Raman study of gap mode and lattice disorder effect in InN films prepared by plasma-assisted molecular beam epitaxy

Raman scattering has been used to study lattice defects induced by non-stoichiometry in indium nitride films grown by plasma-assisted molecular beam epitaxy with different In/N ratios. A gap mode located at about 375 cm−1 is observed in InN films grown at low In/N ratios. This is in good agreement with the recursion method calculation for the In vacancy-induced vibration mode. In addition, a spatial correlation model has been used to estimate the lattice disorder in InN samples. The shortest correlation length is L = 5.9 nm.