Formation of ZnO Doped with Mn Thin Film by Electrodeposition and Magnetic Behaviour.
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Formation of ZnO doped with Mn thin film by electrodeposition and magnetic behaviour. M. Abid1, C.Terrier1, J-P Ansermet1, K. Hjort2 1. EPFL, Institut de Physique des Nanostructures, Station 3, CH-1015 Lausanne (Switzerland). 2. Uppsala University,Angstrom Laboratory, Materials Science department, Polackbäcken (Sweden).
Abstract Following the theory, ferromagnetism is predicted in Mn- doped ZnO, Indeed, ferromagnetism above room temperature was recently reported in thin films as well as in bulk samples made of this material. Here, we have prepared Mn doped ZnO by electrodeposition. The samples have been characterized by X-ray diffraction and spectroscopic methods to ensure that the dopants are substitutional. Some samples exhibit weak ferromagnetic properties at room temperature, however to be useful for spintronics this material need additional carriers provided by others means.
1. Introduction In recent years, ferromagnetism in semiconductors has received significant attention partly due to interest in spintronic device concepts1-3. In the year 2000, Dietl et al
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made the
theoretical prediction that Mn-doped ZnO and GaN would be ferromagnetic at room temperature and would therefore be suitable for applications in spintronics. A report of ferromagnetism in Co-doped TiO2 gave the hope that Co- and Mn- doped oxides may indeed be useful for spintronics. The theoretical calculations of Sato and KatayamaYoshida5 showed that ZnO doped with several 3d transition metal ions such as V, Cr, Fe, Co and Ni may exhibit ferromagnetic ordering. Much of the recent effort has focused on conventional II-VI and III-V semiconductor materials. Recently, low temperature epitaxial growth has been used with Mn-doped ZnO, in achieving ferromagnetism with showing a transition temperature of 470 K which is the highest TC6 for doped semiconductor. In this
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paper, we will describe a method to form ZnO doped with around 3% Mn (one phase) by a low cost process (electrodeposition) and we will give the magnetic response obtained on the sample prepared by this method.
2. Experimental section Electrodeposition experiments are carried out in a classical three electrode glass cell. We use two different substrates (working electrode) a gold layer deposited on a silicon wafer, and ITO Conductive glass (Resistivity of 30 Ω cm-2) to allow optical measurements. Before each experiment, we use a glassy carbon electrode, polished mechanically with Diamond powder 1 µm diameter to determine the cyclic voltamperogramms. After polishing, the electrode is immersed in a distilled water ultrasonic bath during 5 min (to remove the dirt on the surface) and finally washed thoroughly with Milli-Q Water and dried. A saturated Ag/AgCl electrode is used as reference, a platinum wire for counter electrode. Cyclic voltammetry was used to determine the potential ranges where the various processes were taking place. The experiments were performed at 343 K under bubbling oxygen during at least 1 hour by using EGG 273A potentiostatic system. The electro
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