A semiconductor device is prepared by the use of a vapor phase method and is provided with a semiconductor layer composed of boron phosphide having a band gap at room temperature of not less than 2. Between the corrugated plates first and second flow channels are arranged, which first flow channels, via first inlet openings and first outlet openings, are connected essentially parallel to in-going and out-going junction channels. The hub sleeves together form the hub, around which the sectors are journalled for limited movement around a central axis extending through the center of the hub.