Enhancement of InN Luminescence by Introduction of Graphene Interlayer

Indium nitride (InN) luminescence is substantially enhanced by the introduction of a multilayer graphene interlayer, mitigating the lattice mismatch between the InN epilayer and the Gallium nitride (GaN) template on a sapphire substrate via weak van der Waals interaction between graphene and nitride layers. The InN epilayers are deposited by radio-frequency plasma-assisted molecular beam epitaxy (MBE), and are characterized by spatially-resolved photoluminescence spectroscopy using confocal microscopy. A small blue shift of the emission band from the band gap evidences a low density of equilibrium carriers, and a high quality of InN on multilayer graphene. A deposition temperature of ~375 °C is determined as optimal. The granularity, which is observed for the InN epilayers deposited on multilayer graphene, is shown to be eliminated, and the emission intensity is further enhanced by the introduction of an aluminum nitride (AlN) buffer layer between graphene and InN.