done for example in known manner at low pressure and a temperature of approximately 650 u00b0 c the undoped layer 5 then is polycrystalline the thickness of the layer 5 may be for example 0 4 to 0 5 u03bcm an n type dopant for example phosphorus is then provided by implantation and or diffusion in the layer 5 and through the layer 5 and the aperture 4 into the semiconductor body 1 the concentration and the heating times and heating temperatures are conventionally chosen such that after the further thermal treatments to be described n type region 8 is formed in the body 1 having a depth of penetration of for example approximately 2 to 2 5 u03bcm this region 8 forms the p n junction 11 with the adjoining p type part of the body 1 the distance between said p n junction and the surface 2 thus being 2 to 2 5 u03bcm this doping treatment may be carried out without the use of a mask the layer 5 then becomes entirely n type the provision of the doping may also be restricted to the aperture 4 and its direct surroundings for example by means of a photoresist mask not shown if the dopant is implanted in the layer 5 by means of ion implantation if the subsequent thermal treatment in which this dopant diffuses deeper in the semiconductor body is carried out entirely or partly in an oxidizing atmosphere the semiconductor layer is covered with an oxide layer this oxide layer not shown may be used as a masking layer in the subsequent doping treatments before these doping treatments a photoresist layer 21 is provided having therein an aperture 22 fig3 and 4 this layer 21.