Investigation of vacancy-type complexes in GaN and AlN using positron annihilation

• Published in: Semiconductors (Woodbury, N.Y.) N.Y.), 2002-10, Vol.36 (10), p.1106-1110
• Main Authors: Arutyunov, N. Yu, Mikhailin, A. V., Davydov, V. Yu, Emtsev, V. V., Oganesyan, G. A., Haller, E. E.
• Format: Article
• Language: English
• Subjects: Aluminum nitride; Angular correlation; Electron density; Electron-positron pairs; Gallium; Momentum; Positron annihilation; Standard model (particle physics); Vacancies
• ISSN: 1063-7826; 1090-6479
• DOI: 10.1134/1.1513852

The momentum distribution of electron-positron pairs in GaN and AlN has been investigated for the first time by measuring the one-dimensional angular correlation of the annihilation radiation (1D-ACAR). The characteristic parameter of the electron density rs′ (the radius of the sphere occupied by an electron) estimated from the experimental data differs noticeably from rs calculated in terms of a standard model of noninteracting particles: rs′ (AlN)≈1.28rs, and rs′(GaN)≈1.66rs, where rs(AlN)≈1.6091 au, and rs(GaN)≈1.6568 au. The chemical nature of atoms in the environment of the annihilating positron in AlN and GaN was identified from the electron-positron ionic radius of Al3+, Ga3+, and N5+ cores, which were determined from the characteristics of the high-momentum component of 1D-ACAR curves. The analysis was based on a comparison of the electron-positron ionic radii with those considered standard for Al and Ga metals and the related compounds GaP, GaAs, and GaSb. A conclusion is made that positron annihilation dominates in the regions of vacancy-type “nitrogen antisite”-“vacancy” complexes, [NGa+VGa] and [NAl+VAl], in GaN and AlN, respectively.