AbstractWe have estimated the longitudinal effective mass (m‖) of electron in n‐type InN films by Raman scattering. The samples were grown by MOVPE (metal organic vapor phase epitaxy) with free carrier concentration of n =6.7×1018‐9.9×1018 cm‐3 according to Hall measurement. A weak Raman signal observed at ∼430 cm‐1 at room temperature was sharpened and shifted to higher frequency toward the A1(TO)‐phonon mode at 447 cm‐1 with increasing n. This mode was assigned to the lower branch (L‐) of the longitudinal‐optic‐phonon‐plasmon‐coupled (LOPC) mode. The line shape was carefully analyzed by a semi‐classical line‐shape fitting analysis assuming deformation potential and electro‐optic coupling mechanisms for the light scattering process. A line‐shape fitting analysis was conducted by adjusting three major parameters; electron density, effective mass and plasmon damping rate. The analysis well reproduced values of electron density and mobility deduced by Hall measurement. Electron effective mass of m‖*/m0 = 0.05 (±0.01) was also obtained as the best‐fit parameter. The result agrees well with previous data obtained by other optical methods. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)