ICMCTF2008 Session H1-2: Nanotube, Nanowire and Nanoparticle Thin-Films and Coatings

Wednesday, April 30, 2008 1:30 PM in Room Terrace Pavilion

Wednesday Afternoon

Start	Invited?	Item
1:30 PM	Invited	H1-2-1 Electrical Contacts to Nanotubes and Nanowires F. Leonard, A.A. Talin (Sandia National Laboratories) There is currently much interest in exploring nanostructures for electronic and optoelectronic applications, either as stand alone or as films. For such applications, good quality electrical contacts are necessary to achieve device performance. In conventional materials, the fundamental properties of such contacts are well understood, and this knowledge is utilized to engineer contacts for the desired application. The situation at the nanoscale is quite different, where even the basic physics of nanostructure/metal interfaces still needs to be established. In this talk, I will discuss how the key physics of electrical contacts to nanotubes and nanowires differs from that in conventional materials, and how this impacts their properties.
2:10 PM		H1-2-4 Supercapacitive Properties of Spray Pyrolyzed Iron-Doped Manganese Oxide Powders Deposited by Electrophoretic Deposition Technique C.-Y. Chen, T.-C. Chien (Feng Chia University, Taiwan); S.-C. Wang (Southern Taiwan University, Taiwan); P.-Y. Lee (National Taiwan Ocean University, Taiwan); C.-K. Lin (Feng Chia University, Taiwan) Nanocrystalline iron-doped manganese oxide powders were prepared by spray pyrolysis (SP) from manganese acetate and iron nitrate solutions at 400°C. The as-obtained powders were subsequently deposited onto graphite substrates via an electrophorectic deposition technique (EPD). The as-prepared powders were examined by transmission electron microscopy (TEM), X-ray diffractometry (XRD) and synchrotron X-ray absorption spectroscopy (XAS); the electrochemical properties of the coatings were further examined by cycling voltammetry (CV). Structural investigation by TEM and XRD revealed that the as-deposited coatings exhibited Mn₃O₄ phase with nanocrystalline structure. The as-prepared manganese oxide powders were hollow particles with shriveled shells and possessed high surface area. CV examinations showed that the iron doping significantly improved the electrochemical properties of the manganese oxide powder coatings. The specific capacitance of as-deposited manganese oxide coating was increased from 281 F/g to 323 F/g when iron content was 2 at.%. Even after 1200 cycles of life test, the iron-doped coatings exhibited higher cycling efficiency (~70% of the initial maximum capacitance) than that undoped one (~60% of its maximum value). The influences of iron doping for the coatings were also investigated by synchrotron XAS analyses.
2:30 PM		H1-2-6 Study on Electrical Characterization of Nanostructured SrBi2Ta₂O₉ Functional Films H.S. Koo (Minghsin Univ. of Science and Technology, Taiwan) We demonstrated a novel nanostructured strontium-bismuth-tantalate ferroelectric films on Si-wafer substrates with multilayered Pt,Ti,SiO₂ have been fabricated using the processing of pyrolysis and annealing. SrBi2Ta₂O₉ functional films have an excellent adhesion on multilayered substrates. The as-sprayed films were thermally treated in the mixture atmosphere of inert and oxygen at different temperatures and periods. Thermal characteristics and crystal structure of the as-sprayed primitive films were observed by DTA/TGA and XRD. The resulting film, which was treated at 800°C for 30mins, shows optimal characteristics of dielectric constant to be 220, remanent polarization to be 4.0 C/cm², saturation polarization to be 8.8C/cm² and coercive field to be 63kV/cm. The appropriated value of leakage current of the resulting film thermally treated at 800°C for 30mins can achieve 10-6A/cm², while leakage characteristics of the films will be remarkable improvement of the films which are treated at temperature 700°C for 10mins and Ar atmosphere. These results exhibit that a pyrolysis-annealed technique is promising method for fabricating nanostructured SrBi₂Ta₂O₉ functional films.
2:50 PM		H1-2-7 Improved Grain Size of Polycrystalline Silicon Using Fluorine/Nitrogen Implantation Technology C.W. Hu (National Chiao Tung University, Taiwan); T.-C. Chang (National Sun Yat Sen University, Taiwan); P.-T. Liu, C.-H. Tu, C.-C. Lin, C.-N. Chiang, C.-Y. Chang, T.-Y. Tseng (National Chiao Tung University, Taiwan) In this work, Fluorine (F)/Nitrogen (N) implantation technology to improve grain size of polycrystalline silicon (poly-Si) was investigated. The influences of F and N-ions-implantation were executed to amorphous silicon (a-Si) before excimer laser crystallization (ELC) and solid phase crystallization (SPC). The larger poly-silicon grain size through F/N ion implantation was revealed from the SEM images. In addition, using ELC method got the same grain sizes of poly-Si at the same F and N implantation dosages. Furthermore, the grain size for N-implanted poly-Si is superior to F-implanted poly-Si at the same implantation dosage using SPC method. The category of ions also affects the re-crystallization of ion implanted a-Si. The technology for F/N implantation can improve grain size and the trap density of re-crystallized poly-Si, especially for the application of thin film transistors and nonvolatile memory.