Giant hydrogen effect on the structure and physical properties of ZnO and Co-doped ZnO films fabricated by the RF magnetron sputtering in Ar + H2 atmosphere

Particles–Matrix Bond in ZnCoO:H and ZnCoAlO:H Films: Issues of Magnetism and Spin Injection

“…The E 4 line near 3.4 eV is attributed to the contribution of the ZnO:Co 2+ matrix. A similar line is observed in the MCD spectra of paramagnetic CZO samples [17,23,34]. The nature of this line, in our opinion, is determined by the spin polarization of electrons in the ZnO conduction band.…”

“…Taking into account the relatively high content of Co in the studied films ( Table 1 ), one can suppose the nanoparticles described by the shown FC-ZFC curves to consist of metallic Co. Though the X-ray diffraction patterns obtained for the films exhibited diffraction peaks corresponding only to the ZnO crystal [ 23 , 24 ], the element-selective XANES spectroscopy at the Co K-edge confirmed the presence of metallic cobalt in the CZO:20 and CZO:30 films. In combination with XRFA data, the relative content of metallic cobalt in the films was estimated as 7.6% and 13%, respectively [ 29 ].…”

“…These targets were prepared from high purity ZnO (99.999%), Co 3 O 4 (99.9985%), and Al 2 O 3 (99.997%) powders by a standard two-step, solid-state reaction method. The targets synthesis is described in detail in [23,24]. The film's deposition was carried out at a total pressure of 30 mTorr and a forward RF power of 80 W. The substrate temperature was 450 • C. Deposition time was 20 min.…”