Surface modification induced photoluminescence enhancement of GaN nanowall network grown on c-sapphire

Surface nitridation of the c-sapphire substrate is used to improve the optical and structural quality of a GaN nanowall network film grown by plasma assisted molecular beam epitaxy. The nitridation results in the formation of a thin AlN layer on the sapphire surface. Several in-situ and ex-situ characterization are complementarily used to probe the changes in epitaxial growth, band edge emission and strain in the films. The GaN nanowall network layer formed on the pre-nitrided substrate shows a two order higher intensity of band edge luminescence than that of a GaN epilayer, demonstrating its potential for light-emission applications.