Ammonothermal Bulk GaN growth and its processing

Abstract

In this paper, we overview the current progress of ammonothermal GaN growth at SixPoint Materials, Inc. and discuss issues in wafer processing. Bulk GaN crystals grown in small prototype reactors present a high-quality microstructure as well as an improved transparency. The dislocation density of the crystal is on the order of 4.0 × 104cm-2. The optical absorption coefficient as low as 4 cm-1 at 450 nm is obtained. Wafer processing techniques, such as wire sawing and chemical mechanical polishing, are one of the challenges in realizing GaN wafers. Crystal cracks are the major and fundamental obstacle in achieving a high-quality surface during wire sawing. The surface quality after chemical mechanical polishing (CMP) is successfully evaluated using X-ray diffraction.