Identification of Raman-active phonon modes in oriented platelets of InN and polycrystalline InN

We report on micro-Raman studies on both randomly oriented polycrystals and groups of oriented, faceted platelets of indium nitride grown from the melt at subatmospheric pressures. Phonon modes were assigned as A(1)(TO) = 445, E-1(TO) = 472, E-2((2)) = 488, and A(1)(LO) = 588 cm(-1). The FWHM of the E-2((2)) peak of 2.5 cm(-1) is the narrowest reported to date for InN. The measured TO phonon frequencies were compared to those calculated from first principles and excellent agreement was found. The results are discussed in the context of previously reported Raman experiments on heteroepitaxial, and hence strained, layers of InN. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.