Impacts of anisotropic lattice relaxation on crystal mosaicity and luminescence spectra of m-plane AlxGa1-xN films grown on m-plane freestanding GaN substrates by NH3 source molecular beam epitaxy

T. Hoshi, K. Hazu, K. Ohshita, M. Kagaya, T. Onuma, K. Fujito, H. Namita, S. F. Chichibu

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9 Citations (Scopus)

Abstract

In-plane anisotropic lattice relaxation was correlated with the crystal mosaicity and luminescence spectra for m -plane AlxGa1-xN films grown on a freestanding GaN substrate by NH3-source molecular beam epitaxy. The homoepitaxial GaN film exhibited A - and B -excitonic emissions at 8 K, which obeyed the polarization selection rules. For Al xGa1-xN overlayers, the m -plane tilt mosaic along c -axis was the same as the substrate as far as coherent growth was maintained (x≤0.25). However, it became more severe than along the a -axis for lattice-relaxed films (x≥0.52). The results are explained in terms of anisotropic lattice and thermal mismatches between the film and the substrate. Nonetheless, all the AlxGa1-xN films exhibited a near-band-edge emission peak and considerably weak deep emission at room temperature.

Original languageEnglish
Article number071910
JournalApplied Physics Letters
Volume94
Issue number7
DOIs
Publication statusPublished - 2009

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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