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Damage annealing in low temperature Fe/Mn implanted ZnO H. P. Gunnlaugsson · K. Bharuth-Ram · K. Johnston · G. Langouche · R. Mantovan · T. E. Mølholt · ´ D. Naidoo · S. Olafsson · G. Weyer

Received: 16 September 2014 / Accepted: 11 November 2014 © Springer International Publishing Switzerland 2014

Abstract 57 Fe Emission M¨ossbauer spectra obtained after low fluence (< 1012 cm−2 ) implantation of 57 Mn (T1/2 = 1.5 min.) into ZnO single crystal held at temperatures below room temperature (RT) are presented. The spectra can be analysed in terms of four components due to Fe2+ and Fe3+ on Zn sites, interstitial Fe and Fe in damage regions (FeD ). The FeD component is found to be indistinguishable from similar component observed in emission M¨ossbauer spectra of higher fluence (∼ 1015 cm−2 )57 Fe/57 Co implanted ZnO and 57 Fe implanted ZnO, demonstrating that the nature of the damage regions in the two types of experiments is similar. The defect component observed in the low temperature regime was found to anneal below RT.

Proceedings of the 5th Joint International Conference on Hyperfine Interactions and International Symposium on Nuclear Quadrupole Interactions (HFI/NQI 2014) Canberra, Australia, 21-26 September 2014 ´ H. P. Gunnlaugsson · S. Olafsson Department of Physics and Astronomy, University of Aarhus, Aarhus, Denmark K. Bharuth-Ram () Physics Department, Durban University of Technology, Durban, 4000, South Africa e-mail: [email protected] K. Johnston PH Department, ISOLDE/CERN, 1211 Geneva 23, Switzerland G. Langouche Instituut voor Kern-en Stralings fysika, University of Leuven, B-3001 Leuven, Belgium R. Mantovan Laboratorio MDM, IMM-CNR, Via Olivetti 2, I-20864 Agrate Brianza, MB, Italy ´ T. E. Mølholt · S. Olafsson Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjav´ık, Iceland D. Naidoo School of Physics, University of the Witwatersrand, Johannesburg, WITS 2050, South Africa

H. P. Gunnlaugsson et al.

Keywords ZnO · Low temperature 57 Mn implantation · Emission M¨ossbauer spectroscopy · Damage formation and annealing

1 Introduction ZnO is a wide band gap semiconductor with diverse applications [see, for example, ref. 1 and references quoted therein]. Among the methods to tailor the material for device fabrication is ion implantation. The radiation hardness of ZnO has been evidenced in several studies [2 - 4], pointing to the possible applications of ZnO based devices in high radiation environments. However, the physics of the high radiation resistance of ZnO is still not fully understood, and further work is needed to better understand the mechanisms of damage formation in this material. Formation of implantation damage and its annealing in monocrystalline material is commonly followed by Rutherford backscattering/channelling techniques (see e.g. [ref. 5] and references therein). Here we report on the application of emission M¨ossbauer spectroscopy (eMS) to study defect annealing in low fluence, low temperature Mn/Fe implanted ZnO. eMS is strictly a local probe method that gives infor