In situ spectroscopic ellipsometry in plasma-assisted molecular beam epitaxy of InN under different surface stoichiometries

InN epilayers grown by radio-frequency plasma-assisted molecular beam epitaxy under different surface stoichiometries were characterized by in situ spectroscopic ellipsometry in the range from 0.731eV (1697nm) to 4.95eV (250nm). Nitrogen polarity InN epilayers were grown at 600°C on GaN-underlayer/sapphire substrate. The surface stoichiometry during growth was changed by varying the indium-beam flux under the same nitrogen-beam flux. It was found that the pseudodielectric functions were drastically affected by the surface stoichiometry. The dielectric functions of InN grown under different stoichiometries were obtained. Both real and imaginary parts of the dielectric functions tended to be larger with increasing In-beam flux.