8 research outputs found
Investigation of pulse compression technique and time-frequency analysis in medical ultrasound imaging
Linear frequency modulation (LFM) followed by pulse Compression processing has bee
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Electrodeposition of Copper on Ruthenium Oxides and Bimetallic Corrosion of Copper/Ruthenium in Polyphenolic Antioxidants
Copper (Cu) electrodeposition on ruthenium (Ru) oxides was studied due to important implications in semiconductor industry. Ruthenium, proposed as the copper diffusion barrier/liner material, has higher oxygen affinity to form different oxides. Three different oxides (the native oxide, reversible oxide, and irreversible oxide) were studied. Native oxide can be formed on exposing Ru in atmosphere. The reversible and irreversible oxides can be formed by applying electrochemical potential. Investigation of Cu under potential deposition on these oxides indicates the similarity between native and reversible oxides by its nature of inhibiting Cu deposition. Irreversible oxide formed on Ru surface is rather conductive and interfacial binding between Cu and Ru is greatly enhanced. After deposition, bimetallic corrosion of Cu/Ru in different polyphenols was studied. Polyphenols are widely used as antioxidants in post chemical mechanical planarization (CMP). For this purpose, different trihydroxyl substituted benzenes were used as antioxidants. Ru, with its noble nature enhances bimetallic corrosion of Cu. Gallic acid (3,4,5 - trihydroxybenzoic acid) was chosen as model compound. A mechanism has been proposed and validity of the mechanism was checked with other antioxidants. Results show that understanding the chemical structure of antioxidants is necessary during its course of reaction with Cu
Preparation of a Binder-Free Three-Dimensional Carbon Foam/Silicon Composite as Potential Material for Lithium Ion Battery Anodes
We report a novel three-dimensional
nitrogen containing carbon foam/silicon (CFS) composite as potential
material for lithium ion battery anodes. Carbon foams were prepared
by direct carbonization of low cost, commercially available melamine
formaldehyde (MF, Basotect) foam precursors. The carbon foams thus
obtained display a three-dimensional interconnected macroporous network
structure with good electrical conductivity (0.07 S/cm). Binder free
CFS composites used for electrodes were prepared by immersing the
as-fabricated carbon foam into silicon nanoparticles dispersed in
ethanol followed by solvent evaporation and secondary pyrolysis. In
order to substantiate this new approach, preliminary electrochemical
testing has been done. The first results on CFS electrodes demonstrated
initial capacity of 1668 mAh/g with 75% capacity retention after 30
cycles of subsequent charging and discharging. In order to further
enhance the electrochemical performance, silicon nanoparticles were
additionally coated with a nitrogen containing carbon layer derived
from codeposited poly(acrylonitrile). These carbon coated CFS electrodes
demonstrated even higher performance with an initial capacity of 2100
mAh/g with 92% capacity retention after 30 cycles of subsequent charging
and discharging