Abstract: An apparatus for preparing a semiconductor compound, having one compound with a substantially higher vapor pressure than the other using a closed horizontal tube disposed in a pressure vessel. The two ends of the tube are located in respective heating ovens having their ends facing away from the tube closed. The heating ovens and tube are disposed within a pressure vessel with the heating ovens having an outside diameter which is considerably smaller than the inside diameter of the pressure vessel and with the total length of the heating ovens arranged one behind the other in the axial direction of the tube substantially smaller than the length of the pressure vessel. In addition, a portion of the tube located between the ovens has associated therewith a separate cooling device.

Abstract: A process for the production of compact polycrystalline III A - V B compounds such as GaP through direct synthesis from the components in a closed horizontal system, in which at least one of the components has a substantially higher partial vapor pressure over the molten compound being produced than do the other components. In carrying out the process, the components which are more difficult to vaporize are heated in a narrow reaction zone to a temperature in the range of 100.degree. to 500.degree. C below the congruent melting temperature of the compound being produced while the pressure of the easily vaporized components is adjusted so that it amounts to between 0.14 and 0.33 times the decomposition vapor pressure of the compound being produced and thus to 50 to 120 times the decomposition vapor pressure of the solution of the compound being produced in the components which are difficult to vaporize at the reaction temperature.

Abstract: In an apparatus for the preparation of compounds in which one of the components is a highly volatile reactive component, in particular when preparing gallium phosphide, under pressure in an ampoule located in a pressure vessel, between 0.5 and 25% by volume and preferably 1.5 to 3% by volume of a gas capable of reacting with the highly volatile component, such as oxygen, air or carbon dioxide, is mixed in the pressure vessel to the gas which is used for pressurizing and as a cooling medium and the pressure in the pressure vessel is matched to the internal pressure of the ampoule in which the reaction is taking place.

Abstract: A semiconductor layer, such as an epitaxial layer on a suitable substrate is subjected to controlled bombardment by neutrons whereby the atoms of the semiconductor layer are converted via nuclear reaction into doping material atoms.