• 한국재료학회지
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• 제23권12호
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• pp.714-721
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• 2013

A stoichiometric mixture of evaporating materials for $ZnAl_2Se_4$ single-crystal thin films was prepared in a horizontal electric furnace. These $ZnAl_2Se_4$ polycrystals had a defect chalcopyrite structure, and its lattice constants were $a_0=5.5563{\AA}$ and $c_0=10.8897{\AA}$.To obtain a single-crystal thin film, mixed $ZnAl_2Se_4$ crystal was deposited on the thoroughly etched semi-insulating GaAs(100) substrate by a hot wall epitaxy (HWE) system. The source and the substrate temperatures were $620^{\circ}C$ and $400^{\circ}C$, respectively. The crystalline structure of the single-crystal thin film was investigated by using a double crystal X-ray rocking curve and X-ray diffraction ${\omega}-2{\theta}$ scans. The carrier density and mobility of the $ZnAl_2Se_4$ single-crystal thin film were $8.23{\times}10^{16}cm^{-3}$ and $287m^2/vs$ at 293 K, respectively. To identify the band gap energy, the optical absorption spectra of the $ZnAl_2Se_4$ single-crystal thin film was investigated in the temperature region of 10-293 K. The temperature dependence of the direct optical energy gap is well presented by Varshni's relation: $E_g(T)=E_g(0)-({\alpha}T^2/T+{\beta})$. The constants of Varshni's equation had the values of $E_g(0)=3.5269eV$, ${\alpha}=2.03{\times}10^{-3}eV/K$ and ${\beta}=501.9K$ for the $ZnAl_2Se_4$ single-crystal thin film. The crystal field and the spin-orbit splitting energies for the valence band of the $ZnAl_2Se_4$ were estimated to be 109.5 meV and 124.6 meV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}_5$ states of the valence band of the $ZnAl_2Se_4/GaAs$ 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.

• 한국정보통신학회논문지
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• 제7권4호
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• pp.712-718
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• 2003

진공 증착한 CdS 박막의 질소 이온 주입 효과를 X-선 회절 검사, 광 투과율, 라만 산란 특성을 통하여 조사하였다. 질소 이온 주입하지 않은 CdS 박막은 (0 0 2)면으로의 우선 방위를 가지고 성장하였다. 질소 이온 주입한 시편의 경우 metallic Cd가 형성됨을 XRD 분석 결과 알 수 있었다. 가시광 영역에서의 광투과율은 질소 이온 주입 양이 많아짐에 따라 크게 감소하였다. 또한 질소 이온 주입 양에 따라 CdS 박막의 흡수 계수는 지수 함수적으로 증가하였고, 밴드 갭은 감소하였다 CdS 박막의 라만 peak 위치는 질소 이온 주입 양에 관계없이 299 cm-1로 거의 일정하지만, peak의 FWHM은 이온 주입 양이 증가함에 따라 커졌고, peak 면적은 감소하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 논문집 센서 박막재료연구회 및 광주 전남지부
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• pp.41-41
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• 2008

Al-doped ZnO (AZO) thin films have been fabricated by vertical in-line dc magnetron sputtering for transparent conducting oxides (TCOs) applications. The effects of substrate temperature and dc power on the characteristics of AZO thin films are investigated and also optimized the process conditions to get the best electrical and optical properties. The fabricated thin films show a good electrical and optical uniformity within ${\pm}5%$ over the whole area of substrate ($200mm\;{\times}\;200mm$) ; the minimum resistivity of $8\;{\times}\;10^{-4}\;{\Omega}cm$ and the average transmittance of 90% within the visible wavelength range. We have found that the band gap ($E_g$) increases with increasing substrate temperature and dc power, whereas the crystallinity is getting improved with increasing substrate temperature. The binding energy of Zn $2p_{3/2}$ and O 1s is observed to decrease as the substrate temperature increases.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.257-260
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• 2007

In this study, $CuInSe_{2}$ (CISe) and $CuInZnSe_{2}$ (CIZSe) thin films were prepared on Corning 1737 glass by radio frequency (RF) magnetron sputtering from binary chalcogenide mixed powder targets. The targets were initially prepared by mixing appropriate weights of CuSe, InSe powder and various ZnSe contents. From the film bulk analysis result, it is observed that Zn concentration in the films increases proportionally with the addition of ZnSe in the sputtering targets. Under optimized conditions, CISe and CIZSe thin films grow as a chalcopyrite structure with strong (112), (220/204) and (312/116) reflections. Films are found to exhibit a high absorption coefficient of $10^{4}$ $cm^{-1}$. An increasing of optical band gap from 1.0 eV (CISe) to 1.25 eV (CIZSe) is found to be proportional with an increasing of Zn concentration as expected. All films have a p-type semiconductor characteristic with a carrier concentration in the order of 1014 $cm^{-3}$, a mobility about $10^{1}$ $cm^{2{\cdot}-1}{\cdot}s^{-1}$ and a resistivity at the range of $10^{2}-10^{6}$ W${\cdot}$m.

• 한국분말재료학회지
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• 제23권4호
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• pp.307-310
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• 2016

$TiOF_2$, which has remarkable electrochemical and optical properties, is used in various applications such as Li-ion batteries, electrochemical displays, and photocatalysts. In addition, it is possible to utilize the template which is allowed to synthesize fluorine doped $TiO_2$ powders with hollow or faceted structures. However, common synthesis methods of $TiOF_2$ powders have some disadvantages such as the use of expensive and harmful precursors and batchtype processes with a limited production scale. In this study, we report a synthetic route for preparing $TiOF_2$ powders by using an inexpensive and harmless precursor and a continuous ultrasonic spray pyrolysis process under a controlled atmosphere to address the aforementioned problems. The synthesized powder has an average size of $1{\mu}m$, a spherical shape, a pure $TiOF_2$ phase, and exhibits a band-gap energy of 3.2 eV.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 영호남 합동 학술대회 및 춘계학술대회 논문집 센서 박막 기술교육
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• pp.55-60
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• 2006

Thermally stable and solution-processable poly(N-arylcarbazole-alt-aniline) copolymers with high structural integrity were synthesized in good yields via palladium-catalyzed polycondensation of aniline with corresponding N-arylcarbazole monomers such as N-(2-ethylhexyloxyphenyl)-3,6-dibromocarbazole,bis[6-bromo-N-(2-ethylhexyloxyphenyl)carbazole-3-yl] and N-(4-(2-ethylhexyl)-3,5-dibromomethylene-phenyl) carbazole, respectively. The optical and electrochemical properties of these copolymers were measured and compared with those of poly(N-alkylcarbazole-alt-aniline) copolymer. All synthesized poly(N-arylcarbazole-alt-aniline) copolymers showed maximum UV-Vis absorption peaks at around 300 nm in THF solution, and exhibited maximum photoluminescence peaks in the blue emission range from 430 to 460 nm. It was also found that poly(N-arylcarbazole-alt-aniline) copolymers had wider band gap energy than poly(N-alkylcarbazole-alt-aniline) copolymer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 영호남 합동 학술대회 및 춘계학술대회 논문집 센서 박막 기술교육
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• pp.49-51
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• 2006

Ternary chalcopyrite $CuInS_2$ thin film material is very promising for photovoltaic. Power generation because of its excellent optical and semiconductor properties, $CuInS_2$ thin films were performed from S/In/Cu/SLG stacked elemental layer (SEL) method with post annealing treatment. $CuInS_2$ thin films were appeared from 0.84 to 1.27 of Cu/In composition ratio and sulfur composition ratios of $CuInS_2$ thin films fabricated. Analysis of the optical energy band gap of $CuInS_2$ value of l.5eV interior and exterior.

• 한국재료학회지
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• 제17권9호
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• pp.475-479
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• 2007

Pulsed laser deposition was utilized to grow MnS thin films on c-sapphire substrate using a KrF excimer laser at growth temperatures that ranged from room temperature to $700^{\circ}C$. The results of X-ray diffraction (XRD) and UV-visible spectroscopy were employed to investigate the structural and optical properties of the MnS films. While the growth rate decreased as $T_s$ increased, the overall quality of the film improved. The highest quality MnS film was obtained at $700^{\circ}C$. Variations in the $T_s$ resulted in the MnS films exhibiting different growth mechanisms. The oriented (200) rocksalt MnS film was grown at room temperature. In the case of higher $T_s,\;200{\sim}500^{\circ}C$, the films consisted of mixed phases of rocksalt and wurtzite. The main structure of the films was altered to (111) rocksalt when the temperature was increased to in excess of $600^{\circ}C$. This behavior may very well be the result of elements such as surface energy and atomic arrangement during the growth process. The optical band gap of the obtained ${\alpha}-MnS$ film was estimated to be 3.32 eV.

• Journal of Korean Vacuum Science & Technology
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• 제2권2호
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• pp.78-84
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• 1998

ZnO:Al films were prepared by an rf magnetron sputtering and targets for the experiments were fabricated by sintering the mixture of ZnO and Al2O3. The most conductive film was obtained from the target with 2.0∼2.2 wt.% of Al2O3. Optical properties studied with spectroscopic ellipsometry showed band gap widening, i.e., the Burstein-Moss shift, with aluminum doping as well as with the elevation of deposition temperature. And it is found that the optical and electrical properties were related to the density of states as well as the variation of donor level. when hydrogen atoms were introduced into the films, the activation energy for the generation of oxygen vacancy was smaller for the films showing higher conductivity. This indicates that the optimum deposition condition for highly conductive ZnO:Al film has strong relation to the optimum doping condition.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.236-237
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• 2012

ZnO nanorods were grown on R-plane sapphire substrates with the seed layers annealed at different temperature. The effects of annealing temperature for the seed layers on the properties of the ZnO nanorods were investigated by scanning electron microscopy, X-ray diffraction, UV-visible spectroscopy, and photoluminescence. For the as-prepared seed layers, the ZnO nanorods and the ZnO nanosheets were observed. Only the ZnO nanorods were grown as the annealing temperature was above $700^{\circ}C$. The optical transmittance in the UV region was almost zero while that in the visible region was gradually increased as the annealing temperature increased to $700^{\circ}C$. The optical band gap of the ZnO nanorods was increased as the annealing temperature increased to $700^{\circ}C$. In the visible region, the refractive index was decreased with increasing the wavelength, and the extinction coefficient was decreased as the annealing temperature increased to $700^{\circ}C$. The non-linear exciton radiative life time of the FX emission peak was established by cubic equation. The values of Varshni's empirical equation fitting parameters were ${\alpha}=4{\times}10^{-3}eV/K$, ${\beta}=1{\times}10^4K$, and $E_g(0)=3.335eV$ and the activation energy was found to be about 94.6 meV.