Micro-Raman measurements were performed to study the nitrogen-related modes in ZnO samples implanted with N+. The two stable N isotopes, N14 and N15, were implanted. Distinct peaks at 277 and 512cm−1 are observed irrespective of the implanted isotope, both before and after rapid thermal annealing. The insensitivity of the mode frequencies to the implanted isotope rules out the explanation of these modes as local vibrational modes involving N motion. These modes were not detected in ZnO samples implanted with Zn+, O+, or P+, which suggests that they may be associated with distortions∕defects favored by the presence of N.

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The angular dependence of the optical phonons of high-quality bulk ZnO has been systematically studied by means of Raman scattering. We report the observation of quasi-TO and quasi-LO modes for propagation directions covering the whole a–c mixing plane using a beveled ZnO single crystal sample. Scattering experiments performed in two different configuration geometries indicate that birefringence effects are not relevant for the phonon analysis in this material. The observed angular dependence of the quasimode frequencies is in good agreement with Loudon’s model.

Intrinsic defects are generated by e‐irrradiation, and plastic deformation in ZnO crystals. Spectrally resolved cathodoluminescence (CL) experiments permit the analysis of the optical signature of those defects. We present herein a CL analysis of ZnO crystals irradiated with high energy electrons, and plastically deformed by Vickers indentation. Spectral changes around 3.3 eV and in the deep level emission are observed in the irradiated samples. These changes are compared to those observed around the extended defects introduced by Vickers indentation, which present a similar signature to the e‐irradiated samples, suggesting relation between the defects generated by plastic deformation and e‐irradiation. Zn vacancies seem to be the dominant defects generated in both processes (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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