In situ x-ray topography of silicon carbide during crystal growth by sublimation method

We have developed an instrument for real-time observation of silicon carbid e (SiC) crystal during the sublimation growth process by x-ray topography. It is constructed by combining an x-ray goniometer and a crystal-growth cha mber. The vertical goniometer consists of three circles, an alpha circle fo r the x-ray source, a beta circle for the detector, and a phi circle for th e azimuthal rotation of the sample. The growing crystal boule is set at the center of the goniometer glued on a crucible lid. Transmission topographs are taken using an asymmetric (10(1) over bar 1) reflection with the scatte ring angle 2 theta(B) = beta-alpha from the (0001)-oriented boule. A rotati ng-anode 18 kW generator with a molybdenum target is employed as the x-ray source. Topographs are observed by a direct imaging system using a charge-c oupled device camera. Incident and scattered x-ray beams pass through beryl lium windows mounted on the bottom and top flanges of the crystal-growth ch amber, respectively. The crucibles are also designed for in situ measuremen ts so that the x-ray beam path is separated from the source materials. The in situ topographs demonstrated the movement of micropipes and other defect s during the crystal growth. (C) 2000 American Institute of Physics. [S0034 -6748(00)03407-9].