Observation of Ga vacancies and negative ions in undoped and Mg doped GaN bulk crystals

K. Saarinen (Corresponding Author), J. Nissilä, J. Oila, V. Ranki, M. Hakala, M. Puska, P. Hautojärvi, Jari Likonen, T. Suski, I. Grzegory, B. Lucznik, S. Porowski

    Research output: Contribution to journalArticleScientificpeer-review

    22 Citations (Scopus)


    Gallium vacancies and negative ions are observed in GaN bulk crystals by applying positron lifetime spectroscopy. The concentration of Ga vacancies decreases with increasing Mg doping, as expected from the behavior of the VGa formation energy as a function of the Fermi level. The concentration of negative ions correlates with that of Mg impurities determined by secondary ion mass spectrometry. We thus attribute the negative ions to MgGa. The negative charge of Mg suggests that Mg doping converts n-type GaN to semi-insulating mainly due to the electrical compensation of ON+ donors by MgGa acceptors.
    Original languageEnglish
    Pages (from-to)33-38
    Number of pages6
    JournalPhysica B: Condensed Matter
    Publication statusPublished - 1999
    MoE publication typeA1 Journal article-refereed


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