• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.134-135
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• 2006

$AgInS_2$ single crystal thin filmsl was deposited on throughly etched semi-insulator GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $680^{\circ}C$ and $410^{\circ}C$ respectively, and the thickness of the single crystal thin films is $6{\mu}m$. From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the $AgInS_2$ single crystal thin film, we have found that the values of spin orbit coupling ${\Delta}So$ and the crystal field splitting ${\Delta}Cr$ were 0.0098 eV and 0.15 eV at 10 K, respectively. In order to explore the applicability as a photoconductive cell, we measured the sensitivity ($\gamma$), the ratio of photocurrent to darkcurrent (pc/dc), maximum allowable power dissipation (MAPD), spectral response and response time. The result indicated that the samples annealed in S vapour the photoconductive characteristics are best. Therefore we obtained the sensitivity of 0.98, the value of pc/dc of $1.02{\times}10^6$, the MAPD of 312 mW, and the rise and decay time of 10.4ms and 10.8ms respectively.

• Journal of the Korean Magnetics Society
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• v.24 no.3
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• pp.71-75
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• 2014

Ground state energy levels of the $Fe^{3+}$ paramagnetic impurity ion in stoichiometric $LiTaO_3$ and in congruent $LiTaO_3$ single crystals were calculated with electron paramagnetic resonance constants. Energy levels between six energy levels were obtained with spectroscopic splitting parameter g and zero field splitting constant D for $Fe^{3+}$ ion. The energy diagrams of $Fe^{3+}$ ion were different from different magnetic field directions ([100], [001], [111]) when magnetic field increases. The calculated ZFS energies of $Fe^{3+}$ ion in stoichiometric and congruent $LiTaO_3$ single crystals for ${\mid}{\pm}5/2$ > ${\leftrightarrow}{\mid}{\pm}3/2$ > and ${\mid}{\pm}3/2$ > ${\leftrightarrow}{\mid}{\pm}1/2$ > transitions were 12.300 GHz and 6.150 GHz, and 59.358 GHz and 29.679 GHz, respectively. It turns out that energy levels of $Fe^{3+}$ paramagnetic impurity in $LiTaO_3$ crystal are different from different crystal growing condition.

• Journal of the Korean Magnetics Society
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• v.15 no.5
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• pp.261-264
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• 2005

The elastic constants, C', of $Th_{3}P_4$-type structure compounds, $La_{3}S_4\;and\;Ce_{3}S_4$, have been analyzed on the basis of band Jahn-Teller mechanism. The distinct difference between two compounds lies in the fact that $Ce^{3+}$ ion has a f electron which produces magnetism. It is shown that the band Jahn-Teller effect is sensitively influenced by the energy splitting of f electronic bands by a cubic crystal field in $Ce_{3}S_4$, and f electrons suppress the elastic softening effect. The energy splitting value obtained from the calculation of elastic constants is found to agree well with the experimental value obtained from the magnetic susceptibility measurement.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.307-308
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• 2006

We have synthesized $CaS:Eu^{2+}$ phosphor by using a sealing vessel and evaluated its photoluminescence properties. The method using a sealing vessel is simple and economical in comparison with other methods reported up to date, As an activator concentration was increased from 0.1 mol to 4 mol, the main emission wavelength of the phosphor was increased from 642 nm to 651 nm due to crystal field splitting of 5d level of $Eu^{2+}$ ions. Although the same amount of $Eu_2O_3$ was used, the concentration of the activator ions which were reduced from $Eu^{3+}$ to $Eu^{2+}$ and substituting $Ca^{2+}$ ions was increased with increase of firing temperature. Therefore, the main emission wavelength was also increased from 645 nm to 651 nm with increase of firing temperature from $1100^{\circ}C$ to $1300^{\circ}C$.

• Korean Journal of Materials Research
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• v.30 no.8
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• pp.413-420
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• 2020

Lu₃Al_5-xGa_xO₁₂:Ce³⁺,Cr³⁺ powders are prepared using a solid-state reaction method. To determine the crystal structure, Rietveld refinement is performed. The results indicate that Ga³⁺ ions preferentially occupied tetrahedral rather than octahedral sites. The lattice constant linearly increases, obeying Vegard's law, despite the strong preference of Ga³⁺ for the tetrahedral sites. Increasing x led to a blue-shift of the Ce³⁺ emission band in the green region and a change in the emission intensity. Persistent luminescence is observed from the powders prepared with x = 2-3, occurring through a trapping and detrapping process between Ce³⁺ and Cr³⁺ ions. The longest persistent luminescence is achieved for x = 2; its lifetime is at least 30 min. The findings are explained using crystal structure refinement, crystal field splitting, optical band gap, and electron trapping mechanism.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.157-157
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• 2003

수평 전기로에서 CdIn2Te4 다결정을 용융법으로 합성하고 Bridgman법으로 tetragonal structure의 c축에 평행한 CdIn2Te4 단결정을 성장시켰다. c축에 평행한 시료의 광흡수와 광전류 spectra를 293K에서 10K까지 측정하였다. 광흡수 spectra에 의해 band gap Eg(T)는 varshni공식에 따라 계산한 결과 1.4753eV-(7.78$\times$$10^{-3}$eV/K)T$^2$/(T+2155K)임을 확인하였다. Hall 효과는 van der Pauw 방법에 의해 측정되었으며, 온도에 의존하는 운반자 농도와 이동도는 293K에서 각각 9.01$\times$$10^{16}$ /㎤, 219 $\textrm{cm}^2$/V.S였다. 광전류 스펙트럼으로부터 Hamilton matrix(Hopfield quasicubic mode)법으로 계산한 결과 crystal field splitting $\Delta$cr값이 0.2704 eV이며 spin-orbit $\Delta$so 값은 0,1465 eV임을 확인하였다. 10K일 때 광전류 봉우리들은 n=1일때 Al-, Bl-와 Cl-exciton 봉우리임을 알았다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.4
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• pp.138-147
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• 2001

The stochiometric mixtures mixture of evaporating materials for the $ZnIn_{2}S_{4}$ single crystal thin film was prepared from horizontal furnace. To obtain the $ZnIn_{2}S_{4}$ single crystal thin film, $ZnIn_{2}S_{4}$ mixed crystal was deposited on throughly etched semi-insulting GaAs(100) in the Hot Wall Epitaxy(HWE) system. The sourceand substrate temperature were $610^{\circ}C$ and $450^{\circ}C$, respectively and the growth rate of the $ZnIn_{2}S_{4}$ single crystal thin film was about 0.5$\mu\textrm{m}$/hr. The crystalline structure of $ZnIn_{2}S_{4}$ single crystal thin film was investigated by photoluminescence and double crystal X-ray diffraction (DCXD) measurement. The carrier density and mobility of $ZnIn_{2}S_{4}$ single crystal thin film measured from Hal effect by van der Pauw method are $8.51{\times}10^{17}{\textrm}{cm}^{-3}$, 291$\textrm{cm}^2$/V.s at $293^{\circ}$K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the $ZnIn_{2}S_{4}$ single crystal thin film, we have found that the values of spin orbit splitting $\Delta$So and the crystal filed splitting DCr were 0.0148eV and 0.1678 eV at $10^{\circ}$K, respectively. From the photoluminescence measurement of $ZnIn_{2}S_{4}$ single crystal thin film, we observed free excition($E_{X}$) typically observed only in high quality crystal and neutral donor bound exicton ($D^{\circ}$, X) having very strong peak intensity. The full width at half maximum and binding energy of neutral donor bound excition were 9meV and 26meV, respectively. The activation energy of impurity measured by Haynes rule was 130meV.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.273-280
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• 2002

The stochiometric mix of evaporating materials for the CuGaTe$_2$ single crystal thin films was prepared from horizontal furnance. For extrapolation method of X-ray diffraction patterns for the CuGaTe$_2$ polycrystal, it was found tetragonal structure whose lattice constant a$\_$0/ and c$\_$0/ were 6.025 ${\AA}$ and 11.931 ${\AA}$, respectively. To obtain the single crystal thin films, CuGaTe$_2$ mixed crystal was deposited on throughly etched semi-insulator GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were 670 $^{\circ}C$ and 410 $^{\circ}C$ respective1y, and the thickness of the single crystal thin films is 2.1 $\mu\textrm{m}$. The crystalline structure of single crystalthin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). Hall effect on this sample was measured by the method of van der Pauw and studied on carrier density and mobility dependence on temperature. The carrier density and mobility of CuGaTe$_2$ single crystal thin films deduced from Hall data are 8.72${\times}$10$\^$23/㎥, 3.42${\times}$10$\^$-2/㎡/V$.$s at 293K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the CuGaTe$_2$ single crystal thin film, we have found that the values of spin orbit coupling Δs.o and the crystal field splitting Δcr were 0.0791 eV and 0/2463eV at 10K, respectively. From the PL spectra at 10K, the peaks corresponding to free bound excitons and D-A pair and a broad emission band due to SA is identified. The binding energy of the free excitons are determined to be 0.0470eV and the dissipation energy of the donor -bound exciton and acceptor-bound exciton to be 0.0490eV, 0.00558eV, respectively.

• Journal of the Korean Chemical Society
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• v.34 no.1
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• pp.37-43
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• 1990

An effect of the spin-orbit coupling interaction of ligand orbitals and the intermixing │3d 〉and│4p > transition metal atomic orbitals on the ground state for a 3$d^9$ system in a strong crystal field of tetragonally distorted tetrahedral symmetry that belongs to the $D_{2d}$ point group has been investigated in this work, applying the degenerate perturbation theory. An LCAO-MO analysis in terms of the known energies of the d-d transitions for the tetragonally distorted $CuCl_4^{2-}$ ion in a single crystal of$Cs_2CuCl_4$shows that the covalent mixing of Cu 3d and ligand Cl 3p orbitals decreases dramatically with increasing Cu 4p contribution. The extent of effect on the energy level splitting for the ground state by the spin-orbit coupling interaction of ligand orbitals decreases significantly in orderTEX>$\Gamma_7(E)\;\to\;\Gamma_6(E)\; >\;\Gamma_7(B_2)\;\to\;\Gamma_6(E)\; >\;\Gamma_7(B_2)\;\to\;\Gamma_7(E)$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.167-170
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• 2004

The stochiometric mix of evaporating materials for the $CuGaT_2$ single crystal thin films was prepared from horizontal furnance. Using extrapolation method of X-ray diffraction patterns for the $CuGaTe_2$ polycrystal, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were 6.025 ${\AA}$ and 11.931 ${\AA}$, respectively. To obtain the single crystal thin films, $CuGaTe_2$ mixed crystal was deposited on throughly etched semi-insulator GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $670^{\circ}C$ and $410^{\circ}C$ respectively, and the thickness of the single crystal thin films is $2.1{\mu}m$. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the $CuGaTe_2$ single crystal thin film, we have found that the values of spin orbit coupling ${\Delta}s.o$ and the crystal field splitting ${\Delta}cr$ were $0.079\underline{1}eV$ and $0.246\underline{3}eV$ at 10 K, respectively. From the PL spectra at 10K, the peaks corresponding to free bound excitons and D-A pair and a broad emission band due to SA is identified. The binding energy of the free excitons are determined to be $0.047\underline{0}eV$ and the dissipation energy of the donor-bound exciton and acceptor-bound exciton to be $0.049\underline{0}eV$, $0.055\underline{8}eV$, respectively.