• Journal of the Korean Magnetics Society
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• v.15 no.2
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• pp.92-95
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• 2005

$Zn_{1-x}\;^{57}Fe_xO(x=0.01, 0.02, 0.03)$ compounds were fabricated using the solid-state reaction method. In order to determine magnetic behavior and ionic state of the doped transition metal ($^{57}Fe$) in ZnO, we carried out $M\ddot{o}ssbauer$ measurements at various temperatures ranging from 13 to 295 K. $M\ddot{o}ssbauer$spectra for $Zn_{0.97}\;^{57}Fe_{0.03}O$ at 4.2 K have shown the ferromagnetic phase (sextet), but the only paramagnetic phase (doublet) is seen at 295 K. The hysteresis loop below 77 K for $Zn_{0.97}\;^{57}Fe_{0.03}O$ indicated the coexistence of ferromagnetic and paramagnetic phases.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.6
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• pp.269-269
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• 2002

ZnTe/ZnMnTe single quantum well of high quality was grown by hot-wall epitaxy, in which ZnMnTe layer was used as a barrier. It was found that ZnTe well layer was under severe strain. Very sharp luminescent peaks of the heavy-hole exciton (el-hhl) and the light-hole exciton (el-lhl) were observed from the photoluminescence (PL) measurement. As the well layer thickness increases, the peaks associated with excitons of (el-hhl) and (el-lhl) were shifted toward the lower energy side. The temperature dependence of the PL peak intensity was well explained by the thermal activation theory.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.6
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• pp.267-271
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• 2002

ZnTe/ZnMnTe single quantum well of high quality was grown by hot-wall epitaxy, in which ZnMnTe layer was used as a barrier. It was found that ZnTe well layer was under severe strain. Very sharp luminescent peaks of the heavy-hole exciton (el-hhl) and the light-hole exciton (el-lhl) were observed from the photoluminescence (PL) measurement. As the well layer thickness increases, the peaks associated with excitons of (el-hhl) and (el-lhl) were shifted toward the lower energy side. The temperature dependence of the PL peak intensity was well explained by the thermal activation theory.

• Journal of the Korean Vacuum Society
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• v.12 no.4
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• pp.269-274
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• 2003

The electrical, optical and structural properties of ZnNiO thin _ films deposited on Si substrates using rf-magnetron sputtering method have been investigated before and after the thermal annealing processes. The crystallinity of the ZnNiO thin film become degraded with increasing the Ni contents. This is mainly because the lattice of the thin film was expanded due to the oxygen-deficient conditions. Concerning the electrical properties of the thin film, the carrier concentration increases ($6.81\times10^{14}\textrm{cm}^{-2}$) and Hall mobility decreases (36.3 $\textrm{cm}^2$/Vㆍs) with higher doping concentration of Ni. However, the carrier concentration and Hall mobility became low ($1.10\times10^{14}\textrm{cm}^2$ and high (209.6 $\textrm{cm}^2$/Vㆍs), respectively, after the thermal annealing process at $1000 ^{\circ}C$. We also observed a strong luminescene center peaking at 546 nm in photoluminescence spectra, which was caused by a deep level center in the ZnO band gap with oxygen deficient ZnNiO structure.

• Journal of the Korean Vacuum Society
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• v.21 no.5
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• pp.258-263
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• 2012

Fe-diluted Si alloys grown on p-type Si (100) substrates by pulsed-laser deposition method were studied for structural, electrical, and magnetic properties. The X-ray diffraction patterns for these alloy samples showed a few of peaks with cubic structures such as FeSi, $Fe_3Si$, and $Fe_4Si$. The Fe-composition in alloys are confirmed as Fe atomic percent about 1.25~6.49 % from energy dispersive spectroscopy measurement. The resistivity as a function of the reciprocal temperature was indicated an exponential increase with two activation energies of 5.21 and 7.79 meV. The maximum value of the magnetization at 10 K was about 100 emu/cc, and the ferromagnetism was also observed until 350 K from total magnetization as a function of temperature with applied magnetic field of 3,000 Oe.

• Journal of the Korean Magnetics Society
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• v.13 no.6
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• pp.237-242
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• 2003

$Ti_{1-x}$$^{57}$ F $e_{x}$ $O_2$(0.0$\leq$x$\leq$0.07) compounds were fabricated using the sol-gel method, and the crystal structure and magnetic properties were investigated as a function of doped $^{57}$ Fe concentration. X-ray diffraction patterns showed a pure anatase single phase, without any segregation of Fe into particulate. With varying $^{57}$ Fe concentration, we could observe unusual magnetic phenomena in these materials. Doping $^{57}$ Fe into the Ti $O_2$ nonmagnetic semiconductor formed magnetic properties, but the gradual increase of $^{57}$ Fe concentration decreased rapidly the ferromagnetic properties rather than enhanced the ferromagnetic properties. Obvious ferromagnetic behavior was shown for the samples with x$\leq$0.01, while paramagnetic behavior was shown for the sample with x$\geq$0.03. These phenomena could be verified using Mossbauer measurement. Separation of the ferromagnetic phase (sextet) and the paramagnetic phase (doublet) of the samples with different $^{57}$ Fe concentration was characterized. Samples with x$\leq$0.01 have sextet and doublet simultaneously, but samples with x$\geq$0.03 have only doublet at room temperature. This indicates that the sample x$\leq$0.01 have the ferromagnetic phase at room temperature. This result corresponded with the M-H loops referenced above and reveals an interesting feature that there is a critical limit of $^{57}$ Fe concentration (0.01$\leq$0.01 samples was fundamentally attributable to the paramagnetic phase as well as the ferromagnetic phase.e.