Growth of N-polar GaN Using a CrN buffer layer on (0001) Al_2O_3 via plasma-assisted molecular beam epitaxy

摘要

The growth of N-polar GaN films on (0001) Al_2O_3 substrates by plasma-assisted molecular beam epitaxy was demonstrated using a CrN buffer layer. Analysis of reflection high energy electron diffraction (RHEED) patterns and a chemical etching method were used in order to confirm the polarity of GaN on CrN. RHEED patterns show the 3 x 3 pattern characteristic of GaN. Chemical etching significantly changes the GaN surface morphology which implies that the N-polar GaN was grown on the CrN buffer layer. In addition, an improvement in the crystal properties of GaN was achieved using the annealing process for the CrN buffer layers.