XRD patterns for ZnO, , and thin films deposited on Si(100) substrate using the radiation of Co.
Bright-field plane-view TEM images [(a), (c), and (e)] with corresponding SAED patterns [(b), (d), and (f)] of ZnO, Co-doped ZnO, and (Co, Al)-codoped ZnO thin films.
Transmittance spectra of ZnO, , and measured at room temperature. The inset shows a zoom of the absorption lines.
(a) XPS spectra of and thin films measured at room temperature. (b) Spectra of Co peaks for the two samples. (c) Spectrum of the Al peak for the thin film.
Magnetization hysteresis curves of and thin films deposited on Si(100) substrates. The curves were recorded with an AGFM magnetometer at room temperature. The inset shows the low temperature magnetization vs field curve of the film measured with the SQUID magnetometer. For comparison, the room temperature magnetization curve was reported as well. For all measurements the magnetic field was applied in the film plane.
Unit cell used in the present calculations: Zn atoms are in blue, O in red, Co in orange, and Al in green.
DOSs projected on the ZnO matrix (black line), on the two Co atoms (red line), and on the Al atom (green line) for (left), (center), and (right) obtained with the GGA method. The DOSs correspond, respectively, to the majority and minority spin bands for the P case and to the majority or minority spin DOS for the AP case. The Fermi level is shown by the vertical gray line. [(a) and (b)] The DOSs were calculated in the GGA and formalism, respectively.
Lattice parameters and grain size calculated from the XRD patterns of ZnO, , and thin films.
Room temperature resistance measurements of Co-doped ZnO and (Co, Al)-codoped ZnO thin films as-deposited and successively annealed under argon at for .
Interaction energies between the Co ions in Co- and (Co, Al)-doped ZnO calculated in the GGA and approximations from the total energy difference between P and AP magnetic configuration. and correspond to the and sites of Fig. 6, respectively.
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