Effect of additional N2O gas on the suppression of polycrystal formation and high-rate GaN crystal growth by OVPE method

Abstract

One of the challenges in the oxide vapor phase epitaxy (OVPE) method is to suppress polycrystal formation for the high-rate growth of thick GaN crystals. In this study, we present the addition of N2O gas as the method to suppress the polycrystal formation in the OVPE-GaN growth. We confirmed that N2O gas could remove the Ga droplet, the origin of polycrystalline GaN. Results showed that the polycrystal density decreased by adding N2O gas. The decline in growth rate with the increase of N2O gas flow rate was smaller compared to that with H2O vapor, which was consistent with the fact that N2O would not affect directly the GaN growth reaction. Furthermore, we obtained a 512-µm-thick OVPE-GaN layer at the growth rate of 128 µm/h, which is the highest value for growing thick GaN layers in the OVPE method.