• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.36.2-36.2
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• 2010

A small amount of Na incorporated in $CuInSe_2$ (CIS) absorption layer has become widely accepted as a requirement for efficient polycrystalline CIS solar cells. However, there is ongoing argument on the role of sodium incorporated in the absorber. In this paper, CIS absorption layers have been deposited using the three-stage co-evaporation process on Mo coated non-Alkali glass substrates. The NaF was evaporated during the second-stage with various fluxes. This paper is focusing on differences of micro-structure and composition ratio of the absorber realized with different Na contents and the variation of electrical properties of the cells with the corresponding absorbers. The analytical results of x-ray diffraction (XRD) patterns, field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS) and current-voltage characteristics will be discussed to investigate the effect of NaF flux on the CIS absorber formation and its cell performance.

• Korean Journal of Materials Research
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• v.6 no.9
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• pp.931-936
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• 1996

비휘발성 메모리 소자에의 적용을 위한 SrBi2Ta2O9(SBT)박막이 고순도의 Sr, Bi, Ti 금속타겟을 사용하여 Pt/Ti/SiO2/Si 기판 위에 reactive sputtering 법에 의해 증착되었다. 조성의 영향을 평가하기 위하여 Bi 타겟에 인가되는 전원의 변화와 열처리에 따른 C-F(capacitance-frequency), P-E(polarization-electric field), I-V(current-voltage)등의 전기적 특성이 조사되었다. Bi의 양이 증가함에 따라 Bi layer 구조를 나타내는 (105)회절 피크가 증가하였고 $700^{\circ}C$, 산소분위기에서 1시간 동안 열처리후 Sr과 Bi가 심하게 휘발되었으며 박막의 미세구조는 다공질이 되었다. 이러한 이유로 열처리된 박막의 누설 전류 밀도는 증가하였다. 열처리된 시편의 조성은 거의 화학양론비를 이루었으며 4.5$\mu$C/$\textrm{cm}^2$의 Pr값을 갖는 강유전(ferroelectric)특성을 나타내었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.5
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• pp.399-405
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• 1990

Rapid Thermal Process(RTP) has been used to precisely control and study the reaction rate for the formation of refractory titanuium silicide. Samples were prepared by sputtering deposition layer of titanium on n-type, poly-deposit silicon wafers. The process were then sujected to a matrix of rapid time-temperature profile under nitrgen, argon gas ambient to precisely control the silicide formation. Reacted films were analyzed by the sheet resistance measursrement, SEM, ASR and X-ray diffraction. Results were shown that the resistivity of the silicide films are below 20u-cm and the thickness of silicide films are about two times than that of as-deposited titanium films. Silicidation ambient was likely to happen at the same tamperature-time condition for argon and nitrogen gas.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.185-190
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• 2003

In this paper, it was demonstrated that the organic thin film transistors were fabricated by the organic gate insulators with vapor deposition polymerization (VDP) processing. In order to form polyimide as a gate insulator, vapor deposition polymerization process was also introduced instead of spin-coating process, where polyimide film was co-deposited by high-vacuum thermal evaporation from 4,4'-oxydiphthalic anhydride (ODPA) and 4,4'-oxydianiline (ODA) and 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and ODA, and cured at $150^{\circ}C$ for 1hr. Electrical output characteristics in our organic thin film transistors using the staggered-inverted top-contact structure obtained to the saturated slop in the saturation region and the subthreshold non-linearity in the triode region. Field effect mobility, threshold voltage, and on-off current ratio in $0.45\;{\mu}m$ thick gate dielectric layer were about $0.17\;cm^2/Vs$, -7 V, and $10^6\;A/A$, respectively. Details on the explanation of compared to organic thin-film transistors (OTFTS) electrical characteristics of ODPA-ODA and 6FDA-ODA as gate insulators by fabricated thermal co-deposition method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.73-76
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• 2001

We deposited epitaxial $Ba_{0.6}Sr_{0.4}TiO_{3}(BST)$ films having thickness of 400 nm on MgO(001) substrates, where a 10 nm thick $Ba_{1-x}Sr_{x}TiO_{3}$ (x = 0.1 - 0.7) interlayer was inserted between BST and MgO to manipulate the stress of the BST films. Since the main difference of those epitaxial BST films was the lattice constant of the interlayers, we were very successful in controlling the stress of the BST films. BST films under small tensile stress showed larger dielectric constant than that without stress as well as those under compressive stress. Stress relaxation was investigated using epitaxial BST films with various thicknesses grown on different interlayers. For BST films grown on $Ba_{0.7}Sr_{0.3}TiO_{3}$ interlayers, the critical thickness was about 600 nm. On the other hand, the critical thickness of single-layer BST film was less than 100 nm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.63-66
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• 2002

Bi-layer Mo films were deposited on sodalime glass substrates using DC magnetron sputtering. As the gas pressure and power density, the resistivity varied from $1.5{\times}10^{-5}$ to $4.97{\times}10^{-4}{\Omega}{\cdot}cm$. Furthermore, stress direction yielded compressive-to-tensile transition stress curves. The microstructure of the compressive stress films which had poor adhesion consists of tightly packed columns, but of the tensile-stressed films had less dense structure. Under all gas pressure conditions, Mo films exhibited distinctly increasing optical reflection with decreasing gas pressure. The expansion of (110) peak width with the gas pressure meant the worse crystalline growth. Also, The highest efficiency was 15.2% on 0.2 $cm^2$. The fill factor, open circuit voltage and short circuit current were 63 %, 570 m V and 42.6 $mA/cm^2$ respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.99-100
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• 2005

We have grown carbon nanotubes (CNTs) with a microwave plasma chemical vapor deposition (MPECVD) method, which has been regard as one of the most promising candidates for the synthesis of CNTs due to the vertical alignment, the low temperature and the large area growth. We use methane ($CH_4$) and hydrogen ($H_2$) gas for the growth of CNTs. 60 nm thick Ni catalytic layer were deposited on the TiN coated glass substrate by RF magnetron sputtering method. In this work, we report the effects of pressure on the growth of CNTs. We have changed pressure of processing (10 $\sim$ 20 Torr) deposition of CNTs. SEM (Scanning electron microscopy) images show diameter, length and cross section state CNTs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.55-56
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• 2005

The properties of phosphorus doped ZnO thin films deposited on (001) sapphire substrates by pulsed laser deposition (PLD) were investigated depending on various deposition conditions. The phosphorus (P) doped ZnO target was composed of ZnO + x wt% Al (x=1, 3, 5). The structural, electrical and optical properties of the ZnO thin films were measured by X-ray diffraction (XRD), Hall measurements and photoluminescence (PL). As the deposition temperature optimized, the electrical properties of the phosphorus doped ZnO (ZnO:P) layer showed a electron concentration of $7.76\times10^{16}/cm^3$, a mobility of 10.225 $cm^2/Vs$, a resistivity of 7.932 $\Omega$cm. It was observed the electrical property of the film was changed by dopant activation effect as target variations and deposition conditions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.5
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• pp.435-443
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• 2001

As power durable RF SAW filters, AL-(0∼2wt%)Cu alloy multi-layered thin electrodes were deposited on 42° LiTaO$_3$ piezoelectric substrates by magnetron sputtering process, and then ladder-type RF SAW filters, satisfying the electrical specification of CDMA transmission band, were fabricated through optimizing SAW resonator structures. The temperature of film electrodes in SAW filter was increased with RF power, and reached the maxima to cause a failure of SAW filters at the cut-off frequencies of the RF filter band. As RF power increases, the electrodes of Al-Cu alloy showed higher power durability than that of pure Al. The multi-layer laminated film of Al-1wt.% Cu/Cu/Al-1wt%Cu resulted in the best power durability up to 4W of RF power. Every film electrode, however, was destroyed within seconds whenever applying a critical RF power to SAW filters, regardless of the composition and structure of film electrodes. The breakdown of film electrodes under FR power seems to believe due to the fatigue of electrodes caused by repetitive cyclic stress of surface acoustic wave, which is amplified as RF power increases.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.160-163
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• 2003

This paper describes on anodic bonding characteristics of MLCA(Multi Layer Ceramic Actuator) to Si-wafer using evaporated Pyrex #7740 glass thin-films for MEMS applications. Pyrex #7740 glass thin-films with same properties were deposited on MLCA under optimum RF magneto conditions(Ar 100 %, input power $1\;/cm^2$). After annealing in $450^{\circ}C$ for 1 hr, the anodic bonding of MLCA to Si-wafer was successfully performed at 600 V, $400^{\circ}C$ in - 760 mmHg. Then, the MLCA/Si bonded interface and fabricated Si diaphragm deflection characteristics were analyzed through the actuation test. It is possible to control with accurate deflection of Si diaphragm according to its geometries and its maximum non-linearity is 0.05-008 %FS. Moreover, any damages or separation of MICA/Si bonded interfaces do not occur during actuation test. Therefore, it is expected that anodic bonding technology of MICA/Si wafers could be usefully applied for the fabrication process of high-performance piezoelectric MEMS devices.