Abstract: A soft recovery diode of the invention includes a first semiconductor layer having N type conductivity. A second N-type semiconductor layer is disposed on the first semiconductor layer and has a lower impurity concentration than the first semiconductor layer. In the surface of the second semiconductor layer opposite to the surface contacting the first semiconductor layer, a plurality of spaced-apart first metallic layers are formed. A second metallic layer is disposed on the first metallic layers and/or the exposed portions of the second semiconductor layer. The first and second metallic layers provide barriers of different heights.

Abstract: A precision casting device especially suitable for dental use, which includes melting and casting chambers supported by a frame such that they are arranged coaxially up and down in the frame under a normal operating state and can be drawn horizontally out of the frame during service time in order to facilitate access to the interiors of them, and which is provided with evacuating apparatus and an inert gas supply and can carry out the casting process in which a casting material is molten in an inert atmosphere, the molten material is then supplied to a mold in a vacuum state and, therafter, casting is effected under a pressure of inert atmosphere.