Vacancy-type defects in GaN self-assembled nanowires probed using monoenergetic positron beam

Akira Uedono (1) , Alexandra-Madalina Siladie (2) , Julien Pernot (3, 4) , Bruno Daudin (2) , Shoji Ishibashi (5)

1 Université de Tsukuba = University of Tsukuba
2 NPSC - Nanophysique et Semiconducteurs
3 NEEL - SC2G - Semi-conducteurs à large bande interdite
4 IUF - Institut universitaire de France
5 AIST - National Institute of Advanced Industrial Science and Technology

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.

Domaines: Science des matériaux [cond-mat.mtrl-sci]; Micro et nanotechnologies/Microélectronique

Akira Uedono, Alexandra-Madalina Siladie, Julien Pernot, Bruno Daudin, Shoji Ishibashi. Vacancy-type defects in GaN self-assembled nanowires probed using monoenergetic positron beam. Journal of Applied Physics, 2019, 125 (17), pp.175705. ⟨10.1063/1.5088653⟩. ⟨hal-02164173⟩