• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권2호
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• pp.107-112
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• 2000

$(Sr_{0.85}Ca_{0.15})TiO_3$(SCT) thin films were deposited on Pt-coated $TiO_2/SiO_2/Si$ wafer by the rf sputtering method. Experiments were conducted to investigate the electrical properties of SCT thin films with various top electrodes. Various top electrodes as Pt, Al, Ag, Cu were deposited on SCT thin films by sputter and thermal evaporator. The characteristics of C-F and C-V of SCT thin films were not obviously varied with various top electrodes, SCT thin films annealed at $600^{\circ}C$ represents as favorable capacitance characteristics than SCT thin films not annealed, and Pt top electrode have the most high capacitance. The characteristic of I-V of SCT thin films showed that Pt top electrode revealed more less leakage current density than other electrodes, had a leakage current density below 10-8$[A/cm^2]$ until 25[V] applied voltage.

• 한국광학회지
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• 제18권6호
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• pp.452-460
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• 2007

ZERODUR와 용융 석영으로 저산란 반사경을 제작하고 산란 특성을 연구하였다. Bowl feed 법을 이용하여 초연마면인 표면거칠기 0.326 ${\AA}$인 용융 석영 기판과 표면거칠기 0.292 ${\AA}$의 ZERODUR 기판을 얻었다. 이온빔 스퍼터링 방법으로 초연마된 기판 위에 $SiO_2$와 $Ta_2O_5$를 교번으로 22층을 증착하여 다층박막 고반사 거울을 얻었다. 용융 석영 반사경과 ZERODUR 반사경의 산란이 각각 4.6 ppm과 30.9 ppm으로 측정되었으며, 이로부터 산란이 매우 작은 경우 기판의 표면거칠기가 산란을 결정하는 주요 파라미터가 아니라는 것을 알았다. 나아가 반사경의 표면거칠기를 AFM으로 측정한 결과. ZERODUR 반사경이 용융 석영 반사경 보다 박막의 표면거칠기가 2.3배 더 높게 측정 되었다. 이 결과는 기판-박막 경계면에서 박막 형성 초기에 기판의 화학조성 또는 결정방향과 증착물질의 상호관계로 인하여 박막 형성 초기에 표면거칠기가 급격히 나빠져서 발생하는 것으로 유추되었다. SEO 300A으로 접촉각 측정을 하여 Giriflaco-Good-Fowkees-Young 방법으로 표면에너지를 계산하였다. 표면거칠기 0.46 ${\AA}$을 갖는 용융 석영 기판이 표면거칠기 0.31 ${\AA}$을 갖는 ZERODUR 기판보다 접촉각이 더 작고 표면에너지는 크게 나타났다. 이러한 차이가 기판 종류에 따라 박막형성 초기에 표면거칠기를 다르게 하는 한 요인으로 판단되며, 기판의 표면에너지가 높을수록 미려한 박막표면을 얻는 것으로 확인되었다. ZERODUR의 표면에너지 차이를 설명하기 위해 XPS 분석으로 용융 석영은 Si, O로 구성되었고 ZERODUR는 Si, O, Al, Na 그리고 F로 구성되었다는 것을 알 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 광주전남지부
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• pp.107-108
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• 2006

High $J_c$ $YBa_2Cu_3O_x$, superconducting films were fabricated by MOD method using fluorine-free dichloroacetic acid(DCA) as chelating solvent for preparing precursor solution. DCA-MOD precursor solution was coated on a single crystal (001) $LaAlO_3$(LAO) substrate by a dip coating method with a speed of 25 mm/min. Coated films were calcined at lower temperature up to $500^{\circ}C$ and Conversion heat treatment was performed at various temperatures of $780{\sim}810^{\circ}C$. SEM observations showed that films have very dense microstructures for the films prepared at the temperature higher than $800^{\circ}C$ regardless of diluting solvent; methanol or 2-methoxyethanol. A High critical current density ($J_c$) of 1.28 $MA/cm^2$ (@77 K and self-field) was obtained for the YBCO film prepared using 2-methoxyethanol as a solvent.

• Progress in Superconductivity
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• 제8권1호
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• pp.93-97
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• 2006

YBCO films were deposited on a moving substrate by a spray pyrolysis method using nitrate aqueous solution as precursors. Deposition was made on $LaAlO_3$(100) single crystal substrate by spraying precursor droplets generated by a concentric nozzle. The cation ratio of precursor solution was Y:Ba:Cu=1:2.65:4.5. The distance between nozzle and substrate was 15 cm. Substrate was transported with a speed ranging from 0.23 cm/min to 0.5 cm/min. Films were deposited at the pressure ranging from 10 Torr to 20 Torr and the deposition temperature was ranged from $740^{\circ}C\;to\;790^{\circ}C$. Oxygen partial pressure was controlled between 1 Tow and S Torr. Superconducting YBCO films were obtained from $740^{\circ}C\;to\;790^{\circ}C$ with an oxygen partial pressure of 3 Torr. Scanning electron microscope(SEM) and X-ray diffraction(XRD) observation revealed that films are smooth and highly texture with(001) plans parallel to substrate plane. Highest Jc was 0.72 $MA/cm^2$ at 77K and self-field for the film with a thickness of 0.15 m prepared at a substrate temperature of $740^{\circ}C$ and $PO_2$=3 Torr.

• 한국진공학회지
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• 제16권6호
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• pp.463-467
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• 2007

[ $Al_2O_3$ ]기판을 산소 plasma 또는 수소 plasma로 표면 처리한 후 그 위에 plasma-assisted molecular beam epitaxy 방법으로 성장된 ZnO 박막의 구조적 특성과 광학적 발광 특성을 체계적으로 조사하였다. 제작된 ZnO 박막은 high resolution X-ray diffraction 측정과 atomic force microscope를 사용하여 구조적 특성과 표면 특성을 관찰하였으며, photoluminescence (PL) 측정을 통하여 엑시톤과 관련된 광학적 전이특성을 온도에 따라 조사하였다. free exciton, bound exciton, 그리고 이들의 phonon replica들의 특성을 온도에 따라 분석하였으며, 산소 plasma로 표면 처리한 시료의 PL 세기가 수소 plasma 표면 처리한 시료의 PL 세기보다 상당히 커짐을 관찰하였다. 산소 plasma로 처리된 기판 위에 성장된 ZnO 시료가 수소 plasma로 처리된 경우보다 우수한 구조적 특성과 광학적 특성을 보였는데, 이는 산소 plasma로 표면 처리함으로써 산소 공공(oxygen vacancy)과 같은 결함 구조가 적게 생성되고 좋은 격자 상수 일치를 보여주므로 구조적 특징과 발광 특징이 향상되는 것으로 해석되었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.55.1-55.1
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• 2010

Cost efficient and large area deposition of superior quality $Al_2O_3$ doped zinc oxide (AZO) films is instrumental in many of its applications including solar cell fabrication due to its numerous advantages over ITO films. In this study, AZO films were prepared by a highly efficient rotating cylindrical dc magnetron sputtering system using AZO target, which has a target material utilization above 80%, on glass substrates in argon ambient. A detailed analysis on the electrical, optical and structural characteristics of AZO thin films was carried out for solar cell application. The properties of films were found to critically depend on deposition parameters such as sputtering power, substrate temperature, working pressure, and thickness of the films. A low resistivity of ${\sim}5.5{\times}10-4{\Omega}-cm$ was obtained for films deposited at 2kW, keeping the pressure and substrate temperature constant at 3 mtorr and $230^{\circ}C$ respectively, mainly due to an increase in carrier mobility and large grain size which would reduce the grain boundary scattering. The increase in carrier mobility with power can be attributed to the columnar growth of AZO film with (002) preferred orientation as revealed by XRD analysis. The AZO films showed a high transparency of>87% in the visible wavelength region irrespective of deposition conditions. Our results offers a cost-efficient AZO film deposition method which can fabricate films with significant low resistivity and high transmittance that can find application in thin-film solar cells.

• E2M - 전기 전자와 첨단 소재
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• 제7권5호
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• pp.409-416
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• 1994

A double layered photoreceptor using phthalocyanine dye was made by dip-coating method. The under cutting layer(UCL) was coated with A1$\_$2/O$\_$3/ or polyamide, and the charge generation layer(CGL) was formed by .tau.-type metal-free phthalocyanine. The oxadiazole was used as a charge transport layer(CTL) and polycarbonate and poly(vinyl butyral) was employed as a host polymer. The .tau.-H$\_$2/Pc had an absorption peak around 780nm, which coincided with the emitting wavelengths of GaAlAs diode lasers. Maximum charge acceptance of CTL that gives thickness of 12.mu.m was -900V by corona charge of -6.0kV. In photo-induced discharge measurements, residual potential was less than -20V and sufficient for ordinary use, and sample films using of poly(vinyl butyral) was showed good charge retention. In printing test, drum that was employed polycarbonate as a host polymer showed the good print quality.

• 한국전기전자재료학회논문지
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• 제18권6호
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• pp.554-559
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• 2005

Ni/Cr thin film is very interesting material as thin film resistors, filaments, and humidity sensors because their relatively large resistivity, more resistant to oxidation and a low temperature coefficient of resistance (TCR). These interesting properties of Ni/Cr thin films are dependent upon the preparation conditions including the deposition environment and subsequent annealing treatments. Ni/Cr thin films of 250 nm were deposited by DC magnetron sputtering on $Al_2O_3/Si$ substrate with 2-inch Ni/Cr (80/20) alloy target at room temperature for 45 minutes. Annealing treatments were performed at $400^{\circ}C,\;500^{\circ}C,\;and\;600^{\circ}C$ for 6 hours in air or $H_2$ ambient, respectively. The clear crystal boundaries without crystal growth and the densification were accomplished when the pores were disappeared in air ambient. Most of surface was oxidic including NiO, $Ni_2O_3$ and $Cr_xO_y$(x=1,2, y=2,3) after annealing in air ambient. The crystal growth in $H_2$ ambient was formed and stabilized by combination with each other due to the suppression of oxidized substance on film surface. Most oxidic Ni was restored when the oxidic Cr was present due to its stability in high-temperature $H_2$ ambient.

• 한국전기전자재료학회논문지
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• 제21권5호
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• pp.415-420
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• 2008

AAO films were fabricated on two kinds of substrates such as $Al/SiO_2/Si$ and Al/Ni/Ti/Si. To obtain well-aligned AAO film, we optimized process condition for buffer layer, electrolyte and voltage. In the case of oxalic acid, the AAO film with pore size of approximately 45 nm was obtained at voltage of 40 V, temperature of $10^{\circ}C$, oxalic acid of 0.3 M and widening time of 60 min. Then the thickness of barrier is less than 600 nm. In the case of sulfuric acid, the AAO film has pore size of 40 nm and barrier thickness of 400 nm with optimum conditions such as voltage of 25 V, temperature of $8^{\circ}C$, sulfuric acid of 0.3 M and widening time of 60 min.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.168-168
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• 2008

Dimension of a transistor has rapidly shrunk to increase the speed of device and to reduce the power consumption. However, it is accompanied with several problems like direct tunneling through the gate dioxide layer and low conductivity characteristic of poly-Si gate in nano-region. To cover these faults, study of new materials is urgently needed. Recently, high dielectric materials like $Al_2O_3$, $ZrO_2$, and $HfO_2$ are being studied for equivalent oxide thickness (EOT). However, poly-Si gate is not compatible with high-k materials for gate-insulator. Poly Si gate with high-k material has some problems such as gate depletion and dopant penetration problems. Therefore, new gate structure or materials that are compatible with high-k materials are also needed. TiN for metal/high-k gate stack is conductive enough to allow a good electrical connection and compatible with high-k materials. According to this trend, the study on dry etching of TiN for metal/high-k gate stack is needed. In this study, the investigations of the TiN etching characteristics were carried out using the inductively coupled $BCl_3$-based plasma system and adding $Cl_2$ gas. Dry etching of the TiN was studied by varying the etching parameters including $BCl_3$/Ar gas mixing ratio, RF power, DC-bias voltage to substrate, and $Cl_2$ gas addition. The plasmas were characterized by optical emission spectroscopy analysis. Scanning electron microscopy was used to investigate the etching profile.