Vacancy-type defects introduced by mechanical polishing in ammonothermal GaN studied by a monoenergetic positron beam

Akira Uedono; Shoji Ishibashi; Kohei Shima; Shigefusa F. Chichibu; Kacper Sierakowski; Makoto Oishi; Noriyuki Okada; Takuro Nagai; Michal Bockowski

doi:10.1016/j.jcrysgro.2026.128622

論文 Vacancy-type defects introduced by mechanical polishing in ammonothermal GaN studied by a monoenergetic positron beam

Akira Uedono ; Shoji Ishibashi ; Kohei Shima ; Shigefusa F. Chichibu ; Kacper Sierakowski ; Makoto Oishi ; Noriyuki Okada ; Takuro Nagai ; Michal Bockowski

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Akira Uedono, Shoji Ishibashi, Kohei Shima, Shigefusa F. Chichibu, Kacper Sierakowski, Makoto Oishi, Noriyuki Okada, Takuro Nagai, Michal Bockowski. Vacancy-type defects introduced by mechanical polishing in ammonothermal GaN studied by a monoenergetic positron beam. Journal of Crystal Growth. 2026, 688 (), 128622. https://doi.org/10.1016/j.jcrysgro.2026.128622

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(abstract)

Vacancy-type defects introduced by mechanical polishing in basic ammonothermal GaN and their annealing behavior were studied using a monoenergetic positron beam. The major vacancy-type defect in the sample was identified as a Ga-vacancy (V_Ga) coupled with hydrogen atoms. After mechanical polishing, high-density dislocations and stacking faults were introduced in the subsurface region (< 240 nm). In this region, the vacancy-type defects detected by positron annihilation were divacancies (V_GaV_N) and their complexes with hydrogen atoms. After ultra-high-pressure annealing at 1400ºC, {0001} basal slip bands were the predominant defects observed using a transmission electron microscope. The major vacancy-type defects for the annealed samples were identified as V_Ga coupled with multiple V_N [ex V_Ga(V_N)₃] and their complexes with hydrogen atoms. The observed annealing behavior of vacancies agreed with that estimated using photoluminescence spectroscopy.

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