Vacancy-type defects in GaN nanowires (NWs) and the trapping of electrons by the vacancies were studied by positron annihilation. Undoped, Si-, and Mg-doped GaN NWs were grown on Si substrates by plasma-assisted molecular beam epitaxy. The major species of vacancies in the undoped and Si-doped samples was identified as a complex between a Ga vacancy and impurities such as oxygen and hydrogen. For the Mg-doped samples, the trapping rate of positrons for such defects decreased with the increase in Mg concentration because of the downward shift of Fermi level position and a resultant shift of the vacancy charge states from neutral (negative) to positive. Under the illumination of a 325-nm He-Cd laser, positrons were found to be trapped by vacancy-type defects, which was attributed to the trapping of excited electrons by these defects.
Vacancy-type defects in GaN self-assembled nanowires probed using monoenergetic positron beam
Akira Uedono, Alexandra-Madalina Siladie, Julien Pernot, Bruno Daudin, Shoji Ishibashi; Vacancy-type defects in GaN self-assembled nanowires probed using monoenergetic positron beam. J. Appl. Phys. 7 May 2019; 125 (17): 175705. https://doi.org/10.1063/1.5088653
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