Improved utilization efficiency of Ga source and flatness of GaN layer by pulsed-GaCl flow modulation on hydride vapor phase epitaxy

This paper presents the results of pulsed-GaCl flow modulation epitaxy (FME) on hydride vapor phase epitaxy (HVPE) at various interval times, supply times, and V/III ratios under a constant NH3 flow. The best performance was observed at an interval time of 30 s, GaCl gas supply time of 10 s in one cycle and V/III ratio of 10. As compared to the conventional HVPE growth, the utilization efficiency of the GaCl gas improved by 2.5 times in the present method and the root-mean-square (RMS) values reduced to one-fifth of the original, without degradation of crystalline quality. We concluded that the dynamic change in the V/III ratio in one cycle of an FME sequence contributed to a change in the growth mode, resulting in an improved utilization efficiency of the GaCl gas.