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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • electron-transparent membranes
  • micropump
  • field emission electron source
  • ion source
  • ion mobility spectrometry
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Wroclaw University of Science and Technology
209 条数据
?? 中文（中国） ▾

  • Multi-scale ordering in highly stretchable polymer semiconducting films

    摘要： Stretchable semiconducting polymers have been developed as a key component to enable skin-like wearable electronics, but their electrical performance must be improved to enable more advanced functionalities. Here, we report a solution processing approach that can achieve multi-scale ordering and alignment of conjugated polymers in stretchable semiconductors to substantially improve their charge carrier mobility. Using solution shearing with a patterned microtrench coating blade, macroscale alignment of conjugated-polymer nanostructures was achieved along the charge transport direction. In conjunction, the nanoscale spatial confinement aligns chain conformation and promotes short-range π–π ordering, substantially reducing the energetic barrier for charge carrier transport. As a result, the mobilities of stretchable conjugated-polymer films have been enhanced up to threefold and maintained under a strain up to 100%. This method may also serve as the basis for large-area manufacturing of stretchable semiconducting films, as demonstrated by the roll-to-roll coating of metre-scale films.

    关键词： charge carrier mobility,conjugated polymers,solution shearing,stretchable semiconductors,roll-to-roll coating,multi-scale ordering

    更新于2025-11-19 16:56:35

  • Admittance of Organic LED Structures with an Emission YAK-203 Layer

    摘要： The current-voltage characteristics and admittance of multilayer structures for organic LEDs based on the PEDOT:PSS/NPD/YAK-203/BCP system have been experimentally investigated in a wide range of the measurement conditions. It is shown that at voltages corresponding to the effective radiative recombination of charge carriers, a significant decrease in the differential capacitance of the structures is observed. The frequency dependences of the normalized conductance of LED structures are in good agreement with the results of numerical simulation in the framework of the equivalent circuit method. Changes in the frequency dependences of the admittance with a change in temperature are most pronounced in the temperature range of 200–300 K and less noticeable in the temperature range of 8–200 K. From the frequency dependences of the imaginary part of impedance, the charge carrier mobilities are found at various voltages and temperatures. The mobility values obtained by this method are somewhat lower than those determined by the transient electroluminescence method. The dependence of the mobility on the electric field is well approximated by a linear function. As the temperature decreases from 300 to 220 K, the mobility decreases several times.

    关键词： frequency dependence of imaginary part of impedance,LED structure,current-voltage characteristic,transient electroluminescence,organic semiconductor,charge carrier mobility,method of equivalent circuits,admittance

    更新于2025-11-14 17:28:48

  • Highly Stretchable, High‐Mobility, Free‐Standing All‐Organic Transistors Modulated by Solid‐State Elastomer Electrolytes

    摘要： Highly stretchable, high-mobility, and free-standing coplanar-type all-organic transistors based on deformable solid-state elastomer electrolytes are demonstrated using ionic thermoplastic polyurethane (i-TPU), thereby showing high reliability under mechanical stimuli as well as low-voltage operation. Unlike conventional ionic dielectrics, the i-TPU electrolyte prepared herein has remarkable characteristics, i.e., a large specific capacitance of 5.5 μF cm?2, despite the low weight ratio (20 wt%) of the ionic liquid, high transparency, and even stretchability. These i-TPU-based organic transistors exhibit a mobility as high as 7.9 cm2 V?1 s?1, high bendability (Rc, radius of curvature: 7.2 mm), and good stretchability (60% tensile strain). Moreover, they are suitable for low-voltage operation (VDS = ?1.0 V, VGS = ?2.5 V). In addition, the electrical characteristics such as mobility, on-current, and threshold voltage are maintained even in the concave and convex bending state (bending tensile strain of ≈3.4%), respectively. Finally, free-standing, fully stretchable, and semi-transparent coplanar-type all-organic transistors can be fabricated by introducing a poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid layer as source/drain and gate electrodes, thus achieving low-voltage operation (VDS = ?1.5 V, VGS = ?2.5 V) and an even higher mobility of up to 17.8 cm2 V?1 s?1. Moreover, these devices withstand stretching up to 80% tensile strain.

    关键词： free-standing all-organic transistors,stretchable and conformal electronics,high-mobility,elastomer electrolyte,low-voltage operation

    更新于2025-11-14 17:28:48

  • A spark discharge generator for scalable aerosol CVD synthesis of single-walled carbon nanotubes with tailored characteristics

    摘要： We have designed and built an exhaust-free spark discharge generator for robust aerosol CVD synthesis of single-walled carbon nanotubes. The systematic study has shown the generator to provide a facile and repeatable route to precisely control the size of the catalyst particle and, therefore, carbon nanotube growth. Using a comprehensive set of methods (the analysis of differential mobility of the aerosol particles, optical spectroscopy, scanning and transmission electron microscopy, Raman spectroscopy, and atomic force microscopy) we have revealed the relation between the defectiveness, length, diameter distribution of carbon nanotubes and specific features of a generator such as electrode characteristics (breakdown voltage, composition, and current) as well as the nature of the surrounding media (carrier gas nature, flow rate). The design used has resulted in separation of the nanoparticle formation and carbon nanotube nucleation processes. This provides a mutual independence of the growth parameters and the diameter distribution of the single-walled carbon nanotubes enhancing the scalability of the process. For instance, the breakdown voltage has been shown to have nearly zero effect on diameter and length distribution of carbon nanotubes produced while strictly governing the yield. We focus here on producing specifically short carbon nanotubes (l < 500nm) of pronounced defectiveness for drug delivery and transistor applications.

    关键词： single-walled carbon nanotubes,differential mobility analyzer,catalyst activation,spark-discharge generator,aerosol CVD,floating bed reactor

    更新于2025-11-14 17:03:37

  • High-Mobility Inkjet-Printed Indium-Gallium-Zinc-Oxide Thin-Film Transistors Using Sr-Doped Al2O3 Gate Dielectric

    摘要： In this paper, we demonstrate high-mobility inkjet-printed indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) using a solution-processed Sr-doped Al2O3 (SAO) gate dielectric. Particularly, to enhance to the electrical properties of inkjet-printed IGZO TFTs, a linear-type printing pattern was adopted for printing the IGZO channel layer. Compared to dot array printing patterns (4 × 4 and 5 × 5 dot arrays), the linear-type pattern resulted in the formation of a relatively thin and uniform IGZO channel layer. Also, to improve the subthreshold characteristics and low-voltage operation of the device, a high-k and thin (~10 nm) SAO film was used as the gate dielectric layer. Compared to the devices with SiO2 gate dielectric, the inkjet-printed IGZO TFTs with SAO gate dielectric exhibited substantially high field-effect mobility (30.7 cm2/Vs). Moreover, the subthreshold slope and total trap density of states were also significantly reduced to 0.14 V/decade and 8.4 × 1011/cm2·eV, respectively.

    关键词： metal-oxide semiconductors,thin-film transistors,high-k dielectric,high mobility,inkjet printing

    更新于2025-11-14 15:19:41

  • Mobility Evaluation of BTBT Derivatives: Limitation and Impact on Charge Transport

    摘要： Amongst contemporary semiconductors many of the best performing materials are based on [1]benzothieno[3,2-b][1]benzothiophene (BTBT). Alkylated derivatives of these small molecules not only provide high hole mobilities but can also be easily processed by thermal vacuum or solution deposition methods. Over the last decade numerous publications have been investigating molecular structures and charge transport properties to elucidate what makes these molecules so special. However, the race towards ever higher mobilities resulted in significantly deviating values, which exacerbates linking molecular structure to electronic properties. Moreover, a recently arisen debate on overestimation of organic field-effect transistor mobilities calls for a revaluation of these numbers. We synthesised and characterised four BTBT derivatives with either one or two alkyl chains (themselves consisting of either eight or ten carbon atoms), and investigated their spectroscopic, structural and electrical properties. By employing two probes, gated 4-point probe and gated van der Pauw measurements, we compare field effect mobility values at room and low temperatures, and discuss their feasibility and viability. We attribute mobility changes to different angles between molecule planes and core-to-core double layer stacking of asymmetric BTBT derivatives and show higher mobilities in the presence of more and longer alkyl chains. A so called “zipper effect” brings BTBT cores in closer proximity promoting stronger intermolecular orbital coupling and hence higher charge transport.

    关键词： charge transport,mobility,BTBT,organic electronics,organic transistors

    更新于2025-10-23 16:08:52

  • Percolation Effects in Electrolytically-Gated WS <sub/>2</sub> /Graphene Nano:Nano Composites

    摘要： Mixed networks of conducting and non-conducting nanoparticles show promise in a range of applications where fast charge transport is important. While the dependence of network conductivity on the conductive mass fraction (Mf) is well understood, little is known about the Mf-dependence of mobility and carrier density. This is particularly important as the addition of graphene might lead to increases in the mobility of semiconducting nanosheet-network transistors. Here, we use electrolytic gating to investigate the transport properties of spray-coated composite networks of graphene and WS2 nanosheets. As the graphene Mf is increased, we find both conductivity and carrier density to increase in line with percolation theory with percolation thresholds (~8 vol%) and exponents (~2.5) consistent with previous reporting. Perhaps surprisingly, we find the mobility increases modestly from ~0.1 cm2/Vs (for a WS2 network) to ~0.3 cm2/Vs (for a graphene network) which we attribute to the similarity between WS2-WS2 and graphene-graphene junction resistances. In addition, we find both the transistor on- and off-currents to scale with Mf according to percolation theory, changing sharply at the percolation threshold. Through fitting, we show that only the current in the WS2 network changes significantly upon gating. As a result, the on-off ratio falls sharply at the percolation threshold from ~104 to ~2 at higher Mf. Reflecting on these results, we conclude that the addition of graphene to a semiconducting network is not a viable strategy to improve transistor performance as it reduces the on:off ratio far more than it improves the mobility.

    关键词： graphene,ionic liquid,thin film transistor,WS2,carrier density,composite,mobility,Printed electronics

    更新于2025-10-22 19:40:53

  • A reliable and efficient small-signal parameter extraction method for GaN HEMTs

    摘要： In this paper, a reliable and efficient parameter extraction method for GaN high electron mobility transistor (HEMT) small‐signal models has been proposed. By utilizing parameter scanning method, the initial values of the extrinsic elements are first extracted from the cold pinch‐off and cold unbiased measurement conditions, respectively. An iterative optimization algorithm is employed then to optimize the extrinsic elements. This scanning and iteration combined algorithm based on a direct extraction method of extrinsic elements can reduce the impact of the approximation error, which makes the determined values of the small‐signal parameters more reliable. The extraction flow has been realized in a Matlab program for efficiency. A 16‐element small‐signal equivalent circuit model (SSECM) for GaN HEMTs has been employed, and the new parameter extraction method has been validated by comparing the simulated small‐signal S‐parameters with the measured data from 0.1 GHz to 40 GHz for two different device dimensions.

    关键词： small‐signal modeling,parameter extraction,GaN high electron mobility transistor (HEMT)

    更新于2025-09-23 15:23:52

  • Fabricating ZnSnN2 with cosputtering

    摘要： The deposition of ZnSnN2 by co-sputtering was studied systematically. Different deposition parameters, including substrate temperatures, N2 flow rates and different work pressure etc. were tried and the structural, optical and electrical properties were studied. The results show that the deposition parameters to fabricate ZnSnN2 are relatively wide. The suitable substrate temperature to obtain polycrystalline ZnSnN2 is around 350 °C when other parameters are kept constant. Relatively larger N2 flow rate can suppress the formation of metallic phase such as Sn and favour the deposition of ZnSnN2 with relatively pure phase, with other parameters to be constant. The addition of the substrate bias voltage or a relatively lower power of the Sn target is harmful to the film crystallization of ZnSnN2. The samples are considered to be wurtzite due to the absence of the orthorhombic (110) and (011) peaks at 20°–22°. The hexagonal lattice constants a and c are about 3.36–3.40 ? and 5.49 ?, respectively. The sputtering pressure can affect the structural and electrical properties of ZnSnN2. ZnSnN2 prepared at larger work pressure such as 7.0 Pa has a lower electron density (6.72 × 10^19 cm^-3) and a higher mobility (24.3 cm^2 V^-1 s^-1) as compared with those prepared at 1.0 and 3.0 Pa.

    关键词： Sputtering,Wurtzite,Degenerate,ZnSnN2,Mobility

    更新于2025-09-23 15:23:52

  • Uniformity and repeatability of InAlN-barrier HEMTs growth by high-speed-rotation single-wafer MOCVD tool

    摘要： We fabricated high-electron-mobility transistor structures with InAlN as a barrier layer on 8- or 6-inch Si substrates by using a recently developed high-speed-wafer-rotation single-wafer MOCVD tool. It has been reported that Ga inclusion in the InAlN layer causes serious problems in the control of group III metal composition in some cases, but the samples grown using the tool exhibited an InAlN layer with an abrupt interface and almost no Ga inclusion. Excellent in-wafer uniformity, repeatability, and wafer-to-wafer uniformity of device structure are also reported. The results shown in this paper indicate high performance of the tool in the real production of devices.

    关键词： A3. Metalorganic vapor phase epitaxy,B1. Nitrides,B2. Semiconducting III-V materials,B3. High electron mobility transistors

    更新于2025-09-23 15:23:52