Publisher’s Note: This paper, originally published on 2/22/17, was replaced with a corrected/revised version on 5/16/17. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance.
Metal anodes in high power source (HPS) devices erode during operation due to hydrogen outgassing and plasma formation; both of which are thermally driven phenomena generated by the electron beam impacting the anode’s surface. This limits the lowest achievable pressure in an HPS device, which reduces its efficiency. Laser surface melting the 304 stainless steel anodes by a continuous wave fiber laser showed a reduction in hydrogen outgassing by a factor of ~4 under 50 keV electron bombardment, compared to that from untreated stainless steel. This is attributed to an increase in the grain size (from 40 - 3516 μm2), which effectively reduces the number of characterized grain boundaries that serve as hydrogen trapping sites, making such laser treated metals excellent candidates for use in vacuum electronics.
This article [J. Nanophoton.. 8, (1 ), 083890 ( Feb 5 , 2014)] mistakenly appeared in the Special Section on Metamaterials and Photonic Nanostructures. It was republished in the Special Section on Nanostructured Thin Films VI with a corrected CID on 10 February 2014. The updated citation is shown below:
The role of the Hf nanoclusters as near-UV, nanosecond-pulse laser-damage initiators in HfO2 and SiO2-pair–based
multilayer coatings remains speculative. In this work we use photothermal heterodyne imaging (PHI) to investigate
absorption in HfO2 and SiO2 monolayers containing embedded nanometer-sized Hf clusters produced by backsidethrough-
thin-film ablation. Hf cluster size and areal-density distributions were characterized using transmission electron
microscopy. PHI measurements were taken for cluster-containing samples and for similarly prepared HfO2 and SiO2 film samples of the same thickness without clusters. These data allow us to evaluate a possible role in the damageprocess
initiation of two hypothetical sources of the localized absorption—Hf clusters and high-density areas of
electronic defects.
The role of the nickel catalyst size and its chemical and structural evolution during the early stages of carbon
nanopearl nucleation and growth, by chemical vapor deposition from acetylene/argon mixture, was investigated and
correlated with the resulting nanopearls morphological and structural properties. Carbon nanopearls were grown using Ni
nanoparticles that were 20 nm and 100 nm in size, at a growth temperature of 850 °C, for the following growth times: 10sec, 30 sec, 60 sec, 90 sec, 120 sec and 300 sec. X-ray diffraction, X-ray photoelectron spectroscopy and transmission
electron microscopy were performed on the carbon nanopearl samples. The X-ray diffraction and X-ray photoelectron
spectra showed the following chemical constituents were present during the growth of carbon nanopearls: NiO, Ni2O3, Ni3C, Ni, CO and C (both amorphous and graphite). Transmission electron microscopy showed an increase in carbon nanopearl size with larger Ni nanoparticles. Finally, the results showed that the 20 nm Ni nanoparticles chemically reacted sooner than the 100 nm Ni nanoparticles.
Adaptive coded aperture (diffraction) sensing, an emerging technology enabling real-time, wide-area IR/visible sensing
and imaging, could benefit from new high performance biologically inspired image processing architectures. The
memristor, a novel two terminal passive device can enable significantly powerful biologically inspired processing
architectures. This device was first theorized by Dr. Leon Chua in 1971. In 2008, HP Labs successfully fabricated the
first memristor devices. Due to its unique properties, the memristor can be used to implement neuromorphic functions as
its dynamics closely model those of a synapse, and can thus be utilized in biologically inspired processing architectures.
This paper uses existing device models to determine how device parameters can be tuned for the memristor to be used in
neuromorphic circuit design. Specifically, the relation between the different models and the number of states the device
can hold are examined.
The memristor, experimentally verified for the first time in 2008, is one of four fundamental passive circuit elements (the
others being resistors, capacitors, and inductors). Development and characterization of memristor devices and the design
of novel computing architectures based on these devices can potentially provide significant advances in intelligence
processing systems for a variety of applications including image processing, robotics, and machine learning. In
particular, adaptive coded aperture (diffraction) sensing, an emerging technology enabling real-time, wide-area
IR/visible sensing and imaging, could benefit from new high performance biologically inspired image processing
architectures based on memristors. In this paper, we present results from the fabrication and characterization of
memristor devices utilizing titanium oxide dielectric layers in a parallel plate conuration. Two versions of memristor
devices have been fabricated at the University of Dayton and the Air Force Research Laboratory utilizing varying
thicknesses of the TiO2 dielectric layers. Our results show that the devices do exhibit the characteristic hysteresis loop in
their I-V plots.
We have developed a laser-based technique for fabricating thin films, nanoparticles, and nanocomposite thin films.
The process is denoted Through Thin Film Ablation (TTFA) and entails using a thin film target that is ablated from
the backside. The deposits produced by this process show neither evidence of the larger (micrometer-sized) particles
nor the extent of agglomeration that are produced by conventional laser ablation. The TTFA technique offers the
potential for fabricating a wide variety of materials in thin film, nanoparticle, and nanocomposite form. In this paper
we present the results of Fe nanoparticle synthesis by TTFA including nanoparticle size distributions, time of flight
distributions, and time resolved spectral data. These data provide a more complete understanding of the TTFA
process.
We studied nanoparticles by several high resolution microscopic methods as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and scanning probe techniques especially atomic force microscopy (AFM) in contact and non-contact mode. While AFM in non-contact mode gives reliable information for 100 nm range
nanoparticles it fails for smaller particles, showing lack of reproducibility. TEM and SEM prove to be reliable. By SEM imaging the agglomeration behavior and the structure of agglomerates are discussed in detail.
We have formed nanoparticles of Si, C, Ti, and Fe by pulsed laser ablation and have explored the feasibility of passivating these particles during the synthesis process in order to minimize particle coarsening. Passivation was done by forming the nanoparticles in an Ar/N2 background, which allowed the formation of a thin nitride layer on the nanoparticle surface. In this paper we describe the synthesis procedure for synthesizing and passivating the nanoparticles. The characterization results indicate the nanoparticle synthesis in N2 does not significantly affect agglomeration.
KEYWORDS: Copper, Atomic force microscopy, Ultrasonics, Signal detection, Thin films, Acoustics, Atomic force microscope, Microscopes, Ion beams, Manufacturing
The material being used to construct interconnects in microelectronic circuitry is changing as developers switch from aluminum alloys to copper in order to make increasing smaller circuit wires. The performance of copper interconnects can be adversely affected by electromigration, precipitation formation, and changes in the grain microstructure of the wire. There is a need for characterization methods that can allow examination of the interconnects/wires and their grain structure in the nanometer range. One of the most powerful tools that are routinely used for characterization of nanostructured materials is the Atomic Force Microscope. The combination of AFM with ultrasonics (UFM) allows a near field acoustic microscopic image to be generated. By having the AFM tip detect the ultrasonic signal, the lateral resolution limitation of the acoustic wavelength that occurs in conventional acoustic microscopy can be overcome so that imaging with nanometer resolution is possible. In this paper, we present a qualitative comparison of AFM-UFM images on different forms of copper nanograins from two sources namely, ion beam deposited thin films samples containing polycrystalline sections and the aligned copper grains in the wires of an actual working microelectronic device. Images of the nanometer grain structure will be presented. Explanations for the image differences between samples will be discussed and possible applications are suggested.
Rand Biggers, Paul Murray, David Mast, I. Maartense, T. Peterson, D. Dempsey, C. Varanasi, S. Murray, D. Lubbers, S. Laube, B. Lovett, Eric Moser, J. Brown, D. Liptak, John Busbee
We examine the time-resolved spectral components emitted at approximately 327 nm and approximately 550 nm in YBCO plumes during pulsed laser deposition of thin films using a KrF excimer laser at (lambda) equals 248 nm. The studied emission signals last for approximately 20 microsecond(s) ec, and show variations when process parameters such as laser power, laser excitation voltage, beam focus, chamber pressure, substrate temperature, pulse repetition rate, and target rotation rate are changed. These signals are also dependent on other factors such as target wear and age of the laser gas mixture. Spectral-component monitoring is a supplementary method of real-time plume evaluation, and allows observation of changes both prior to deposition and during the actual deposition. Adjustments can be made to the process parameters to make the plume conform to criteria necessary for the growth of films with specific qualities. The use of these spectral components as real-time process- control state variables for more reproducible fabrication of high quality thin films will be assessed.
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