10-11 December 2019
Europe/Berlin timezone

Vacancy-type defects in ion-implanted GaN probed by monoenergetic positron beams

10 Dec 2019, 13:15
Marriott Conference room - Munich (Marriott)

Marriott Conference room - Munich


Berliner Str. 93 80805 München Germany
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Invited talk Positrons Positrons


Akira Uedono (University of Tsukuba)


Gallium nitride is a direct wide-bandgap semiconductor and an ideal material for power electronics. In device structure fabrication, controlled impurity doping in a selective area is essential. Ion implantation is the most commonly used technique to control carrier concentrations. A drawback of ion implantation is the introduction of defects. Thus, controlling damage during and after ion implantation is a key for the reduction of residual defects in GaN. In the present study, we used monoenergetic positron beams constructed at University of Tsukuba and TUM FRM-II to study the annealing behaviors of vacancy-type defects in Mg-implanted GaN.

Mg and H ions were implanted into GaN to obtain 0.1 and 0.7-micrometer-deep box profiles with Mg and H concentrations of 1E19 cm-3 and 2E20 cm-3, respectively. For the as-implanted samples, the major defect species was determined to be Ga-vacancy related defects such as Ga-vacancy, divacancy, and their complexes with impurities. For Mg-implanted samples, an agglomeration of vacancies started at 800C annealing, leading to the formation of vacancy clusters. For Mg- and H-implanted samples, the hydrogenation of vacancy-type defects started after 800C annealing. Comparing with the annealing behavior of defects for the samples without H-implantation, the clustering of vacancy-type defects was suppressed, which can be attributed to the interaction between Mg, H, and vacancies.

Primary authors

Akira Uedono (University of Tsukuba) Werner Egger (Universität der Bundeswehr München) Mr Tönjes Koschine (Universität der Bundeswehr München) Prof. Christoph Hugenschmidt Marcel Dickmann Shoji Ishibashi (AIST)

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