Papers

ICMCTF2004 Session F3: Surface and Thin Film Analysis

Friday, April 23, 2004 8:30 AM in Room Sunset

Friday Morning

Start	Invited?	Item
8:30 AM		F3-1 Characterization of Nanostructures by Plasmon Energy Measurements with Auger Electron Spectroscopy H.J. Steffen (Steffen Engineering Inc., Germany) A useful concept for the characterization of phases and their spatial distribution in nanostructures is introduced that is based on the assumption that there is a correspondence between phases and their mean local homogeneous electron density with a susceptibility to a collective electron oscillation. Consequently, phase characterization in a heterogeneous material is performed by probing the site-dependent local electron density, which may be equivalent to plasmon energy measurements due to the energy-electron density relation. After outlining the theoretical basis with respect to collective electron oscillations and the electron-density dependent thermodynamic state of matter, various experimental studies on ion beam synthesis of silicon compounds investigated with Auger electron spectroscopy are presented that clarify this idea. The phase and structure formation of silicon oxide, silicon carbide and magnesium silicide after high dose ion implantation of silicon with oxygen, carbon and magnesium, respectively, are characterized by plasmon energy measurements.
8:50 AM		F3-2 A Diffusion Corrected Simultaneous Multilayer Growth Model T. Wagner, Q. Fu (MPI for Metals Research, Germany) Due to its simplicity, Auger electron spectroscopy (AES) is still widely recognized as an effective and popular tool for the determination of growth modes during thin film deposition. To enable a rapid identification of different film growth modes we modified the existing simultaneous multilayer (SM) growth model developed by Barthès et al.[1]. The modification was achieved by including a diffusion terms in the rate equations, taking into account the up-step and down-step diffusion of adatoms. This diffusion-corrected simultaneous multilayer (DCSM) model [2] can be used to fit experimental results based on AES, XPS, and LEIS measurements or other in-situ spectroscopic observations of thin film growth. We applied the DCSM model to the initial growth of Cr on (100) SrTiO₃ and (0001) α-Al₂O₃ surfaces, monitoring the deposition process by in-situ Auger electron spectroscopy (AES). We conclude with general remarks on different AES growth models and present a simple analytical formula to semi-quantitatively distinguish between different growth modes. [1] M. G. Barthès and A. Rolland, Thin Solid Films 76, 45 (1981). [2] Q. Fu and T. Wagner, Phys. Rev. Lett. 90, 1061051 (2003).
9:10 AM		F3-3 Real Time Monitoring of the Structure and Morphology of Growing Nanoparticles by Grazing Gilles Renaud, F. Leroy, C. Revenant (CEA-Grenoble, France); R. Lazzari, J. Jupille (GPS, France); C.R. Henry (CRMC2, France); O. Fuchart (Laboratoire Louis Neel, France) Islands of nanometer size grown on substrates display fascinating properties, which are of interest for both basic and applied research. They include model catalysts made of supported metallic particles whose reactivity and selectivity can be adapted to given needs, single-domain magnetic particles which show original spin-dependent transport properties and coherently strained semiconductor aggregates, the so-called "quantum dots", which exhibit remarkable opto-electronic properties. The properties of these particles depend to a great extent on their internal atomic structure, their strain, their shape, size, size distribution and ordering, which in turn rely on the growth mechanisms. In this context, a challenging issue is to control the growth of large collections of particles by monitoring the relevant parameters in situ and in real time. Unique techniques to probe collections of very small objects are Grazing Incidence Small Angle X-ray Scattering (GISAXS) and Grazing Incidence X-Ray Scattering (GIXS). We have developped these two techniques in situ, during growth, and sometimes in real time. We will first illustrate their use on two prototypical cases: the growth of metals (Ag, Pd, Pt) on MgO(001) at different temperatures, which are models of Volmer-Weber 3D growth of metal on oxide surfaces, and are thoroughly studied to investigate the elementary processes of heterogeneous catalysis, and the self-organized growth of cobalt on the herringbone reconstructed Au(111) surface. We will next show examples of recent results in different systems, such as the growth of germanium on molecularly bonded Si(001) or the self-organized growth of cobalt on nanostructured W(111) surfaces.
9:50 AM		F3-5 Thermal Reliability of Electroless Ni-P-W Coating During The Aging Treatment S.K. Tien, F.B. Wu, J.G. Duh (National Tsing Hua University, Taiwan, R.O.C.) The Ni-P-W coating was fabricated by electroless technique in the alkaline solution. The phase transition temperature of Ni-P compound analyzed by differential scanning calorimetry (DSC) was 406°C. To evaluate the thermal stability of Ni-P-W coating under long-term aging treatment, the operation temperature (375°C and 450°C) under and above the crystallization temperature of Ni-P compound was chosen. The phase transformation during thermal evolution was studied by X-ray diffraction (XRD). The microstructure and grain size at different stages of aging time were identified by transmission electron microscope (TEM). The surface roughness at as-deposited and final heat-treated states was explored by atomic force microscope (AFM). During the long-term heat treatment at 375°C, the microhardness firstly increases owing to the crystallization of nickel as well as Ni₃P and then maintains an elevated hardness value. The Ni-P-W coating at 450°C also exhibits a high reliability after aging treatment.
10:10 AM		F3-6 Corrosion Resistance of ZrN_xO_y Thin Films Obtained by RF Reactive Magnetron Sputtering E. Ariza, L.A. Rocha, F. Vaz, L. Cunha, P. Carvalho, L. Rebouta (Universidade do Minho, Portugal); E. Alves (ITN, Portgual); Ph. Goudeau, J.P. Rivière (Université de Poitiers, France) The main aim of this work is the investigation of the corrosion resistance of single layered zirconium oxynitride, ZrN_xO_y, thin films in artificial sweat solution at ambient temperature. The films were produced by rf reactive magnetron sputtering, using a pure Zr target at a constant temperature of 300°C. Two different sets of samples were produced. In the first set of films the substrate bias voltage was the main variable, whereas in the second set, the flow rate of reactive gases (oxygen/nitrogen ratio) was varied. The control of the amount of oxygen allowed the film properties to be tailored from those of covalent zirconium nitride to those of the correspondent ionic oxide. The corrosion behaviour was evaluated by potentiodynamic polarisation and Electrochemical Impedance Spectroscopy (EIS) tests. The analysis of EIS data provided detailed information of the corrosion processes occurring at the surface of the system throughout the immersion time. The modifications of the coating microstructure and/or chemical composition induced by the variation of the deposition parameters was also evaluated and correlated with the corrosion mechanisms occurring in each system.
10:30 AM		F3-7 A Study on the Pore Controlling of Porous Alumina Filters with SiC Whiskers by CVI Process W.S. Park, S.M. Hwang, Y.J. Lee, D.J. Choi (Yonsei University, South Korea); H.D. Kim (Korea Institue of Machinery and Materials, South Korea) In this study, SiC whiskers were grown in porous alumina substrate to enhance the filtering efficiency, performance, and durability through the controlling of pore morphology. This process was performed by chemical vapor infiltration (CVI). The deposition temperature varied between 1000°C to 1150°C, and the input gas ratio α [H₂/MTS] was 20, 30, and 40. The shapes of deposits which can be affected from deposition conditions such as temperatures, input gas ratios, and deposition depths of substrates were examined by using SEM (scanning electron microscopy) and they showed the shapes of whiskers, films, and debris. And we examined the fractural strength, gas permeability, and specific surface area which are important factors in the point of application to filtering systems.
10:50 AM		F3-8 The Effect of Au Thickness and Annealing Conditions on SiO₂ Formation in the Au/Si System B.A. Julies, D. Adams (University of the Western Cape, South Africa); J.W. Mayer (Arizona State University) In this study an investigation into low temperature silicon-dioxide formation in the Au/Si binary system was made. Rutherford Backscattering Spectrometry (RBS) and Cross-sectional Transmission Electron Microscopy (XTEM) were mainly employed in the characterization of the layers and their interfaces. Upon annealing of a Au/Si structure at about 300°C in an oxygen ambient, RBS clearly suggests the formation of a surface oxide layer on top of the gold overcoating layer to form a SiO₂/Au/Si(100) structure. XTEM furthermore reveals that when the Au layer is less than or equal to about 50 nm, the Au layer breaks up during the annealing process as a result of some grains growing at the expense of others, to the extent they become detached from one another. This phenomenon is less prevalent at lower annealing temperatures. Optimum annealing conditions and Au thicknesses are presented in order to obtain the best results in terms of surface SiO₂ thickness.
11:10 AM		F3-9 Interface Characterization of CuInSe₂ Films on Silicon Grown by Stepwise Evaporation P. Malar, V. Damodara Das, S. Kasiviswanathan (Indian Institute of Technology, Madras, India) Si/CuInSe₂ interface was formed by the stepwise flash evaporation of CuInSe₂ (CIS) films onto p-Si(100) substrates held at 520K. Single-phase polycrystalline bulk CIS synthesized by melt quenching of constituent elements was used as the source material. Phase purity of the grown films was confirmed by transmission electron microscopy (TEM) and selected area diffraction (SAD) studies performed on films grown over glass substrates. The Si/CIS interface was characterized by Rutherford backscattering spectrometry (RBS). Composition and thickness of the deposited layer were determined from the analysis of RBS data. The interface between the substrate and the thin film is expected to be non-abrupt due to the possibility of interdiffusion of constituent elements and substrate-thin film mismatch. RBS results confirm the presence of such an interfacial layer formed by the diffusion of elements. Indium was not found to be present in this layer, probably due to the very negligible solubility of it in silicon. In this paper we discuss the interface features in terms of the exceptional diffusion of copper in silicon, which also accounted for the deviation from ideal stiochiometry of cu- poor CIS films.
11:30 AM		F3-10 The Magnetic Properties of Fe-Co-Pt Alloys Films Y.C. Lai, Y.H. Chang, Y.K. Chen (National Cheng Kung University, Taiwan, R.O.C.) The magnetic alloy films such as L10 phase of Fe-Co-Pt are used to the application of a spin-valve giant magnetoresistive sensor or a magnetic recording media. For achieving low-noise and ultra-high-density recording media, not only smaller grains can be used to create greater ratio of surface area to volume; but also through the advantage of sputtering technology to improve the grain size distribution. The (Fe_1-xCox)Pt₃₃ magnetic layer are sputtered onto the Si (100) substrate and are followed by the deposition of a chromium or titanium underlayer which is selected to give an ideal lattice match to the magnetic layer. The saturation magnetization increases as the content of Co element increases, and furthermore when the content of Pt increases between 33-50 at%, it also increases the coercivity. This stands that large transition energies are needed during reversal magnetization and control the optimum concentration of Co and Pt in perpendicular recording media is very important. In contrast with Cr underlayer and non-coated underlayer, FeCoPt films on Ti underlayer improves its permeability obviously. Magnetic properties measurements shows that the in-plane coercivity, Hc, greater than 8K Oe is sufficient to employ as a pinned layer in sensors (SV-GMR). However, optimum out of plane coercivity about 3K Oe can be used as perpendicular magnetic recording media.