Effects related to deposition temperature of ZnCoO films grown by Atomic Layer Deposition – uniformity of Co distribution, structural, electric and magnetic properties
|Małgorzata I. Łukasiewicz 1, Bartłomiej S. Witkowski 2, Bogdan J. Kowalski 1, Maciej Sawicki 1, Wojciech Paszkowicz 1, Rafał Jakieła 1, Tomasz A. Krajewski 1, Grzegorz Łuka 1, Elżbieta Guziewicz 1, Marek Godlewski 1,2|
1. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland
ZnCoO films are the promising semiconductor material for spintronic applications . For these applications films should be highly conductive and ferromagnetic (FM). The present situation is however very confusing. Ferromagnetic phase was observed by some groups and not by others. In most of the cases ZnCoO films showing FM phase were deposited at temperatures well above 300°C. This indicates that the growth temperature and deposition method (as shown by Ueda et al. ) may affect magnetic properties of the obtained films. Moreover, it is still controversial if high conductivity can be achieved in films containing Co. A similar situation was observed for ZnMnO and was related by us to nonuniform Mn distribution, formation of foreign phases , and carriers trapping by Mn ions.
In the present study we report properties of ZnCoO films grown at relatively low temperature by Atomic Layer Deposition (ALD), using two reactive organic precursors (DEZn and DMZn). The use of these precursors allowed us the significant reduction of a growth temperature to 300 oC and below. The so-obtained ZnCoO layers were studied as as-grown and after a thermal treatment. The influence of growth conditions on the Co distribution, structure and magnetic properties were investigated using the SIMS, SEM, CL, EDX, XRD and SQUID methods. We demonstrate that the films grown at low temperature are uniform. Such films are paramagnetic. For nonparamagnetic films formation of foreign phases was evidenced using the high resolution EDX method.
This work was supported by FunDMS ERC Advanced Grant Research
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Presentation: Poster at E-MRS Fall Meeting 2009, Symposium C, by Małgorzata I. Łukasiewicz
See On-line Journal of E-MRS Fall Meeting 2009
Submitted: 2009-05-08 16:44 Revised: 2013-02-28 15:04