We report on the infrared (IR) reflection and Raman measurements of InN thin films grown by radio frequency (RF) magnetron sputtering and microwave-excited metalorganic vapor phase epitaxy (ME-MOVPE) on GaAs (I 1 1) and sapphire (0 0 0 1) substrates. X-ray diffraction measurements were employed to evaluate the quality of the InN films. By fitting the IR reflection spectra and from the Raman spectra, A(1) (TO), E-1 (TO), A(1) (LO) and E-2 (high) modes have been observed and attributed. The phonon characteristics in InN thin films as well as the film quality of InN films are found to be dependent on the growth conditions from a comparison of the results. The carrier concentration and mobility are also obtained from fitting the IR reflection spectra. The frequencies of El (TO) and A, (LO) phonon modes show a manifest blueshift due to the residual compressive stress in the films. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 30]
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