Monitoring of GaN crystal growth rate in the Na flux growth via electroresistometry of Ga-Na solution

Monitoring the GaN crystal growth process in the Na-flux method has been difficult due to the challenging growth process, namely high temperature and high pressure and corrosive nature of Ga and Na. This paper describes the unique method to monitor GaN crystal growth by measuring the electrical resistance of Ga-Na solution. We found that the electrical resistance of Ga-Na solution decreased along with the crystal growth. Furthermore, the decreasing rate of resistance is proportional to growth pressure, which influences the growth rate. During the growth process, Ga in the solution is consumed, reducing the Ga/Na ratio of the Ga-Na solution. The compositional shift toward Na-rich resulted in the decrease of electrical resistance.