Contribution of GaN template to the unexpected Ga atoms incorporated into AlInN epilayers grown under an indium-very-rich condition by metalorganic chemical vapor deposition (MOCVD)

A large amount of Ga atoms, sometimes nominally as high as 45% of the total group III constituents, was found in the AlInN films prepared by metalorganic chemical vapor deposition (MOCVD) under an In-very-rich environment, even when no Ga precursor was introduced. GaN template has been found to be the main source supplying most of the unexpected Ga atoms during epitaxial growth, of which about 2% might be contributed from other residual Ga-contained sources in the reactor. Secondary ion mass spectroscopy (SIMS) profile measurement shows that atom interdiffusion between In, Al, and Ga atoms is the main path of the high percentage of unexpected Ga atoms incorporating into the AlInN epilayers. A high growth temperature and the H2 added in carrier gas may enhance the Ga atom incorporation into AlIn(Ga)N epilayer by promoting decomposition of GaN template and increasing atom diffusing ability.

► Unexpected Ga atoms were found in AlInN epilayers.
► GaN template was determined to be the source supplying unexpected Ga atoms.
► Unexpected Ga atoms incorporated into AlInN epilayers by atom interduffusion.
► H2 in carrier gas leads to an increased amount of unexpected Ga atoms.