Optimization of N-polar GaN growth on bulk GaN substrate by MOCVD

Abstract

N-polar GaN samples under different V/III ratio were grown on bulk N-polar GaN substrates by metal organic chemical vapor deposition. The V/III ratio was optimized by adjusting the flow rate of trimethylgallium, meanwhile the flow rate of ammonia is consistent. The samples were characterized by High Resolution X-Ray Diffraction, Raman, photoluminescence and Van-der-Pauw Hall measurement. The best dislocation density of the samples is approximately 3.72 × 106 cm−2 which is three orders of magnitude smaller than the common heteroepitaxy of N-polar GaN. The background carrier concentration of the samples is reduced by about 95% as the flow rate of trimethylgallium decreasing.