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 mel t 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 firs t principles and excellent agreement was found. The results are discussed i n the context of previously reported Raman experiments on heteroepitaxial, and hence strained, layers of InN. (C) 2000 Published by Elsevier Science L td. All rights reserved.