, and wherein, assuming a depth position in the surface of the second semiconductor layer as D1, a depth position in a deepest portion of the high concentration diffusion region as D2, a depth position which is deeper than the depth position D2 and is shallower than a boundary surface between the first semiconductor layer and the second semiconductor layer as D3, a depth position of the boundary surface between the first semiconductor layer and the second semiconductor layer as D4, and a depth position in the opposite surface of the first semiconductor layer as D5, the concentration of the heavy metal at the depth position D2 is higher than the concentration of the heavy metal at the depth position D3 and the concentration of the heavy metal at the depth position D5 is higher than the concentration of the heavy metal at the depth position D4; the device being characterised in that the concentration of the heavy metal is maximum in said surface of the second semiconductor layer and in that the concentration of the heavy metal at the depth position D4 is higher than the concentration of the heavy metal at the depth position D3. a semiconductor base body having the structure where a first semiconductor layer of a first conductive type and a second semiconductor layer of a first conductive type containing an impurity of a first conductive type at a concentration lower than a concentration of the impurity of the first conductive type contained in the first semiconductor layer are laminated to each other in this order; a high concentration diffusion region of a second conductive type selectively formed on the surface of the second semiconductor layer opposite to the first semiconductor layer, and containing an impurity of a second conductive type opposite to the conductive type of the impurity of the first conductive type at a concentration higher than a concentration of the impurity of the first conductive type which the second semiconductor layer contains; and a barrier metal layer formed on said surface of the second semiconductor layer and a surface of the high concentration diffusion region, forming a Schottky junction between the barrier metal layer and the second semiconductor layer, and forming an ohmic junction between the barrier metal layer and the high concentration diffusion region, wherein heavy metal is diffused into the semiconductor base body, and wherein, assuming a depth position in the surface of the second semiconductor layer as D1, a depth position in a deepest portion of the high concentration diffusion region as D2, a depth position which is deeper than the depth position D2 and is shallower than a boundary surface between the first semiconductor layer and the second semiconductor layer as D3, a depth position of the boundary surface between the first semiconductor layer and the second semiconductor layer as D4, and a depth position in the opposite surface of the first semiconductor layer as D5, the concentration of the heavy metal at the depth position D2 is higher than the concentration of the heavy metal at the depth position D3 and the concentration of the heavy metal at the depth position D5 is higher than the concentration of the heavy metal at the depth position D4; the device being characterised in that the concentration of the heavy metal is maximum in said surface of the second semiconductor layer and in that the concentration of the heavy metal at the depth position D4 is higher than the concentration of the heavy metal at the depth position D3.