Optical properties of GaN grown on Si(111) substrates by MOCVD

GaN epilayers were grown on Si (111) substrates by MOCVD. The optical properties of the samples under different growth conditions were characterized The abnormal peaks of excitonic emissions related to cubic-GaN were observed on the samples under improper growth conditions based on the LT PL measurements. Also the peak intensity is much higher than that of hexagonal-GaN. The higher intensity of exciton peaks is attributed to the local quantum well formed between the hexagonal- and cubic-GaN. No exciton peaks of cubic-GaN were found on the sample using the optimal growth conditions.