Raman characterization of the optical phonons in Al x Ga 1-x N layers grown by MBE and MOCVD
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Raman characterization of the optical phonons in AlxGa1−xN layers grown by MBE and MOCVD A. Cros, H. Angerer, R. Handschuh, O. Ambacher and M. Stutzmann MRS Internet Journal of Nitride Semiconductor Research / Volume 2 / January 1997 DOI: 10.1557/S1092578300001691, Published online: 13 June 2014
Link to this article: http://journals.cambridge.org/abstract_S1092578300001691 How to cite this article: A. Cros, H. Angerer, R. Handschuh, O. Ambacher and M. Stutzmann (1997). Raman characterization of the optical phonons in AlxGa1−xN layers grown by MBE and MOCVD . MRS Internet Journal of Nitride Semiconductor Research, 2, pp e43 doi:10.1557/ S1092578300001691 Request Permissions : Click here
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M R S
Internet Journal o f
Nitride S emiconductor Research
Volume 2, Article 43
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 June 11, 1997 and accepted on October 8, 1997.
Abstract We present the results of Raman measurements performed on Alx Ga1-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 A 1(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.
1. Introduction Many scientific groups have been attracted by the properties of the wide band-gap III-V nitrides in the last years. The progress achieved in the control of the growth and doping of GaN, AlN and their alloys, [1] and the successful application of these materials in the fabrication of optoelectronic devices, encourages increasing work on the characterization of the fundamental properties of these materials. The knowledge of these properties is important to determine the limits of their performance in device applications. Despite the successful fabrication of GaN/Alx Ga1-xN heterostructures showing two-dimensional electronic properties [2] and room-temperature stimulated em
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