Although GaN has been used in optical materials and power devices, the extent of its application is determined by the crystal quality. Bulk GaN has been reported to produce high-quality GaN. Therefore, it can be used in applications that require highquality crystals, such as high-brightness light-emitting diode, power devices, etc. We grew a 2-inch bulk GaN crystal, using the hydride vapor phase epitaxy (HVPE) method, on a sapphire substrate to a thickness of ~5 mm. X-ray diffraction (XRD) was used to analyze the structure of GaN. Scanning electron microscopy (SEM) was used to measure the etch pits density (EPD) of GaN after wet chemical etching. In addition, high-resolution XRD (HR-XRD) and Raman spectrometry were employed for radius of curvature and residual strains measurements, respectively.

Keywords: HVPE, bulk GaN, dislocation, residual thermal strain, radius curvature