Negligible Interface Research Articles

Divergent Richtmyer–Meshkov instability on a heavy gas layer

Experiments on divergent Richtmyer–Meshkov (RM) instability at a heavy gas layer are performed in a specially designed shock tube. A novel soap-film technique is extended to generate gas layers with controllable thicknesses and shapes. An unperturbed gas layer is first examined and its two interfaces are found to move uniformly at the early stage and be decelerated later. A general one-dimensional theory applicable to an arbitrary-thickness layer is established, which gives a good prediction of the layer motion in divergent geometry. Then, six kinds of perturbed SF $_6$ layers with various thicknesses and shapes surrounded by air are examined. At the early stage, the amplitude growths of the inner interface for various-thickness layers collapse quite well and also can be predicted by the Bell model for cylindrical RM instability at a single interface, which indicates a negligible interface coupling effect. Later, a rarefaction wave accelerates the inner interface, causing a dramatic rise in the growth rate. It is found that a thicker gas layer will result in a larger extent that the rarefaction wave can promote the instability growth. A modified Bell model accounting for both Rayleigh–Taylor (RT) instability and interface stretching caused by a rarefaction wave is established, which well reproduces the quick instability growth. At late stages, reverberating waves inside the layer are negligibly weak such that the inner interface growth is dominated by RM instability and RT stability. The major factors driving the outer interface development are a compression wave and interface coupling. A new interface coupling phenomenon existing uniquely in divergent geometry caused by the gradual thinning of the gas layer is observed and also modelled.

Sputter-Deposited Amorphous Li3PO4 Solid Electrolyte Films.

This paper reports the thin-film synthesis of Li3PO4 solid electrolytes by RF magnetron sputtering. A relatively high ionic conductivity of more than 1 × 10–6 S cm–1 is achieved. It is revealed that the crystallization of Li3PO4 impedes ionic conduction, and a moderate amount of O2 addition to Ar suppresses the crystallization and guarantees long-term deposition. Another important finding in this study is that when Li3PO4 is deposited on a LiCoO2 film to construct a thin-film battery, the LiCoO2 film can be damaged depending on the substrate bias potential relative to the cathode potential propagated through the sputtering plasma. Active control of the bias potential to avoid the damage realizes negligible interface resistance in the thin-film battery.

Layer-by-layer assembly of cation exchange membrane for highly efficient monovalent ion selectivity

The development of cation exchange membranes (CEMs) with high monovalent/divalent cation selectivity has great potential for enhanced salt separation for wastewater reclamation, and layer-by-layer (LbL) self-assembly of polyelectrolyte films with high monovalent selectivities among cations has expanded the applications of such membranes. However, the structure–property relationship for constructing multilayered polyelectrolyte films with enhanced separation performance remains poorly understood. This study reports a novel CEM engineered by coating a [polyethyleneimine/polystyrene sulfonate (PEI/PSS)]n alternate electro-deposition multilayer on a polyacrylate substrate membrane. The newly developed CEM exhibited a monovalent selectivity of 4.59 for Li+/Mg2+ with an optimal permeation of 0.16 mmol·cm−2·h−1 for Li+, demonstrating a competitive separation property compared to state-of-the-art permselective membranes. A detailed quantitative investigation provides the underlying insights into the monovalent selectivity for each polyelectrolyte layer. The results indicate negligible interface impedance toward monovalent cations but strengthened repulsion against divalent cations, thereby promoting a quick passage for monovalent cations while imposing temporal retardation on divalent cations during the electrodialysis (ED) process. Therefore, this study elucidates the characteristic reason for the enhanced monovalent ion permselectivity of LbL polyelectrolyte membranes in electro-driven separation processes.

Frequency and importance of interpersonal communication about a school-based intervention with parents, peers, and teachers: application of social interface model

ABSTRACT Social interface model (SIM) explicates the important roles of family, peer, and school microsystems in intervention research. The present study used surveys to explore how Nicaraguan adolescents who participated in a school-based substance use and violence prevention intervention communicated about the intervention with parents, peers, and teachers. Latent class analysis was run to identify distinctive typologies of interfaces characterized by occurrence and importance of conversations. Five latent classes (N = 109) were discovered: optimal transference (21%), neutral transference (17%), limited positive transference (17%), negligible neutral interface (28%), and negligible adverse interface (16%). The optimal transference and neutral transference groups reported having conversations with all three microsystems (i.e. their mother, father, best friend, and teachers) and that those conversations resulted in seeing the curriculum the same way or as more important. The negligible neutral interface and negligible adverse interface groups reported minimal or no conversation across microsystems, which resulted in viewing the curriculum as not important or less important. The limited positive transference group reported selective conversations mostly with their mother and teachers, which was evaluated as important and/or neutral. Findings discuss the application of SIM in prevention research and provide a more nuanced understanding of how intervention messages are recalled and processed post-delivery.

Modulation Compression in Next Generation RAN: Air Interface and Fronthaul Trade-offs

Modulation compression is a technique considered in the recent Open-RAN (O-RAN) framework, which has continued the 3GPP effort toward the definition of new virtualized and multi-vendor RAN architectures. Basically, fronthaul compression is achieved by means of reducing the modulation order, thus enabling a dramatic reduction of the required fronthaul capacity with a simple technique. In this work, we provide a survey of the architectures, functional splits, and fronthaul compression techniques envisioned in 3GPP and O-RAN. Then we focus on assessing the trade-offs that modulation compression exhibits in terms of reduced fronthaul capacity vs. the impact on the air interface performance, through a dynamic multi-cell system-level simulation. For that, we use an ns-3-based system-level simulator compliant with 5G New Radio (NR) specifications and evaluate different traffic load conditions and NR numerolo-gies. In a multi-cell scenario, our results show that an 82 percent reduction of the required fronthaul capacity can be achieved with negligible air interface performance degradation by reducing the modulation order down to 64-QAM for different numerologies and load conditions. A higher modulation order reduction without degradation is permitted in low/medium traffic loads (reaching up to 94 percent fronthaul capacity reduction).

Modulation Compression in Next Generation RAN: Air Interface and Fronthaul trade-offs

Modulation compression is a technique considered in the recent Open-RAN (O-RAN) framework, which has continued the 3GPP effort towards the definition of new virtualized and multi-vendor RAN architectures. Basically, fronthaul compression is achieved by means of reducing the modulation order, thus enabling a dramatic reduction of the required fronthaul capacity with a simple technique. In this work, we provide a survey of the architectures, functional splits, and fronthaul compression techniques envisioned in 3GPP and O-RAN. Then, we focus on assessing the trade-offs that modulation compression exhibits in terms of reduced fronthaul capacity versus the impact on the air interface performance, through a dynamic multi-cell system-level simulation. For that, we use an ns-3 based system-level simulator compliant with 5G New Radio (NR) specifications and evaluate different traffic load conditions and NR numerologies. In a multi-cell scenario, our results show that an 82% reduction of the required fronthaul capacity can be achieved with negligible air interface performance degradation by reducing the modulation order down to 64QAM, for different numerologies and load conditions. A higher modulation order reduction without degradation is permitted in low/medium traffic loads (reaching up to 94% fronthaul capacity reduction).

Influence of the Processing on the Ionic Conductivity of Solid-State Hybrid Electrolytes Based on Glass-Ceramic Particles Dispersed in PEO with LiTFSI

For the first time, glass-ceramic particles (LATP and LLZO) have been processed with both a tumbling-mixer and a kneader on semi-industrial scale. Although sintered LATP and LLZO discs reveal a statistically negligible ionic interface resistance to PEO with LiTFSI, the total conductivity of dispersed particles within a PEO-LiTFSI matrix is only slightly enhanced at 80 °C. However, for a tumbling mixing process, SEM investigations prove insufficient contact of particles within the matrix as well as agglomerates, cracks and voids. With the shear intensive kneader, dense and homogeneous samples were obtained. Compared to nanometer-sized SiO2 particles, the LATP filler enable an increase of the ionic conductivity of the hybrid PEO system by a factor of about two. These finding help to overcome solvent-based mixing processes that may cause uncontrolled decomposition and surface reactions of filler particles thereby changing microscopic conduction mechanisms in the hybrid electrolytes.

Fast Charge Transfer across the Li7La3Zr2O12 Solid Electrolyte/LiCoO2 Cathode Interface Enabled by an Interphase-Engineered All-Thin-Film Architecture.

Lithium garnet Li7La3Zr2O12 (LLZO) is being investigated as a potential solid electrolyte for next-generation solid-state batteries owing to its high ionic conductivity and electrochemical stability against metallic lithium and high potential cathodes. While the LLZO/Li metal anode interface has been thoroughly investigated to achieve almost negligible interface resistances, the LLZO/cathode interface still suffers from high interfacial resistances mainly due to the high-temperature sintering required for proper ceramic bonding. In this work, the LLZO solid electrolyte/LiCoO2 (LCO) cathode interface is investigated in an all-thin-film model system. This architecture provides an easy access to the interface for in situ and ex situ characterization, allowing one to identify the degradation processes taking place under high-temperature cosintering and to test solutions such as interface modifications. Introducing an in situ-lithiated Nb2O5 diffusion barrier at the interface, we were able to lower the LLZO/LCO charge transfer resistance to about 50 Ω cm2, a 3-fold reduction with respect to previously reported values. The low interfacial resistance combined with the high conductance through the LLZO thin-film electrolyte allows one to investigate the charge transfer at high charge-discharge rates, unlike in bulk systems. At 1C, discharge capacities of about 140 mA h g-1 were measured, and at 10C, 60% of the theoretical capacity was retained with a cycle life over 100 cycles. Besides the role of this architecture in the interface investigation, this work also constitutes a milestone in the development of thin-film solid-state batteries with higher power densities.

Role of ionization fraction on the surface roughness, density, and interface mixing of the films deposited by thermal evaporation, dc magnetron sputtering, and HiPIMS: An atomistic simulation

The effect of ionization fraction on the epitaxial growth of Cu film on Cu (111) substrate at room temperature is explored. Three deposition methods, thermal evaporation, dc magnetron sputtering (dcMS), and high power impulse magnetron sputtering (HiPIMS) are compared. Three deposition conditions, i.e., fully neutral, 50% ionized, and 100% ionized flux were considered thermal evaporation, dcMS, and HiPIMS, respectively, for ∼20000 adatoms. It is shown that higher ionization fraction of the deposition flux leads to smoother surfaces by two major mechanisms, i.e., decreasing clustering in the vapor phase and bicollision of high energy ions at the film surface. The bicollision event consists of local amorphization which fills the gaps between islands followed by crystallization due to secondary collisions. The bicollision events are found to be very important to prevent island growth to become dominant and increase the surface roughness. Regardless of the deposition method, epitaxial Cu thin films suffer from stacking fault areas (twin boundaries) in agreement with recent experimental results. Thermal evaporation and dcMS deposition present negligible interface mixing while HiPIMS deposition presents considerable interface mixing.

The diverse electronic properties of C/BN heteronanotubes with polar discontinuity

Linear interfaces from within the heteronanotubes between carbon nanotubes (CNTs) and h-BN nanotubes (BNNTs) introduce unexpected electronic and spintronic properties that are different from individual components. In particular, for heteronanotubes with zigzag boundaries (ZCBNNTs) polar discontinuities occur at the interfaces, generating an intrinsic electric field acting on the segment CNTs. In turn, the electric field will cause a charge transfer between the two interfaces to compensate for the potential difference, thus the interface states (or boundary states) show new phenomena. For example, the half-metallic can be found in ZCBNNTs. Furthermore, the length and diameter of the ZCBNNTs can effectively adjust the electronic properties, due to the compensatory effects of the free charge to the polarization charge. Our results shed light on the future design of miniature superconducting spintronic devices and the realization of high performance nanoelectronic devices with negligible interface contact resistance barriers.

Graphite as a potassium ion battery anode in carbonate-based electrolyte and ether-based electrolyte

The graphite as the potassium ion battery anode is studied in KPF6-EC/DMC and KPF6-DME electrolytes. It is found that the graphite demonstrates superior rate performance with a capacity of 87 mAh g−1 at a current rate of 10 C (corresponding to 2.8 A g−1) and excellent capacity retention ability of 84% after 3500 cycles in DME-based electrolyte. Moreover, its initial coulombic efficiency is 87.4%, higher than 69.6% in EC/DMC-based electrolyte. The K+ solvating with DME complexes co-intercalate into graphite leading a high operational voltage at ∼0.7 V vs. ∼0.2 V in carbonate-based electrolyte, a fast apparent K+ diffusion coefficient of 10−8 cm2 s−1, a negligible solid-electrolyte interface film, a small volume expansion (7.7% in (002) plane vs. 63% in EC/DMC electrolyte). This study addresses the importance of electrolyte in altering the potassium storage mechanisms to tune the energy density and power density in potassium ion batteries (KIBs).

(Invited) Stability and Kinetics of the Li/Solid-State Electrolyte Interface

While there have been recent advances in solid ion conductors exhibiting conductivities comparable to liquid electrolytes, how to best capitalize on these materials discoveries to enable new energy storage technology is currently not known. Of particular interest is the integration solid-state electrolyte into solid-state batteries; however, numerous questions remain. What are the design rules? How are solid-solid interfaces formed? How does charge transfer occur at interfaces? Essentially, there are two interfaces of interest in solid-state batteries, distinguished by the electrode type; the alkali metal electrode and the ceramic electrode. Several key scientific challenges related to these two interfaces must be addressed to mature solid-state batteries. This discussion is centered on the alkali metal/solid electrolyte interface. The solid electrolyte based on garnet-type oxide, of nominal composition Li7La3Zr2O12 (LLZO), is used as a model system that simultaneously exhibits fast-ion conductivity and stability against metallic Li. To date, there are few examples of bulk-scale Li-ion conducting solid electrolytes that are stable at the Li/Li+ redox potential. This paper elucidates stability and kinetics as a function of LLZO composition and surface chemistry. EIS, TEM, and electron spin resonance analysis describes the subtle interaction at the interface between Li metal and LLZO. Simple approaches to achieving negligible Li-LLZO interface resistance (~1 Ohm.cm-2) with no coatings is described. Based on this mechanism, a simple procedure for removing these surface layers is demonstrated, resulting in a dramatic increase in Li wetting and the elimination of nearly all interfacial resistance. Combined, the demonstrated stability and low interfacial resistance suggests a pathway to achieving viable high energy density solid-state batteries enabled by the LLZO-based solid electrolyte.

Social Interface Model: Theorizing Ecological Post-Delivery Processes for Intervention Effects.

Successful prevention programs depend on a complex interplay among aspects of the intervention, the participant, the specific intervention setting, and the broader set of contexts with which a participant interacts. There is a need to theorize what happens as participants bring intervention ideas and behaviors into other life-contexts, and theory has not yet specified how social interactions about interventions may influence outcomes. To address this gap, we use an ecological perspective to develop the social interface model. This paper presents the key components of the model and its potential to aid the design and implementation of prevention interventions. The model is predicated on the idea that intervention message effectiveness depends not only on message aspects but also on the participants' adoption and adaptation of the message vis-à-vis their social ecology. The model depicts processes by which intervention messages are received and enacted by participants through social processes occurring within and between relevant microsystems. Mesosystem interfaces (negligible interface, transference, co-dependence, and interdependence) can facilitate or detract from intervention effects. The social interface model advances prevention science by theorizing that practitioners can create better quality interventions by planning for what occurs after interventions are delivered.

Lithium Diffusion Coefficient of Amorphous Lithium Phosphate Thin Films Measured By Secondary Ion Mass Spectroscopy

1． Introduction Thin-film solid-state batteries have attracted attention due to their low risk of fire and explosion, reduced environmental impact, and high energy density. Amorphous lithium phosphate (a-Li3PO4) is used as a solid electrolyte for thin-film batteries because of its wide electrochemical window and negligible interface resistance. Lithium diffusion is an important factor affecting the characteristics of solid-state batteries. However, the technique for measuring lithium self-diffusion in solid-state batteries is limited because the lifetime of lithium radioactive isotope, 8Li, is too short to measure the diffusion coefficient. Stable isotopes, 6Li and 7Li, are applied to measure the trace diffusion of lithium. Secondary ion mass spectrometry (SIMS) is useful as it is able to distinguish the isotopes of 6Li and 7Li. In this study, we intended to measure the tracer diffusion coefficient of lithium (D* Li) directly using secondary ion mass spectrometry (SIMS) with isotope exchange methods because they have negligible interface effect on the transport of lithium. Here, we used the “ ion-exchange method ” and the “ mask method ” to prepare diffusion couples (6Li/7Li). Analyzing the diffusion equation allowed us to obtain the tracer diffusion coefficient of lithium (D* Li). The Haven ratio (H R) of a-Li3PO4was obtained by contrasting lithium tracer diffusion coefficient with the lithium conductivity diffusion coefficient (Dσ). 2． Experimental The 6Li3PO4 target (6Li : 7Li = 95% : 5%) was synthesized by the solid-phase reaction method. The target was applied to prepare a-6Li3PO4 thin films (6Li : 7Li = 95% : 5%) by the pulsed laser deposition (PLD) method with an ArF excimer laser at room temperature. The structure of the target and the thin films were analyzed by XRD. Diffusion couples (6Li/7Li) were prepared using two methods, ion-exchange method and mask method. In ion-exchange method, the thin films were immersed in a natLiClO4/PC electrolyte solution with a natural abundance ratio (6Li : 7Li = 7.5% : 92.5%) for 10 hours at room temperature. In mask method, the a-6Li3PO4 thin films were half covered with the a-natLi3PO4 thin films (6Li : 7Li = 7.5% : 92.5%) using a mask. The thin films prepared by the two methods were cut into several pieces and annealed at different temperatures (25~160 ℃) and time. The line analysis was performed using a double-focusing magnetic sector SIMS (IMS-7f). Isotope concentration ratios of 6Li and 7Li could be calculated from the counts of 6Li and 7Li isotopes obtained from SIMS.The isotope profiles of 6Li and 7Li were analyzed to obtain the tracer diffusion coefficient of lithium (D* Li) by fitting them using the diffusion equation.Moreover, alternating current (AC) impedance method was used to measure the ionic conductivity of thin films (σ). The a-6Li3PO4 thin films were deposited on interdigitated array (IDA) platinum electrodes. Impedance spectra were collected using an impedance/gain-phase analyzer (SI-1260) in the temperature range 0~140 ℃. The conductivity diffusion coefficient of lithium (Dσ) was obtained by using the Nernst-Einstein equation from the ionic conductivity. 3． Results & Discussion Fig.1. Shows the temperature dependence of D* Li and Dσ of a-Li3PO4 thin film. The lithium tracer diffusion coefficient determined by the ion-exchange method marked as D* Li ion-exchange, and the mask method marked as D* Li mask. The tracer diffusion coefficient of a-Li3PO4 thin film is D* Li ion-exchange-RT = 6.0 × 10-13 cm2/s at 25 ℃ obtained by ion-exchange method, and D* Li mask-RT = 6.85 × 10-13 cm2/s at 25 ℃ obtained by mask method. The ionic conductivity is σRT = 2.87 × 10-7 S/cm at 25 ℃ obtained by alternating current impedance method.The activation energy and pre-exponential factor is Ea (D* Li ) = 0.58 eV, D0 = 3.92 × 10-3 cm2/s, Ea (D σ ) = 0.56 eV, D0 = 3.86 × 10-3 cm2/s. The tracer diffusion coefficient of lithium obtained by those methods were confirmed to be almost coincident with Dσ. Haven ratio, which is defined by ratio of tracer and conductivity diffusion coefficient as H R ≡ D*/Dσ, H R = 0.55. Figure 1

Comparative study on interface and bulk charges in AlGaN/GaN metal–insulator–semiconductor heterostructures with Al2O3, AlN, and Al2O3/AlN laminated dielectrics

In this paper, the interface and bulk charges in AlGaN/GaN metal–insulator–semiconductor (MIS) heterostructures with AlN, Al2O3, and Al2O3/AlN laminated dielectrics were studied. In situ plasma pretreatment resulted negligible interface trap states and voltage hysteresis. The fixed charge density at Al2O3/AlN (or Al2O3/barrier) interface was estimated to be 1.66 × 1013 cm−2 by using flat-band voltage shift, and the oxide bulk charge concentration was 2.86 × 1017 cm−3. The interface charge density at other interfaces were at the order of 1011 cm−2. Simulation results using the above charge density/concentration indicated that Al2O3/AlN interface fixed charges dominated the dielectric-related voltage shift in AlGaN/GaN MIS heterostructures, which caused a large voltage shift of −3 V with 10 nm Al2O3 thickness, while the flat-band voltage variety resulting from other types of charges was within 0.1 V.

Tuning the Schottky Barrier at the Graphene/MoS2 Interface by Electron Doping: Density Functional Theory and Many-Body Calculations

Using ab initio calculations we investigate the energy level alignment at the graphene/MoS2 heterostructure and the use of electron doping as a strategy to lower the Schottky barrier and achieve a low-resistance Ohmic contact. For the neutral heterostructure, density functional theory (DFT) with a generalized gradient approximation predicts a Schottky barrier height of 0.18 eV, whereas the G0W0 method increases this value to 0.60 eV. While the DFT band gap of MoS2 does not change when the heterostructure is formed, the G0W0 gap is reduced by 0.30 eV as a result of the enhanced screening by the graphene layer. In contrast to the case of metal substrates, where the band alignment is governed by Pauli repulsion-induced interface dipoles, the graphene/MoS2 heterostructure shows only a negligible interface dipole. As a consequence, the band alignment at the neutral heterostructure is not changed when the two layers are brought into contact. We systematically follow the band alignment as a function of doping co...

Magnetization boundary conditions at a ferromagnetic interface of finite thickness

We develop a systematic approach to derive boundary conditions at an interface between two ferromagnetic materials in the continuous medium approximation. The approach treats the interface as a two-sublattice material, although the final equations connect magnetizations outside of the interface and therefore do not explicitly depend on its structure. Instead, the boundary conditions are defined in terms of some average properties of the interface, which may also have a finite thickness. In addition to the interface anisotropy and symmetric exchange coupling, this approach allows us to take into account coupling resulting from inversion symmetry breaking in the vicinity of the interface, such as the Dzyaloshinskii-Moriya antisymmetric exchange interaction. In the case of negligible interface anisotropy and Dzyaloshinskii-Moriya exchange parameters, the derived boundary conditions represent a generalization of those proposed earlier by Barnaś and Mills and are therefore named ‘generalized Barnaś–Mills boundary conditions’. We demonstrate how one could use the boundary conditions to extract parameters of the interface via fitting of appropriate experimental data. The developed theory could be applied to modeling of both linear and non-linear spin waves, including exchange, dipole-exchange, magnetostatic, and retarded modes, as well as to calculations of non-uniform equilibrium micromagnetic configurations near the interface, with a direct impact on the research in magnonics and micromagnetism.

High-Temperature Performance of Stacked Silicon Nanowires for Thermoelectric Power Generation

Deep reactive-ion etching at cryogenic temperatures (cryo-DRIE) has been used to produce arrays of silicon nanowires (NWs) for thermoelectric (TE) power generation devices. Using cryo-DRIE, we were able to fabricate NWs of large aspect ratios (up to 32) using a photoresist mask. Roughening of the NW sidewalls occurred, which has been recognized as beneficial for low thermal conductivity. Generated NWs, which were 7 μm in length and 220 nm to 270 nm in diameter, were robust enough to be stacked with a bulk silicon chip as a common top contact to the NWs. Mechanical support of the NW array, which can be created by filling the free space between the NWs using silicon oxide or polyimide, was not required. The Seebeck voltage, measured across multiple stacks of up to 16 bulk silicon dies, revealed negligible thermal interface resistance. With stacked silicon NWs, we observed Seebeck voltages that were an order of magnitude higher than those observed for bulk silicon. Degradation of the TE performance of silicon NWs was not observed for temperatures up to 470°C and temperature gradients up to 170 K.

Resistance and 1/f noise between circular contacts on conductive thin films

There is a need to characterize the quality of contacts and the noise properties of new materials deposited or grown as thin films. Poor contacts are interface dominated. Perfect contacts have a negligible interface contribution and there is only a resistance and noise contribution from outside the contact region. The presence of current crowding enhances the resistance and noise contribution. Such contacts are called constriction dominated contacts. The conductive film is characterized by its sheet resistance and normalized conductance fluctuations for a unit surface. The resistance and noise is studied between two circular top electrodes of the same diameter on the conductive. To distinguish between perfect and poor contacts and to characterize the thin film in case of good contacts, we need a set of contacts with different diameters. Models for perfect and poor contacts are investigated. The scaling of resistance and noise with contact radius r is for interface dominated poor contacts: R i 1/ r 2 and S Ri 1/ r 6 . In contrast, perfect contacts with contact diameter (2 r ) much smaller than the distance between the centers (2 b ) show: R c ln( b / r ) and S Rc 1/ r 2 . From the resistance and noise measurements between constriction dominated perfect contacts, the sheet resistance and normalized noise of the thin film are calculated.

Application of tosylate-doped poly(3,4ethylenedioxythiophene) (PEDOT) films into bottom contact pentacene organic thin film transistors (OTFTs)

The effect of iron(III) p-toluenesulfonate hexahydrate (Fe(PTS) 3) concentration on the formation and patternability of poly(3,4ethylenedioxythiophene) (PEDOT) films on (3-aminopropyl)trimethoxysilane (APS) monolayer was investigated. Low deposition rate yielded highly conductive and very smooth PEDOT films. However, the spin-coated oxidants in low Fe(PTS) 3 concentrations were susceptible to moistures, leading to the poorly patterned PEDOT films. Increasing Fe(PTS) 3 concentration enabled the fine patterning of the films. The fabricated thin film transistors with PEDOT electrodes formed on 30 wt.% Fe(PTS) 3 revealed the saturation mobility of 0.16 cm 2/V s and subthreshold slope of 0.5 V/decade. The obtained low contact resistance was 12 kΩ cm, possibly due to the negligible interface morphological discontinuity at the pentacene-PEDOT interface.