Vacancy clustering and acceptor activation in nitrogen-implanted ZnO

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

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en

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6
1-6

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Physical Review B, Volume 77, issue 4

Abstract

The role of vacancy clustering and acceptor activation on resistivity evolution in N ion-implanted n-type hydrothermally grown bulk ZnO has been investigated by positron annihilation spectroscopy, resistivity measurements, and chemical profiling. Room temperature 220keV N implantation using doses in the low 1015cm−2 range induces small and big vacancy clusters containing at least 2 and 3–4 Zn vacancies, respectively. The small clusters are present already in as-implanted samples and remain stable up to 1000°C with no significant effect on the resistivity evolution. In contrast, formation of the big clusters at 600°C is associated with a significant increase in the free electron concentration attributed to gettering of amphoteric Li impurities by these clusters. Further annealing at 800°C results in a dramatic decrease in the free electron concentration correlated with activation of 1016–1017cm−3 acceptors likely to be N and/or Li related. The samples remain n type, however, and further annealing at 1000°C results in passivation of the acceptor states while the big clusters dissociate.

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Moe Børseth , T , Tuomisto , F , Christensen , J S , Monakhov , E V , Svensson , B G & Kuznetsov , A Y 2008 , ' Vacancy clustering and acceptor activation in nitrogen-implanted ZnO ' , Physical Review B , vol. 77 , no. 4 , 045204 , pp. 1-6 . https://doi.org/10.1103/PhysRevB.77.045204