Raman characterization of the optical phonons in AlxGa1-xN layers grown by MBE and MOCVD
A. Cros
Walter Schottky Institut, Technische Universität München
and
Dep. Física Aplicada, Univ. Valencia
H. Angerer, R. Handschuh, O. Ambacher, M. Stutzmann
Walter Schottky Institut, Technische Universität München
This article was received on Wednesday, June 11, 1997 and
accepted on Wednesday, October 8, 1997. Abstract
We present the results of Raman measurements performed on AlxGa1-xN layers grown by MBE and MOCVD. The films were deposited on (0001) c-sapphire substrates, and the aluminum content covered the whole composition range for x from 0 (GaN) to 1 (AlN). It is shown that the energies of both A1(TO) and A1(LO) phonon modes smoothly increase with increasing x, indicating a one-mode behavior. The E2 phonon mode, however, presents a different behavior. Its energy increases very slowly with aluminum content and, for x
0.4, a new phonon mode shows up which is shifted to higher energies by 50 cm-1. This new line leads to the E2 AlN mode for increasing aluminum content. The linewidths and intensities of these modes strongly depend on composition. These results are compared with recent theoretical calculations. Finally, the Raman selection rules in the MBE and MOCVD samples are compared and conclusions about the quality of the layers are drawn. Outline
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Cite this article as: MRS Internet J. Nitride Semicond. Res. 2, 43(1997).
last updated Sunday, December 20, 1998 11:36:00 AM.© 1997-1998 The Materials Research Society
