Raman scattering study of zincblende InxGa1-xN alloys

We report on first-order micro-Raman and resonant micro-Raman scattering me asurements on c-InxGa1-xN (0 less than or equal to x less than or equal to 0.31) epitaxial layers. We have found that both, the transverse-optical (TO ) and longitudinal-optical (LO) phonons of InxGa1-xN alloy exhibit a one-mo de-type behavior. Their frequencies at Gamma lie on straight lines connecti ng the corresponding values obtained for the c-GaN and c-InN binary compoun ds. Evidence for phase separation is shown in the sample with the alloy com position x = 0.31. The Raman spectra, with excitation energy dose to 2.4 eV , show an enhanced additional peak, with frequency between the values found for the LO and TO phonon modes of the c-In0.31Ga0.69N epitaxial layer. We ascribed this peak to the LO phonon mode of a minority phase with In conten t of approximate to 0.80.