Universal Compact Model for Thin-Film Transistors and Circuit Simulation for Low-Cost Flexible Large Area Electronics
TL;DR: A user-friendly tool was developed to provide an interactive way for convenient parameter extraction and the model is continuous from the off-state and subthreshold regimes to the above-threshold regime, avoiding the convergence problems when being used in SPICE circuit simulations.
Abstract: Thin-film transistors (TFT) in hydrogenated amorphoussilicon, amorphousmetal oxide, andsmallmolecule and polymer organic semiconductors would all hold promise as potential device candidates to large area flexible electronics applications. A universal compact dc model was developed with a proper balance between the physical and mathematical approaches for these thin-film transistors (TFTs). It can capture the common key parameters used for device performance benchmarking of the different TFTs while being applicable to a wide range of TFT technologies in different materials and device structures. Based on this model, a user-friendly tool was developed to provide an interactive way for convenient parameter extraction. The model is continuous from the off-state and subthreshold regimes to the above-threshold regime, avoiding the convergence problems when being used in SPICE circuit simulations. Finally, for verification, it was implemented into a SPICE circuit simulator using Verilog-A to simulate a TFT circuit examplewith the simulated results agreeing verywell with the experimental measurements.
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06 Sep 2019
TL;DR: This review will present the state of the art in thin-film electronics and demonstrate examples of low-cost printable transistors and biosensors that are flexible/stretchable for wearable and other applications and a concept for an integrated system comprising sensors and interfacing circuits that has the potential to enable batteryless operation.
Abstract: Thin-film electronics has hugely benefitted from low-cost processes, large-area processability, and multifunctionality. This has not only stimulated innovation in display and sensor technology but has also demonstrated great potential for the integration of components for human–machine interfaces. For electronics to be deployed as sensor interfaces and signal processing, the quest for low power is compelling due to the inherently limited battery lifetime. This review will present the state of the art in thin-film electronics and demonstrate examples of low-cost printable transistors and biosensors that are flexible/stretchable for wearable and other applications. Ultralow-power design for thin-film transistors will be discussed from the standpoint of reducing both operating voltage and operating current, taking into account the challenges in meeting frequency requirements. Compact models for circuit design will be reviewed along with new insights into ultralow-power transistors and high-gain amplifier circuits. Finally, a concept for an integrated system comprising sensors and interfacing circuits will be demonstrated, which has the potential to enable batteryless operation.
43 citations
Cites background from "Universal Compact Model for Thin-Fi..."
...[193] developed a universal compact model with a proper balance between the physical and mathematical approaches....
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TL;DR: In this article, the design, fabrication and characterization of digital logic gates, flip-flops and shift registers based on lowvoltage organic thin-film transistors (TFTs) on flexible plastic substrates is presented.
33 citations
22 Jan 2018
TL;DR: The key elements of FHE-PDK include technology files for design rule checking, layout versus schematic and layout parasitics extraction, as well as SPICE-compatible models for flexible thin-film transistors (TFTs) and passive elements.
Abstract: Flexible Electronics (FE) is emerging for wearables and low-cost internet of things (IoT) nodes benefiting from its low-cost fabrication and mechanical flexibility. Combining FE with thinned silicon chips, known as flexible hybrid electronics (FHE), can take advantages of both low-cost printed electronics and high performance silicon chips. To design a FHE system, the process design kit (PDK) offering the capabilities for circuit design, simulation and verification for both FE and silicon chips is needed. The key elements of FHE-PDK include technology files for design rule checking (DRC), layout versus schematic (LVS) and layout parasitics extraction (LPE), as well as SPICE-compatible models for flexible thin-film transistors (TFTs) and passive elements. Wafer scale measurements are used to validate our SPICE models and design rules are derived accordingly to assure a satisfactory yield. With FHE-PDK, circuit and system designers can therefore focus on design innovations and can rely on design tools to produce manufacturable designs.
21 citations
Additional excerpts
...Both theories indicate the mobility dependency on the gate voltage [8][11]: μ ∝ (VG − Vth) , γ ≥ 0....
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TL;DR: The essential requirements, up-to-date progresses, and imminent challenges for the OFET compact device modeling toward a universal, physically valid, and applicable description of this fast-developing technology are discussed.
Abstract: In this review, recent advances in compact modeling of organic field-effect transistors (OFETs) are presented. Despite the inherent strength for printed flexible electronics and the extremely aggressive research conducted over more than three decades, the OFET technology still seems to remain at a relatively low technological readiness level. Among various possible reasons for that, the lack of a standard compact model, which effectively bridges the device- and system-level development, is clearly one of the most critical issues. This article broadly discusses the essential requirements, up-to-date progresses, and imminent challenges for the OFET compact device modeling toward a universal, physically valid, and applicable description of this fast-developing technology.
19 citations
TL;DR: A SPICE-compatible compact model for a range of thin-film transistors that can be manufactured at low cost and on flexible materials using printing technologies is described.
Abstract: Editor’s note: Thin-film transistors can be manufactured at low cost and on flexible materials using printing technologies. These characteristics make them very well suited to many IoT applications, particularly wearable electronics. However, circuit and system designers require device models for these new devices. This article describes a SPICE-compatible compact model for a range of thin-film transistors. The authors have validated the models on three thin-film transistor technologies. — Dimitrios Serpanos, University of Patras — Marilyn Wolf, Georgia Institute of Technology
19 citations
Cites background from "Universal Compact Model for Thin-Fi..."
...Some studies focus only on modeling the DC behavior [8], which doesn’t support transient simulations....
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References
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TL;DR: A novel semiconducting material is proposed—namely, a transparent amorphous oxide semiconductor from the In-Ga-Zn-O system (a-IGZO)—for the active channel in transparent thin-film transistors (TTFTs), which are fabricated on polyethylene terephthalate sheets and exhibit saturation mobilities and device characteristics are stable during repetitive bending of the TTFT sheet.
Abstract: Transparent electronic devices formed on flexible substrates are expected to meet emerging technological demands where silicon-based electronics cannot provide a solution. Examples of active flexible applications include paper displays and wearable computers1. So far, mainly flexible devices based on hydrogenated amorphous silicon (a-Si:H)2,3,4,5 and organic semiconductors2,6,7,8,9,10 have been investigated. However, the performance of these devices has been insufficient for use as transistors in practical computers and current-driven organic light-emitting diode displays. Fabricating high-performance devices is challenging, owing to a trade-off between processing temperature and device performance. Here, we propose to solve this problem by using a novel semiconducting material—namely, a transparent amorphous oxide semiconductor from the In-Ga-Zn-O system (a-IGZO)—for the active channel in transparent thin-film transistors (TTFTs). The a-IGZO is deposited on polyethylene terephthalate at room temperature and exhibits Hall effect mobilities exceeding 10 cm2 V-1 s-1, which is an order of magnitude larger than for hydrogenated amorphous silicon. TTFTs fabricated on polyethylene terephthalate sheets exhibit saturation mobilities of 6–9 cm2 V-1 s-1, and device characteristics are stable during repetitive bending of the TTFT sheet.
7,301 citations
"Universal Compact Model for Thin-Fi..." refers background in this paper
...Since the work by Hosono’s group in 2004 [5], amorphous oxide semiconductors (AOS)-based TFTs have attracted wide attention for their advantages of high mobility, small subthreshold swing, low leakage current, and process compatibility with the established a-Si TFT manufacturing facilities [6]....
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TL;DR: In this paper, the state-of-the-art in organic field effect transistors (OFETs) are reviewed in light of requirements for demanding future applications, in particular active-matrix addressing for flexible organic light-emitting diode (OLED) displays.
Abstract: Over the past 25 years, organic field-effect transistors (OFETs) have witnessed impressive improvements in materials performance by 3–4 orders of magnitude, and many of the key materials discoveries have been published in Advanced Materials. This includes some of the most recent demonstrations of organic field-effect transistors with performance that clearly exceeds that of benchmark amorphous silicon-based devices. In this article, state-of-the-art in OFETs are reviewed in light of requirements for demanding future applications, in particular active-matrix addressing for flexible organic light-emitting diode (OLED) displays. An overview is provided over both small molecule and conjugated polymer materials for which field-effect mobilities exceeding > 1 cm2 V–1 s–1 have been reported. Current understanding is also reviewed of their charge transport physics that allows reaching such unexpectedly high mobilities in these weakly van der Waals bonded and structurally comparatively disordered materials with a view towards understanding the potential for further improvement in performance in the future.
1,992 citations
"Universal Compact Model for Thin-Fi..." refers background in this paper
...Stacks of organic semiconductors (OSCs) and dielectrics are materials of choice for making truly flexible electronics by printing, with supermechanical flexibility of the films and stack structures, very low temperature and fast processing, and compatibility with various printing/coating technologies [11], [12]....
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TL;DR: The growth of a highly aligned meta-stable structure of 2,7-dioctyl[1]benzothieno[3,2-b][1] Benzothiophene (C8-BTBT) is described from a blended solution of C8- BTBT and polystyrene by using a novel off-centre spin-coating method, indicating their potential for transparent, high-performance organic electronics.
Abstract: One of the advantages of organic over inorganic semiconductors is they can be grown from solution, but their electrical mobility is often poor. Yuan et al. report a technique for fabricating organic transistors with mobilities far beyond that of amorphous silicon and close to that of polycrystalline silicon.
1,130 citations
"Universal Compact Model for Thin-Fi..." refers background in this paper
...As a result of extensive research efforts on material design, process development, and device engineering, the performance of both reported p- and n-type organic TFTs (OTFTs) can outperform a-Si TFTs [13]–[15]....
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13 May 2012
TL;DR: The current status of flexible electronics is reviewed and the future promise of these pervading technologies in healthcare, environmental monitoring, displays and human-machine interactivity, energy conversion, management and storage, and communication and wireless networks is predicted.
Abstract: Thin-film electronics in its myriad forms has underpinned much of the technological innovation in the fields of displays, sensors, and energy conversion over the past four decades. This technology also forms the basis of flexible electronics. Here we review the current status of flexible electronics and attempt to predict the future promise of these pervading technologies in healthcare, environmental monitoring, displays and human-machine interactivity, energy conversion, management and storage, and communication and wireless networks.
881 citations
"Universal Compact Model for Thin-Fi..." refers background in this paper
...With low temperature processibility, AOS TFTs are also regarded as a very promising solution for high performance flexible electronics [7]....
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TL;DR: An approach--termed fluid-enhanced crystal engineering (FLUENCE)--that allows for a high degree of morphological control of solution-printed thin films and may find use in the fabrication of high-performance, large-area printed electronics.
Abstract: Solution coating of organic semiconductors offers great potential for achieving low-cost manufacturing of large-area and flexible electronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of thin-film morphology. Here, we report an approach—termed fluid-enhanced crystal engineering (FLUENCE)—that allows for a high degree of morphological control of solution-printed thin films. We designed a micropillar-patterned printing blade to induce recirculation in the ink for enhancing crystal growth, and engineered the curvature of the ink meniscus to control crystal nucleation. Using FLUENCE, we demonstrate the fast coating and patterning of millimetre-wide, centimetre-long, highly aligned single-crystalline organic semiconductor thin films. In particular, we fabricated thin films of 6,13-bis(triisopropylsilylethynyl) pentacene having non-equilibrium single-crystalline domains and an unprecedented average and maximum mobilities of 8.1±1.2 cm2 V−1 s−1 and 11 cm2 V−1 s−1. FLUENCE of organic semiconductors with non-equilibrium single-crystalline domains may find use in the fabrication of high-performance, large-area printed electronics. Solution printing of organic semiconductors could in principle be scaled to industrial needs, yet attaining aligned single-crystals directly with this method has been challenging. By using a micropillar-patterned printing blade designed to enhance the control of crystal nucleation and growth, thin films of macroscopic, highly aligned single crystals of organic semiconductors can now be fabricated.
876 citations
"Universal Compact Model for Thin-Fi..." refers background in this paper
...Beyond vacuum-based processes, printing or coating approaches are considered to be a more ideal solution for low cost and high throughput manufacturing of large area flexible electronics [8]–[10]....
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