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The fabrication with high energy density and superior electrical/electrochemical properties of hierarchical porous 3D cross-linked graphene-based supercapacitors is one of the most urgent challenges for developing high-power energy supplies. We facilely synthesized a simple, eco-friendly, cost-effective heteroatoms (nitrogen, phosphorus, and fluorine) co-doped graphene oxide (NPFG) reduced by hydrothermal functionalization and freeze-drying approach with high specific surface areas and hierarchical pore structures. The effect of different heteroatoms doping on the energy storage performance of the synthesized reduced graphene oxide is investigated extensively. The electrochemical analysis performed in a three-electrode system via cyclic voltammetry (CV), galvanostatic charging–discharging (GCD), and electrochemical impedance spectroscopy (EIS) demonstrates that the nitrogen, phosphorous, and fluorine co-doped graphene (NPFG-0.3) synthesized with the optimum amount of pentafluoropyridine and phytic acid (PA) exhibits a notably enhanced specific capacitance (319 F g−1 at 0.5 A g−1), good rate capability, short relaxation time constant (τ = 28.4 ms), and higher diffusion coefficient of electrolytic cations (Dk+ = 8.8261 × 10−9 cm2 s−1) in 6 M KOH aqueous electrolyte. The density functional theory (DFT) calculation result indicates that the N, F, and P atomic replacement within the rGO model could increase the energy value (GT) from −673.79 eV to −643.26 eV, demonstrating how the atomic level energy could improve the electrochemical reactivity with the electrolyte. The improved performance of NPFG-0.3 over NFG, PG, and pure rGO is mainly ascribed to the fast-kinetic process owing to the well-balanced electron/ion transport phenomenon. A symmetric coin cell supercapacitor device fabricated using NPFG-0.3 as the anode and cathode material with 6 M KOH aqueous electrolyte exhibits maximum specific energy of 38 W h kg−1, a maximum specific power of 716 W kg−1, and ∼88.2% capacitance retention after 10 000 cycles. The facile synthesis approach and promising electrochemical results suggest this synthesized NPFG-0.3 material has high potential for future supercapacitor application.

This study determines the relationship between retention and endurance reliability for a HfOx-based resistive random access memory (ReRAM). A TiN (15 nm) / HfOx (6 nm) / Ti (10 nm) / TiN (40 nm) stacked structure is fabricated and tested to verify its basic characteristics and reliability. The high resistance states (HRS) retention behavior is characterized and is found to degrade over 100x on the endured bits because there is a sequential high temperature procedure. The degradation is reduced slightly to a ~30x drop for the endured devices with one single refresh cycle. During the endurance and retention test procedures, the HRS resistance decreases because neutral oxygen vacancy filaments grow and this cannot be reversed. The I-V characteristics for endured devices are also determined. The results show that isothermal treatment causes a gradual SET and RESET process with multiple feasible states. The thermally induced filament degradation model (isolated filament vs. continuous filament) is verified by the relationship between retention and endurance reliability. Design guidance is recommended for an improvement in ReRAM reliability.

Carbon-bridged organosilicate films deposited by using different precursors are studied by both experimentally and theoretically. It is shown that carbon-bridged OSG films have higher Young Modulus (E) than methyl-terminated films and E(phenylene) > E(ethylene) > E(methylene). However, the k-values of these films show the same tendency and this is one of the drawbacks of carbon terminated materials when they are considered as low-k candidates. It is shown that the films having a phenylene bridge can be destructed by UV light with wavelength > 200 nm while ethylene or an ethylene bridged samples are stable. Mechanism of UV initiated destruction of phenylene bridged materials is analyzed by using quantum chemical calculations. The presented results allow to conclude that the presence of long aliphatic and aromatic bridges makes OSG materials more sensitive to UV light.

Organosilicate glass-based porous low dielectic constant films with different ratios of terminal methyl to bridging organic (methylene, ethylene and 1,4-phenylene) groups are spin-on deposited by using a mixture of alkylenesiloxane with organic bridges and methyltrimethoxysilane, followed by soft baking at 120&ndash, 200 &deg, C and curing at 430 &deg, C. The films&rsquo, porosity was controlled by using sacrificial template Brij&reg, L4. Changes of the films&rsquo, refractive indices, mechanical properties, k-values, porosity and pore structure versus chemical composition of the film&rsquo, s matrix are evaluated and compared with methyl-terminated low-k materials. The chemical resistance of the films to annealing in oxygen-containing atmosphere is evaluated by using density functional theory (DFT). It is found that the introduction of bridging groups changes their porosity and pore structure, increases Young&rsquo, s modulus, but the improvement of mechanical properties happens simultaneously with the increase in the refractive index and k-value. The 1,4-phenylene bridging groups have the strongest impact on the films&rsquo, properties. Mechanisms of oxidative degradation of carbon bridges are studied and it is shown that 1,4-phenylene-bridged films have the highest stability. Methylene- and ethylene-bridged films are less stable but methylene-bridged films show slightly higher stability than ethylene-bridged films.

In the present study, the structural, morphological, compositional, nanomechanical, and surface wetting properties of Bi2Se3 thin films prepared using a stoichiometric Bi2Se3 target and a Se-rich Bi2Se5 target are investigated. The Bi2Se3 films were grown on InP(111) substrates by using pulsed laser deposition. X-ray diffraction results revealed that all the as-grown thin films exhibited were highly c-axis-oriented Bi2Se3 phase with slight shift in diffraction angles, presumably due to slight stoichiometry changes. The energy dispersive X-ray spectroscopy analyses indicated that the Se-rich target gives rise to a nearly stoichiometric Bi2Se3 films, while the stoichiometric target only resulted in Se-deficient and Bi-rich films. Atomic force microscopy images showed that the films&rsquo, surfaces mainly consist of triangular pyramids with step-and-terrace structures with average roughness, Ra, being ~2.41 nm and ~1.65 nm for films grown with Bi2Se3 and Bi2Se5 targets, respectively. The hardness (Young&rsquo, s modulus) of the Bi2Se3 thin films grown from the Bi2Se3 and Bi2Se5 targets were 5.4 GPa (110.2 GPa) and 10.3 GPa (186.5 GPa), respectively. The contact angle measurements of water droplets gave the results that the contact angle (surface energy) of the Bi2Se3 films obtained from the Bi2Se3 and Bi2Se5 targets were 80&deg, (21.4 mJ/m2) and 110&deg, (11.9 mJ/m2), respectively.

A method is built for describing the relationship between adhesion strength and chemical states of Co/polymer and Cr/polymer interfaces. Based on the chemical bonding model, the adhesion strength is confirmed to be dominated by the metal–organic complex at the interfaces. For Cr/polymers interfaces, the formation of metal–organic complex is restricted by the oxidation of metal atoms during deposition, which leads to almost no variation in adhesion from low [benzocyclobutene(BCB)] to high (AZ 4620) oxygenated polymers. On the other hand, a strong adhesion is observed at the Co/BCB interface that arises from the metal–organic bonds associated with hydroxyl groups in the polymer. The method is expected to provide clear analysis to other metal–polymer interfaces for seeking proper combination in heterogeneous integration.

In this study, amorphous silicon carbonitride (SiC x N y ) films were fabricated by radio frequency (RF) chemical vapor deposition (PECVD) using a single silazane precursor and a low power density (0.15 W/cm 3 ) for better compositional control. The effects of the precursor chemical structure (C/Si ratio, C Si N structure, and vinyl groups) and deposition temperature ( T s ) on the chemical structure and optical properties of SiC x N y films were examined using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Specifically, two new single precursors; namely, n -methyl-aza-2,2,4-trimethylsilacyclopentane (MTSCP) and 1,3-divinyl-1,1,3,3-tetramethyl-disilazane (DVTMDS) were studied and compared. SiC x N y films deposited using MTSCP involving Si C 3 N rings formed Si N and Si (CH 2 ) 3 crosslinked structures at T s ≤ 100 °C, and were then changed to predominantly Si CH 2 N Si crosslinked structures at T s > 300 °C, leading to a wide range of optical band gap from 5.2 to 3.7 eV. Compared to DVTMDS-deposited SiC x N y films, their relatively higher percentage of Si C N structure accounted for the lower optical band gap and reduced transmission. DVTMDS with di-vinyl groups readily formed a Si (CH 2 ) 2 bridge in SiC x N y films T s ≤ 200 °C, resulting in excellent optical transmittance. The transmittance in the visible wavelengths of 400 °C-deposited SiC x N y film using DVTMDS still showed 85%. Also, tunable refractive index between 1.44 and 2.10 were obtained for SiC x N y films deposited at T s ≤ 400 °C.

This study reports the material and thermoelectric properties of n-type nanocrystalline Bi-Se-Te thin films grown using pulse laser deposition (PLD) with a Bi2Se2Te single crystal as the target. In order to optimize the transport and thermoelectric properties, Bi-Se-Te thin films are fabricated by maintaining the substrate temperature (TS) between 200 and 350 °C and a helium gas pressure (PHe) from 0.027 to 86.7 Pa. Unlike the target, all deposited films unexpectedly exhibit Bi3Se2Te phase with highly c-axis orientation, because of the high re-evaporation rates of Se and Te at the elevated TS ≥ 200 °C. The estimated grain (crystalline) size ranges between 18.4 and 39.4 nm, and this monotonically increases as TS increases. The Bi3Se2Te films demonstrate excellent electrical conductivities owning to the high carrier concentration in the order of 1020 cm−3. A window of deposition conditions for high thermoelectric power factors (PF) is TS of 250–350 °C and PHe of 40 Pa. The optimal PF is 8.3 μW/cmK2 for the Bi3Se2Te film prepared at 250 °C and 40 Pa.

Organosilicate-glass films with a varying ratio of terminal methyl and bridging ethylene groups are synthesized using 1,2-bis(trimethoxysilyl)ethane/methyltrimethoxysilane mixtures and sol-gel technology. The films are characterized by Fourier Transform Infrared spectroscopy, Ellipsometric Porosimetry and Positron Annihilation Spectroscopy. The hard bake at 400 °C generates the final pore structure, which depends on the curing environment. It is shown that ethylene bridge is destructed during the hard bake in the air via formation of peroxide radicals that form ≡SiOH during the transformation. Continuous hard bake leads to condensation of silanol groups and form a structure similar to the ordinary silica. The pore size of highly porous materials (>30%) is larger in air cured films. Destruction of the ethylene bridge makes the films matrix soft and micropores collapse due to the capillary forces during the template evaporation. It leads to the film shrinkage, increases the size of internal voids. The air cured samples showed better mechanical properties than N2 cured ones although in the last case ethylene bridging groups were preserved. The reason is that the collapse of micropores increase the internal density and creates more favorable condition for condensation of silanol groups.

We investigated the microstructure changes in abnormal grain growth of nanotwinned Cu (nt-Cu) upon annealing by electron backscattered diffraction (EBSD) and focused ion beam (FIB). The nt-Cu films were produced by electrodeposition on a Si wafer with a barrier/seed layer of TiW/Cu. When a 3 μm thick nt-Cu film was annealed at 350 °C for 45 min, its microstructure was found to have changed from the (111) oriented twins to the (200) oriented grains with an average grain size larger than 100 μm. When the nt-Cu film is thicker than 5 μm, the change can occur at a lower temperature of 300 °C. We observed that there is a critical abnormal grain growth temperature, below which no microstructure change can occur. We propose that it is due to nucleation limitation. After nucleation, the growth is highly anisotropic, where the lateral growth is at the least one order of magnitude faster than the normal growth. We have attempted to use JMAK theory of phase transformation to analyze the abnormal grain growth kinetics, yet we obtained very little success.

In this work, SiCxNy-based resistive switching memory by using a single precursor for the back end of line (BEOL) integration has been investigated. SiCxNy films were deposited on the aluminum (Al) substrates using plasma enhanced atomic layer deposition (PEALD) method. The effects of SiCxNy chemical structure with respect to resistive switching characteristics have been studied, and the results suggest that the resistive switching mechanism is dominated by the interfacial Schottky junction with SiCxNy composition. This work not only demonstrates a PEALD method in fabricating SiCxNy-based electronics active devices but also provides additional insights into the interaction between the electrical and chemical structures in bi-functional resistive switching or threshold switching behavior. A demonstrated PEALD tool with simple single-precursor for SiCxNy deposition shows excellent feasibility to be used as functional memory and selector devices, further giving the potential pathway for advanced BEOL process integration.

Organosilicate (OSG) low dielectric constant films containing different concentrations of 1,3- and 1,3,5-benzene bridges between Si atoms are fabricated using 1,3,5-tribromobenzene via spin-on deposition and evaporation induced self-assembling. Chemical composition, pore structure, mechanical, dielectric and hydrophobic properties of as-prepared benzene bridged OSG thin films are studied using Nuclear magnetic resonance, Fourier-transform infrared spectroscopy, Ellipsometric porosimetry, Nanoindentation, CV measurements and water contact angle. The precursors were synthesized by using two methods with the goal of understanding the effect of 1,3,5-benzene concentration on the films properties. It is shown that the films have very small pore size that is not changing with porosity. No significant change in mechanical properties was observed at two different ratios of 1,3- and 1,3,5-benzene bridged films.

Low-k SiCxNy films were prepared using radio-frequency plasma-enhanced chemical vapor deposition (PECVD), with only 1,3,5-trimethyl-1,3,5-trivinylcyclotrisilazane (VSZ) as the precursor; VSZ has cyclic Si–N–Si linkages and three pendent vinyl groups. At lower PECVD temperatures, SiCxNy films possess relatively low film densities, indicating the existence of a loose structure or voids within the cross-linked matrix structure. The pore morphology of SiCxNy films deposited at distinct temperatures were examined using grazing-incidence small-angle X-ray scattering, while the chemical bondings and structural information were analyzed using Fourier-transform infrared spectroscopy. At 100 °C, SiCxNy films without porogen displaying 4.9 nm pores and a mean pore spacing of 30.1 nm generated low-density films because Si-(CH2)n-Si and/or Si-(CH2)n-CH3 could be incorporated free volume into the N–Si–C cross-linked structure under plasma deposition. At 300 °C, the N–Si–C cross-linked structure and the some organic phase were disrupted and transformed into a denser structure, reducing pore size (3.5 nm) and losing pore correlation. Thus, low deposition temperatures facilitate the formation of large pores and the ordering of the pores. Post annealing converted the 100 and 300 °C as-deposited SiCxNy films into loose and dense structures, respectively, and maintained slightly reduced pore size and pore correlation in the annealed films.

Nanostructured n-type bismuth telluride (Bi2Te3) thin films were grown on SiO2/Si (1 0 0) substrates at argon ambient pressure (PAr) of 80 Pa by pulsed laser deposition (PLD). The effects of film morphologies, structures, and compositions on the thermoelectric properties were investigated. At a substrate temperature (Ts) of 220–340 C, stoichiometric films with highly (0 0 l)-oriented and layered structures showed the best properties, with a carrier mobility l of 83.9–122.3 cm 2 /Vs, an absolute Seebeck coefficient |a |o f 172.8–189.7 lV/K, and a remarkably high power factor (PF) of 18.2–24.3 l Wc m � 1

Low-k porous SiCxNy films were prepared through plasma-enhanced chemical vapor deposition, using 1,3,5-trimethyl-1,3,5trivinylcyclotrisilazane (VSZ) as the matrix precursor and epoxycyclohexane (ECH) as a porogen. The effects of porogen loading and deposition temperature on porogen incorporation, pore morphology, and the properties of porous SiCxNy films were examined. In addition, the impact of film shrinkage and the corresponding nanopore structures after annealing were studied. The porosity of films deposited at 100◦C increased from 1.8% to 19.8% when ECH loading increased to 30%, above which the porosity remained nearly constant because of high film shrinkage. The pore size decreased slightly from 4.1 to 3.7 nm when ECH loading increased to 30%, above which the pores became larger and were broadly distributed. By contrast, increasing deposition temperature at 20% ECH loading decreased porogen incorporation and increased film density. The porosities and pore size of films decreased, respectively, when the deposition temperature increased. A short-range ordering of pores was observed only at low deposition temperatures because the N-Si-C cross-linked structures and organic phase were present. Optimized processing parameters facilitated the fabrication of low-k porous SiCxNy films exhibiting 19.8% porosity, 3.7-nm pores, a k value of 3.18, and an elastic modulus of 7.7 GPa. © The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0031501jss] All rights reserved.

This study demonstrates that the electromigration (EM) behavior of dual damascene Cu lines is strongly affected by the layout which surrounded the tested EM lines, especially for Cu line below [email protected] used for 40nm or below technologies. The Cu EM lifetime declines as the number of local dummy lines increase, and the global dummy line density increases with the width of the Cu line below [email protected] This work presents mechanisms of layout effects that explain the EM characteristics and can be exploited to improve the layout effect. Therefore, not only the stressed Cu line structures, but also the surrounding layouts must to be considered in assessing EM reliability of a real IC circuit in 40nm or below technology.

In this paper, the interfacial adhesion strength between metal layer and benzocyclobutene (BCB) polymer dielectric in 3-D integration applications is investigated. The effects of layer thickness, layer stacking order, and additional adhesion layer of titanium (Ti) layer between copper (Cu) and BCB polymer are investigated. Surprisingly, the conventional titanium adhesion layer commonly used in the semiconductor industry weakens the interfacial adhesion strength between copper and BCB. Additionally, to figure out the interfacial adhesion mechanisms, the interfacial structures probed by sum-frequency-generation vibrational spectroscopy are correlated to the adhesion strengths measured from corresponding sample interfaces. It is found that ordered C-H groups at the metal/BCB interface, such as titanium/BCB or molybdenum/BCB, lead to weak interfacial adhesion strength, whereas disordered interfaces, i.e., copper/BCB, lead to strong interfacial adhesion strength.

The effect of absorbed moisture on the electrical characteristics and reliability of low dielectric constant materials (low-k) was investigated in this study. The experimental results reveal that porous low-k dielectrics absorb more moisture than dense low-k dielectrics. This absorbed moisture degrades the electrical performance and reliability of both classes of low-k dielectrics. Annealing at a higher temperature of 400^oC is required to decompose the physically-adsorbed moisture and thereby restore reliability performance. However, the chemically-adsorbed moisture seems to be difficult to remove by annealing at 400^oC, causing a degraded TDDB performance.

Polycrystalline, thermoelectric thin films of bismuth selenide (Bi 2 Se 3 ) were grown on SiO 2 /Si (1 1 1) substrates, using pulsed laser deposition (PLD). Bi 2 Se 3 films with highly c -axis-oriented and controlled textures were fabricated by maintaining the helium gas pressure ( P ) between 0.7 and 173 Pa and the substrate temperature ( T s ) between 200 and 350 °C. The carrier concentration ( n ) of films decreased with increasing P , which was attributed to the increase of Se concentration from Se deficiency ( P ≤ 6.7 Pa) to stoichiometry to slight Se enrichment ( P ≥ 40 Pa). The Seebeck coefficient ( S ) was enhanced considerably because of the reduction in n , following the S ∼ n − 2/3 relation approximately. The average grain size increased from approximately 100 to 500 nm when T s was raised from 200 to 350 °C, resulting in enhanced carrier mobility ( μ ) and electrical conductivity ( σ ) and a reduced full width at half maximum of (0 0 6) peaks. The shape of grains transformed from rice-like at T s of 200–250 °C to layered-hexagonal platelets (L-HPs) or super-layered flakes (S-LFs) at T s of 300–350 °C. Films that were grown at 300 °C and 40 Pa and contained highly c -axis oriented L-HPs possessed the highest power factor (PF = S 2 σ ), which reached 5.54 μW cm −1 K −2 , where S = 75.8 μV/K and σ = 963.8 S cm −1 .

Low dielectric constant (low-k) porous films are needed for advanced technologies to improve signal propagation. The integration of porous low-k films faces more severe challenges due to the presence of porosity. Plasma treatments have been considered to be critical steps to impact the low-k films' properties. In this study, the effect of various H2/He plasma treatments on the porous low-k dielectrics deposited by plasma enhanced chemical vapor deposition was investigated. All the plasma treatments resulted in the formation of a thin and dense layer on the surface of the porous low-k films. Additionally, the properties of this top dense layer are modified and changed for the standard H2/He plasma treatment, leading to a degraded electrical and reliability performance. However, H2/He plasma-treated low-k dielectric by the remote plasma method shows a better electrical and reliability performance. As a result, the remote plasma treatment on the porous low-k dielectrics appears to be a promising method in the future interlayer dielectrics application.

The effect of absorbed moisture on the electrical and reliability characteristics of the low-k dielectrics was investigated in this study. The experimental results indicate that the porous low-k dielectrics would absorb more moisture as compared to the dense low-k dielectrics. This absorbed moisture degrades the electrical and reliability performance of the low-k dielectrics. A higher temperature anneals at 400oC is needed to decompose physically-adsorbed water, which is benefit to restore reliability performance. On the other hand, the chemically-adsorbed moisture seems to be difficult to be removed by a 400oC annealing, causing a degraded TDDB performance.

Bismuth selenide (Bi 2 Se 3 ) thin films were grown on SrTiO 3 (111) (STO) substrates using pulsed laser deposition (PLD). The structural, morphological, electrical, and transport properties were studied at various substrate temperatures ( T S ) from 120 to 350 °C. Amorphous films grown at T S T S ≥ 180 °C exhibited metallic behavior. Bi 2 Se 3 thin-films were epitaxially grown on STO substrates at 300 and 350 °C. Thickness-dependent characteristics were also investigated for optimized Bi 2 Se 3 films deposited at T S = 230 °C. The semiconducting or metallic characteristics of Bi 2 Se 3 films prepared using PLD were observed through electrical and transport results.

a b s t r a c t Novel agarose gel electrolytes are prepared by allylimidazolium iodides-based ionic liquids and environmentally benign co-solvents (propylene carbonate (PC) and dimethyl sulfoxide (DMSO)) for dye-sensitized solar cells (DSSCs). Among 1-allyl-3-ethylimidadolium iodide (AEII), 1-allyl-3-propylimidazolium iodide (APII), 1-3-diallylimidazolium iodide (DAII), and 1-methyl-3propylimidazolium iodide (MPII) ionic liquids, the agarose gel electrolyte containing AEII exhibits the best DSSC performance. The efficiency of the DSSC using the agarose gel electrolyte containing 1.5 M AEII and 0.65 wt% agarose is 5.89% with the highest I3 − diffusion coefficient of 7.7 × 10−6 cm2 s−1. The performance of the AEII ionic liquid-based agarose gel electrolyte is comparable to the liquid electrolyte based on 3-methoxypropionitrile (MPN) (5.84%) under illumination at AM 1.5, 100 mW cm−2. Moreover, the DSSC performance of the allylimidazolium iodides ionic liquid-based agarose electrolyte is determined by the interaction between ionic liquid and agarose, which affects the rigidity of the ion channels and the I3 − diffusion coefficient.

The effects of thermal annealing on the physical, electrical properties and reliability of porogen-containing and porogen-free ultralow- k dielectrics prepared by plasma-enhanced chemical vapor deposition (PECVD) are investigated. The porogen-free low- k dielectrics are obtained by using UV curing process to removal organic sacrificial phase and to generate open porosity. The results are compared with PECVD porogen-containing low- k films fabricated without UV curing process and PECVD low- k dielectrics deposited without organic sacrificial phase. The experimental results show that all low- k films remained stable after they were experimentally heating to temperatures up to 700 °C. The non-porous low- k films also showed the highest reliability. Although the porous-free low- k film requires an additional UV curing process, the heat stress confirmed that its thermal stability was better than that of the porogen-containing low- k film. At an annealing temperature above 500 °C, the heating process is comparable to UV curing, but does not provide Si O Si cross-linking within the film. At an annealing of 600 °C, the porogen-free low- k films have a relatively higher breakdown electric-field and longer failure time in comparison to the porogen-containing low- k films. However, pores generated in porogen-containing low- k films at high temperature cause reliability to degrade with annealing temperature.

The surface state, electrical, and reliability characteristics of copper (Cu) interconnects after ammonia (NH3) or hydrogen (H2) plasma treatment were investigated in this study. The experimental results show that H2plasma treatment has excellent Cu oxide removal efficiency, less impact on the formation of Cu hillocks, and less damage on low-dielectric constant (low-k) dielectrics in comparison to NH3plasma treatment. However, H2plasma treatment results in a higher leakage current between the Cu lines and shorter electromigration (EM) failure time due to a weaker adhesion strength at the Cu film interface. On the other hand, NH3plasma treatment without the sufficient treatment time would lead to an increased probability of delamination at the Cu/barrier layer interface since the Cu oxide layer can not be completely removed. As a result, extending NH3plasma treatment time can efficiently reduce the adhesion failure and enlarge EM resistance as well.

An anionic surfactant, sodium dodecylbenzenesulfonate (NaDBS) and a cationic surfactant, domiphen bromide (DB) were used to modify the surface potential of polystyrene (PS) porogen in a post-integration porogen removal scheme. The effect of surfactant modification on the porogen and pore size in the low-k methylsilsesquioxane (MSQ)/PS hybrid films at 10 wt% PS loading, under a slow curing rate, was studied by grazing incidence small-angle X-ray scattering, viscosity measurement, and Fourier-transform infrared analysis. For PS porogen without modification, the porogen aggregated and its size increased from 10.0 to 16.5 nm at different rates, up to 200 C, depending on the porogen diffusivity and steric hindrance by the successively cross-linked MSQ matrix at T P Tg. In contrast, the NaDBS- and DB-modified porogens with higher surface potential impede their aggregation within the cross-linking MSQ matrix, resulting in a smaller porogen size, by electrostatic repulsion and increased viscosity due to electroviscous effect.

The structural and morphological transformations of TiO 2 nanotube arrays (TNAs) treated by excimer laser annealing (ELA) were investigated as a function of the laser fluence using parallel and tilted modes. Results showed that the crystallinity of the ELA-treated TNAs reached only about 50% relative to that of TNAs treated by furnace anneal at 400 °C for 1 h. The phase transformation starts from the top surface of the TNAs with surface damage resulting from short penetration depth and limited one-dimensional heat transport from the surface to the bottom under extremely short pulse duration (25 ns) of the excimer laser. When a tilted mode was used, the crystallinity of TNAs treated by ELA at 85° was increased to 90% relative to that by the furnace anneal. This can be attributed to the increased area of the laser energy interaction zone and better heat conduction to both ends of the TNAs.

TiO2 nanowires connected directly with TiO2 nanotubes arrays (TNWs/TNAs) were successfully fabricated with a mixture of ethylene glycol and water that contained NH4F electrolyte via a one-step method without mechanical stirring. The morphology of the TNWs/TNAs structure was investigated by changing the anodizing voltage and processing time to elucidate its formation mechanism. Well-developed anodic oxide nanowires are only observed under specific anodizing voltage and processing time conditions. The evolution of TNWs follows four stages: (1) thinning of the tube wall thickness with high roughness near the TNA mouths, (2) forming strings of through holes in the upper section of the TNAs, (3) splitting into nanowires, and (4) collapsing and further thinning of nanowires. For photocatalytic application, TNWs/TNAs film demonstrated a better photocatalytic performance than regular TNAs due to higher surface area predominantly and improved charge transport. Moreover, TNWs/TNAs film (20 nm wire/40 nm pore diameter) achieved a performance comparable to that of the film made from TiO2 nanoparticles. © 2012 The Electrochemical Society. [DOI: 10.1149/2.063208jes] All rights reserved.

for increased mechanical and tribo-logicalperformance,havebeenthesubjectofmuchresearch,becausethey retain the ready fragments and allow better control of the com-position of films, compared to multi-precursors.In this paper, a new, cyclic organosilazane, 1, 3, 5-trimethyl-1,3, 5-trivinyl- cyclotrisilazane (VSZ) with a cyclic Si-N-Si, pendentCH

A methyltrimethoxysilane (MTMS) modified silica zeolite (MSZ) film has been prepared using a high ratio of MTMS/tetraethyl orthosilicate (TEOS). This study investigated the effect of MTMS addition on the low-k matrix structure, elastic modulus, and pore geometry. High MTMS loading reduced the k-value of MSZ film down to 2.0, but yielded a lower elastic modulus, 2.7 GPa. Based on grazing-incidence small-angle X-ray scattering (GISAXS) 2D pattern analysis, the pore geometry of the MSZ film was found to be small but elliptical (Rin-plane ∼3.75 nm; Rout-of-plane ∼3.04 nm). The elliptical pore shape was formed by a collapse of film structure at 150–160◦C as a result of ∼32% thickness shrinkage due to the decomposition of tetra-n-propylammonium hydroxide (TPAOH), a structure directing catalyst, and due to a large degree of crosslinking reaction in the silica matrix. Combining GISAXS, 29Si-NMR, and FT-IR results, we propose that the lower elastic modulus was caused by the incorporation of a large amount of methyl groups from the MTMS precursor and the elliptic pores. © 2012 The Electrochemical Society. [DOI: 10.1149/2.074203jes] All rights reserved.

Two high-temperature pore generators (porogens) have been used to study the effect of porogen structure on moisture uptake and k-value in methylsilsesquioxane/porogen hybrid films and their corresponding porous films in a postintegration porogen removal scheme. Poly(styrene-b-4-vinylpyridine) containing di-block structure and pyridine polar group leads to higher moisture uptake and k-value in the hybrid films as compared to poly(styrene-block-butadiene-block-styrene) with symmetrical structure and nonpolar groups. Moreover, the moisture uptake behavior in both as-prepared hybrid films is in physical sorption mode based on their reversible adsorption-desorption curve measured by quartz crystal microbalance. After porogen removal, the k-values of porous films are favorably not influenced by porogen structures, and their moisture uptake is as low as 1.78 wt% even at 40 vol.% porosity. However, based on the simulation of the modified-Rayleigh model, the porous films are found to possess 0.4 vol.% chemisorbed moisture on the pore surface, resulting in 17-23% deviation from the ideal k-values.

article i nfo We studied the effects of CF4 plasma surface treatment on moisture uptake, diffusion, and the water-vapor- transmission-rate (WVTR) of poly(ethylene terephthalate) (PET) films using a CF4 plasma generated by a radio-frequency (13.56 MHz) reactive ion etcher at 60 W. After CF4 plasma treatment, moisture uptake in PET film was reduced with increasing treatment time due to (1) lower adsorption of water molecules onto the hydrophobic surface, as confirmed by contact angle measurement and XPS analysis, and (2) reduced diffusion coefficient through the denser fluorinated top-layer as detected by XRR. In addition, the WVTR of untreated PET is found to be 2.7 g/m 2 /day, while a significant reduction (84%) of WVTR to 0.43 g/m 2 /day, is achieved for

The ionic agarose gel electrolytes are prepared by using environmental benign solvents and co-solvents to improve the agarose solubility and capacities of the additives for dye-sensitized solar cells. The effects of single solvents (dimethyl sulfoxide (DMSO), propylene carbonate (PC), propylene glycol, triethylene glycol, and tetraethylene glycol) and DMSO-based co-solvents are examined on the conductivities, diffusion coefficients of triiodide, and energy conversion efficiencies. The highest conductivity, 14.2 mS cm−1, and the highest diffusion coefficient of triiodide, 2.7 × 10−6 cm2 s−1, are achieved for the electrolyte containing the co-solvent of 80 vol.% PC and 20 vol.% DMSO. The environmental benign co-solvent such as DMSO/PC can significantly increase the conversion efficiency to 3.4% with agarose compared to pure MPII with agarose (1.4%), while retaining ∼80% of the energy conversion efficiencies of the reference cell without agarose under the illumination at AM 1.5, 100 mW cm−2.

For porous low-k materials using a templating porogen, one of the challenges is the tendency of porogens to aggregate, leading to large pore size/distribution and exacerbated aggregation at higher porosity. Although reactive porogen is effective to limit porogen aggregation and reduce pore size [1], little work explores the reactive high-temperature porogen for the late-porogen removal integration scheme. In this study, a reactive high-temperature porogen, triethoxy(polystyrene)silane (TEPSS) was synthesized by atom transfer radical polymerization (ATRP) [2] to obtain tight molecular weight (MW) distribution, then grafted onto the poly(methyl-silsesquioxane) (MSQ) matrix to circumvent the phase separation between matrix and porogen in the conventional hybrid approach. Upon the removal of polystyrene by thermal decomposition, uniformly distributed, spherical pores have been successfully achieved for mesoporous low-k MSQ films without porogen aggregation at high porosity up to 40% (k=2.37).

Nitrogen-doped TiO2 nanotube arrays (N-TNAs) were successfully fabricated by a simple thermal annealing process in ambient N2 gas at 450 &deg, C for 3 h. TNAs with modified morphologies were prepared by a two-step anodization using an aqueous NH4F/ethylene glycol solution. The N-doping concentration (0&ndash, 9.47 at %) can be varied by controlling N2 gas flow rates between 0 and 500 cc/min during the annealing process. Photocatalytic performance of as-prepared TNAs and N-TNAs was studied by monitoring the methylene blue degradation under visible light (&lambda, &ge, 400 nm) illumination at 120 mW&middot, cm&minus, 2. N-TNAs exhibited appreciably enhanced photocatalytic activity as compared to TNAs. The reaction rate constant for N-TNAs (9.47 at % N) reached 0.26 h&minus, 1, which was a 125% improvement over that of TNAs (0.115 h&minus, 1). The significant enhanced photocatalytic activity of N-TNAs over TNAs is attributed to the synergistic effects of (1) a reduced band gap associated with the introduction of N-doping states to serve as carrier reservoir, and (2) a reduced electron‒hole recombination rate.

Low-k dielectric silicon carbonitride (SiCxNy) films are deposited by plasma-enhanced chemical vapor deposition using a carbon-rich silazane precursor, N-methyl-aza-2,2,4-trimethylsilacyclopentane (SiC7NH17), at 100 °C. The post-treatments of SiCxNy films are carried out by thermal annealing and a broadband UV-assisted thermal annealing (UV-annealing) at 400 °C for 5 min. Compared to the thermal annealing treatment, UV-annealing can improve both dielectric and mechanical properties of low-k SiCxNy films. Under thermal annealing, SiCxNy films show great thermal stability, but little structural change. In contrast, upon UV-annealing, most of the Si–H and N–H bonds are broken up, which induces more Si–N cross-linking and converts Si–C matrix into Si–N matrix. The ethylene bridges in Si–(CH2)2–Si also remain intact, but the unbridged hydrocarbons in Si–(CH2)2–N and Si–CH2–CH3 bonds decompose completely during the UV-annealing process. These account for the reduced dielectric constant to k = 3.2 from 3.6 and a...

A late porogen removal scheme was used to make low-k materials (k = 2.72 to 2.02) using methylsilsesquioxane (MSQ) and a high-temperature porogen, poly(styrene-b-4-vinylpyridine) (PS-b-P4VP), to circumvent the reliability issues related to as-deposited porous dielectric. Based on the nanoindentation and Fourier transform infrared spectroscopy (FTIR) analysis, the moduli of the hybrid films were found to be higher than their porous forms, and even better than the dense MSQ film, for porogen loading below a critical level (˜69.5 vol%). This could be attributed to their enhanced degree of cross-linking in MSQ as evidenced by the network/cage structural ratios. Besides, high-temperature porogen plays different roles during the cross-linking of MSQ depending on its loadings. In this study, with immediate loading at 16.7 vol%, PS-b-P4VP can serve as plasticizer to enhance the degree of cross-linking, but at a large loading >16.7 vol%, it becomes a steric hindrance reducing the degree of cross-linking.

In present condition, the ever-growing demand for sustainable and renewable energy resources, limited fossil fuels and environment issues like solar, wind, global warming and hydro energy have become a focal point of the leading world power and research [1-2]. Recently, supercapacitors due to their high power density (>10 kWkg-1), long cycle life (>105 cycles) and fast charge discharge response have captivated much interest. However, the poor energy density of supercapacitors (SCs) is the main issue, which hinders their potential industrial utilization [3-4]. However poor energy density of supercapacitor (SCs) is the main issue, which hinders their high potential industrial utilization. Basically, carbon based materials (CNT, graphene, activated carbon and mesoporous carbon) are used as the active electrode materials for the development of practical electric double layer supercapacitors (EDLCs). Besides this, the chemical doping of foreign atoms (such as N, B, P, I and S) in the carbon based materials is an effective tool to achieve the electron-donor characteristics, which effectively enhance the electrochemical performance of the material [5]. Such doping of heteroatoms in graphene would provide acid/base characteristics for upgraded electrochemical properties. Among the pure graphene, N and B co-doped graphene has attracted a lot of interest because of its superior electrochemical properties, cost-effective and eco-friendly behavior. In this work we developed a simple one step hydrothermal method to prepare N, B co-doped graphene at low temperature 180°C. Melamine diborate precursor has been utilized as source of N and B. Electrodes fabrication process done by the electrophoretic deposition (EPD) technique at 50 V. Best fabricated sample, labeled as NBG-0.7, exhibits highest specific capacitance of 217 Fg-1 at the scan rate of 5 mVs-1 which is about 1.2 times higher than the specific capacitance (180 Fg-1 at 5 mVs-1) of pristine reduced graphene oxide. The structural analysis, morphological studies, thermal stability and specific surface area of pure rGO and N, B co-doped graphene have been investigated via XRD, FE-SEM, TGA, TEM and BET surface area analyzer. The electrochemical measurements have been carried out using three electrodes measurement system in 6M KOH electrolyte using cyclic voltammetry (CV), galvanostatic charge-discharge cycling (GCD) and electrochemical impedance spectroscopy (EIS). Keywords: N, B co-doping; reduced graphene oxide; energy storage; supercapacitors References： [1] T. R. Cook, D. K. Dogutan, S. Y. Reece, Y. Surendranath, T. S. Teeth and D. G. Nocera, Chem. Rev., 2010, 110, 6474. [2] Renewable Energy Policy Network for the 21 st Century (REN21), Renewables Global Status Report, 2016, ISBN 978–3-9818107–0-7. [3] H. Jiang, P. S. Lee and C. Li, Energy Environ. Sci., 2013, 6, 41. [4] X. Lang, A. Hirata, T. Fujita and M. Chen, Nat. Nanotechnol., 2011, 6, 232. [5] Yong Qin, Jie Yuan , Juan Li, Dongchang Chen, Yong Kong, Fuqiang Chu ,Yongxin Tao, and Meilin Liu Adv. Mater. 2015, 27, 5171–5175. Figure 1