GaN boule growth: A pathway to GaN wafers with improved material quality

Hydride vapor phase epitaxial growth of GaN boules was investigated. GaN boules were formed at growth rates in excess of 100 μm/h, resulting in boules as long as 5 mm in the c-axis direction. The boules were sliced into wafer blanks. Lapping, polishing and chemical-mechanical polishing was employed to produce wafers with a slightly stepped surface. Dislocations were decorated with hot phosphoric acid etching so that the change in defect density with boule length might be studied. Etch pit density correlated to threading dislocation density as measured by plan-view transmission electron microscopy and synchrotron white beam X-ray topography. The dislocation density of the GaN fabricated from the boules was as low as 10 4 cm -2 .