Characterization of oxide precipitates in epitaxial InN by transmission electron microscopy

InN thin films have been grown epitaxially on GaN-buffered sapphire substrates by molecular-beam epitaxy at 500 °C. A high level of oxygen contamination in the growth chamber led to formation of In2O3 precipitates in the films. These precipitates were characterized in detail by transmission electron microscopy TEM . The concentration of In2O3 was estimated to be less than 0.07 vol % in the present samples of oxygen content 0.5 at. %. Cross-sectional TEM investigations revealed that the precipitates adopt a preferred crystallographic orientation within the InN matrix, and show a characteristic diameter of 5 nm with average distance of 500 nm. These observations suggest the effective solubility of O in InN could be below 1 at. % at 500 °C. © 2005 American Institute of Physics. DOI: 10.1063/1.2035330