Enhanced growth rate for ammonothermal gallium nitride crystal growth using ammonium iodide mineralizer

High-temperature gallium nitride (GaN) crystal growth using the acidic ammonothermal method with ammonium iodide (NH4I) as a mineralizer was investigated. The growth rate reached 105 μm/day, which was much higher than that previously achieved using acidic ammonothermal methods, and exceeded 100 μm/day, which is the minimum growth rate required for industrial applications. When NH4I was used as a mineralizer, high-speed crystal growth was achieved at a relatively low pressure compared to the case of using an ammonium chloride (NH4Cl) as a mineralizer.

► Acidic ammonothermal high-temperature GaN growth with NH4I mineralizer was studied.
► Growth rate (105 μm/day) was much higher than the previously achieved using this method.
► We obtained a 1.24-mm-thick GaN epilayer on the Ga-polar side of HVPE-seed crystal.