Subclass 21/08: Processes or apparatus specially adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer, carrier concentration layer the devices having semiconductor bodies comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials Preparation of the foundation plate