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Cellulosic materials are widely used in daily life for paper products and clothing as well as for emerging applications in sustainable packaging and inexpensive medical diagnostics. Cellulose has a high density of hydroxyl groups that create strong intra- and interfiber hydrogen bonding. These abundant hydroxyl groups also make cellulose superhydrophilic. Schemes for hydrophobization and spatially selective hydrophobization of cellulosic materials can expand the application space for cellulose. Cellulose is often hydrophobized through wet chemistry surface modification methods. This work reports a new modification method using a combination of atomic layer deposition (ALD) and atmospheric heating to alter the wettability of purely cellulosic chromatography paper. We find that once the cellulosic paper is coated with a single ALD cycle (1cy-ALD) of Al2O3, it can be made sticky superhydrophobic after a 150 °C ambient post-ALD heating step. An X-ray photoelectron spectroscopy investigation reveals that the ALD-modified cellulosic surface becomes more susceptible to adsorption of adventitious carbon upon heating than an untreated cellulosic surface. This conclusion is further supported by the ability to use alternating air plasma and heat treatments to reversibly transition between the hydrophilic and hydrophobic states. We attribute the apparent abruptness of this wetting transition to a Cassie-Wenzel-like phenomenon, which is also consistent with the sticky hydrophobic wetting behavior. Using scanning probe methods, we show that the surfaces have roughness at multiple length scales. Using a Cassie-Wenzel model, we show how a small change in the surface's Young's contact angle-upon adsorption of adventitious carbon-can lead to an abrupt increase in hydrophobicity for surfaces with such roughnesses. Finally, we demonstrate the ability to spatially pattern the wettability on these 1cy-ALD-treated cellulosic papers via selective heating. This ALD-treated hydrophobic paper also shows promise for microliter droplet manipulation and patterned lab-on-paper devices.

Nonvolatile memory thin-film transistors (TFTs) fabricated on paper substrates were proposed as one of the eco-friendly electronic devices. The gate stack was composed of chicken albumen gate insulator and In-Ga-Zn-O semiconducting channel layers. All the fabrication processes were performed below 120 °C. To improve the process compatibility of the synthethic paper substrate, an Al2O3 thin film was introduced as adhesion and barrier layers by atomic layer deposition. The dielectric properties of biomaterial albumen gate insulator were also enhanced by the preparation of Al2O3 capping layer. The nonvolatile bistabilities were realized by the switching phenomena of residual polarization within the albumen thin film. The fabricated device exhibited a counterclockwise hysteresis with a memory window of 11.8 V, high on/off ratio of approximately 1.1 × 10(6), and high saturation mobility (μsat) of 11.5 cm(2)/(V s). Furthermore, these device characteristics were not markedly degraded even after the delamination and under the bending situration. When the curvature radius was set as 5.3 cm, the ION/IOFF ratio and μsat were obtained to be 5.9 × 10(6) and 7.9 cm(2)/(V s), respectively.

Indium Gallium Zinc Oxide (IGZO) films are deposited using plasma-enhanced spatial Atomic Layer Deposition (sALD) on substrates as large as 32 cm x 35 cm. Excellent uniformity and thickness control leads to high-performing and stable co-planar top-gate self-aligned (SA) thin-film transistors (TFTs), demonstrating the viability of atmospheric spatial ALD as a novel deposition technique for the flat-panel display Industry.

In this work, we evaluated the oxygen evolution performance of cobalt oxide (CoOx)-coated carbon fiber paper in electrochemical water splitting. For a uniform coating of CoOx layers along the carbo...

It remains a great challenge for the simple and affordable production of membranes for oil/water separation. We prepare low-cost but highly efficient paper-based membranes for oil/water separation through hydrophobic modification to filter papers. The simple modification contains only two steps: a thin layer of aluminum oxide is first coated on the surface of the filter paper by atomic layer deposition, and silane molecules are subsequently coupled on the precoated aluminum oxide layer via their reaction with hydroxyl groups on the surface. Both the alumina layer and the silanization layer are very thin with a total thickness less than 10 nm. The modified filter paper is endowed with strong hydrophobicity and oleophilicity, therefore exhibits strongly retarded permeation to water and enhanced permeation to nonpolar oils. The modified filter paper is demonstrated to show excellent separation efficiencies greater than 90% in the separation of various types of oils and organic solvents from their mixtures wi...

Surface modification of cellulosic paper is demonstrated by employing plasma assisted atomic layer deposition. Al2O3 thin films are deposited on paper substrates, prepared with different fiber sizes, to improve their barrier properties. Thus, a hydrophobic paper is created with low gas permeability by combining the control of fiber size (and structure) with atomic layer deposition of Al2O3 films. Papers are prepared using Kraft softwood pulp and thermomechanical pulp. The cellulosic wood fibers are refined to obtain fibers with smaller length and diameter. Films of Al2O3, 10, 25, and 45 nm in thickness, are deposited on the paper surface. The work demonstrates that coating of papers prepared with long fibers efficiently reduces wettability with slight enhancement in gas permeability, whereas on shorter fibers, it results in significantly lower gas permeability. Wettability studies on Al2O3 deposited paper substrates have shown water wicking and absorption over time only in papers prepared with highly refined fibers. It is also shown that there is a certain fiber size at which the gas permeability assumes its minimum value, and further decrease in fiber size will reverse the effect on gas permeability.

The growth of metal organic framework (MOF) nanocrystal material onto the flexible non-woven fabric is an advanced strategy to expand its practical applications. In this study, a novel polyphenylene sulfide (PPS) paper-based sensor (Eu-MOF@ALD-PPS) was designed and successfully fabricated for efficient sensing of Fe3+. The PPS non-woven fabric was first modified by atomic layer deposition (ALD) technology, and then the Eu-MOF nanocrystals can formally grow on it via hydrothermal approaches. It exhibited excellent solvent resistant (water, methanol, ethanol, DMF and acetone) and thermal stability (120 °C). In addition, the obtained Eu-MOF@ALD-PPS showed high selectivity and sensitivity in response to Fe3+ among many metal ions (Na+, K+, Zn2+, Ni+, Mg2+, Ag+, Ba2+, Ga2+, Cu2+, Gd2+, Co2+ and Fe3+). The sensing mechanism investigation revealed that the weak interactions of Fe3+ with oxygen atoms of hydroxyl and carboxylic acids protruding into the pores of MOFs quenched the luminescence of PPS paper-based sensor effectively. This study provides a promising method to fabricate flexible sensor for detection of Fe3+.

A highly efficient adsorbent containing a Cu-BTC/CuO/CFP composite with a microporous copper benzene–1,3,5-tricarboxylate/CuO coating on a macroporous carbon fiber paper was designed via atomic layer deposition with the synthesis time of 6 h. The existing moderate CuO in Cu-BTC/CuO/CFP forms micropores between CuO and Cu-BTC and CuO and CFP to promote selectivity of CH4/N2. The effects of synthesis time and CuO content on the selectivity of CH4/N2 and effective thermal conductivity were experimentally investigated. The pressure drop and adsorption rate of the adsorption bed and temperature response of the desorption bed were numerically predicted. The selectivity of equimolar CH4/N2 for Cu-BTC/CuO/CFP (0.30 : 0.13 : 0.57) (6 h) is 2.15–2.65 times higher than that of pure Cu-BTC. The Cu-BTC/CuO/CFP material has higher effective thermal conductivity, lower pressure drop, higher adsorption rate, and better temperature uniformity compared to pure Cu-BTC powder in the adsorption bed.

Amorphous V2O5 (a-V2O5) thin films were conformally coated onto the surface of hydroxyl (–OH) functionalized multi-walled carbon nanotubes (CNTs) and carbon nanotube (CNT) paper using atomic layer deposition (ALD). In order to achieve 3 Li+ intercalation (442 mA h g−1) and prevent V2O5 dissolution at 1.5 V, a conformal TiO2 protective layer is coated on the surface of V2O5/CNT. A free-standing paper electrode can be made by vacuum filtration or coating pre-fabricated CNT paper directly. The electrochemical characteristics of the TiO2/V2O5/CNT paper electrode were then determined using cyclic voltammetry and galvanostatic charge/discharge curves. Because the TiO2 and V2O5 ALD films were ultrathin, the poor electrical conductivity and low ionic diffusivity of V2O5 did not limit the ability of the V2O5 ALD films to display high specific capacity and high rate capability. A high discharge capacity of ∼400 mA h g−1 is obtained for 15 cycle ALD TiO2 coated 50 cycle ALD V2O5/CNT samples by depositing pre-fabricated CNT paper. We believe that this is the highest capacity for V2O5 cathodes reported in the literature. The capacities of the a-V2O5/CNT nanocomposites are higher than the bulk theoretical values. The extra capacity is attributed to additional interfacial charge storage resulting from the high surface area of the a-V2O5/CNT nanocomposites. These results demonstrate that metal oxide ALD on high surface-area conducting carbon substrates can be used to fabricate high power and high capacity electrode materials for lithium ion batteries. In addition, ultrathin and conformal TiO2 ALD coating can be used to mitigate the dissolution and capacity fading of the cathode.

Surface-limited redox replacement reactions using the electrochemical atomic layer deposition (EC-ALD) technique were used to synthesize PdPt bimetallic electrocatalysts on carbon paper substrate. Electrocatalysts having different Pd:Pt ratio were electrodeposited by varying the deposition cycles of Pd and Pt. Diverse structural shapes of PdPt electrocatalysts were obtained with scanning electron microscopy (SEM). Higher number of deposition cycle produced more agglomerates and less dense particles on the support surface. The EDX profiles confirmed the presence of Pd and Pt particles on carbon paper. Cyclic voltammograms (CV) and linear scanning voltammetry (LSV) in oxygen showed that the electrodeposited catalysts were active for ORR and some were less affected by the methanol introduced in the vessel.

A novel anode electrode consisting of Pt NPs on layered porous TiO2/CFP (Pt/LP-TiO2/CFP) was fabricated by an innovative approach, which can be directly integrated in membrane electrode assembly (MEA) as the catalyst layer without any binder. Firstly, a two-step anodization method was applied to prepare a layered porous TiO2 on the CFP as a hybrid support, and then Pt NPs are deposited onto it by atomic layer deposition (ALD) technology. It effectively prevents Pt nanoparticles from detachment, migration, and aggregation during the catalyst preparation and electrochemical reaction process. The electrocatalytic performance of Pt/LP-TiO2/CFP electrode for methanol oxidation reaction exhibits excellent mass activity (1182.8 mA mgPt−1), enhanced stability, and CO tolerance, which is much better than those of the Pt/HT-TiO2/CFP and the Pt/C/CFP electrode prepared by conventional hydrothermal and spray method, respectively. The reason can be attributed to the unique structure of layered porous TiO2 supports, strong metal−support interactions (SMSI) between ALD Pt NPs and the LP-TiO2/CFP, and more exposed active sites for methanol oxidation. The presented ALD approach is an effective strategy for the homogeneous distribution of precious Pt nanoparticles on a binder-free and porous electrode for the design of advanced catalysts.

We report fabrication of a flexible, thorn-like ZnO-multiwalled carbon nanotube (MWCNT) hybrid paper with high aspect ratio for efficient ultraviolet (UV) sensing and photocatalyst applications. The thorn-like ZnO-MWCNT hybrid paper was synthesized via atomic layer deposition (ALD) of a uniform ZnO thin film on the outside surface of the MWCNT followed by hydrothermal growth of ZnO branches. The hybrid paper achieved very high surface to volume ratio, which is favorable for photodetector and photocatalyst applications. A photodetector fabricated from the hybrid paper demonstrates a high sensitivity to UV light with a maximum photoresponsivity of 45.1 A W(-1) at 375 nm, corresponding to an external quantum efficiency as high as 14927%. The rise time and fall time of the UV photodetector are 29 ms and 33 ms, respectively, indicating fast transient response characteristics for the device. The high photoresponsivity and fast transient response are attributed to efficient carrier transport and collection efficiency of the hybrid paper. Besides, the thorn-like ZnO-MWCNT hybrid paper demonstrates excellent photocatalytic performance under UV irradiation, enabling photo-degradation of organic dyes such as Rhodamine B (RhB) within 90 minutes, with good recyclability.

Large-scale growth of low-cost, efficient, and durable non-noble metal-based electrocatalysts for water splitting is crucial for future renewable energy systems. Atomic layer deposition (ALD) provides a promising route for depositing uniform thin coatings of electrocatalysts, which are useful in many technologies, including the splitting of water. In this communication, we report the growth of a NiO/Ni catalyst directly on carbon fiber paper by atomic layer deposition and report subsequent reduction and oxidation annealing treatments. The 10–20 nm NiO/Ni nanoparticle catalysts can reach a current density of 10 mA·cm−2 at an overpotential of 189 mV for hydrogen evolution reactions and 257 mV for oxygen evolution reactions with high stability. We further successfully achieved a water splitting current density of 10 mA·cm−2 at 1.78 V using a typical NiO/Ni coated carbon fiber paper two-electrode setup. The results suggest that nanoparticulate NiO/Ni is an active, stable, and noble-metal-free electrocatalyst, which facilitates a method for future water splitting applications.

The ultra-high resolution display is in demand as virtual reality (VA) and augmented reality (AR) displays, and hologram display become much more important. We present vertical TFTs for the application to the driving TFT of ultra-high resolution display. The IGZO deposited by sputtering and InOx deposited by means of plasma-enhanced atomic layer deposition (PEALD) have been adopted as the channel layers. While the IGZO vertical TFT shows on-current of 0.23 mA at Vg = 5 V and Vds = 2.1 V, that of InOx TFT shows 1.26 mA at the same driving condition.

We report a flexible AMOLED display driven by oxide thin film transistors (TFTs) based on a polyimide (PI) substrate. In the oxide TFT, a triple-stacked structure of active layer is employed to improve the mobility and stability. The fabricated TFT exhibit a high field-effect mobility of 38.8 cm2 V−1 s−1, a subthreshold swing of 0.15 V/dec, and an Ion/Ioff ratio of 109. Meanwhile, Al2O3 film prepared by the method of atomic layer deposition (ALD) is used as the encapsulation of AMOLED display, which demonstrating a superior water vapor transmission rate (WVTR) as low as 5.43×10−5 g/m2/day estimated by Calcium (Ca) corrosion method at 40 °C/100%.

International audience; In this paper we present the recent advances in the understanding of microscopic mechanisms driving the resistive switching in ReRAM devices using ab initio theoretical methods. We highlight the complex interplay between interface reactions and charge injection in the generation of oxygen Frenkel pairs during the forming step. Energy barrier calculations suggest that the formation/destruction of the conductive filament can be due to movements of oxygen vacancies composing the filament or interaction with oxygen atoms released from the metal electrode. © 2017 IEEE.

In this paper, we present the results of mechanical testing that reveals the onset crack strain and fatigue crack growth of TiO2 and Al2O3 films deposited by atomic layer deposition. Data show that both films have a strong thickness dependence of the onset crack strain, with the strain reducing with increasing film thickness. Additionally, TiO2 films have a lower onset crack strain and strain for fatigue damage than Al2O3. However, TiO2 films are more resilient in harsh environments where fatigue damage in Al2O3 films grows faster.

The adoption of bi-layered etch stop layer (BiESL) for oxide thin film transistor with high carrier mobility was proposed for the application to the large area high resolution AMOLED. A novel bi-layered etch stop structure composed of Al2O3/SiO2, in which thin and dense Al2O3 film prepared by atomic layer deposition was deposited on the PECVD SiO2 layer. High mobility of In-Ga-Zn-O TFT with the proposed BiESL showed no significant change in turn-on voltage, even without passivation film. The field-effect saturation mobility and sub-threshold swing were measured as 29 cm2/V.s and 0.21 V/dec, respectively. Hydrogen doping during the PECVD SiNx passivation process can be effectively prevented by the introduction of Al2O3. Furthermore organic planarization film can be coated directly on top of the TFT array without causing any significant degradation of TFT performance.

We have developed a full color flexible top-emission AMOLED display with 80 ppi resolution using In-Ga-Zn-O TFT backplane on PEN foil under the maximum process temperature of 150 oC. Notwithstanding the low processing temperature, the TFTs with SiOx passivation layer show high reliability with VTH shift of less than 0.2 V at 10,000 seconds under bias-stress of -10 V. cop. 2013 Society for Information Display.

Conductive coatings on complex fi brous systems are attracting interest for new electronic and other functional systems. Obtaining a quantitative conductivity value for complex surface coatings is often diffi cult. This work describes a procedure to quantify the effective electrical conductivity of conductive coatings on non-conductive fi brous networks. By applying a normal force orthogonal to the current and fi eld direction, fi ber/fi ber contact is improved and consistent conductance values can be measured. Nylon fi bers coated with an electroless silver plating shows effective conductivity up to 1950 S cm − 1 , and quartz fi bers coated with tungsten by atomic layer deposition (ALD) show values up to ∼ 1150 S cm − 1 . Cotton fi bers and paper coated with a range of ZnO fi lm thicknesses by ALD show effective conductivity of up to 24 S cm − 1 under applied normal force, and conductivity scaled as expected with fi lm coating thickness. Furthermore, we use the conductive coatings to produce an “all-fi ber” metal‐insulator‐metal capacitor that functions as a liquid chemical sensor. The ability to reliably analyze the effective conductivity of coatings on complex fi ber systems will be important to design and improve performance of similar devices and other electronic textiles structures.

Acid degradation of cellulosic paper in archival books, periodicals, and historic documents is a serious and widespread problem. Using acidic page samples from ∼40 year old books, we demonstrate that atomic layer deposition (ALD) ZnO can adjust and controllably neutralize the paper acid content. The paper samples were collected and analyzed in accordance with recognized Technical Association of the Pulp and Paper Industry (TAPPI) test standards. The average pH of the starting paper was 3.7 ± 0.4 and 4.4 ± 0.1 as determined using the TAPPI surface probe and cold water extraction methods, respectively. After 50 ALD ZnO cycles, the same tests on the coated paper produced an average pH of 7.39 ± 0.08 and 7.3 ± 0.4, respectively. Scanning electron microscopy confirmed that the cellulose structure remained intact during ALD. Additional tests of recently printed newspaper samples coated with ALD ZnO also show that ALD can effectively prevent paper discoloration and embrittlement caused by UV sunlight photoexposure. While there are many known methods for paper preservation, including others using diethyl zinc, the control afforded by ALD provides attractive advantages over other known approaches for preservation of archival paper and other natural fibrous materials.

The requirements and development of high-k dielectric films for application in storage cells of future generation flash and Dynamic Random Access Memory (DRAM) devices are reviewed. Dielectrics with k-value in the 9-30 range are studied as insulators between charge storage layers and control gates in flash devices. For this application, large band gaps (>6eV) and band offsets are required, as well as low trap densities. Materials studied include aluminates and scandates. For DRAM metal-insulator-metal (MIM) capacitors, aggressive scaling of the equivalent oxide thickness (with targets down to 0.3nm) drives the research towards dielectrics with k-values >50. Due to the high aspect ratio of MIMCap structures, highly conformal deposition techniques are needed, triggering a substantial effort to develop Atomic Layer Deposition (ALD) processes for the deposition of metal gates and high-k dielectrics. Materials studied include Sr- and Ba-based perovskites, with SrTiO"3 as one of the most promising candidates, as well as tantalates, titanates and niobates.

Numerous metal oxides have been studied worldwide as possible high-k gate dielectric candidates for MOS devices on alternative semiconductor materials (Ge, III/V compounds). We will discuss thermal and plasma-enhanced atomic layer deposition (ALD) of a few materials, HfO"2 and Al"2O"3. We will spend some attention to characteristic features of the growth process and specific growth precursors as this is known to influence strongly the quality of the layer bulk as well as the interface. Detailed electrical characterization of MOS capacitors build on such dielectric layers, before and after forming gas anneals, shows that these interface modifications can lead to a marked decrease of the smaller interface state peaks close to the edges of the bandgap, whereas the larger mid-gap peaks are barely touched. The results of atomistic modeling of the oxidation of a GaAs surface help to understand the origin of these mid-gap electronic states, which are responsible for the apparent pinning of the Fermi level.

Atomic Layer Deposition (ALD) was used to grow single-crystalline epitaxial layers of high-k dielectric oxides on semiconductors with remarkably few defects or traps at the interfaces. La 2 O 3 on GaAs(111) produced record-breaking transistors with both n-and p-channels, and CMOS circuits entirely in GaAs, including inverters, logic circuits and 5-stage ring oscillators. More conventionally oriented GaAs(100) substrates with etched (111) slopes also produced working transistors. ALD also grew single-crystalline epitaxial La 2 O 3 films on Ge(111), and (Ca, Mg)O films on GaN(0001) substrates with high-quality epitaxial interfaces. These processes can be run in commercial ALD reactors using precursors produced by the Dow Chemical Company.

Paper, a low-cost and flexible substrate made from cellulose fiber, is explored in this study as a platform for fast electrochemical energy storage devices. Conductivity and Li-storage capabilities are introduced to the paper by functionalization with carbon nanotubes (CNTs) and V2O5, respectively. The Li-storage paper cathodes present a remarkably high rate performance due to the high conductivity of CNTs, short Li+ diffusion length in V2O5 nanocrystals, and more importantly the hierarchical porosity in paper for Li+ transport. The specific capacity of V2O5 is as high as 410 mA h g−1 at 1 C rate, and retains 116 mA h g−1 at a high rate of 100 C in the voltage range of 4.0–2.1 V. To understand the role of mesoporosity in individual cellulose fibers, we created a control structure by intentionally blocking the mesopores in paper with a 20 nm Al2O3 coating applied via atomic layer deposition (ALD). We found that the V2O5 capacity decreases by about 30% at high rates of 5–100 C after blocking, which serves to be the first confirmative evidence of the critical role of mesoporosity in paper fibers for high-rate electrochemical devices.

We report using a novel, weak oxidant, plasma-enhanced atomic layer deposition (PEALD) process at 200 °C to fabricate stable, high mobility ZnO thin film transistors (TFTs) and fast circuits on glass and polyimide substrates. Weak oxidant PEALD provides a simple, fast deposition process that results in uniform, conformai semiconductor and dielectric layers and enhancement-mode MOSFETs from uncompensated films. Highly conformai PEALD Al2O3 layers provide a high yield dielectric on rough plastic substrates for both PEALD ZnO TFTs and cross-overs. Our PEALD ZnO TFTs have field-effect mobility of >20 cm2/V·s on polyimide substrates with excellent bias stress stability. TFTs biased continuously for 40,000s showed