Material properties of GaN films with Ga-or N-face polarity grown by MBE on Al{sub}2O{sub}3 (0001) substrates under different growth conditions

摘要

The material properties of GaN films grown on Al{sub}2O{sub}3 (0001) substrate nitridated at high and low temperatures were investigated. The effects of GaN or AlN nucleation layers and different 111/V flux ratio on the polarity of the films were also investigated Reflected high energy electron diffraction (RHEED) was used for in-situ monitoring of the surface structure and films polarity. The optoelectronic properties were determined by low and room temperature photoluminescence measurements. Finally a method combining etching in a KOH solution and atomic force microscopy (AFM) was developed to identify the polarity of the GaN films.