MBE Growth of Hexagonal InN Films on Sapphire with Different Initial Growth Stages

Abstract

Pure hexagonal InN films were deposited on Al2O3 (0001) substrates by plasma assisted molecular beam epitaxy at various temperatures from 300 to 500 °C. The temperature of 470 °C has been found to be the maximal one allowing In-droplet-free InN growth at a growth rate of 0.2 to 0.3 μm/h. Reflection high energy electron diffraction, scanning electron microscopy, X-ray diffraction, Raman scattering, and Hall-effect measurements are used to investigate the film properties as dependent on initial growth stages. The most effective initial stage involving high temperature annealing of a 15 nm thick InN buffer grown at low temperature results in significantly improved structural properties of the following InN layer. In spite of the high electron concentration of the order of 1020 cm—3, the room temperature Hall mobility up to 600 cm2/Vs has been demonstrated.