Abstract: An injection block having a plurality of geometrically arranged injection sources for gaseous Group III metal organic compounds is oriented substantially perpendicular to the placement of at least one semiconductor wafer substrate within a vacuum reaction chamber. The injector sources are sized to provide disbursing flow of the compounds capable of depositing a layer of about 5% uniform thickness or less over substantially the entire semiconductor wafer. An injection source of Group V compounds is located centrally within the geometrically arranged injection sources for the Group III compounds. The Group V injection source is sized to supply an excess of the Group V compounds required to react with the Group III compounds in order to form Group III-V semiconductor layers on the substrate and partition the Group III sources into groups having substantially equal numbers of injection sources. An excess of Group V comounds is injected.