Structural, magnetic and electronic properties of Zn0.94Co0.06O/ZnO heterostructure
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Date
2021-10-12T00:00:00
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Springer Science and Business Media Deutschland GmbH
Abstract
In the present work, single layers of ZnO, Zn0.94Co0.06O and Zn0.94Co0.06O/ZnO heterostructure thin film on quartz substrates as well as on Si (111) substrate have been prepared using RF ion beam sputtering. Grazing incident X-ray diffraction (GIXRD), UV�Vis spectroscopy, X-ray absorption near edge structure (XANES), vibrating sample magnetometer�(VSM) and photoelectron spectroscopy (PES) were performed to obtain structural, optical, electronic properties. GIXRD measurement confirms Wurtzite structure of ZnO, whereas UV�Vis spectroscopy shows a blue shift of the absorption edge in Zn0.94Co0.06O single layer with respect to ZnO film with band gap of 3.18 and 3.32�eV for ZnO and Zn0.94Co0.06O single layer films, respectively. The O K-edge spectra revealed O 2p hybridization with Zn3d4s/Co3d states, whereas Co L3-edge and Co K-edge XANES spectra confirm Co2+ oxidation state. M-H hysteresis measurement at 300�K shows a weak ferromagnetism for Zn0.94Co0.06O single layer and Zn0.94Co0.06O/ZnO heterostructure thin film. Furthermore, to obtain band offset of Zn0.94Co0.06O/ZnO heterostructure thin films, valance band maximum and core level peaks were measured using PES measurement. The offsets in valance band and conduction band for Zn0.94Co0.06O/ZnO heterostructure thin film were obtained as ~0.41�eV and ~0.55�eV, respectively, and compared with ~0.36�eV and ~0.51�eV, respectively, of Zn0.9Co0.1O/ZnO heterostructure thin films. The results show that a type-II band alignment in the studied system. � 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.
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Keywords
Heterostructure interface, VB, XANES, XPS, XRD