• 한국결정성장학회지
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• 제25권5호
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• pp.173-181
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• 2015

A stoichiometric mixture of evaporating materials for $BaIn_2S_4$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $BaIn_2S_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were $620^{\circ}C$ and $420^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by double crystal X-ray diffraction (DCXD). The carrier density and mobility of $BaIn_2S_4$ single crystal thin films measured from Hall effect by van der Pauw method are $6.13{\times}10^{17}cm^{-3}$ and $222cm^2/v{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $BaIn_2S_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=3.0581eV-(3.9511{\times}10^{-3}eV/K)T^2/(T+536K)$. The crystal field and the spin-orbit splitting energies for the valence band of the $BaIn_2S_4$ have been estimated to be 182.7 meV and 42.6 meV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}_5$ states of the valence band of the $BaIn_2S_4/GaAs$ epilayer. The three photocurrent peaks observed at 10 K are ascribed to the $A_1$-, $B_1$-exciton for n = 1 and $C_{24}$-exciton peaks for n = 24.

• 센서학회지
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• 제24권6호
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• pp.404-411
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• 2015

A stoichiometric mixture of evaporating materials for $BaAl_2Se_4$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $BaAl_2Se_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were $610^{\circ}C$ and $410^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $BaAl_2Se_4$ single crystal thin films measured from Hall effect by van der Pauw method are $8.29{\times}10^{-16}cm^{-3}$ and $278cm^2/vs$ at 293 K, respectively. The temperature dependence of the energy band gap of the $BaAl_2Se_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=3.4205eV-(4.3112{\times}10^{-4}eV/K)T^2/(T+232 K)$. The crystal field and the spin-orbit splitting energies for the valence band of the $BaAl_2Se_4$ have been estimated to be 249.4 meV and 263.4 meV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}_5$ states of the valence band of the $BaAl_2Se_4/GaAs$ epilayer. The three photocurrent peaks observed at 10 K are ascribed to the $A_1$-, $B_1$-exciton for n =1 and $C_{31}$-exciton peaks for n=31.

• 한국표면공학회지
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• 제29권6호
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• pp.829-833
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• 1996

Superconducting YBaCuO thin films were deposited on MgO (100) single crystal substrate by rf reactive sputtering method. Sputtering target was prepared by mixing the original powders of $Y_2O_3$, $BaCO_3$, and CuO at $830^{\circ}C$, and its composition was $YBa_2Cu_{3.3}O_x$ adding the excess CuO to compensate for the loss of Cu in the deposition process. The sputtering conditions for a high quality of YBCO thin film were: substrate temperature of 13$0^{\circ}C$; gas pressure of 10 mTorr; gas mixture ($O_2$: Ar =10: 90); distance of 2.5 inch; and rf power density of 4.87 W /$\textrm{cm}^2$. The deposition rate was 2.4~2.6 nm/min. From the RBS results, it was found that Cu and Ba contents in thin films decreased with the increase of substrate temperature. The increase of gas pressure resulted in significant deficiency of Ba elements.

• 센서학회지
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• 제23권2호
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• pp.134-141
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• 2014

A stoichiometric mixture of evaporating materials for $BaIn_2Se_4$ epilayers was prepared from horizontal electric furnace. To obtain the single crystal thin films, $BaIn_2Se_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were $620^{\circ}C$ and $400^{\circ}C$, respectively. The crystalline structure of the epilayers was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $BaIn_2Se_4$ epilayers measured from Hall effect by van der Pauw method are $8.94{\times}10^{17}cm^{-3}$ and 343 $cm^2/vs$ at 293 K, respectively. The temperature dependence of the energy band gap of the $BaIn_2Se_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)$=2.6261 eV-$(4.9825{\times}10^{-3}eV/K)T^2/(T+558 K)$. The crystal field and the spin-orbit splitting energies for the valence band of the $BaIn_2Se_4$ have been estimated to be 116 meV and 175.9 meV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}_5$ states of the valence band of the $BaIn_2Se_4/GaAs$ epilayer. The three photocurrent peaks observed at 10 K are ascribed to the $A_1-$, $B_1$-exciton for n = 1 and $C_{21}$-exciton peaks for n=21.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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• pp.3-3
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• 2009

In order to investigate the possibility of using mixed rare earth $(Nd_{1/3}Eu_{1/3}Gd_{1/3})Ba_2Cu_3O_{7-x}$ (NEG123) as the superconducting layer of the HTS coated conductor, the NEG123 thin film was deposited epitaxialy on LAO(100) single crystal and IBAD_YSZ metal templates by pulsed laser deposition. Systematic studies were carried out to investigate the influences of deposition parameters of PLD on the micro structure, texture and superconducting properties of NEG-123 coated conductor. Deposition at oxygen partial pressure of 600 mTorr was needed to routinely obtain high quality NEG123 films with $J_c$'s (77K) over 2 MA/$cm^2$ and Tc's over 90K (${\Delta}T{\sim}2\;K$). We verified from magnetization study that the NEG123 has an improved in-field Jc as the field increases at temperatures between 10 K and 77 K compared with Gd123. The $J_c$ (77K, self field) and the value of onset $T_c$ of NEG123 thin film on LAO substrate was $4.0MA/cm^2$ and 92K, respectively. This is the first report, to the best of our knowledge, of coated conductors with NEG123 film as the superconducting layer which have Ic and Jc over 40 A/cm-width and 1.6 MA/$cm^2$ at 77K, self field. This study shows the possibility of using NEG123 film as the superconducting layer of the HTS coated conductor which can be used in high magnetic field power electric devices.