Challenges and prospects of ammonothermal GaN crystal growth and substrate fabrication

Gallium nitride (GaN) crystals of the best structural quality are grown by ammonothermal method in a supercritical ammonia solution inside high pressure autoclaves. This lecture will focus on the basic ammonothermal growth. The growth mechanism in different crystallographic directions, growth morphology and structural quality of GaN crystals, will be discussed. Structural properties and shape of the seeds will be shown. The influence of the crystallization run parameters, the internal configuration of the autoclave and the structural quality of the obtained GaN will be discussed. The path from bulk crystal to finished substrate of GaN will be presented. All challenges and difficulties to grown bulk GaN from ammonothermal method will be demonstrated. Scenarios for the further development of bulk GaN crystallization will be presented.