Temperature Gradient Control with an Air-Pocket Design for Growth of High Quality SiC Crystal

The hot-zone design using an air-pocket was adopted to produce uniform temperature gradient in horizontal direction. In order to investigate the change of temperature gradient toward horizontal direction with growth time, the front shape of SiC growing crystal was measured with different growth stages such as initial, growing and finished stage. While SiC ingot grown in conventional hot-zone design exhibited inhomogeneous growth front in the initial stage of growth and multi facet formation in final stage, which could result in increased defect density, a homogeneous temperature gradient and improved crystal quality was obtained in the modified hot-zone design. Based on the mapping measurement of FWHM (Full width at half maximum) value in X-ray rocking curve, the crystal quality of SiC crystals grown with the modified hot-zone design was observed to be definitely better than conventional design.