ICMCTF2006 Session CP: CP Poster

Thursday, May 4, 2006 5:00 PM in Room Town & Country

Thursday Afternoon

Time Period ThP Sessions | Topic C Sessions | Time Periods | Topics | ICMCTF2006 Schedule

CP-1 Self-Assembled Growth and Plasmon-Enhanced Green Emission of Gold Nanowhisker Coatings
T. Qiu, X.L. Wu, P.K. Chu (City University of Hong Kong, PR China)
Recent experiments have shown that there are surprisingly strong metal-metal interactions between gold atoms in molecular complexes, and chemists have started to use them to design new structures with unusual physical properties. Photoluminescence (PL) of gold nanostructures is interesting from the perspective of electroluminescence devices in which semi-transparent gold electrodes are used. In this paper, we present a relatively rapid method to fabricate gold nanowhisker coatings with a unique structure by electroless metal deposition on Si wafers in a KAuCl4-HF solution. A self-assembled localized microscopic electrochemical cell model and diffusion-limited aggregation process are described for the formation of the Au nanowhisker coatings. A green PL band is recorded and spectral analyses suggest that the green PL arises from the radiative recombination of sp-band electrons with d-band holes in the Au nanowhisker coatings and its intensity enhancement is due to local electric field associated with the Au particle plasmons oscillation. A red PL band is also observed from the etched Si substrates and believed to be related to the Si nanocrystals in the surface layer of the etched Si wafer. The good stability arises from the formation of stable SiAu bonds on the surfaces of the Si nanocrystals.
CP-2 Effect of Substrate Temperature and Annealing Treatment on the Electrical and Optical Properties of Silver Based Multilayer Coating Electrodes
D.R. Sahu, C.-Y Chen, S.-Y Lin, J.-L. Huang (National Cheng Kung University, Taiwan)

Multilayer coating consisting of thin silver layers sandwiched between layers of transparent conducting metal oxides are investigated from the view pint of low resistance electrodes for use in flat panel displays, solar cells etc.. ZnO/Ag/ZnO multilayer films were prepared on glass substrates by simultaneous RF magnetron sputtering of ZnO and dc magnetron sputtering of Ag. Optimization of the deposition conditions of both layers and metallic layers were performed for better electrical and optical properties. The structural, electrical and optical properties of the films (deposited at room temperature, different substrate temperature and annealed at different conditions) were characterized with various techniques. We could not get high quality transparent electrode under the condition of various substrate temperature. The surface roughening due to the agglomeration during substrate heating resulted in more scattering of the incident light causes reduction in transmittance and the sheet resistance was also increased by the enhanced surface scattering effect. However, improved electrical properties and considerable shift in the transmittance curves was observed after heat treatment. The experimental results show that the electrical resistivity of as grown films can be decreased to 10-5 -.cm level with post annealing at 400°C for 2h in vacuum atmosphere. By heat treatment the sheet resistance was reduced as much as 25% which was due to the increased grain size of Ag film. The samples heat treated at 200-400°C under vacuum or nitrogen atmosphere showed the best electrical properties. The key to the superior electrical and optical properties of the multilayer is the optimization of growth condition of the silver layer by careful control of the oxide properties and the use of appropriate annealing temperature and atmosphere.

1TCO, multilayers, Optical and electrical properties.
CP-4 Study of Aluminum-Doped SnO2 Transparent Conducting Films Prepared by Sol-Gel Method
H.C. Kim, Hyeong-H. Park, Hyung-H. Park (Yonsei University, Korea)
Conventional n-type transparent conducting oxides (TCOs) have been investigated for more 40 years. Optical transparency over 90% and resistivity less than 1 x 10-4Ωcm have been demonstrated. Recently new TCO materials have been studied to alternate ITO and realize p-type TCO. The p-type TCOs are necessary for the fabrication of inorganic transparent p-n junctions. Needless to say, the junction is an essential structure in a wide variety of optoelectronic semiconductors and transparent transistor of n-type and p-type TCOs can be used for transparent display panel. In this work, SnO2 films were prepared on glass substrate by sol-gel procedure and doping effect of Al on the crystallization, resistivity, transparency, and energy band structure of SnO2 thin film was investigated. Acceptor doping in semiconductors produces holes and increase hole concentration and p-type conductivity. X-ray diffraction and ellipsometry were served to provide the information of the crystalline structure and thickness of films. Scanning electron microscopy was used to investigate the microstructure of films. The optical transmission spectra of the films were obtained by using UV-VIS-NIR spectrophotometer and optical band-gap energy was calculated.
CP-5 Secondary Electron Emission Coefficient of MgO-NiO Composite Thin Films as a Transparent Layer for PDPs
A. Ide-Ektessabi, A. Nakao, Y. Morimoto, Y. Tanaka (Kyoto University, Japan)
Magnesium oxide (MgO) thin film is very important as a protecting layer for recent AC-type plasma display panels (AC- PDPs) because of its transparency and high secondary electron emission coefficient γ. The γ is one of the most significant factors for the protecting layer because greater numbers of electrons decrease an ignition voltage and a sustaining voltage, and this results in reduction of electric power consumption of the PDPs. Although the MgO thin film is commonly used, it is essential to develop new materials possessed higher γ for further progress of PDPs industry. In order to overcome the γ of pure MgO, adding some materials of which band gap are low is effective way. In this study, the authors focused nickel oxide (NiO) and added it to MgO thin films in various concentrations. The relationship between the γ and the concentration of Ni was investigated. To obtain the values of γ, two types of measurement systems were developed. One of them measured a breakdown voltage and the γ was calculated using Townsend coefficient. The other measured the γ directly by irradiating inert ion beam to the thin films. All the prepared thin films were annealed at constant temperature (400°C). Other characteristics of the thin films were also investigated using Rutherford backscattering spectroscopy (RBS), X-ray diffraction (XRD), Atomic force microscope (AFM), and X-ray photoelectron spectroscopy (XPS). The result shows that the change of the concentration of the added-NiO causes the change in the surface chemical condition and the crystal structure. Moreover, the secondary electron emission coefficient γ was improved with the concentration of added-NiO.
CP-6 Effect of Oxygen Concentration on the Properties of AnO:In Films by Simultaneous RF and DC Magnetron Co-Sputtering
C.-Y Chen, D.R. Sahu, J.-L. Huang (National Cheng Kung University, Taiwan)
The ZnO:In films were prepared by simultaneous radio frequency (RF) magnetron sputtering of ZnO and dc magnetron sputtering of metal In. The effects of oxygen concentration on the electrical and optical properties of ZnO:In films were investigated. Crystalline structure, roughness characteristics electrical and optical properties of the films were studied by XRD, AFM, four-point probe and UV-VIS spectrophotometer. Deposition conditions of the films were optimized to obtain a good quality transparent conducting ZnO:In films. When the oxygen flow rate increased from 4 to 24 sccm, the crystalinity of films increased. The minimum resistivity of ZnO:In films at O2 flow rate of 16 sccm was 1.51 х 10-3 Ω.cm, which is mainly due to the higher product of carrier concentration and mobility. At various O2 flow rate, variation of visible transmission of ZnO:In films was found. Details of the optimization procedure and variation in properties of film will be presented.
CP-7 Optical, Electrical and Mechanical Properties of the Tantalum Oxynitride Thin Films Deposited by Pulsing Reactive Gas Sputtering
H. Le Dreo, O. Banakh, H. Keppner, P.-A. Steinmann (University of Applied Sciences, Switzerland); D. Briand, N. de Rooij (Institute of Microtechnology, University of Neuchatel, Switzerland)
Thin films of tantalum oxynitride were prepared by reactive magnetron sputtering using a Ta target and nitrogen and oxygen as reactive gases. The nitrogen flow was kept constant while the oxygen flow was pulsed using an exponential signal. The film composition evolves progressively from TaO0.25N1.51 to TaO2.42N0.25 while increasing the oxygen pulse duty cycle without any abrupt change in the elemental content. The optical transmission spectra collected on films deposited on glass show a blue shift of the absorption edge with increasing oxygen content. X-ray diffraction (XRD) patterns of all films exhibit broad peaks typical for nanocrystalline materials. Cross-section film morphology is rather featureless and surface topography is smooth exhibiting very small grains, in agreement with the results obtained by XRD. The optical properties of the films are very sensitive to their chemical composition. All films exhibit semiconductor behaviour with an optical band gap changing from 2.2 to 4.2 eV with increasing the oxygen pulse duty cycle. In order to evaluate the potential of the tantalum oxynitride films for microelectronic applications the integration of some films in a MOS structure was done. The results of the capacitance-voltage measurements of the system Al//Ta-O-N//p-Si are discussed with respect to the chemical composition of the Ta-O-N films.
CP-8 Effect of the Introduction of Metal-Dopants and/or Ag-Nanoparticles on the Optical and Electrical Properties of ZnO Thin Film
C.-S. Hong, Hyung-H. Park (Yonsei University, Korea)
Zinc oxide (ZnO) has drawn much interest as a potential transparent conducting oxide (TCO) for applying to solar cell and front electrode of EL devices due to non-toxicity, low cost, and high abundance and stability in hydrogen plasma. For the enhancement of electrical property of TCOs, dopant-introduction and hybridization with metal-nanoparticles have been investigated. For example, 3A metal-dopants of Al, Ga, and In and Ag-nanoparticles have been used in the electronic industry for the manufacture of conductive thick film circuits and internal electrodes of multilayer ceramic capacitor. However an introduction of metal-dopants and nanoparticles in TCOs influences conductivity and also transparency but the influence sometimes turns out unexpectedly. In this work, the optical and electrical characteristics of ZnO films with the introduction of 3A metal elements and/or metal-nanoparticles are investigated to reveal the effect of incorporation on the properties of ZnO film. ZnO films were formed on glass substrate by chemical solution deposition of Ag-nanoparticles dispersed or metal(Al, In, or Ga)-contained ZnO solutions. The phase formation and crystallinity of ZnO film were monitored with x-ray diffractometer. The optical transmittance measurement was carried out using UV-visible spectrometer and the electrical properties such as sheet resistance and conductivity were observed. The change in surface morphology of the films was monitored with scanning electron microscopy and atomic force microscopy.
CP-9 Fabrication of Al doped ZnO Films by Reactive Sputter-Deposition Using an Al/Zn Metal Composite Target
T. Ichinohe, Y. Masuda, S. Masaki (Tokyo National College of Technology, Japan); K. Kawasaki (TDY, Co, Ltd.)
Transparent conductive oxide films have been extensively studied and fabricated by various deposition techniques such as sputtering, CVD, sprayed deposition, laser ablation, etc. In this study, we fabricated Al doped ZnO (AZO) films using reactive sputter-deposition. A metal composite (Al/Zn) target was employed and O2 gas was flowed near the target during sputter-deposition. The Al concentration in the films was varied from 0.8 to 6.7% with the Al area ratio of the target, being estimated by an XPS. The peak intensity at 74.5 eV in binding energy originating from the aluminum oxide increased with the Al area ratio of the target, which indicates the contents formed Al oxide. The resistivity of the AZO films as-deposited were too high to measure, on the other hand, the resistivity of the samples annealed at 400°C was in a range between 10-1 and 10-2 Ωcm. A 1.1% Al oxide doped AZO (1.1%-AZO) film showed a minimum resistivity of 8x10-2 Ωcm. It was observed that the O2 gas flow rate hardly attributed to the resistivity of the AZO films when it flowed during sputter-deposition.
CP-10 Hybridization of PEDOT:PSS with Surface-Treated CdSe Nanocrystals
S.-J. Wang, Hyung-H. Park (Yonsei University, Korea)
Organic-inorganic hybrid materials are media for electronic, optoelectronic, and photovoltaic applications. We investigated the influence of the pyridine capped CdSe nanocrystals on the properties of poly (3,4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS). CdSe nanocrystals were prepared using the conventional technique of pyrolisis of organometallic reagents in a hot coordinating solvent medium capped with organic molecules such as trioctylphosphine oxide and trioctylphosphine, and these surface capping organic molecules were exchanged with pyridine. Primitive chemical and physical modification were conducted by the doping of surface-treated CdSe nanoparticles into PEDOT:PSS. Surface morphology and electrical properties of PEDOT:PSS/CdSe nanocomposite films were observed. Especially, electronic structure and bonding state of PEDOT:PSS/CdSe nanocomposite films were studied by means of ultra violet and x-ray photoelectron spectroscopy and near edge x-ray fine structure.
CP-11 Glancing Angle Deposited Porous Titanium Oxide Films as Visible Light Photocatalysts
S.F. Shu, M.S. Wong (National Dong Hwa University, Taiwan)
Porous titanium oxide thin films were fabricated by glancing angle deposition (GLAD) with different rotational rate and vapor incident angle. The porous films structure, energy bandgap, and photocatalytic properties were explored and compared with the dense films. The GLAD structure was anatase phase characterized by X-ray diffraction and Raman spectra. The morphology of GLAD structure was surveyed by scanning electron microscopy. Energy bandgap values of porous and dense films measured by thermoreflectance modulation and UV-visible absorption spectra were 3.7 eV and 3.5 eV, respectively, which fall in the UV light regime and both are higher than the reported 3.2 eV for anatase. Although the energy bandgap of porous film was larger than the dense one, the photocatalytic performance was better under visible light irradiation based on the measurements of photodegradation of methylene blue, photoreduction of silver-ions and hydrophilic property.
CP-12 The Effect of Ar + H2 on the Low Temperatue ITO Film Synthesis on Polymer
C.S. Moon (Sungkyunkwan University, Korea)
The indium tin oxide (ITO) films have mainly been used for transparent conducting electrodes in flat panel displays and touch panels. Recently ITO films deposited on polymer substrates have received a lot of spotlights for their applications in mobile devices due to lightweight, small volume and flexibility compared with those deposited on glass substrates. However, it is difficult to obtain satisfactory film properties because of the restriction on the substrate temperature during deposition process. In other words, it is hard to obtain the resistivity and transmittance at the lower temperature as good as those at the higher temperature. In this work, to overcome this drawback, ITO films were prepared on glass and polymer substrates by asymmetric bipolar pulsed d.c. CFUBM (Closed Field Unbalanced Magnetron) sputtering at room temperature. By controlling pulse parameters, it is possible to prepare the good films properties at low temperature. Moreover, it was confirmed that electro-optical properties of films were improved by hydrogen dilution process. And to investigate the influence of hydrogen on electro-optical properties of ITO films, we analyzed a variety of ion fraction changes in the generated plasma with hydrogen partial pressure using optical emission spectroscopy (OES). As a result, the averages resistivity of 0.75 Tcm and the average transmittance of 86 % were obtained on polymer substrate.
CP-13 Characteristics of SiOxNy Films Deposited by PECVD at Low Temperature Using HMDS-NH3-O2-Ar
J.H. Lee, C.H. Jeong, J.T. Lim, V.A. Zavaleyev, M.S. Kim, S.J. Kyung, G.Y. Yeom (Sungkyunkwan University, Korea)

To prevent the permeation of H2O and O2 to the devices, the encapsulation of the devices such as metal encapsulation and glass encapsulation are currently used for organic light-emitting diode (OLED) devices. However, thin film passivation instead of the encapsulation on these devices is preferred for the lighter weight, wider viewing angle, flexibility, etc. Therefore, various permeation barrier materials and various deposition methods for these materials are intensively investigated for the passivation of the next generation flexible flat panel display (FPD) devices such as OTFTs and OLEDs.

In this study, using the hexamethyldisilazane (HMDS) as the precursor of Si, SiOxNy thin films were deposited on plastic substrates at a low temperature less than 700C using plasma enhanced chemical vapor deposition (PE-CVD) method and its properties were investigated. HMDS was used as the precursor of Si because it shows a low impurity content after the deposition and it is safe, easy to handle as a liquid form, and chemically stable compared to other silicon precursors such as SiH4, SiHxCly, etc. Also, by forming multiple layers of SiOxNy/parylene, the water permeation properties of the deposited SiOxNy films were also investigated.

In this presentation, the deposited SiOxNy film characteristics applied for the organic devices such as deposition rate, film crystallization, chemical composition, H2O permeation, and optical transmittance will be reported.
CP-14 Influence of Photoresist Grating Thickness on Performance of Periodically Poled LiNbO3 for a Quasi-Phase Matching Device
S.W. Kwon, Y.S. Song (Hankuk Aviation University, Korea); W.S. Yang, H.M. Lee, W.K. Kim, H.Y. Lee (Korea Electronics Technology Institute, Korea); B.-Y. Kim (University of Incheon, Korea); M.-H. Lee (KICET, Korea); D.-Y. Lee (Daelim College of Technology, South Korea)
Periodically poled ferroelectric crystals with domain inverted periods of quasi-phase-matching(QPM)-SHG, QPM-SFD, and QPM-optical parametric oscillator are attractive because of their large nonlinear optical coefficients, d33. Periodically poled lithium niobate is known to be one of the most promising candidates for QPM-OPO devices. PPLN is fabricated by the electric-field-poling method using an electrode on the LN surface consisting of patterned photoresist insulator with liquid electrolyte contact. The phase-matching wavelength and the efficiency of a QPM device are strongly affected by the periodicity and the duty cycle of the domain-inverted structures, respectively. To achieve the uniform domain reversal period and the 50/50 duty cycle, the poling voltage, current, electric control system, and process conditions should be optimized. The PPLN fabrication, the subject of this study, is carried out systematically using the electric control system. The LN wafers (Z-cut, 0.5 mm thickness, 3 inch Diameter) were surface cleaned. A 16.6µm-period photoresist grating of 1.7µm and 3µm thickness deposited on +Z-face of LN with LiCl saturated solution as liquid electrodes were patterned. After dicing the wafers into a dimension of 65*10 mm2, the specimen was placed in the poling jig connected to the circuitry to investigate the variation of current and charge during the poling for the optimization. A 0.5 mm thick PPLN with a 16.6µm domain-inverted period, a 3.0µm thick PR, and a 3.3µm pattern open width has been fabricated by the electric field poling process using the liquid electrode technique. The effects of PR thickness and pattern open width on the domain reversal period and the duty cycle were investigated to optimize the PPLN performance. A relatively thick PR and thin pattern open width were determined to be better for the PPLN performance. The average duty cycle for the fabricated PPLN was approximately 50%.
CP-15 Accelerated Degradation of Indium Tin Oxide Film Fabricated by Paste System
M.-H. Lee, J.-H. Kang, H.-S. Choi, W.-S. Seo (KICET, Korea); D.-Y. Lee (Daelim College of Technology, Korea); B.-Y. Kim (University of Incheon, Korea); W.-K. Bang (Korea Nano Co., Korea)
For preparation of Indium tin oxide (ITO) films, a number of techniques such as vacuum evaporation, sputtering, etc. have been adopted. Recently, endeavor of process development for them reached to using wet process and much interest has been focused on it. The wet process, using sol-gel or paste, is very useful for the film preparation because films of desired shape and area can be prepared easily and homogeneously without using expensive and complicated equipment. There were many studies about application of paste system in electronic device fields and it was revealed that the final film properties are correlated to a number of factors including thermodynamics and kinetics during burnout and firing, powder characteristics and rheological properties of paste. However, there were a few studies using paste system in application of transparent conductive oxide. In previous work, ITO paste was prepared by using nano ITO sol and cellulose vehicle system. ITO sol (solid 30 wt%) was fabricated by milling and mixing 30-50nm ITO powder with ethyl alcohol. Rheological property of paste was controlled by varying composition of organics. Thin films was deposited on glass substrate, using spin coating techniques and treated at 350°C for 1h and post-annealed at 550°C for 1h in N2 gas flow. With increasing the firing temperature, resistance of films decreased drastically while optical transmittance of films showed relatively steady value after showing their minimum. The optimized ITO film exhibited a sheet resistance of 140Ω/square and an optical transmittance of 82%, which is comparable to the value obtained by other wet deposition techniques. In this work, The ITO film was tested in accelerated conditions of temperature and voltage. The relationship with acceleration factors and degradation of ITO films are discussed through their effects and the activation energy of degradation is calculated.
CP-16 Optimization of AZO Thin-Film Deposition by Magnetron Sputtering for LCD Applications
T. Minami, T. Miyata, Y. Ohtani, Y. Mochizuki (Kanazawa Institute of Technology, Japan)
This paper describes the optimization of ZnO:Al (AZO) thin films formed by a magnetron sputtering method for the purpose of substituting these transparent electrodes for the ITO transparent electrodes used in liquid crystal display (LCD) applications. For these applications, it is necessary to prepare AZO thin films with a resistivity of approximately 5X10-4Ωcm using magnetron sputtering (MSP) on large area substrates at a temperature below approximately 200°C. However, it is relatively difficult to prepare such low resistivity AZO films on a low temperature substrate when using a conventional MSP method because the resulting films always exhibit a spatial distribution of resistivity on the substrate surface. For the purpose of resolving this problem, new AZO film preparation techniques for both lowering resistivity as well as improving resistivity distribution have been investigated using MSP deposition in a weakly reducing atmosphere and also newly developed MSP deposition techniques. The reducing atmosphere was achieved by lowering sputter deposition pressure and by controlling zinc vapor pressure or by introducing hydrogen gas or water vapor in the deposition chamber. In addition, new techniques such as adding an r.f. component to a d.c. MSP AZO film deposition that featured a lowered sputter voltage and localized sputtering region (erosion area) were attempted using a high field magnetron cathode and/or a hybrid plasma discharge resulting from supplying both r.f. and d.c. power. A low resistivity below 5X10-4Ωcm and improvement of the resistivity distribution could be obtained using a commercially available high density sintered AZO target by controlling zinc vapor pressure or introducing hydrogen gas in the deposition chamber during depositions with r.f. MSP or d.c. MSP incorporating r.f. power.
CP-17 Effect of Thin Film Structure on the Mechanical Properties of TiAl-Si-N Coatings
M.G. Kim, E.Y. Kim, J.T. Kim, S.Y. Lee (Hankuk Aviation University, Korea)
The structure of a thin film is considered to have a strong effect on the mechanical properties of thin film coating. In this work, a series of multi-layered TiAlN/Si3N4 films with various coating thickness were deposited by unbalanced magnetron sputtering processes. Compositions, crystalline structures and morphologies were characterized by Auger electron spectroscopy (AES), X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS) and transmission electron microscopy (TEM). The mechanical properties of these coatings were characterized by nanoindentation, wear tester, and scratch tester and compared to those of nano-composite TiAlSiN with various Si content. Our experimental results show that the present series of multi-layered TiAlN/Si3N4 were consisted of a nm-scale layers of crystalline TiAlN and amorphous Si3N4. The hardness of films was dependent on the Si content and the hardness and elastic modulus of approximately 40 and 450 GPa, respectively were measured from the nano-composite TiAl-Si-N thin films. However, the maximum microhardness and elastic modulus obtainable from the multi-layered TiAlN/Si3N4 thin films was approximately 16 -20 GPa and 190" 220 Gpa, respectively. Further investigation on the properties of two types of thin films are in progress and detailed experimental analysis results will be presented.
CP-18 Electroluminescence of a Device Based on Europium-βDiketonate with Phosphine Oxide Complex
R.D. Adati, S.A.M. Lima, M.R. Davolos, M.Jr. Jafelicci (UNESP, Brazil); W.G. Quirino (Pontificia Universidade Catolica, Brazil); C. Legnani, M. Cremona (Pontificia Universidade Catolica do Rio de Janeiro (PUC-RIO), Brazil)
Rare earth (RE3+) complexes with β-diketone ligands show high fluorescence emission efficiency due to the high absorption coefficient of β-diketone. High efficiency of energy transfer can be achieved when appropriate organic ligand is selected, which is known as antenna effect. Organic light emitting diodes (OLEDs) can be used to make flat, flexible, and transparent displays. The light is emitted from an optically active layer of high efficiency, high intensity, long lifetime, and low voltage operation. Rare earth (RE) ions have spectroscopic characteristics to emit light in narrow lines, which makes RE complexes with organic ligands candidates for full color OLED application. In this work we report the electro- and photoluminescence investigation of a diketone complex. The Eu(bmdm)3(tppo)2 where bmdm = butyl methoxy dibenzoy -methane and tppo = triphenylfphosphine oxide was prepared by the reaction of β-diketone in ethanolic solution. This complex was used to build an OLED device as follow: onto an ITO-coated glass substrate, that works as cathode, it was deposited a layer of N,N' -bis(3-metilfenil)-N,N'-difenilbenzidine as hole injector; a layer of the europium-containing complex as the active and electron injector layer; and a layer of aluminum, as anode. All the films were deposited by thermo evaporation carried out in a high vacuum environment system. Electroluminescence spectra show emission from Eu3+ ions attributed to the 5D0 to 7Fj (J=0,1,2,3 and 4) transitions and also a transition from 5D1 to 7F1 is observed around 538 nm. The OLED light emission was almost linear with the current density. The CIE chromaticity coordinates from the photoemission (x = 0.633 and y = 0.308) show dominant wavelength, λd = 615 nm, and an emission color purity near 1, and from the electroemission (x = 0.626 and y = 0.318) show color purity near 0.8.
CP-20 A Study on Optical Characteristics of Reflection and Semipenetration Silver-Alloy Reflecting Layers
C.-Y Su (National Taipei University of Technology, Taiwan); C.S. Yaung (KLA-Tencor Corporation, Taiwan); S.C Lin (National Taipei University of Technology, Taiwan); W. Lin (Central Mint, Taiwan)
This research is to investigate the microstructure, components and optical analysis of the target made by adding some elements to silver base material, such as copper or titanium with DC magnetron sputtering method. The optical properties and morphology of the silver thin film tested by heat treatment, weatherability test, and corrosion resistance test were discussed .The corrosion behavior were also studied through Ecorr measurement. The results show that the copper contents of the silver base materials are from 0.5% to1.5 % and the sizes of secondary phase of the target are smaller. It will help to enhance the uniformity of the sputtered thin films, weatherability and corrosion resistance of the NaCl thin films.1 wt% of copper could control effectively the low-temperature deterioration of sliver atoms and maintain the processing characteristics of the targets. The heat-resistance of the films will be improved. When the copper contents are increased to 3 wt%, the larger grain sizes of the target will make the target hard to process and lower the sputtering rate.
CP-22 Atmospheric Pressure Chemical Vapour Deposition of VO2 and VO2/TiO2 Films From the Reaction of VOCl3 and Water
U. Qureshi, I.P. Parkin (University College London, United Kingdom)

Intelligent window coatings respond to an external stimulus with increasing sophistication on an ‘as needs’ basis. This includes thermochromic coatings, these are coatings that change their reflectance - transmission properties with temperature. Thermochromic materials are often characterised by a semi-conductor to metal transition due to a reversible change in structure as a function of temperature. This change has been observed in a number of transition metal oxides such as Ti2O3, Fe3O4, Mo9O26 and in several forms of vanadium oxide1-2. Among them VO2 has received significant attention because of the large reversible change of electric, magnetic and optical properties at 70 uses a sharp decrease in optical transmission and an increase in reflectivity and electrical conductivity4. Because of this unusual behaviour, VO2 thin films have potential for electrical or optical switches, optical storage, laser protection and solar energy control in space satellites5. For VO2 films to be used in these applications, it is desirable that the thermochromic switching temperature, Tc be brought closer to room temperature. This has been partially achieved in sol-gel films where doping with tungsten has led to a reduction in Tc from 70 to ca. 25°C. Other dopant elements in sol-gel VO2 films such as titanium have been shown to both increase and decrease the Tc6.

This abstract details the production of single phase VO2 films via the atmospheric pressure chemical vapour deposition (APCVD) reaction of VOCl3 and water at a temperature of 650°C. It also details the effect of introducing titanium tetrachloride on the VO2 growth morphology and the production of TiO2/VO2 composite films that uniquely display three functional properties- photocatalytic activity, hydrophilicity and a thermochromic switching temperature. Attempts to deposit layered TiO2/VO2 and VO2/TiO2 are reported. Finally the effects of introducing a tantalum precursor (TaCl5) are presented.

Pure VO2 films were successfully deposited on glass via the APCVD reaction of VOCl3 and water at 650 °C. Introduction of TiCl4 to the reaction mixture at 650°C did not incorporate TiO2 into the Pure VO2 matrix - however it did change the growth morphology from needle shaped particles to spherical nano-meter sized balls. These nanodimensioned pure VO2 balls showed a reduction in thermochromic switching temperature from 70 to 49°C - this was attributed to strain. APCVD of TiCl4 and VOCl3 at a substrate temperature of 600 and 550°C afforded composite TiO2/VO2 films. Interestingly the composite films showed the functional properties of the individual components - a reduction in switching temperature to 51°C combined with photoinduced hydrophilicity and photocatalytic activity.

Changing the titanium precursor to titanium isopropoxide also deposited composite TiO2/VO2 films that exhibited photocatalysis and photo-induced hydrophilicity. The thermochromic switching temperature was found to be 54 °C. An attempt to form layered TiO2/VO2 and VO2/TiO2 films using titanium isopropoxide, VOCl3 and water at substrate temperatures of 650, 600 and 550°C lead to the deposition of TiO2/VO2 composite films with similar properties to the composite films prepared before.

The introduction of a tantalum precursor (TaCl5) lead to the deposition of tantalum oxide doped V2O5 films that did not display thermochromic properties in the temperature range 18 - 100°C. The films showed unexpected photo-induced hydrophilicity, but minimal photocatalytic activity, an effect only seen with Nb2O5 films to date7. It has been thought on the basis of previous work that photocatalytic activity and photoinduced hydrophilicity occur through a related mechanism, and hence are observed together in the same sample. This research, and work by Parkin et al suggests that this does not necessarily follow. A mechanism for this behaviour has been proposed by Parkin et al8.

1N. F. Mott, Rev. Mod. Phys., 1968, 40, 677, 2D. Adler, Rev. Mod. Phys., 1968, 40, 714, 3.F. J. Morin, Phys. Rev. Lett., 1959, 3, 34, 4H. S. Choi, J. S. Ahn, J. H. Jung and T. W. Noh, Phys. Rev. B, 1996, 54, 4621, 5Y. Sato, T. Nomura, H. Tanka and K. Kobayakawa, J. Electrochem. Soc., 1991, 138, 37., 6I. P. Parkin and T. D. Manning, J. Mater. Chem., 2002, 12, 2936, 7. M. Miyauchi, A. Nakajima, T. Watanabe and K. Hasimoto, Chemistry of Materials, 2002, 14, 2812, and 8. S.A. O’Neill, I.P. Parkin, R.J.H. Clark, A. Mills and N. Elliot, Journal of Materials Chemistry, 2003, 13, 2952.
CP-23 Controllable Formation of Er3±Yb3+ codoped Al2O3 Films by the Nonaqueous Sol-Gel Method
Z.H. Zhu, M.J. Sha, M.K. Lei (Dalian University of Technology, PR China)
The Er3+-Yb3+ codoped Al2O3 waveguide films have been prepared on the thermally oxidized SiO2/Si(100) substrate in dip-coating process by the sol-gel method using aluminum isopropoxide [Al(OC3H7)3] as precursor, acetylacetone as chelating agent, nitric acid as catalyzer, N,N-dimethylformamin (DMF) as drying control chemical additive (DCCA) and rare earth nitrate as dopant under isopropanol environment. Addition of the DMF suppressed the formation of cracks in films when the rare earth nitrate was doped with the high concentration. The homogeneous, smooth and crack-free waveguide films were obtained under the introduced conditions with molar ratio of 1:1 for DMF:Al(OC3H7)3. The hydrogen bond between DMF and hydroxy at the surface of gel particle resulted in that the proton was removed from the group of =Al-O-H and further the sol dehydrated to enhance the polymerization degree of sol and increase the mechanical properties of gel films. With increasing the molar ratio of 1:1 for DMF:Al(OC3H7)3 to 4:1, the enlargement of the gel particle and the increase of the porosity led to the formation of crack-free films with homogeneous holes. It is found that the controllable effect on Er3+-Yb3+ codoped Al2O3 waveguide films was carried out by adding of DMF in the nonaqueous sol-gel method.
CP-24 Hard UV-Curable Organo-Mineral Coatings for Optical Applications
D. Blanc (Universite Jean Monnet UMR CNRS 5516, France); A. Last (Institute for Microstructure Technology-Research Center Karlsruhe, Germany); J. Franc (Universite Jean Monnet UMR CNRS 5516, France); S. Pavan, J.L. Loubet (Ecole Centrale de Lyon, France)
New developments in optics stimulate research in the field of new materials with improved mechanical properties, environmental stability and other specific characteristics like electric properties or surface functionality. Organic-inorganic hybrid materials synthesized at room temperature via a sol-gel route are particularly attractive for optical coatings as they combine advantages of organic polymers (ease of processing, elasticity, new functionalities) with characteristics of inorganic oxides (hardness, thermal and chemical stability, transparency). In the present work, acrylate-modified silica incorporating various amounts of zirconium precursor is synthesized via a sol-gel route. The material is deposited as thin films on PMMA substrates and densified by UV-curing. Mechanical properties are measured by nanoindentation. In addition to the static depth sensing procedure, a dynamic approach at fixed frequency (32 Hz) is used. Consequently the mechanical data can be determined continuously as a function of the penetration depth during the loading-unloading cycles. Values of hardness and Young modulus are respectively in the range 340 to 440 MPa and 4 to 6 GPa. They increase with the relative amount of zirconium in the layer. The hardness and elastic behavior of the coatings are related to the high degree of cross linking of the layers that is assessed by infrared spectroscopy. Results are compared with measurements published by various groups on related materials. Although further investigations including scratch resistance are necessary, the mechanical properties reported here, together with the high transparency over a wide range of the optical spectrum make this class of material promising for optical coatings.
CP-25 In-Situ Ellipsometric Monitor with Layer-by-Layer Analysis for Precise Thickness Control of EUV Multilayer Optics
T. Tsuru, M. Yamamoto (Tohoku University, Japan)

In the extreme ultraviolet (EUV) wavelength region, applications of multilayer mirrors are spreading over various normal incidence X-ray imaging optics such as a microscope, a telescope, and a lithography tool for the next generation. For constructive interference of specific EUV radiation, the period thickness of a few nanometers is necessary to be controlled precisely over several tens to hundreds period in a multilayer on a curved substrate. Furthermore, deposition conditions have to be carefully optimized to form smooth and sharp interface at every boundary for achieving high reflectance.

An automatic null ellipsometer of picometer thickness sensitivity was successfully applied to monitor layer thickness and optimize sputtering conditions during Mo/Si multilayer fabrication by ion beam sputtering. The ellipsometric data of complex relative amplitude attenuation are recorded at every 200 msec and used to depict a growth curve on a complex plane. By using layer-by-layer analysis we developed, a series of ellipsometric data are analyzed to determine the individual thicknesses of Mo/Si multilayer. The period thickness determined by our system was well coincidence with the results of EUV reflectometry and X-ray diffractometry. The ellipsometric growth curves clearly revealed the difference of sputtering settings. Our in-situ ellipsometric monitor could be extremely useful in controlling layer thickness and also forming homogeneous and optically isotopic layer structures.
Time Period ThP Sessions | Topic C Sessions | Time Periods | Topics | ICMCTF2006 Schedule