bluuebunny/crossref_metadata_2025 huggingface dataset:
Advances in Amorphous Silicon Integrated Photonics Science and Technology
Authors: Halada G.P. , Chawda Samrat , Mawyin J. , Tonucci R.J. , Mahan A.H. , Fortmann C.M.
Published: June 2019

Over the past few years we have been developing a scientific basis for amorphous silicon-based integrated photonics technology. Waveguides using hydrogen-implanted, optically-smooth, hot-wire-deposited films have been prepared and demonstrated, and structures were characterized by Raman spectroscopy of the implanted and the non-implanted regions of the waveguide samples. The analysis is consistent with greater disorder in the film structure induced through implantation. More recently, materials prepared by femtosecond laser ablation of silicon powder have been characterized by Raman spectroscopy indicating a structure having both amorphous and crystalline components. As amorphous silicon photonics continues to evolve, the patterning of materials of differing crystallinity may become an issue of interest.
Two-dimensional a-Si:H/a-SiC:H n-i-p sensor array with ITO/a-SiNx antireflection coating
Authors: Vygranenko Yu. , Chang J. H. , Nathan A.
Published: June 2019

This paper presents a two-dimensional a–Si:H/a-SiC:H n–i–p photodiode array with switching diode readout, developed specifically for fluorescence-based bio-assays. Both device structure and fabrication processing has enabled enhancement of the external quantum efficiency of the encapsulated device up to 80%, reduction of the photodiode leakage down to 10 pA/cm2 at -1V reverse bias, and increase of the rectification current ratio of the switching diodes up to 109. The critical fabrication issues associated with deposition of device-quality materials, tailoring of defects at the i–p interface, device patterning with dry etching, junction passivation, and contact formation will be discussed. Both sensing and switching diodes were characterized. While the observed dark current in the photodiodes at low reverse bias voltages is primarily due to carrier emission from deep states in the a–Si:H bulk, the leakage in the small switching diodes stems from peripheral defects along junction sidewalls. Optical losses in the photodiodes with ITO/a–SiNx:H antireflection coating were evaluated using numerical modeling, and the calculated transmission spectra correlated well with the spectral response characteristics. Measurements of the charge transfer time and output linearity demonstrated the efficiency of the single-switching diode readout configuration. The response of the array to optical excitation was also investigated. The observed long term retardation in the signal rise and decay at illumination levels less than 1010 photons/cm2-s can be associated with charge trapping in the undoped layer.
Amorphous Silicon Based p-i-i-n Structure for Color Sensor
Authors: Zhang S. , Raniero L. , Fortunato E. , Pereira L. , Águas H. , Ferreira I. , Martins R.
Published: June 2019

This work deals with the study of the role of the film thickness and composition on the color selectivity of the collecting spectrum of glass/ZnO:Ga/p-a-Si1-xCx:H/ a-Si1-xCx:H /a-Si:H/n-a-Si:H/Al photoelectronic detectors produced in a single chamber plasma enhanced chemical vapor deposition (PECVD) system. The cross contaminations were minimized by a rotate-cover substrate holder system. The devices can detect the blue illumination at small reverse bias and detect red illumination at large reverse bias. The role of the process parameters, especially the thickness of the p-type and intrinsic a-Si1-xCx:H, and the intrinsic a-Si:H layers on the device performances were studied in detail aiming to achieve a better detectivity.
Comparison of the Effect of Light Soaking in Porous Silicon and a-Si:H
Authors: Mandal N. P. , Agarwal S. C.
Published: June 2019

In undoped a-Si:H thin films, light soaking (LS) decreases dark current and photocurrent and increases the electron spin resonance signal monotonically with increasing exposure time, (Staebler-Wronski Effect, SWE). On the other hand, in porous silicon (PS) the light-soaking effect is non-monotonic. For short durations, LS increases dark current, photo current and photoluminescence and decreases the ESR signal. Long exposures of PS, however, have the opposite effect, which is similar to the SWE observed in a-Si:H. All metastabilities in PS as well as in a-Si:H can be removed by annealing, but not by exposure to infrared light. We find that the combined effect of NH3vapor exposure and LS on PS yields a final state that depends upon the order in which the two steps are performed. This is in contrast to the corresponding observation in a-Si:H. We could arrest the light-induced degradation of PS over long times by coating with a thin polystyrene, which resulted in constant PL and ESR intensities. However, in the case of a-Si:H the polymer coating decreases the SWE, but does not eliminate it. The results can be understood, if we were to propose that LS affects the surface in PS, but affects mainly the bulk in a-Si:H.
Solid state MAS NMR spectroscopic characterization of plasma damage and UV modification of low k dielectric films
Authors: Abell Thomas , Houthoofd Kristof , Iacopi Francesca , Grobet Piet , Maex Karen
Published: June 2019

29Si magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy was employed to characterize short-range atomic structure modifications to low k dielectric films that were subjected to post-deposition plasma exposure or UV curing. Comparison of spectra from single thick depositions of a CVD low k film (k∼3.0) with sequential thin depositions of the same film revealed ∼3% increase in Si-O crosslinking that was attributed to interfacial plasma damage. Comparison of a second CVD low k film (k∼3.0) before and after UV curing revealed ∼11% increase in Si-O crosslinking with commensurate losses of Si-OH and Si-CH3 groups. UV curing was believed to result in bulk modification. This crosslinking was found to increase the Young's modulus of the film from 11 to 16 GPa as measured on 700 nm films by nanoindentation. NMR analysis was found to provide significant information beyond that provided by FTIR but required special sample preparation and extensive data collection.
Flip Chip Reliability of GaAs on Si Thinfilm Substrates Using AuSn Solder Bumps
Authors: Oppermann Hermann , Hutter Matthias , Klein Matthias , Engelmann Gunter , Toepper Michael , Wolf Jürgen
Published: June 2019

Au/Sn solder bumps are mainly used for flip chip assembly of compound semiconductors in optoelectronic and RF applications. They allow a fluxless assembly which is required to avoid contamination of optical interfaces and the metallurgy is well suited to the final gold metallization on GaAs or InP. Flip chip assembly experiments were carried out using two layer Au/Sn bumps as plated without prior bump reflow. An RF and reliability test vehicles comprise a GaAs chip which was flip chip soldered on a silicon substrate. Temperature cycling tests with and without underfiller were performed. The different failure modes for underfilled and nonunderfilled samples were discussed and compared. Additional reliability tests were performed with flip chip bonding by gold thermocompression for comparison. The test results and the failure modes are discussed in detail.
Interconnects for Elastically Stretchable and Deformable Electronic Surfaces
Authors: Jones Joyelle , Lacour S.P. , Wagner Sigurd
Published: June 2019

Deformable, large-area electronic surfaces are desirable for many human-machine interfaces. The goal of our research is to fabricate elastically deformable electronics by integrating electronic devices and stretchable interconnects onto a flexible substrate. The focus of this paper is the fabrication and electrical performance of the stretchable interconnects. Au was deposited onto a silicone elastomer (PDMS) and patterned to achieve a resolution of 2 μm. Two patterning techniques are presented: patterning by shadow mask and patterning by photolithography. Photolithographic patterning on PDMS is not straightforward. First, we discuss the challenges in patterning and then the morphology of lines patterned by both techniques. The electrical resistance of the Au lines under tensile strain is presented. Interconnects patterned by shadow mask remain electrically conductive up to 100 % strain. Those patterned by photolithography maintain electrical conductivity when strained up to 60 %.
Double-layered Structure of Surface Modification of Low-k Dielectrics Induced by He Plasma
Authors: Yanai Ken-Ichi , Hasebe Tadayoshi , Sumiya Kouji , Oguni Seiki , Koga Kazuhiro
Published: June 2019

Surface modification of a p-SiOC film induced by Helium (He) plasma was investigated using various measurements. Differential Fourier transform infrared absorption (FT-IR) spectra and the etch-depth measurements with the immersion in the mixed hydrofluoric acid (HF) indicate that the almost all of Si-CH3 bonds are broken in the modification layer, resulting in carbon-depletion, an SiO2-like composition. The x-ray photoelectron spectroscopy (XPS) measurements at different take-off angles reveal that the modified surface forms a double-layered structure, a thin carbon-rich top layer (about 1 nm thick) on a thick carbon-depletion layer (about 20 nm thick) with the irradiation of He plasma over 300 W. Atomic force microscopy (AFM) observations show that the modified surface is the smoothest in the case of the carbon-depletion surface.
Fracture Property Improvements of a Nanoporous Thin Film Via Post Deposition Bond Modifications
Authors: Jacques Jeannette M. , Tsui Ting Y. , McKerrow Andrew J. , Kraft Robert
Published: June 2019

For 90 nm node devices, the group of materials known as organosilicate glass (OSG) has emerged as the predominant choice for intermetal dielectrics. A potential failure mechanism for this class of low-k dielectric films during the manufacturing process is catastrophic fracture due to channel cracking. The use of an electron beam curing process is being investigated for improvement in the mechanical strength of these silicon-based materials. Within this work, the effects of curing dose (micro-C/cm2) upon the mechanical properties of OSG thin films were characterized. For a set process voltage and current, linear relationships exist between the dose and several mechanical film properties. Channel crack growth velocities were also measured for these cured materials. As the cure dose is increased, the crack growth rate decreases according to a power law relationship. The structural film changes induced by the electron beam cure process are addressed, focusing on their impact upon the mechanical strength of OSG thin films.
Structure Evolution in Plated Cu Films
Authors: Field D.P. , Park NJ , Besser PR , Sanchez JE
Published: June 2019

Structure evolution in plated Cu films is a function of sublayer stacking, film thickness, plating chemistry, plating parameters, and temperature. The present work examines grain growth and texture evolution in annealed plated Cu on a 25 nm thick Ta sublayer for films of 480 and 750 nm in thickness. These results are compared against those obtained from damascene Cu lines fabricated from a similar process, using a series of line widths. The results show that the initial structures of the plated films are similar, with slightly weaker (111) texture, a higher fraction of twin boundaries, and larger grains in the thicker films. The microstructure of the Cu within the trench constraints is a strong function of line geometry with the propensity for twin boundary development controlling structural evolution.
Effect of Temperature on Incubation Time for Spontaneous Morphology Change in Electrodeposited Copper Metallization
Authors: Ahmed S. , Buckley D.N. , Nakahara S. , Kuo Y.
Published: June 2019

A systematic investigation of the effect of annealing time and temperature on the incubation period for spontaneous morphology change (SMC) in electrodeposited copper metallization is reported. The incubation time is greatly reduced at higher temperatures. At each temperature, the remaining incubation time at room temperature was found to decrease approximately linearly with increasing annealing time. An Arhennius plot of the measured rates of decrease showed good linearity and yielded a value of 0.48 eV for the activation energy. This is consistent with a vacancy diffusion mechanism for the process occurring during the incubation period and supports our proposed mechanism for SMC.
Integration of ALD-TaN Liners on Nanoporous Dielectrics
Authors: Moon Bum Ki , Iijima Tadashi , Malhotra Sandra , Simon Andrew , Shaw Thomas , Ryan Todd , Labelle Cathy , Fuller Nick , Bolom Tibor , Dunn Derren , Flaitz Philip , Mehta Sanjay , Inoue Keishi , McGahay Vincent
Published: June 2019

Ultra-thin ALD-TaN/PVD-Ta liners have been developed to prevent Cu diffusion into porous interlayer dielectric (ILD) materials envisioned for future copper interconnections. The porous ultra-lowk(p-ULK) film is prepared using the spin-on method, and typical k-value and the average pore size of p-ULK used in this paper are 2.3 and 2-3 nm, respectively. Interaction and phenomena at the ILD/ALD-TaN interface have been investigated, and the electrical measurements of samples with a bi-layered ALD-TaN/PVD-Ta barrier were performed after completing the metallization and CMP process.

A deep penetration of ALD-TaN was observed on the as-deposited p-ULK, which is due to the interconnected pore structures. However, the surface of the p-ULK is drastically changed after the etch process, where changes are attributed to plasma damage and re-deposition of etched species. Pores can therefore be sealed during the etch process. Furthermore, the plasma damage makes the sidewall more hydrophilic, which may promote the growth of ALD-TaN layer. Based on EELS and EDS profiles, there is no signature of TaN penetration into the etched p-ULK at M1 level with a sharp Ta peak, which indicates excellent stability of ultra-thin ALD-TaN liner.

An oxidation test in air ambient and at elevated temperature confirmed the barrier properties of the stacked ALD-TaN/PVD-Ta layers. Any weak point in the barrier allows the Cu to oxidize and to make a color change under an optical microscope. However, all of our samples showed no color change, which implies that the barrier is very uniform and stable. Electrical properties measured at M1 showed excellent results. Our results demonstrate the ability to successfully integrate ALD-TaN barriers with a nanoporous ULK film.
Degradation of Fracture and Fatigue Properties of MEMS Structures Under Cyclic Loading
Authors: Kim Jong-Jin , Kwon Dongil
Published: June 2019

The fracture and fatigue properties of LIGA nickel MEMS structures were evaluated by microtensile and fatigue test methods. A microtensile/fatigue device was developed and specimens with feature size ten micrometers were used. The fatigue property was derived from displacement amplitude – the number of cycles to failure curve by applying a dynamic load with a piezoelectric actuator. The tensile/fracture properties after various cyclic loading were also measured. Both fatigue and tensile test results showed a cyclic softening phenomenon.
New Carbon-bridged Hybrid Polymers for Low-k Materials
Authors: Choi Bum-Gyu , Kim Byung Ro , Moon Myung-Sun , Kang Jung-Won , Ko Min-Jin
Published: June 2019

Reducing interline capacitance and line resistance is required to minimize RC delays, reduce power consumption and crosstalk below 100nm node technology. For this purpose, various inorganic- and organic polymers have been tested to reduce dielectric constants in parallel with the use of copper as metal line. Lowering the dielectric constants, in particular, causes the detrimental effect on mechanical properties, and then leads to film damage and/or delamination during chemical-mechanical planarization CMP) or repeated thermal cure cycles. To overcome this issue, new carbon-bridged hybrid materials synthesized by organometallic silane precursors and sol-gel reaction are proposed.

In this work, we have developed new organic-inorganic hybrid low-k dielectrics with linear or cyclic carbon bridged structures. The differently bridged carbon structures were formed by a controlled reaction. 1H NMR, 29Si NMR analysis and GC/MSD analysis were conducted for the structural characterization of new hybrid low-k dielectric. The mechanical and dielectric properties of these hybrid materials were characterized by using nanoindentation with continuous stiffness measurement and Al dot MIS techniques. The results indicated that these organic-inorganic hybrid materials were very promising polymers for low-k dielectrics that had low dielectric constants with high thermal and mechanical properties. It has been also demonstrated that electrical and mechanical properties of the hybrid films could be tailored by copolymerization with PMSSQ and through the introduction of porogen.
The Effect of Methylating Treatments on the Dielectric Reliability of Low-k/Cu Structures
Authors: Borthakur Swarnal , Satyanarayana Sri , Knorr Andreas , Ho Paul S.
Published: June 2019

Post ash chemical treatments were evaluated for improving the reliability of Cu/low-k structures. The RC delays, leakage current, ramp-voltage-breakdown and timedependent- dielectric-breakdown lifetimes resulting from different treatments were compared. The pitch dependence of capacitance and breakdown was also evaluated. Post ash chemical treatments were more beneficial for the smaller line spaces. FTIR and TEM/EELS analysis were performed to determine the chemical changes occurring at the sidewall due to the post ash chemical treatments. The analysis showed that the chemical treatments increased the carbon content at the trench sidewalls. The post ash treatments were found to improve the electrical characteristics.
Modeling the Impact of Packaging Stress on Device Performance
Authors: Xu Xiaopeng , Moroz Victor
Published: June 2019

In this study the stress evolution for the entire transistor fabrication process is simulated and the packaging stress is modeled as the external pressure/normal stress acting on the boundaries of the transistor unit cell. The impact on device performance from both the fabrication stress and the packaging stress is investigated using a classical piezo-resistance mobility model. The effect of the packaging stress on device mobility can be either beneficial or detrimental depending on whether the stress is tensile or compressive, on stress pattern, its magnitude, and the transistor type. The results suggest that utilizing both the fabrication stress and the packaging stress for stress engineering can lead to additional device performance enhancements.
Electromigration of Electroplated Gold Interconnects
Authors: Kilgore Steve , Gaw Craig , Henry Haldane , Hill Darrell , Schroder Dieter
Published: June 2019

Electromigration tests were performed on passivated electroplated Au four terminal Kelvin line structures using the conventional in situ resistance monitoring technique. The stress conditions were a current density of 2.0 MA/cm2 with ambient temperatures ranging from 325°C to 375°C. The temperature coefficients of resistance (TCR) values were measured prior to current stressing to calculate the Joule heated film temperatures. The times to failure (lifetimes) for the Au line structures were considered as a 50% ΔR/R0 change. The median time to failure (t50%) was plotted against the inverse film temperature to determine the activation energy value as 0.59 ± 0.09 eV. Failure analysis of void location and suggested diffusion mechanism will be discussed.
Characterization of Temporary Extrusion Failures in Quarter-Micron Copper Interconnects
Authors: Zhang Yan , Choy Junho , Chapman Glenn H. , Kavanagh Karen L.
Published: June 2019

We report an unusual circuit failure mode induced by short-lived extrusions observed during DC and AC electromigration (EM) tests of quarter-micron damascene copper interconnects. This novel “soft” failure mode consists of extrusions forming, then self-dissolving before the traditional permanent void or extrusion failure. These failures shorten the lifetime significantly and bring new challenges to reliability tests. Two self-dissolution mechanisms under DC test conditions are discussed and extrusion shape evolution is modeled assuming both capillary and electron wind forces are present. Our model confirms that the electrical stress will accelerate the shape evolution process.
Thin Film on ASIC (TFA) - A Technology for Advanced Image Sensor Applications
Authors: Sterzel Juergen , Blecher Frank
Published: June 2019

Thanks to its three-dimensional integration and the use of amorphous as well as crystalline silicon, the TFA technology is suitable for advanced image sensor applications. This paper describes the fundamentals of the properties: sensitivity, dark current, temporal and fixed-pattern noise of these TFA image sensors. It compares the different sensitivity definitions, especially current sensitivity and the charge conversion factor. Further, the dark current sources are pointed out, and their temperature behavior is described. By noise calculations, different pixel input stages are compared with regard to low light level detection.
Application of Magnetic Ferrite Electrodeposition and Copper Chemical Mechanical Planarization for On-Chip Analog Circuitry
Authors: Washburn Cody , Brown Daniel , Cabacungan Jay , Venkataraman Jayanti , Kurinec Santosh K.
Published: June 2019

Inductors are important components of analog circuit designs, from matching circuitry to passive filters. In this study, the application of electrophoretically deposited nano-ferrite material has been investigated as a technique to increase the inductance of integrated copper planar inductors fabricated using copper plating and chemical mechanical planarization. Sintered Mn-Zn ferrite particles are suspended in a medium of isopropyl alcohol with magnesium nitrate and lanthanum nitrate salts. The transportation of the particles to the substrate surface is assisted by applied electric field and particles adhere to the substrate surface by a glycerol based surfactant. Electrophorectic deposition process forms a self aligned polymeric thin film on the surface of a p-type silicon substrate selectively with respect to copper. This ferrite deposition method yields high selectivity to the inductor coils and patterned silicon substrates compatible with standard silicon technology.
A CMOS Medium Density DNA Microarray with Electronic Readout
Authors: Thewes Roland , Paulus Christian , Schienle Meinrad , Hofmann Franz , Frey Alexander , Schindler-Bauer Petra , Atzesberger Melanie , Holzapfl Birgit , Haneder Thomas , Hanke Hans-Christian
Published: June 2019

A CMOS chip-based approach is reviewed for fully electronic DNA detection. The electrochemical sensor principle used, CMOS integration of the required transducer materials, chip architecture and circuit design issues are discussed, respectively. Electrochemical and biological results obtained on the basis of medium density microarray sensor CMOS chips with 16×8 sensor sites prove proper operation.
Small Angle X-Ray Scattering, FTIR and SEM Characterization of Nanostructured PVA/TEOS Hybrids by Chemical Crosslinking
Authors: Mansur Herman S. , Mansur Alexandra A.P.
Published: June 2019

In the present work, novel hybrid nanostructured composites were produced to be used in many potential applications such as biomedical, drug delivery systems, tri-dimensional scaffolds for biomaterials and tissue engineering, biomembranes and optical devices among others. Hybrids were synthesized by reacting poly (vinyl alcohol) (PVA) in aqueous acid solution with silicon alcoxide tetraethoxysilane (TEOS). PVA/TEOS hybrids were also modified in the nanometer-scale by crosslinking with glutaraldehyde (GA) during the synthesis involving hydrolysis and policondensation of PVA/TEOS. The hybrids were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Small Angle X-ray Scattering (SAXS) and Scanning Electron Microscopy (SEM). FTIR spectra have shown major vibration bands associated with organic-inorganic chemical groups present in the hybrid composite PVA/TEOS. Also, typical absorption bands related to glutaraldehyde alkyl chain have indicated the crosslinking reaction of the hybrid network with glutaraldehyde (PVA/TEOS/GA). SAXS results have indicated different nano-ordered disperse phases for PVA, PVA/TEOS hybrid and PVA/TEOS/GA chemically crosslinked hybrid. SEM micrographs have shown morphology difference between PVA and PVA hybrid samples.
In Situ Characterization of Surface Evolution on Titanium in Hydrogen Peroxide Containing Solutions
Authors: Muyco Julie J. , Gray Jeremy J. , Ratto Timothy V. , Orme Christine A. , McKittrick Joanna , Frangos John
Published: June 2019

Titanium implants have been used for decades with success in various applications. The characteristics of titanium that allows acceptance in the body are not well defined. It is known that hydrogen peroxide is a chemical species produced during the inflammatory response following implantation. When titanium is exposed to hydrogen peroxide, a Ti-peroxy gel (TiOOH) is formed. Three possible functions of Ti-peroxy gel are: reduction of the inflammatory response through the reduction of hydrogen peroxide and other reactive oxygen species; creation of a favorable surface for calcium phosphate nucleation; and as a transitional layer between the soft tissue and the stiff titanium. These studies utilized atomic force microscopy (AFM) force spectroscopy, electrochemical techniques, Raman spectroscopy, and optical transparency in situ to define kinetic and mechanical properties of Ti-peroxy gel as it forms on titanium during exposure to hydrogen peroxide. Peaks attributed to Ti-peroxy gel were seen to emerge over the course of several hours using in situ Raman spectroscopy. Force-distance curves suggest a layer that thickens with time on the titanium sample surface.
Surface Roughness Values Closer to Bone for Titania Nanoparticle/Poly-lactic-co-glycolic Acid (PLGA) Composites Increases Bone Cell Adhesion
Authors: Liu Huinan , Slamovich Elliott B. , Webster Thomas J.
Published: June 2019

Bone substitutes are often required to replace damaged tissue due to injuries, diseases and genetic malformations. Traditional bone substitutes, such as autografts, allografts, xenografts and metal implants, are far from ideal as each have their own specific problems and limitations. Bone tissue engineering offers a promising opportunity for bone regeneration in a natural way. However, currently the scientific challenges of bone tissue engineering lie in the development of suitable scaffold materials that can improve bone cell adhesion, proliferation and differentiation. The design of nanophase titania/polymer composites offers an exciting approach to combine the advantages of a degradable polymer with nano-size ceramic grains that optimize biological properties for bone regeneration. Importantly, nanophase titania mimics the size scale of constituent components of bone since bone itself is a nanostructured composite composed of nanometer hydroxyapatite crystals well-dispersed in a mostly collagen matrix. Previous studies have shown significant improvement in protein adsorption, osteoblast (bone-forming cell) adhesion and long-term functions on nano-grain ceramic materials compared to traditional micron-grain ceramic materials. This study used nanometer grain size titania dispersed in a model polymer (PLGA or poly-lactic-co-glycolic acid) matrix by using various sonication powers to increase osteoblast adhesion. The surface characteristics of the composites, such as topography, titania surface area coverage and surface roughness, were studied by scanning electron microscopy and atomic force microscopy. Of all the composites formulated in this study, osteoblast adhesion was the greatest on nanophase titania/PLGA (30/70 wt.%) sonicated at 118.75 for 10 minutes; this composite was the closest in terms of nanometer surface roughness compared to bone of all the composites formulated. In this manner, this study suggests that nanophase titania sonicated in PLGA under these conditions should be further studied for orthopedic applications.
Fabrication of Semiconductor Nano-particles in the Protein Cage of Apoferritin
Authors: Iwahori Kenji , Yoshizawa Keiko , Muraoka Masahiro , Yamashita Ichiro
Published: June 2019

We specially designed a slow chemical reaction system to synthesize the zinc selenide nanoparticles (ZnSe NPs), in the cavity of the cage-shaped protein, apoferritin. The newly designed chemical synthesis system for ZnSe NPs makes the chemical reaction of compound semiconductor element ions dramatically slow, resulting in that ZnSe NPs can be synthesized in the internal cavity of the apoferritin. The ZnSe NPs synthesized by the optimized reaction parameters are efficiently produced in the aqueous solution. The UVVis spectrum analysis of synthesized ZnSe-ferritin suggests that the formation of ZnSe nuclei in the apoferritin cavity takes about 6 hours by using our slow chemical reaction system. The synthesized ZnSe NPs were characterized by high resolution TEM, X-ray powder diffraction (XRD) and Energy Dispersive Spectrometory (EDS) and it was revealed that the synthesized NPs are a collection of cubic ZnSe crystals.
The Bio-Nano-Process: Making Semiconductor Devices Using Protein Supramolecules.
Authors: Yamashita Ichiro
Published: June 2019

The biology and semiconductor technology have progressed independently. There was a large distance between them and a substantial interdisciplinary research area was left untouched. Recently, this situation is gradually changing. Some researchers are stimulating semiconductor technology by introducing bio-molecules into the nano-fabrication process. We proposed a new process for fabricating functional nano-structure on a solid surface using protein supramolecules, which we named “Bio Nano Process” (BNP). We employed a cage-shaped protein, apoferritin and synthesized several kinds of nanoparticles (NP) in the apoferritin cavity. A two-dimensional array of them was made on the silicon wafer and this array was heat treated or UV/ozone treated. These processes produced a two-dimensional inorganic NP array on the silicon surface. The size of the NP is small enough to be used as quantum dot and the floating nanodots memory using this NP array is now under development. We also proposed another application of the BNP, making use of the obtained nanodot array as the nanometric etching mask. This was realized by employing the neutral beam etching and 7nm Si nano columns with high aspect ratio were fabricated. These experimental results demonstrate that the BNP can fabricate the inorganic nanostructure using protein supramolecules and the BNP opened up a biological path to nanoelectronics devices.
Bio-Inspired Evolution of Zinc Oxide-Based Materials Directed by Amino Acids and Peptides.
Authors: Bill Joachim , Gerstel Peter , Hoffmann Rudolf C. , Jeurgens Lars P. H. , Lipowsky Peter , Wildhack Stefanie , Aldinger Fritz
Published: June 2019

Within this paper the suitability of amino acids and dipeptides as structure-directing agents is discussed. According to that bio-inspired approach these biomolecules were investigated with respect to the evolution of zinc oxide-based architectures. Those small molecules are able to trigger the morphology of these materials ranging from grain-like via two up to three dimensional features. Besides morphological aspects the structural characterization of these solids by means of electron and atomic force microscopy as well as by photoelectron spectroscopy and X-ray diffraction are discussed in order to extract the function of the biomolecules with regard to the formation of the inorganic phases.
Fabrication and Characterization of an Active Matrix Thin Film Transistor Array for Intracellular Probing
Authors: Jun Seung-Ik , McKnight Timothy E. , Melechko Anatoli V. , Simpson Michael L. , Rack Philip D.
Published: June 2019

In order to achieve multiple intracellular stimulation and recording devices with high electrode density and low manufacturing cost, we have fabricated and characterized an active matrix thin film transistor array with integrated vertically aligned carbon nanofibers. This device has the potential for cell probing and screening that provides great potential to execute direct cell sensing/probing and recording with a high electrode density. Each unit pixel in the array is individually addressed by a thin film transistor (TFT) and the vertically aligned carbon nanofibers (VACNF) used to impale the cell are fabricated on the drain electrode of the TFT. The VACNF is grown by direct current plasma enhanced chemical vapor deposition (DCPECVD) using a nickel catalyst. Electroanalysis or impedance differences between the cell probing site and a reference electrode are recorded with a potentiostat or a semiconductor analyzer connected to the output terminals. Additionally, the impedance change with frequency of the intracellular probe can be measured by applying a frame signal input and the signal can be recorded in storage capacitors after the frame scan of the TFTs. Consequently, actively addressed nanofiber arrays enable bidirectional interfacing with tissue matrices in a format that provides intercellular positioning of electrode elements as well as the potential for intracellular residence of probes within individual cells. In our research, we exploit these non-planar electrode systems for efficient coupling with excitable cell matrices as well as for intracellular biochemical manipulation and sensing of and delivery to single cells. In this paper, we will discuss the fabrication sequence of the inverted metal-oxide-semiconductor (MOS) TFT, and will elaborate the materials issues related to integrating the carbon nanofibers with the TFT.
Epitaxial Growth Of Nickel Nanocrystals By Domain Matching Epitaxy
Authors: Narayan Jagdish
Published: June 2019

We show that epitaxial nickel (fcc structure, lattice constant of 0.3528nm) nanocrystals are formed inside magnesium oxide (sodium chloride structure, lattice constant of 0.4201nm) matrix, where the misfit ranges from 3.0% to 31.3% on different interfaces. By controlling the annealing conditions, we obtained two distinct epitaxial morphologies: (1) cube-on-cube with <100>Ni // <100> MgO with a misfit of about 18.0%; and (2) <112> morphology with <112> // <002> MgO (misfit 31.3%); <111> Ni // <200> MgO (misfit 3.0%); and <110> Ni // <020> MgO (misfit 17.0%). These results on epitaxial growth of nickel on MgO with misfit ranging from 3.0% to 31.3% are consistent with the domain matching epitaxy paradigm (DME), where integral multiple of lattice planes match across the film-substrate interface. The lattice planes include all the planes in a crystal structure, not just the diffraction planes involved in the X-ray, electron and neutron scattering. The residual misfit away from the integral multiples is accommodated by the principle of domain variation, where two or three sets of domains alternate with a certain frequency to minimize the misfit close to zero. The epitaxy in the DME paradigm is defined as the film having a fixed orientation which could be the same under certain conditions. From these results on Ni epitaxy, the dominant role of planes and matching of integral multiples of planes to accommodate small to large misfit are clearly established according to the DME paradigm.
Carbon Encapsulated Magnetic Nanoparticles Produced by a Catalytic Disproportionation of Carbon Monoxide
Authors: Prilutskiy Oleg , Katz Eugene A. , Shames Alexander I. , Mogilyanski D. , Mogilko Emma , Bruckental Ishai
Published: June 2019

Carbon nanocapsules with a ferromagnetic core of single-crystalline Fe3O4 are demonstrated to be effectively synthesized and collected separately from the other nano-carbon products of the low-temperature reaction of catalytic disproportionation of carbon monoxide. HRTEM demonstrated a defect-free crystalline structure of the Fe3O4 nanoparticles. The encapsulating carbon shells of the Fe3O4 nanoparticles are stable in air at room temperature, but do not prevent them at high temperatures. Accordingly, these nanoparticles may also act as catalysts for the corresponding production of carbon nanomaterials via carbon monoxide disproportionation. In particular, we demonstrate the corresponding transformation of a Fe3O4 core to an iron carbide nanoparticle with simultaneous formation of additional encapsulating carbon layers. Characterization of the synthesized materials by DC magnetization represents clearly resolved hysteresis loops. However characteristic S-shape of the loops (magnetization is still not saturated at 16 kOe) points out some superparamagnetic effects driven by the nano-size origin of the samples. Analysis of the sample's EPR spectra provides an additional insight to the coexistence of several magnetic phases in the synthesized nanomaterials.
Novel Medical Ferrite Nanobeads with Bioactive Molecules Immobilized Strongly onto the Surfaces
Authors: Abe Masanori , Matsushita Nobuhiro , Tada Masaru , Gokon Nobuyuki , Nishio Kosuke , Handa Hiroshi
Published: June 2019

Under neutral conditions (pH=7-9) and temperature as low as 4°C we successfully synthesized ferrite nanoparticles with an intermediate structure between Fe3O4 and γ -Fe2O3 from an aqueous solution. These experimental conditions enabled us to immobilize even very unstable bioactive molecules onto the surfaces of the ferrite nanoparticles during their synthesis. The bioactive molecules were strongly fixed onto the ferrite surface intermediated by specific amino-acids or related-structure molecules each having pairs of carboxyl (COOH) groups. The COOH group pair was found to make a chemical bond with the ferrite particles. Utilizing the strong bond between such molecules and ferrites, we successfully prepared bioactive ferrite nanobeads where the ferrite nanoparticles were encapsulated in a polymer that exhibited negligible non-specific absorption of proteins. We also succeeded in fixing bioactive molecules onto the surfaces of the polymer coating of the ferrite nanobeads. We describe promising applications of our novel bioactive ferrite nanobeads such as high performance magnetic carriers for bio-screening, hypothermia, MRI contrast enhancement and magnetic drug delivery.
Low Temperature Synthesis of Silicon Oxide Nanowires
Authors: Siddique Rezina , Sirinakis George , Carpenter Michael A.
Published: June 2019

Silicon Nanowires (SiNWs) have many potential applications that include diodes, transistors, logic gates, circuitry, and sensors. SiNWs also open the possibility for integrating optoelectronics with microelectronics, since silicon has semiconducting properties and amorphous silicon nanowires have been shown to emit blue light. It has been demonstrated that SiNWs have tunable electrical properties, depending on the dopant used. With such a range of applications, the ability to mass-produce silicon nanowires simply and easily with no other source of silicon needed other than the substrate itself will prove very useful. Such methods have previously been reported, but our method involves production of the SiNWs at a lower temperature than those widely observed. A (100) silicon substrate was cleaned for five minutes each in ethanol followed by acetone. Films with thicknesses of less than 20 nm of either gold or 60/40 gold/palladium were deposited on the substrate through physical vapor deposition to serve as the growth center for the SiNWs. The samples were placed in a furnace and annealed to 900° C, under a 1500 sccm flow of argon at atmospheric pressure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for characterization of the SiNWs. The resulting SiNWs were amorphous in structure and very convoluted, with lengths on the order of tens of microns, diameters of 40 nm and a bed thickness of approximately 10 m. The effect of varying gold concentration, annealing time, temperature, and gas flow rate were then investigated. The results, which will be discussed in further detail, indicate that adjusting these parameters allows for control over the length, thickness, density, and morphology of the nanowires.
AC Electrodeposition of Uniform High Aspect-Ratio Metal Nanowires in Porous Aluminum Oxide Templates
Authors: Gerein Nathan J. , Mithani Shazma S. , Haber Joel A.
Published: June 2019

The use of alternating current (ac) electrodeposition permits deposition through the resistive Al2O3 barrier layer, enabling the use of the as-grown porous aluminum oxide (PAO) template. This results in a process that is cost effective, simple, and scalable. However, achieving uniform filling using this technique is challenging. We have carried out a systematic study of the effect of multiple variables on the ac electrodeposition of copper nanowires using a fractional factorial design of experiment (FFDOE). This experiment led to the identification of template damage that occurs when continuous wave ac deposition conditions are employed, as well as to effective pulsed wave ac electrodeposition conditions. Subsequent examination of the effect of wave shape has identified the impact of this variable on electrodeposition, producing a further optimized set of ac electrodeposition conditions. The utility of these electrodeposition conditions has also been extended to the deposition of iron nanowires with similar results.
Interactions of Ge Atoms with High- ê Oxide Dielectric Surfaces
Authors: Stanley Scott K. , Ekerdt John G.
Published: June 2019

Ge is deposited on HfO2 surfaces by chemical vapor deposition (CVD) with GeH4. 0.7-1.0 ML GeHx (x = 0-3) is deposited by thermally cracking GeH4 on a hot tungsten filament. Ge oxidation and bonding are studied at 300-1000 K with X-ray photoelectron spectroscopy (XPS). Ge, GeH, GeO, and GeO2 desorption are measured with temperature programmed desorption (TPD) at 400-1000 K. Ge initially reacts with the dielectric forming an oxide layer followed by Ge deposition and formation of nanocrystals in CVD at 870 K. 0.7-1.0 ML GeHx deposited by cracking rapidly forms a contacting oxide layer on HfO2 that is stable from 300-800 K. Ge is fully removed from the HfO2 surface after annealing to 1000 K. These results help explain the stability of Ge nanocrystals in contact with HfO2.
Sol Gel Preparation of Ta2O5 Nanorods Using DNA as Structure Directing Agent
Authors: Monreala Humberto A. , Villafañe Alberto M. , Chacón José G. , García Perla E. , Martínez Carlos A.
Published: June 2019

Transition metal oxides are being considered as the next generation materials in field such as electronics and advanced catalysts; between them is Tantalum (V) Oxide; however, there are few reports for the synthesis of this material at the nanometer size which could have unusual properties. Hence, in this work we present the synthesis of Ta2O5 nanorods by sol gel method using DNA as structure directing agent, the size of the nanorods was of the order of 40 to 100 nm in diameter and several microns in length; this easy method can be useful in the preparation of nanomaterials for electronics, biomedical applications as well as catalysts.
Synthesis of Nanocarbon Materials by Carburization of Nanocrystalline Iron
Authors: Narkiewicz U. , Arabczyk W. , Kucharewicz I. , Wozniak M.J. , Matysiak H. , Kurzydlowski K.J.
Published: June 2019

Two products are formed in the process of carburization of iron with hydrocarbons: iron carbide (Fe3C, cementite) and in the next stage - carbon deposit. This paper deals with the formation of carbon deposit on nanocrystalline iron from ethylene decomposition and the reduction of its product with hydrogen.

The carburization process was controlled using spring thermobalance. The samples after carburization contained cementite and some amount of carbon deposit in the form of carbon nanofibers and carbon nanotubes. In the next step iron carbide had been reduced under hydrogen flow at 400 – 500°C and pure iron was obtained. Some carbon was hydrogenated and the morphology of the remaining carbon deposit was changed – thicker carbon nanofibers were eliminated and thinner carbon nanotubes remained.

The samples after carburization and reduction processes were characterized using XRD (X-rays Diffraction) and HRTEM (High Resolution Transmission Electron Microscopy) methods.
A Novel Spray Based Method for the Production of Semiconductor Nanocrystals
Authors: Amirav Lilac , Lifshitz Efrat
Published: June 2019

We present a novel spray based method for the formation and production of semiconductor nanocrystals that provides an attractive alternative to the commonly used epitaxial and colloidal procedures. According to this spray-based method, mainly thermospray, solutions of semiconductor salts are first sprayed into monodispersed droplets, which subsequently become solid nanoparticles by solvent evaporation. A semiconductor nanoparticle is produced from a single spray droplet upon the full vaporization of the solvent. The average diameter and size distribution of the final nanocrystals are controlled and determined by the solute concentration of the sprayed solution and by the droplet size, hence by the spray production parameters. The spray-produced nanocrystals are collected on any selected solid support. Representative results, shown in this paper, reveal the formation of CdS nanocrystals in the size range of 3 to 6 nanometer and with a size distribution of as low as five percents. A further structural analysis of these nanocrystals showed that they were formed in the zinc blend phase with high degree of crystallinity.
Growth and Characterization of [001] ZnO Nanorod Array on ITO Substrate with Electric Field Assisted Nucleation
Authors: Kim Young Jung , Shang Huamei , Cao Guozhong
Published: June 2019

This paper reports direct growth of [001] ZnO nanorod arrays on ITO substrate from aqueous solution with electric field assisted nucleation, followed with thermal annealing. Xray diffraction analyses revealed that nanorods have wurtzite crystal structure. The diameter of ZnO nanorods was 60 ∼ 300 nm and the length was up to 2.5 μm depending on the growth condition. Photoluminescence spectra showed a broad emission band spreading from 500 to 870 nm, which suggests that ZnO nanorods have a high density of oxygen interstitials. Low and nonlinear electrical conductivity of ZnO nanorod array was observed, which was ascribed to non-ohmic contact between top electrode and ZnO nanorods and the low concentration of oxygen vacancies.
Synthesis of TiO2 Nanoparticles Using Chemical Vapor Condensation
Authors: Wu Jie , Bai Guo-Ren , Eastman Jeffrey A. , Zhou Guangwen , Vasudevan Vijay K.
Published: June 2019

Nano-sized TiO2 particles are of interest for many applications, including use as photocatalysts and in heat transfer fluids (nanofluids). In the present study, TiO2 nanoparticles with controllable phase and particle size have been obtained through homogeneous gas-phase nucleation using chemical vapor condensation (CVC). The phase and particle size of TiO2 nanoparticles under various processing conditions have been characterized using x-ray diffraction and transmission electron microscopy. Chamber temperature and pressure were found to be two key parameters affecting particle phase and size. Pure anatase phase was observed for synthesis temperatures as low as 600 °C with chamber pressure varying from 20-50 Torr. When the furnace temperature was increased to 1000 °C at a pressure of 50 Torr, a mixture of anatase and rutile phases was observed, with the predominant phase being anatase. The average particle size under all the experimental conditions was observed to be less than 20 nm.