Dependence of polarity inversion on V/III ratio in −c-GaN growth by oxide vapor phase epitaxy

One of the issues in bulk c-GaN growth is the decrease in the diameter of crystals with an increase in thickness owing to the appearance of inclined and facets. In this study, we performed −c-GaN growth by oxide vapor phase epitaxy (OVPE). As a result, truncated-inverted-pyramidal crystals were successfully grown on dot-patterned −c-GaN substrates. The diameter of the top surface of crystals was larger than that of windows. We further investigated the dependence of the ratio of inversion-domain area to growth area (RID) on growth temperature, V/III ratio, and growth rate. The remained results revealed that RID decreased with increasing growth temperature and V/III ratio, and kept constant for growth rate. Additionally, an epitaxial layer on −c-GaN substrates with a growth rate of 12.4 µm/h and an RID as low as 3.8% was obtained under an NH3 partial pressure (PNH3) of 83 kPa at 1200 °C.