• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.1
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• pp.17-20
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• 2015

The physical effects of H-plasma treatment on ZnO thin film have been studied using photoluminescence(PL) spectroscopy. Four characteristic peaks have been identified: (i) $D^0X$ peak (neutral donor-bound exciton), showing relatively small integrated intensity after H-plasma treatment, indicates that H-plasma passivates the neutral donors in ZnO at low temperatures. The rapid decrease in the integrated intensity of the peak as the temperature goes up is considered to be due to the ionization of neutral donors. (ii) H-related complex-bound exciton peak appears at the low temperatures (10 K~80 K) after H-plasma treatment, showing the same thermal evolution as $D^0X$ peak. (iii) FX (free exciton) peak starts to show up at 60 K and grows more and more as the temperature goes up, which is considered to be related to the increase in free electron concentration in the film. (iv) violet band is intensified after H-plasma, which means more defects and impurities are generated by H-plasma process.

• Journal of Sensor Science and Technology
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• v.14 no.6
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• pp.369-373
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• 2005

High quality CdTe single crystal for the solar cell fabrication was grown by vertical Bridgman method. The etch pits patterns of (111) surfaces of CdTe etched by Nakagawa solution was observed the (111)A compesed of Cd atoms with typical triangle etch pits of pyramid mode. From the photoluminescence measurement on (111)A, we observed free exciton ($E_{x}$) existing only high quality crystal and neutal acceptor bound exciton ($A^{0}$,X) having very strong peak intensity. Then, the full width at half maximum and binding energy of neutral acceptor bound exciton were 7 meV and 5.9 meV, respectively. By Haynes rule, an activation enery of impurity was 59 meV. Therefore, the origins on impurity level acting as a neutral acceptor were associated Ag or Cu elements.

• Korean Journal of Crystallography
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• v.11 no.3
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• pp.137-146
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• 2000

The stoichiometric mix of evaporating materials for he CuInS₂ single crystal thin films was prepared. To obtain the single crystal thin films, CuINS₂ mixed crystal was deposited on etched semi-insulator GaAs(100) substrate by the hot wall epitaxy(HWE) system. The source and substrate temperature were 640℃ and 430℃, respectively and the thickness of the single crystal thin films was 2 ㎛. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction(DCXD). The carrier density and mobility deduced from Hall data are 9.64x10/sup 22//㎥ and 2.95x10/sup -2/ ㎡/V·s, respectively at 293 K. he optical energy gap was found to be 1.53 eV at room temperature. From the photocurrent spectrum obtained by illuminating perpendicular light on the c-axis of the thin film, we have found that the values of spin orbit coupling splitting ΔSo and the crystal field splitting ΔCr were 0.0211 eV and 0.0045 eV at 10K, respectively. From PL peaks measured at 10K, were can assign the 807.7 nm (1.5350 eV) peak to E/sub x/ peak of the free exciton emission, the 810.3 nm(1.5301 eV) peak to I₂ peak of donar-bound exciton emission and the 815.6 nm(1.5201 eV) peak to I₁ peak of acceptor-bound excition emission. In addition, the peak observed at 862.0 nm(1.4383 eV) was analyzed to be PL peak due to donor-acceptor pair(DAP).

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.69-69
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• 2010

The research is the structural and optical characteristics of the Cadmium Sulfide(CdS) film, nanowires and nanobelts grown on the $Al_2O_3$ substrate using the vapor phase epitaxy method. The field-emission scanning electron microscopy(FE-SEM) were used to identify the shape of the surface of the nanostructures and x-ray diffraction(XRD) and transmission electron microscopy (TEM) were used to evaluate the structural characterisitcs. As a result, the XRD was confirmed the CdS peak and the substrate peak and TEM showed single crystals with wurtzite hexagonal structure on the nanostructures. As for the optical characteristic of the nanostructures, photoluminescence(PL) and micro-raman spectrum were measured. The PL measurements confirmed the emission peak related bound exciton to neutral donor($D^0X$) peak and free exciton(FX) peak. The micro-raman spectrum showed that the peak of the nanostructures were similar to the pure crystalline CdS peak and each peak were overtone of LO phonon of the hexagonal CdS of the longitudinal optical(LO) phonon mode. Therefore, it is confirmed that the CdS nanostructures grown in this research have superior crystallinity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.230-233
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• 2004

The stochiometric mix of evaporating materials for the $CuInS_2$ single crystal thin films was prepared from horizontal furnance. Using extrapolation method of X-ray diffraction patterns for the $CuInS_2$ polycrystal, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were $5.524\;{\AA}$ and $11.142\;{\AA}$, respectively. To obtain the single crystal thin films, $CuInS_2$ 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 640 t and 430 t, respectively and the thickness of the single crystal thin films was $2{\mu}m$. Hall effect on this sample was measured by the method of van dot Pauw and studied on carrier density and temperature dependence of mobility. The carrier density and mobility deduced from Hall data are $9.64{\times}10^{22}/m^3,\;2.95{\times}10^{-2}\;m^2/V{\cdot}s$ at 293 K, respectively The optical energy gaps were found to be 1.53 eV at room temperature. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the thin film, we have found that the values of spin orbit coupling splitting ${\Delta}So$ and the crystal field splitting ${\Delta}Cr$ were 0.0211 eV and 0.0045 eV at 10 K, respectively. From PL peaks measured at 10K, 807.7nm (1.5350ev) mean Ex peak of the free exciton emission, also 810.3nm (1.5301eV) expresses $I_2$ peak of donor-bound exciton emission and 815.6nm (1.5201eV) emerges $I_1$ peak of acceptor-bound exciton emission. In addition, the peak observed at 862.0nm (1.4383eV) was analyzed to be PL peak due to donor-acceptor pair(DAP).

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.227-231
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• 1996

The reflection spectrum of a $2H-PbI_2$ single crystal grown by vapour phase method were measured at 10 K near the fundamental absorption edge. The n= 1,2,3 Wannier exciton series and $A_{EP}$ reflection line were obtained from the reflection spectrum. Based on the 2nd phonon energy in the Raman spectrum, which is different from Nagamune's report, we suggest that $A_{EP}$ line is due to the bound state between the n=2 exciton and the 2nd phonon which surmise that this is LO phnon due to the second Raman process. The L-T splitting energy of n=1 exciton line was 6.56 meV and was consistent with the emission spectrum. The temperature dependence of the reflection spectrum showed that n=1 exciton peak was shifted to longer wavelength while, as the temperatre is raised, the sharpness of that with the increase of the L-T splitting energy decrease. From Wannier exiton series, the exciton binding energy and exciton radius was 30 meV and 14$\AA$, respectively.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.84-84
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• 2003

The ZnSe epilayers were grown on the GaAs substrate by hot wall epitaxy. After the ZnSe epilayers treated in the vacuum-, Zn-, and Se-atmosphere, respectively, the defects of the epilayer were investigated by means of the low-temperature photoluminescence measurement. The dominant peaks at 2.7988 eV and 2.7937 eV obtained from the PL spectrum of the as-grown ZnSe epilayer were found to be consistent with the upper and the lower polariton peak of the exciton, I$_2$ (D$^{\circ}$, X), bounded to the neutral donor associated with the Se-vacancy. This donor-impurity binding energy was calculated to be 25.3meV The exciton peak, lid, at 2.7812 eV was confirmed to be bound to the neutral acceptor corresponded with the Zn-vacancy. The I$_1$$\^$d/ peak was dominantly observed in the ZnSe/GaAs:Se epilayer treated in the Se-atmosphere. This Se-atmosphere treatment may convert the ZnSe/GaAs:Se epilayer into the p-type. The SA peak was found to be related to a complex donor like a (V$\sub$se/ - V$\sub$zn/) - V$\sub$zn-/

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.3
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• pp.105-110
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• 2003

The ZnSe epilayers were grown on the GaAs substrate by hot wall epitaxy. After the ZnSe epilayers treated in the vacuum-, Zn-, and Se-atmosphere, respectively, the defects of the epilayer were investigated by means of the low-temperature photoluminescence measurement. The dominant peaks at 2.7988 eV and 2.7937 eV obtained from the PL spectrum of the as-grown ZnSe epilayer were found to be consistent with the upper and the lower polariton peak of the exciton, $I_{2}$ ($D^{\circ}$, X), bounded to the neutral donor associated with the Se-vacancy. This donor-impurity binding energy was calculated to be 25.3 meV, The exciton peak, $I_{1}^{d}$ at 2.7812 eV was confirmed to be bound to the neutral acceptor corresponded with the Zn-vacancy. The $I_{1}^{d}$ peak was dominantly observed in the ZnSe/GaAs : Se epilayer treated in the Se-atmosphere. This Se-atmosphere treatment may convert the ZnSe/GaAs : Se epilayer into the p-type. The SA peak was found to be related to a complex donor like a $(V_{se}-V_{zn})-V_{zn}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.120-123
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• 2003

The ZnSe epilayers were grown on the GaAs substrate by hot wall epitaxy. After the ZnSe epilayers treated in the vacuum-, Zn-, and Se-atmosphere, respectively, the defects of the epilayer were investigated by means of the low-temperature photoluminescence measurement. The dominant peaks at 2.7988 eV and 2.7937 eV obtained from the PL spectrum of the as-grown ZnSe epilayer were found to be consistent with the upper and the lower polariton peak of the exciton, $I_2$ ($D^{\circ}$, X), bounded to the neutral donor associated with the Se-vacancy. This donor-impurity binding energy was calculated to be 25.3 meV. The exciton peak, $I_1^d$, at 2.7812 eV was confirmed to be bound to the neutral acceptor corresponded with the Zn-vacancy. The $I_1^d$ peak was dominantly observed in the ZnSe/GaAs:Se epilayer treated in the Se-atmosphere. This Se-atmosphere treatment may convert the ZnSe/GaAs:Se epilayer into the p-type. The SA peak was found to be related to a complex donor like a $(V_{Se}-V_{Zn})-V_{Zn}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.378-378
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• 2010

The ZnSe epilayers were grown on the GaAs substrate by hot wall epitaxy. After the ZnSe epilayers treated in the vacuum-, Zn-, and Se-atmosphere, respectively, the defects of the epilayer were investigated by means of the low, temperature photoluminescence measurement. The dominant peaks at 2.7988 eV and 2.7937 eV obtained from the PL spectrum of the as-grown ZnSe epilayer were found to be consistent with the upper and the lower polariton peak of the exciton, $I_2$ ($D^{\circ}$, X), bounded to the neutral donor associated with the Se-vacancy. This donor-impurity binding energy was calculated to be 25.3 meV. The exciton peak, $I_l^d$, at 2.7812 eV was confirmed to be bound to the neutral acceptor corresponded with the Zn-vacancy.