  An HVPE reactor for the growth of bulk GaN crystals with a diameter of 50 mm
was developed. Growth rate non-uniformity of 1% was achieved using an
axisymmetric vertical gas injector with stagnation point flow.
Chemically-resistant refractory materials were used instead of quartz in the
reactor hot zone. High-capacity external gallium precursor sources were
developed for the non-stop growth of the bulk GaN layers. A load-lock vacuum
chamber and a dry in-situ growth chamber cleaning were implemented to improve
the growth process reproducibility. Freestanding GaN crystals with a diameter
of 50 mm were grown with the reactor.
