Mar 6, 2018

Growth of bulk GaN crystals by the Na-flux point seed technique

In this paper, progress in the Na-flux point seed technique (SPST) will be reviewed. Bulk GaN crystals with a diameter of 2.1 cm, a height of 1.2 cm, and large dislocation-free areas were successfully produced by SPST. Panchromatic cathodoluminescence images of a wafer sliced parallel to the c-face from the crystal showed the lack of dark spots due to dislocations over a large area of the wafer. Structural properties were evaluated using synchrotron X-ray diffraction analysis at SPring-8. The full width at half maximum of the 006 rocking curve was found to be 2.1 arcsec, close to the calculated value of 2.0 arcsec for a perfect GaN crystal, indicating that crystals grown by SPST have an almost perfect structure. In addition, we have extended the use of SPST to the coalescence growth of GaN crystals to increase the wafer diameter and obtained a 2 in. GaN wafer with a low dislocation density and a low curvature by this technique.


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