Band gap energy and bowing parameter of In-rich InAlN films grown by magnetron sputtering

The crystal structure, band gap energy and bowing parameter of In-rich InxAl1−xN (0.7 < x < 1.0) films grown by magnetron sputtering were investigated. Band gap energies of InxAl1−xN films were obtained from absorption spectra. Band gap tailing due to compositional fluctuation in the films was observed. The band gap of the as-grown InN measured by optical absorption method is 1.34 eV, which is larger than the reported 0.7 eV for pure InN prepared by molecular beam epitaxy (MBE) method. This could be explained by the Burstein–Moss effect under carrier concentration of 1020 cm−3 of our sputtered films. The bowing parameter of 3.68 eV is obtained for our InxAl1−xN film which is consistent with the previous experimental reports and theoretical calculations.