Vacancy clustering and acceptor activation in nitrogen-implanted ZnO

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© 2008 American Physical Society (APS). This is the accepted version of the following article: Børseth, Thomas Moe & Tuomisto, Filip & Christensen, Jens S. & Monakhov, Edouard V. & Svensson, Bengt G. & Kuznetsov, Andrej Yu. 2008. Vacancy clustering and acceptor activation in nitrogen-implanted ZnO. Physical Review B. Volume 77, Issue 4. 045204/1-6. ISSN 1098-0121 (printed). DOI: 10.1103/physrevb.77.045204, which has been published in final form at http://journals.aps.org/prb/abstract/10.1103/PhysRevB.77.045204.
Final published version

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Journal Title

Journal ISSN

Volume Title

School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2008

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Mcode

Degree programme

Language

en

Pages

045204/1-6

Series

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 220 keV N implantation using doses in the low 10 exp 15 cm exp −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 10 exp 16–10 exp 17cm exp −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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Keywords

SIMS, positron annihilation, ZnO

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Citation

Børseth, Thomas Moe & Tuomisto, Filip & Christensen, Jens S. & Monakhov, Edouard V. & Svensson, Bengt G. & Kuznetsov, Andrej Yu. 2008. Vacancy clustering and acceptor activation in nitrogen-implanted ZnO. Physical Review B. Volume 77, Issue 4. 045204/1-6. ISSN 1098-0121 (printed). DOI: 10.1103/physrevb.77.045204