• Korean Journal of Materials Research
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• v.32 no.5
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• pp.243-248
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• 2022

This study demonstrates a different approach method to fabricate antimony selenide (Sb₂Se₃) thin-films for the solar cell applications. As-deposited Sb₂Se₃ thin-films are fabricated via electrodeposition route and, subsequently, annealed in the temperature range of 230 ~ 310℃. Cyclic voltammetry is performed to investigate the electrochemical behavior of the Sb and Se ions. The deposition potential of the Sb₂Se₃ thin films is determined to be -0.6 V vs. Ag/AgCl (in 1 M KCl), where the stoichiometric composition of Sb₂Se₃ appeared. It is found that the crystal orientations of Sb₂Se₃ thin-films are largely dependent on the annealing temperature. At an annealing temperature of 250 ℃, the Sb₂Se₃ thin-film grew most along the c-axis [(211) and/or (221)] direction, which resulted in the smooth movement of carriers, thereby increasing the carrier collection probability. Therefore, the solar cell using Sb₂Se₃ thin-film annealed at 250 ℃ exhibited significant enhancement in J_SC of 10.03 mA/cm² and a highest conversion efficiency of 0.821 % because of the preferred orientation of the Sb₂Se₃ thin film.

• Korean Journal of Materials Research
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• v.30 no.10
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• pp.558-565
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• 2020

AZO thin films are grown on a p-Si(111) substrate by RF magnetron sputtering. The characteristics of various thicknesses and heat treatment conditions are investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Hall effect and room-temperature photoluminescence (PL) measurements. The substrate temperature and the RF power during growth are kept constant at 400 ℃ and 200 W, respectively. AZO films are grown with a preferred orientation along the c-axis. As the thickness and the heat treatment temperature increases, the length of the c-axis decreases as Al³⁺ ions of relatively small ion radius are substituted for Zn²⁺ ions. At room temperature, the PL spectrum is separated into an NBE emission peak around 3.2 eV and a violet regions peak around 2.95 eV with increasing thickness, and the PL emission peak of 300 nm is red-shifted with increasing annealing temperature. In the XPS measurement, the peak intensity of Al_2p and O_ll increases with increasing annealing temperature. The AZO thin film of 100 nm thickness shows values of 6.5 × 10¹⁹ cm^-3 of carrier concentration, 8.4 cm^-2/V·s of mobility and 1.2 × 10^-2 Ω·cm electrical resistivity. As the thickness of the thin film increases, the carrier concentration and the mobility increase, resulting in the decrease of resistivity. With the carrier concentration, mobility decreases when the heat treatment temperature increases more than 500 ℃.

• Korean Journal of Materials Research
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• v.12 no.11
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• pp.835-839
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• 2002

Metal-Ferroelectric-Metal(MFM) capacitors were prepared using $Bi_{3.3}$ $La_{0.7}$ $Ti_3$$O_{12}$ (BLT) ferroelectric thin films which were spin coated on $Pt/Ti/SiO_2$/Si substrates by the Sol-Gel method. BLT thin films annealed at above $650^{\circ}C$ showed polycrystalline structures with typical c-axis preferred orientation. The grain size and surface roughness were increased as the annealing temperature increased from $650^{\circ}C$ to $700^{\circ}C$. In addition, the full width at half maximum (FWHM) values were decreased with increasing annealing temperatures, indicating the improvement of crystallinity. The remanent polarization (2Pr= $Pr^{+}$ $+Pr^{-) }$ and leakage current of the BLT film annealed at $650^{\circ}C$ were about 29.3 $\mu$C/cm$^2$ and $2.3$\times$10^{-8}$$ A/cm^2$ at 3V. There were no distinct changes in the retention charges after $10^{10}$ polarization switching cycles, showing good fatigue property of the annealed BLT films.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.581-589
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• 1994

Magnetic properties and microstructures of the $Co_{83}Cr_{17}$ films growing under the applied magnetic field were studied. In comparison, those of the films growing without magnetic field were also studied. Magnetic field does not affect saturation magnetization and in-plane coercivity of the films. On the contrary perpendicular coercivity and effective perpendicular anisotropy field decreased. Grain size and the thickness of the so-called transition layer were not affected and the C-axis alignment of the films was slightly deteriorated due to magnetic field. Also, microstructures of the sputtered films showed larger grain sizes of strong (002) preferred orientation for thicker film specimens independent of applied magnetic field.

• Journal of the Korean institute of surface engineering
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• v.41 no.4
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• pp.129-133
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• 2008

Nitrogen and aluminum codoped ZnO(NAZO) thin films were grown on glass substrates with changing the nitrogen flow ratio by radio-frequency magnetron sputtering. The structural, optical, and electrical properties of the NAZO films were investigated. The surface morphologies and the structural properties of the thin films were analyzed by using the X-ray diffraction and scanning electron microscopy. The NAZO thin film, deposited at nitrogen flow ratio of 0%, showed a strongly c-axis preferred orientation and the lowest resistivity of $3.2{\times}10^{-3}{\Omega}cm$. The intensity of ZnO(002) diffraction peak was decreased gradually with increasing the nitrogen flow ratio. The optical properties of the films were measured by UV-VIS spectrophotometer and the optical transmittances for all the samples were found to be an average 90% in the visible range. Based on the transmittance value, the optical bandgap energy for the NAZO thin film deposited at nitrogen flow ratio of 0% was determined to be 3.46 eV. As for the electrical properties, the carrier concentration and the hall mobility were decreased, but the electrical resistivity was increased as the nitrogen flow ratio was increased.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.247-247
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• 2011

플라즈마 분자선 에피택시(plasma-assisted molecular beam epitaxy)법을 이용하여 다공질 실리콘(porous silicon)에 ZnO 박막을 성장하였다. 성장 후, 아르곤 분위기에서 10분 간 다양한 온도(500~700$^{\circ}C$)로 열처리하였다. 다공질 실리콘 및 열처리 온도가 ZnO 박막의 특성에 미치는 영향을 scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL)을 이용하여 분석하였다. 실리콘 기판에 성장된 ZnO 박막은 일반적은 섬구조(island structure)로 성장된 반면, 다공질 실리콘에 성장된 ZnO 박막은 산맥과 같은 구조(mountain range-like structure)로 성장되었다. 열처리 온도가 증가함에 따라 ZnO 박막의 grain size는 증가하였다. 실리콘 기판 위에 성장된 ZnO 박막은 wurtzite 구조를 나타내는 여러 개의 회절 피크가 관찰된 반면, 다공질 실리콘에 성장된 ZnO 박막은 c-축 배향성(c-axis preferred orientation)을 나타내는 ZnO (002) 회절 피크만이 나타났다. 다공질 실리콘에 성장된 ZnO 박막의 구조적 및 광학적 특성이 실리콘 기판에 성장된 ZnO 박막의 특성보다 우수하게 나타났다. 뿐만 아니라, 열처리 온도가 증가함에 따라 다공질 실리콘에 성장된 ZnO 박막의 PL 강도비(intensity ratio)가 실리콘 기판에 성장된 ZnO 박막의 강도비보다 월등하게 증가하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.246-246
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• 2011

졸-겔 스핀코팅(sol-gel spin-coating)법을 이용하여 실리콘 기판에 ZnO 박막을 증착하였다. 증착된 졸 용액을 전열처리(pre-heat treatment) 후, 다른 속도로 상온까지 냉각시켰다. ZnO 박막의 특성 분석을 위하여 atomic force microscopy (AFM), X-ray diffraction (XRD), Raman, photoluminescence (PL)을 이용하였다. 전열처리 후 5$^{\circ}C$/min의 속도로 천천히 냉각시킨 ZnO 박막은 산맥구조(mountain chain structure)로 표면이 매우 거친 반면, 빠르게 냉각시킨 ZnO 박막은 매우 매끄러운 표면을 나타내었다. 빠르게 냉각시킨 ZnO 박막의 c-축 배향성(c-axis preferred orientation)이 느리게 냉각시킨 ZnO 박막의 배향성보다 더 우세하게 나타났고, 결정성도 우수하였다. 뿐만 아니라, 빠르게 냉각시킨 ZnO 박막의 광학적 특성이 느리게 냉각시킨 ZnO 박막의 특성보다 우수하게 나타났다. 후열처리(post-heat treatment)에 의해 ZnO 박막의 구조적 및 광학적 특성이 더욱 향상되었다.

• Journal of the Korean Ceramic Society
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• v.32 no.7
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• pp.799-808
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• 1995

Transparent conductive films of aluminium doped zinc oxide (AZO) have been prepared by using the DC magnetron sputtering with the ZnO : Al (Al2O3 2 wt%) oxide target oriented to c-axis. Electrical and optical properties depended upon the O2/Ar gas ratio. The optical transmittance and sheet resistance of the AZO coated glass was 60~65% and 75Ω/$\square$, respectively at the O2/Ar gas ratio of 0. With the increase of the oxygen partial pressure to 2.0$\times$10-2, they were increased to the values of 81% and 1kΩ/$\square$, respectively. The films with the resistivities of 1.2~1.4$\times$10-3 Ω.cm, mobilities of 11~13 $\textrm{cm}^2$/V.sec and carrier concentrations of 3.5$\times$1020~4.0$\times$1020/㎤ were produced at the optimum O2/Ar gas ratio, which was 0.5$\times$10-2~1.0$\times$10-2. According to XRD analysis, the films have only one peak corresponding to the (002) plane, which indicates that there is a strong preferred orientation of the films. The grain size of ZnO films were calculated to 200~320 $\AA$, which was increased with the O2/Ar gas ratio and Ar gas flowrate.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.127.1-127.1
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• 2011

In this paper, ZnO:Al thin films with c-axis preferred orientation were prepared on Soda lime glass substrates by RF magnetron sputtering technique. AZO thin film were prepared in order to clarify optimum conditions for growth of the thin film depending upon process, and then by changing a number of deposition conditions and substrate temperature conditions variously, structural and electrical characteristics were measured. For the manufacture of the AZO were vapor-deposited in the named order. It is well-known that post-annealing is an important method to improve crystal quality. For the annealing process, the dislocation nd other defects arise in the material and adsorption/decomposition occurs. The XRD patterns of the AZO films deposited with grey theory prediction design, annealed in a vacuum ambient($2.0{\times}10-3$Torr)at temperatures of 200, 300, 400 and $500^{\circ}C$ for a period of 30min. The diffraction patterns of all the films show the AZO films had a hexagonal wurtzite structure with a preferential orientation along the c-axis perpendicular to the substrate surface. As can be seen, the (002)peak intensities of the AZO films became more intense and sharper when the annealing temperature increased. On the other hand, When the annealing temperature was $500^{\circ}C$ the peak intensity decreased. The surface morphologies and surface toughness of films were examined by atomic force microscopy(AFM, XE-100, PSIA). Electrical resistivity, Gall mobility and carrier concentration were measured by Hall effect measuring system (HL5500PC, Accent optical Technology, USA). The optical absorption spectra of films in the ultraviolet-visibleinfrared( UV-Vis-IR) region were recorder by the UV spectrophotometer(U-3501, Hitachi, Japan). The resistivity, carrier concentration, and Hall mobility of ZnS deposited on glass substrate as a function of post-annealing.

• Korean Journal of Materials Research
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• v.21 no.1
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• pp.34-38
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• 2011

In this study, the effects of an annealed buffer layer with different thickness on heterojunction diodes based on the ZnO/ZnO/p-Si(111) systems were reported. The effects of an annealed buffer layer with different thickness on the structural, optical, and electrical properties of zinc oxide (ZnO) films on p-Si(111) were also studied. Before zinc oxide (ZnO) deposition, different thicknesses of ZnO buffer layer, 10 nm, 30 nm, 50 nm and 70 nm, were grown on p-Si(111) substrates using a radio-frequency sputtering system; samples were subsequently annealed at $700^{\circ}C$ for 10 minutes in $N_2$ in a horizontal thermal furnace. Zinc oxide (ZnO) films with a width of 280nm were also deposited using a radio-frequency sputtering system on the annealed ZnO/p-Si (111) substrates at room temperature; samples were subsequently annealed at $700^{\circ}C$ for 30 minutes in $N_2$. In this experiment, the structural and optical properties of ZnO thin films were studied by XRD (X-ray diffraction), and room temperature PL (photoluminescence) measurements, respectively. Current-voltage (I-V) characteristics were measured with a semiconductor parameter analyzer. The thermal tensile stress was found to decrease with increasing buffer layer thickness. Among the ZnO/ZnO/p-Si(111) diodes fabricated in this study, the sample that was formed with the condition of a 50 nm thick ZnO buffer layer showed a strong c-axis preferred orientation and I-V characteristics suitable for a heterojunction diode.