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Effect of space charge limited current on performance of organic field-effect transistors
摘要： The crucial parameter that determines the performance of a semiconductor material in organic field-effect transistors (OFETs) is the charge carrier mobility. The conventional method of its determination based on Shockley’s equations can lead to incorrect mobility evaluation due to contact effects. Particularly, in the common staggered OFET architecture (top-contact bottom-gate or bottom-contact top-gate), the space-charge limited current (SCLC) effect in the active layer under/above the source and drain contacts decreases the source-drain current. In this work, we model the effect of SCLC under/above the source and drain electrodes on the OFET apparent mobility (i.e., calculated from the device characteristics) and apparent threshold voltage for different active layer thickness and intrinsic mobility anisotropy. For the saturation regime, we derived simple analytical expressions for transfer characteristics and apparent mobility. Our modeling shows that the apparent OFET mobility is more than five times lower than the intrinsic one for the active layer thicker than 100 nm with mobility anisotropy (along vs across the active layer) higher than 100. While the SCLC effect does not change the apparent threshold voltage, it reveals itself as a kink at near zero voltage in the output characteristics. The proposed model gives analytical expressions for the transfer characteristics and apparent mobility as explicit functions of the intrinsic mobility and the device parameters in the saturation regime and as implicit functions in the linear regime. Our findings provide guidelines for accurate evaluation of the intrinsic mobility in OFETs fabricated in the staggered architecture and for further improvement of OFET performance.
关键词： Organic field-effect transistors,Organic thin-film transistors,Space charge limited current,Contact effects,Modeling
更新于2025-09-11 14:15:04
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High-performance p-channel thin-film transistors with lightly doped n-type excimer-laser-crystallized germanium films
摘要： High-performance polycrystalline-germanium (poly-Ge) thin-film transistors (TFTs) fabricated with lightly doped Ge thin films by excimer laser crystallization (ELC) and counter doping (CD) have been demonstrated. High-quality n-type Ge thin films with a grain size as large as 1 μm were fabricated by ELC in the super lateral-growth regime and CD at a dose of 1 × 1013 cm?2 or higher. Consequently, a superior field-effect mobility of 271 cm2 V?1 s?1 and a high on/off current ratio of 2.7 × 103 have been obtained for p-channel Ge TFTs with the channel width and length of both 0.5 μm fabricated by ELC at 300 mJ/cm2 and CD at a dose of 1 × 1013 cm?2. The effects of ELC conditions and CD dose on the electrical characteristics of p-channel Ge TFTs were also investigated.
关键词： field-effect mobility,excimer laser crystallization,thin-film transistors,polycrystalline-germanium,counter doping
更新于2025-09-11 14:15:04
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Poly‐GeSn Junctionless Thin‐Film Transistors on Insulators Fabricated at Low Temperatures via Pulsed Laser Annealing
摘要： High-performance polycrystalline GeSn (poly-GeSn) junctionless thin-film transistors (JL-TFTs) are proposed and fabricated at low process temperatures. Poly-GeSn thin films with a Sn fraction of 4.8% are prepared using cosputtering and pulsed laser annealing (PLA) techniques. The ultra-rapid nonequilibrium thermodynamic process with 25 ns PLA renders a good crystal GeSn thin film at a low temperature. The ION/IOFF ratio increases by three orders of magnitude with GeSn channel thickness varying from 60 to 10 nm, suggesting that switch-off current is dominated by depletion width. A superior effective mobility of 54 cm2 V-1 s-1 is achieved for the JL-TFT with a 10 nm-thick GeSn film as a consequence of gate/channel interface passivation by oxygen plasma.
关键词： pulsed laser annealing,junctionless thin-film transistors,GeSn
更新于2025-09-11 14:15:04
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High performance phototransistors with organic/quantum dot composite materials channels
摘要： Nanomaterials, especially quantum dots, have become one of the most great potential channel transport layer materials in the field of photo detection mainly due to their particular light absorption characteristics. However, there are still many disadvantages such as low carrier transport capability possibly attributable to the discontinuity nature of materials. Therefore, particular phototransistors with pentacene/CdSe@ZnS QDs composite materials channels have been prepared by simply blending and spin-coating 6,13-Bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) and QDs solution in weight ratio of 3:1. The particular device architecture with organic/quantum dot composite materials channels effectively combined the high carrier mobility advantage of organic semiconductors with the strong absorption characteristic of quantum dots in specific optical band regions and further overcame the low conductivity shortcomings of pure quantum dot materials. The device with particular pentacene/CdSe@ZnS QDs composite channel exhibited excellent electrical and optical properties with current switch ratio Ion/off of 104, carriers mobility of ~0.161 cm2/V, photosensitivity P of 105, responsivity R of 0.33 mA/W and detectivity D of 1.48 ? 1011 Jones at drain voltage of (cid:0) 35 V and light intensity of 1.6 mW/cm2, respectively, indicating that this composite, as one of the most promising channel transport layer material candidates for photodetector, provides one chance to improve the characteristic of photodetector transistors just by using hybrid channel technology.
关键词： Solution method,Quantum dots,Photodetectors,Composite materials,Organic thin film transistors
更新于2025-09-11 14:15:04
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Metal Capping on Silicon Indium Zinc Oxide Semiconductor for High Performance Thin Film Transistors Processed at 150 °C
摘要： We fabricated amorphous silicon-indium-zinc-oxide (a-SIZO) thin film transistors (TFTs) by RF sputtering at the low processing temperature of 150 °C. Metal capping (MC) structure on TFTs showed enhanced performance. Even at low annealing temperature, the field-effect mobility (μFE) showed 21.4 cm2/V s, and Vth shift was only 1.3 V. We attribute the enhancement of mobility to the metal capping layer, which effectively prevents the ambient effect of hydrogen and water vapor.
关键词： SiInZnO,Metal Capping,Thin Film Transistors,Oxide Semiconductor
更新于2025-09-11 14:15:04
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Sol-Gel Derived Dip Coated ZnO – La <sub/>2</sub> O <sub/>3</sub> Thin Film Transistors
摘要： ZnO thin ?lms are fabricated utilizing a cost effective sol-gel dip coating technique and potentially applied as active material in thin ?lm transistors (TFT). The channel length of the TFT is maintained at 40 μm. Thermally deposited high –k La2O3 is used as dielectric material. The fabricated ZnO ?lms are annealed in oxygen atmosphere at 500?C for 1 hour and characterized by XRD, EDX and SEM analysis. The TFTs are fabricated in top gate coplanar electrodes structure on glass substrates. The electrical characteristics of the TFTs are investigated and some important electrical parameters are evaluated. The TFTs exhibit ?eld effect mobility of 1.9 cm2/VS, low threshold voltage of 2.5 Volt, high ON/OFF current ratio of 107, sub-threshold swing of 0.8V/decade, transconductace of 1.2 × 10?3 mho and gain band-width product of 20 kHz.
关键词： ZnO,sol-gel dip coating,thin film transistors,electrical characteristics,La2O3
更新于2025-09-11 14:15:04
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New Advances in Hydrogenation Processes - Fundamentals and Applications || Hydrogenation of Polycrystalline Silicon Thin‐Film Transistors
摘要： In this chapter, the behavior of hydrogen (H) atoms in polycrystalline silicon (poly‐Si) thin film is investigated in detail in order to evaluate and improve the quality of hydrogenated poly‐Si thin films. Hydrogenation drastically improves the Hall effect mobility, whereas excessive hydrogenation tends to degrade it. The catalytic method is useful to inhibit excessive hydrogenation and damage suffered by the electric‐field acceleration of charged particle. The H‐termination of the dangling bonds at grain boundaries can be observed indirectly or directly by chemical etching and Raman microscopy. This H‐termination appeared as the 2000?cm‐1 local vibrational mode (LVM) in Raman spectra. The breaking of the Si–Si bonds by hydrogenation was detected as the 2100?cm‐1 LVM. In addition, the defects generated in the plasma process exhibit multiple fine LVMs after hydrogenation. Moreover, we investigated the hydrogenation of low‐temperature (LT) poly‐Si thin‐film transistors (TFTs) from the perspective of the gettering phenomenon. The most important parameter for effective hydrogenation using H gas annealing is the rate of cooling from 400°C.
关键词： Raman scattering,hydrogenation,thin film,polycrystalline silicon,thin‐film transistors
更新于2025-09-10 09:29:36
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Uniform Insulating Properties of Low-Temperature Curable Gate Dielectric for Organic Thin-Film Transistor Arrays on Plastic Substrate
摘要： Achieving a high-resolution display on a plastic substrate requires a to ensure dimensional stability during fabrication process, including the deposition of gate dielectrics. Evaluation platform to confirm the uniform insulating properties of organic dielectric material prior to actual application to organic thin-film transistor (OTFT) arrays was proposed. This test method enabled verification of the suitability of the low-temperature curable dielectric and chemical resistance during fabrication process. A cross-linked poly(hydroxy imide) (PHI) that can be cured at a low temperature of 130°C exhibited stable insulating properties in a large area that sudden breakdown was not observed in an electric field up to 4 MV/cm. Thiophene-thiazole-based copolymer semiconductor was used as an active layer and inkjet-printed. In all the processes, the temperature of the substrate was kept below 130°C, and 4.8-inch electrophoretic display panels on a polyethylene naphthalate (PEN) substrate with a resolution of 98 dpi was demonstrated.
关键词： Organic thin-film transistors,Organic gate dielectric,Plastic substrates,Low-temperature process,Polymer semiconductor,Flexible displays,Inkjet printing
更新于2025-09-10 09:29:36
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[IEEE 48th European Solid-State Device Research Conference (ESSDERC 2018) - Dresden (2018.9.3-2018.9.6)] 2018 48th European Solid-State Device Research Conference (ESSDERC) - Low Temperature and Radiation Stability of Flexible IGZO TFTs and their Suitability for Space Applications
摘要： In this paper, Low Earth Orbit radiation and temperature conditions are mimicked to investigate the suitability of flexible Indium-Gallium-Zinc-Oxide transistors for lightweight space-wearables. Such wearable devices could be incorporated into spacesuits as unobtrusive sensors such as radiation detectors or physiological monitors. Due to the harsh environment to which these space-wearables would be exposed, they have to be able to withstand high radiation doses and low temperatures. For this reason, the impacts of high energetic electron irradiation with fluences up to 1012 e-/cm2 and low operating temperatures down to 78 K, are investigated. This simulates 278 h in a Low Earth Orbit. The threshold voltage and mobility of transistors that were exposed to e- irradiation are found to shift by +0.09 ± 0.05V and -0.6 ± 0.5cm2 V-1 s-1. Subsequent low temperature exposure resulted in additional shifts of +0.38 V and -5.95 cm2 V-1 s-1 for the same parameters. These values are larger than the ones obtained from non-irradiated reference samples. If this is considered during the systems’ design, these devices can be used to unobtrusively integrate sensor systems into space-suits.
关键词： amorphous oxides,flexible electronics,thin film transistors,wearables,space applications
更新于2025-09-10 09:29:36
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Low-Voltage, Flexible InGaZnO Thin-Film Transistors Gated with Solution-Processed, Ultra-Thin AlxOy
摘要： Indium-gallium-zinc-oxide thin-film transistors (TFTs) gated with solution-processed, ultra-thin AlxOy have been fabricated on a plastic substrate. The effects of bending on the gate dielectric leakage current density and capacitance density have been studied. The devices show a low operating voltage of less than 1 V, a high current on/off ratio > 105 and a low subthreshold swing < 90 mV/dec. The devices maintain their high performance even when flexed to a curvature radius of 11 mm. As a result, such devices possess a great potential for low-power, flexible electronics.
关键词： 1 V operation,thin-film transistors (TFTs),plastic substrate,Indium-gallium-zinc-oxide
更新于2025-09-10 09:29:36