Papers

ICMCTF2001 Session H4-1: Novel Materials and Processes

Thursday, May 3, 2001 8:30 AM in Room Sunrise

Thursday Morning

Start	Invited?	Item
8:30 AM		H4-1-1 A Multilayer Semi-Industrial Vacuum Deposition Equipment for Producing Ultrathin Batteries M.M. Martin, F.F. Faverjon (Hef R&d, France) Thin objects like smart cards, tags or electronic labels may find benefit to be powered by an electrical source. This source must be very thin (typically between 0.1 and 0.4 mm) and flexible. It comprises the active elements and the encapsulation. We have developed a rechargeable microbattery whose active element is constituted of a four layers structure (thickness < 10 µm). It is encapsulated in a flexible package (total thickness 0.2 mm). Three of the four layers are deposited by magnetron sputtering, one is done by evaporation. Three of the deposited materials are very sensitive to humidity. A semi-industrial deposition equipment was developed. It is based on a multichamber principle, all connected to a central glove box. This design allows to perform the deposition of the layers in parallel and to work in a fully dry environment. Productivity and quality of the batteries produced are improved at the same time, and the next industrial step is anticipated.
8:50 AM		H4-1-2 AlN Thin Films Deposited by Pulsed Laser Ablation and Filtered Arc Techniques R.D. Vispute, R.P. Sharma, T. Venkatesan (University of Maryland); A.L. Mohammed, S.N. Mohammad (Howard University); S.J. Dikshit, R.S. Bhattacharya (UES, Inc.) The present work describes growth and characterization of AlN thin films grown by pulsed laser deposition (PLD) and filtered arc techniques. We have optimized the processing parameters such as laser fluence in the case of PLD, bias voltage and arc current in the case of filtered arc technique, substrate temperature, background gas pressure, target to substrate distance for the growth of high-quality crystalline thin films. The films have been characterized by X-Ray Diffraction (XRD), Rutherford backscattering and ion channeling spectrometry, high-resolution transmission electron microscopy, atomic force microscopy, UV-visible spectroscopy, and electrical transport measurements. We show that smooth, high-quality AlN thin films can be these techniques at relatively lower substrate temperatures (750-850Â°C) than those employed in Metal Organic Chenical Vapor Deposition, (1000-1100Â°C). The AlN films (~500 nm thick), grown on sapphire (0001) and silicon (111), showed an XRD rocking curve full width at half max of 7 and 12 arc minutes, respectively. The ion channeling minimum yield in the surface region is ~5-10%, indicating a high degree of crystallinity of AlN inspite of a large lattice mismatch between the film and the substrate. The issues related to the properties and conformal deposition as a function of process variables will be discussed.
9:10 AM		H4-1-3 Development of Barium Titanate Thin Films L.C.B.deM. Pinto, A.A. Mendes Filho (Fundação Centro Technológico De Minas Gerais- Cetec, Brazil); J.R.T. Branco (Fundacão Centro Technológico De Minas Gerais-Cetec, Brazil); F.G.S. Araujo, F.A. Machado (Universidade Federal de Ouro Preto-UFOP, Brazil) In previous work barium titanate powder has been sythesized by hydrothermal processing. This material find important use for elctro-electronic devices and ferroelectric applications. In this paper the same synthesis process is investigated as a mean to produce coatings on titanium substrate. Barium titanate films were also deposited by plasma spaying. The latter used powder obtained by the same hydrothermal processing used for coating. The hydrothermal processing was carried out at 250 Celsius, under 50 atm. The coatings microstructure were evaluated by X-ray diffraction. Dielectric constants, adhesion and wear behaviour were evaluated by impedanciometry, scratching and ball cratering, respectivel.
9:30 AM		H4-1-4 A Kilowatt Average Power Laser with Sub-picosecond Pulses for Materials Science and Materials Processing H.F. Dylla, S.V. Benson, G. Biallas, D. Douglas, G.R. Neil, R. Evans, A. Grippo, J. Guebeli, K. Jordan, R. Li, L. Merminga, J. Preble, M. Shinn, T. Siggins, R. Walker, G.P. Williams, B. Yunn (Jefferson Lab); M.J. Kelley (College of William and Mary and Jefferson Lab) A Free Electron Laser (FEL) called the IR Demo is operational as a user facility at Thomas Jefferson National Accelerator Facility in Newport News, Virginia, USA. It utilizes a 48 MeV superconducting accelerator that not only accelerates the beam but also recovers about 75% of the electron-beam power that remains after the FEL interaction. Utilizing this recirculation loop to the machine has lased cw with up to 1720 W output at 3.1 microns. It is presently capable of output wavelengths in the 2 to 6 micron range and can produce ~0.7 ps pulses in a continuous train at ~75 MHz. This pulse length has been shown to be nearly optimal for deposition of energy in materials at the surface. Upgrades in the near future will extend operation beyond 10 kW average power in the near IR and kilowatt levels of power at wavelengths from 0.3 to 30 microns. This paper will cover the performance measurements of this groundbreaking laser and an overview of the applications tests underway by facility users that involve pulsed laser deposition, laser ablation, and laser surface modification. -- This work supported by the Office of Naval Research, the Commonwealth of Virginia, DOE Contract DE-AC05-84ER40150, and the Laser Processing Consortium.
10:10 AM		H4-1-6 Optical Properties of Polycrystalline ZnO Thin Films Deposited by Filtered Cathodic Vacuum Arc XL Xu, S.P. Lau (Nanyang Technological University, Singapore) ZnO has a room-temperature band gap of~3.37eV, combined with high excitonic gain and large exciton binding energy. It is, therefore, a suitable candidate for ultraviolet optoelectronic device applications. For this reason, a lot of methods, such as pulsed-laser deposition, MBE, MOCVD, reactive electon-beam evaporation, spray pyrolysis, as well as sputtering, have been used for ZnO film deposition. In this work, we investigated ZnO thin films prepared by filtered cathodic vacuum arc technique. The structure and orientation were determined by x-ray diffraction. The optical properties of the films were characterized by Raman, photoluminescence (PL) and transmittance spectra. A very strong near band edge PL emission at 380nm was obtained in 230oC without bias voltage. The green emission at 502nm, corresponding to the oxygen vacancies, is strongly quenched. The transmittances of the films with optimized substrate temperature and bias voltage are over 80%. The effects of the substrate temperature and bias voltage on the performance are also discussed.
10:30 AM		H4-1-7 Ceramic Sol-Gel Composite Coatings for Low Temperature Electronic Applications T.R. Olding, M. Sayer (Queen's University, Canada) Sol gel composite technology is a unique and versatile method for fabricating low temperature electronic ceramic materials with a wide range of functionality (dielectric, piezoelectric). Coatings are made by spray, dip or spin depositing a ceramic paint and then firing the coating to 400Â°C to pyrolyze the organic components. Large area coatings of 10-500 Âµm in thickness are easily achievable by multiple depositions, and films can be fabricated on a wide range of substrate materials, including complex shapes and geometries. The simplicity and versatility of this technology enables the development of new electronic device applications that are not feasible with traditional ceramic coating methodologies. Alumina and zirconia coatings have been deposited on steel, aluminum and brass substrates and a room temperature dielectric strength of up to 5000 V AC has been achieved at a coating thickness of 500 µm. Coatings have also been fabricated that pass the 'hi-pot' safety standard (1275 V for 1 sec) at operating temperatures as high as 400°C. The technology is ideally suited to provide cost effective electrical insulation in a wide range of electronic device configurations. Our current focus is the development of low profile heating elements based on inexpensive steel and aluminum substrate materials. In this talk, the properties of the dielectric materials produced with this technology and the performance of related device structures will be described in more detail. .
10:50 AM		H4-1-8 Chambered Capsule Coatings A.F. Jankowski, J.D. Morse (Lawrence Livermore National Laboratory) The sputter deposition of coatings onto polymer capsules is accomplished using a chambered substrate platform as opposed to a conventional, open bounce pan configuration. Metals are sputter deposited through an aperture onto a 1-2 mm diameter hollow sphere within a chamber that is 2-3 times the size of the capsule diameter. The uniformity of the coating thickness can depend upon the method by which the capsules are moved within each chamber. Two methods are assessed to produce a random bounce of the capsules within each chamber. The first is by ultrasonic vibration and the second through gas levitation. Optical cross-sections of aluminum and nickel coated capsules prepared using the ultrasonic drive and gas levitation, respectively, show that uniform coatings can be produced using a chambered substrate platform. Potential advantages of the chambered approach include improved sample yield and reduced surface roughness. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.3.
11:10 AM		H4-1-9 Properties of Transparent Ultra Water-Repellent Films Prepared by Plasma-Enhanced CVD Using Organosilicon Compound O. Takai (Nagoya University, Japan); Y.Y Wu (Nagoya University & Aichi Science and Technology Foundation, Japan); Y. Inoue, H. Sugimura (Nagoya University, Japan) Water repellency is required for glass, plastics and metals in many industrial fields. When the contact angle of a water drop is more than about 150 degrees, we can say that this state is ultra water repellency or super water repellency. This paper reports on the deposition of transparent ultra water-repellent thin films at low substrate temperatures by microwave plasma-enhanced CVD using mixtures of an organosilicon compound and Ar as source gases. The evaluation of water repellency, optical transmittance, surface morphology, chemical composition and mechanical properties of the deposited films is also reported. A reactant used in this study was trimethylmethoxysilane (TMMOS). Water-repellent films were deposited under various conditions. We varied the partial pressures of TMMOS and Ar, the substrate temperature and the substrate position. We obtained the relations between the partial pressure of the organosilicon compound and the contact angle of the films deposited onto glass substrates. The contact angle increased with the pressure and the maximum angle was about 160 degrees. The optical transmittance of the deposited films also depended on the partial pressure of the organosilicon compound and the substrate position. At the substrate position of 118 mm the deposited film gave the contact angle of about 150 degrees and the transmittance of more than 80 % in the visible region for coated glass. We measured the surface roughness by AFM and the states of water drops on water-repellent films by ESEM. The control of the surface morphology of the deposited films is most important to obtain the transparent ultra water-repellent films.
11:30 AM		H4-1-10 In-Situ IR Monitoring in Deposition of Transparent Coatings With Ultra Water Repellency by Low-temperature Plasma-Enhanced CVD Y. Inoue, J. Iwai (Nagoya University, Japan); Y.Y Wu (Nagoya University & Aichi Science and Technology Foundation, Japan); H. Sugimura, O. Takai (Nagoya University, Japan) Water repellency is one of the most important surface properties of materials. Especially transparent coatings with water repellency have been in great demand in various fields. Recently, we developed a new technique to deposit ultra water-repellent films which have a water-contact angle of more than 150 degrees by using plasma-enhanced chemical vapor deposition (PECVD) with organosilicon reactants. In this study, we report on the deposition process of the transparent water-repellent films with detailed analytical studies by means of in-situ infrared reflection absorption spectroscopy (IRRAS). We used a remote-type rf-PECVD system. After evacuation below 10^-4 Pa, reactant organosilicon gases and an oxygen gas were introduced into a deposition chamber. Total pressure was varied from 100 to 200 Pa, and rf power was kept at 200 W. In-situ analyses of vapor phase and deposited films were carried out by using IRRAS. When the reactant gases were introduced, absorption bands due to C-H, Si-CH₃ and Si-O-CH₃ bondings in the reactant molecules were strongly observed. Their absorbance had a linear correlation with the partial pressure of each organosilicon gas. Since the positions of the absorption bands are inherent in each molecule, we can regulate the supply of each reactant gas by the IR absorption intensity. During depositon, the chemical bonding states of the deposited films were monitored by in-situ IRRAS. Si-OH bands were observed as well as Si-O-Si and Si-CH₃. The water repellency of the films was related to the ratio of the band intensities of Si-OH and Si-CH₃.