Phonon structure of InN grown by atomic layer epitaxy

InN single crystal was grown by W-assisted atomic layer epitaxy under atmospheric pressure. The c-axis was perpendicular to the c-plane of sapphire substrate. The obtained InN was a degenerate n-type semiconductor with the carrier concentration of similar to 3 x 10(20)/cm(3). The phonon structure was investigated by the use of infrared and Raman spectra, and six optical phonons were observed; A(1)(TO) at 480 cm(-1), A(1)(LO) at 580 cm(-1), E-1(TO) at 476 cm(-1), E-1(LO) at 570 cm(-1), E-2(low) at 87 and E-2(high) at 488 cm(-1). Moreover two silent B-1 modes were observed at 200 and 540 cm(-1). From the plasma reflection spectra, dielectric constants of epsilon(0) = 8.1, epsilon(infinity) = 5.8 and effective electron mass of m(e perpendicular to)* = 0.24m(0) were obtained. (C) 1999 Elsevier Science Ltd. All rights reserved.