Evolution of native point defects in ZnO bulk probed by positron annihilation spectroscopy
Peng Cheng-Xiao(彭成晓)a)†, Wang Ke-Fan(王科范)a), Zhang Yang(张杨)a), Guo Feng-Li(郭凤丽)a), Weng Hui-Min(翁惠民)b), and Ye Bang-Jiao(叶邦角)b)
aPhysics and Electronics School, Henan University, Kaifeng 475004, China; bModern Physics Department, University of Science and Technology of China, Hefei 230026, China
Abstract This paper studies the evolution of native point defects with temperature in ZnO single crystals by positron lifetime and coincidence Doppler broadening (CDB) spectroscopy, combined with the calculated results of positron lifetime and electron momentum distribution. The calculated and experimental results of the positron lifetime in ZnO bulk ensure the presence of zinc monovacancy, and zinc monovacancy concentration begins to decrease above 600℃ annealing treatment. CDB is an effective method to distinguish the elemental species, here we combine this technique with calculated electron momentum distribution to determine the oxygen vacancies, which do not trap positrons due to their positive charge. The CDB spectra show that oxygen vacancies do not appear until 600℃ annealing treatment, and increase with the increase of annealing temperature. This study supports the idea that green luminescence has a close relation with oxygen vacancies.
Received: 17 September 2008
Revised: 24 October 2008
Accepted manuscript online:
Peng Cheng-Xiao(彭成晓), Wang Ke-Fan(王科范), Zhang Yang(张杨), Guo Feng-Li(郭凤丽), Weng Hui-Min(翁惠民), and Ye Bang-Jiao(叶邦角) Evolution of native point defects in ZnO bulk probed by positron annihilation spectroscopy 2009 Chin. Phys. B 18 2072
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