Open AccessVacancy-type defects in Er-doped GaN studied by a monoenergetic positron beam
Author(s) -
Akira Uedono,
C. Shaoqiang,
S. Jongwon,
Kenichi Ito,
H. Nakamori,
Naoto Honda,
S. Tomita,
Katsuhiro Akimoto,
Hiroshi Kudo,
Shoji Ishibashi
Publication year - 2008
Publication title -
journal of applied physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.699
H-Index - 319
eISSN - 1089-7550
pISSN - 0021-8979
DOI - 10.1063/1.2932166
Subject(s) - doppler broadening , materials science , photoluminescence , vacancy defect , doping , metastability , molecular beam epitaxy , positron , annihilation , spectral line , epitaxy , analytical chemistry (journal) , atomic physics , condensed matter physics , optoelectronics , chemistry , physics , nanotechnology , nuclear physics , electron , organic chemistry , layer (electronics) , chromatography , astronomy
A relationship between intra-4f transitions of Er and vacancy-type defects in Er-doped GaN was studied by using a monoenergetic positron beam. Doppler broadening spectra of the annihilation radiation were measured for Er-doped GaN grown by molecular beam epitaxy. A clear correlation between the defect concentration and the photoluminescence (PL) intensity was observed. The major defect species detected by positrons was identified as a Ga vacancy VGa, and its concentration increased with increasing Er concentration [Er]. For the sample with [Er]=3.3 at. %, the maximum integrated intensity of PL was observed. The VGa concentration was above 1018 cm−3 and additional vacancies such as divacancies started to be introduced at this Er concentration. For the sample with higher [Er], the PL intensity decreased, and the mean size of vacancies decreased due to an introduction of precipitates and/or metastable phases
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