Enlargement of bulk non-polar GaN substrates by HVPE regrowth

M-plane non-polar bulk GaN substrates were regrown by hydride vapour phase epitaxy (HVPE), aiming to enlarge their lateral size. The non-polar GaN substrates were synthesized by growing thick GaN boules by HVPE along the c-axis, and wafering transversely to expose non-polar (m- or a-plane) surfaces. Non-polar GaN substrates obtained in this manner contains lower defect density comparing to those produced by heteroepitaxial growth. After the regrowth, substantial lateral expansion in [0001], [1120] and [1120] was observed. Threading dislocation densities were estimated by cathodoluminescence measured at the cross-section areas. The dislocation densities in the substrate and the regrown areas were approximately 5×10⁶ cm^-2 and 1×10⁶ cm^-2, respectively, indicating a comparable structural quality achieved by the regrowth. Non-polar GaN substrates prepared by this process provide a promising method to fabricate devices for next generation.