Growth and evaluation of bulk GaN crystals grown on a point seed crystal by Ba-added Na flux method

Abstract

We grew bulk gallium nitride (GaN) single crystals on a point seed by using the Baadded Na flux method and evaluated their structural and optical properties. As a result, we successfully grew habit-controlled single GaN crystals. The size of the largest crystal in this study was 7 mm along the [0001] direction and 9 mm along the (11-20) direction after 200 h of growth. The cathodoluminescence (CL) images of (10-10) GaN wafers sliced from the grown crystal revealed that large areas of the wafer were dislocation free. Full widths at half maximum (FWHMs) of the X-ray rocking curve (XRC) of GaN (10-10) at low-dislocation-density sectors were from 32 to 61 arcsec. No green and yellow luminescence (GL and YL, respectively) peaks were detected from the room-temperature photoluminescence spectrum. From these results, it is found that the Ba-added Na flux method of GaN crystal growth on a point seed opens the possibility of fabricating high-quality prismatic GaN bulk single crystals.