Multi-Physics of Nanoscale Thin Films and Interfaces

Author(s):  
M. A. Haque

We present the design and fabrication of a microchip capable of performing mechanical (tensile, fracture, fatigue), electrical (conductivity and band gap) and thermal (conductivity and specific heat) characterization of materials and interfaces. The chip can study thin films and wires of any material that can be deposited on a substrate or study thin coupons if the specimen is in bulk form. The 3 mm × 3 mm size of the chip results in the unique capability of in-situ testing in analytical chambers such as the transmission electron microscope. The basic concept is to ’see’ the micro-mechanisms while ‘measuring’ the deformation and transport properties of materials and interfaces. The advantage of such simultaneous acquisition of quantitative and qualitative data is the accurate and quick physics-based modeling of materials behavior. We present preliminary studies on multi-physics, or the coupling among mechanical thermal and electrical domains in materials will be presented. These results are particularly important when the specimen dimension becomes comparable to the mean free paths of electron and phonons.

Author(s):  
R. E. Herfert

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.


Author(s):  
J. T. Sizemore ◽  
D. G. Schlom ◽  
Z. J. Chen ◽  
J. N. Eckstein ◽  
I. Bozovic ◽  
...  

Investigators observe large critical currents for superconducting thin films deposited epitaxially on single crystal substrates. The orientation of these films is often characterized by specifying the unit cell axis that is perpendicular to the substrate. This omits specifying the orientation of the other unit cell axes and grain boundary angles between grains of the thin film. Misorientation between grains of YBa2Cu3O7−δ decreases the critical current, even in those films that are c axis oriented. We presume that these results are similar for bismuth based superconductors and report the epitaxial orientations and textures observed in such films.Thin films of nominally Bi2Sr2CaCu2Ox were deposited on MgO using molecular beam epitaxy (MBE). These films were in situ grown (during growth oxygen was incorporated and the films were not oxygen post-annealed) and shuttering was used to encourage c axis growth. Other papers report the details of the synthesis procedure. The films were characterized using x-ray diffraction (XRD) and transmission electron microscopy (TEM).


2013 ◽  
Vol 28 ◽  
pp. 84-88 ◽  
Author(s):  
Santosh Khanal ◽  
Alina Shakya ◽  
Goerg H. Michler ◽  
Boulos Youssef ◽  
Jean M. Saiter ◽  
...  

In this work, a commercially available Styrene-Isoprene-Styrene (SIS)triblock copolymer was modified into epoxidised version (ESIS)using performic acid generated in situ from hydrogen peroxide and formic acid. The epoxidised sample was further acrylated to prepare acrylated version (ASIS). The nanocomposites of each sample (SIS, ESIS and ASIS) were prepared using boehmite nanoparticles as filler by solution casting method. The polymers were characterized by Fourier Transform Infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). TEM investigations revealed that that the epoxidation of the diene block enhanced the dispersion of the nanofiller in the polymer matrix while the segregation of the nanoparticles towards the interface of the immiscible polymers was observed in the acrylated block copolymer based nanocomposite. DOI: http://dx.doi.org/10.3126/jncs.v28i0.8112 Journal of Nepal Chemical Society Vol. 28, 2011 Page: 84-88 Uploaded Date: May 24, 2013


1999 ◽  
Vol 564 ◽  
Author(s):  
K. Barmak ◽  
G. A. Lucadamo ◽  
C. Cabral ◽  
C. Lavoie ◽  
J. M. E. Harper

AbstractWe have found the dissociation behavior of immiscible Cu-alloy thin films to fall into three broad categories that correlate most closely with the form of the Cu-rich end of the binary alloy phase diagrams. The motivation for these studies was to use the energy released by the dissociation of an immiscible alloy, in addition to other driving forces commonly found in thin films and lines, to promote grain growth and texture evolution. In this work, the dissociation behavior of eight dilute (3.3 ± 0.5 at% solute) binary Cu-systems was investigated, with five alloying elements selected from group VB and VIB, two from group VillA, and one from group 1B. These alloying elements are respectively V, Nb, Ta, Cr, Mo, Fe, Ru and Ag. Several experimental techniques, including in situ resistance and stress measurements as well as in situ synchrotron x-ray diffraction, were used to follow the progress of solute precipitation in approximately 500 nm thick films. In addition, transmission electron microscopy was used to investigate the evolution of microstructure of Cu(Ta) and Cu(Ag). For all eight alloys, dissociation occurred upon heating, with the rejection of solute and evolution of microstructure and texture often occurring in multiple steps that range over several hundred degrees between approximately 100 and 900°C. However, in most cases, substantial reduction in resistivity of the films took place at temperatures of interest to metallization schemes, namely below 400°C.


2007 ◽  
Vol 561-565 ◽  
pp. 1161-1164
Author(s):  
Xiao Na Li ◽  
Bing Hu ◽  
Chuang Dong ◽  
Xin Jiang

Fe/Si multi-layer films were fabricated on Si (100) substrates utilizing radio frequency magnetron sputtering system. Si/β-FeSi2 structure was found in the films after the deposition. Structural characterization of Fe-silicide sample was performed by transmission electron microscopy, to explore the dependence of the microstructure of β-FeSi2 film on the preparation parameters. It was found that β-FeSi2 particles were formed after the deposition without annealing, whose size is less than 20nm ,with a direct band-gap of 0.94eV in room temperature. After annealing at 850°C, particles grow lager, however the stability of thin films was still good.


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