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Journal ArticleDOI

Oxide Semiconductor Thin‐Film Transistors: A Review of Recent Advances

12 Jun 2012-Advanced Materials (WILEY‐VCH Verlag)-Vol. 24, Iss: 22, pp 2945-2986
TL;DR: The recent progress in n- and p-type oxide based thin-film transistors (TFT) is reviewed, with special emphasis on solution-processed andp-type, and the major milestones already achieved with this emerging and very promising technology are summarizeed.
Abstract: Transparent electronics is today one of the most advanced topics for a wide range of device applications. The key components are wide bandgap semiconductors, where oxides of different origins play an important role, not only as passive component but also as active component, similar to what is observed in conventional semiconductors like silicon. Transparent electronics has gained special attention during the last few years and is today established as one of the most promising technologies for leading the next generation of flat panel display due to its excellent electronic performance. In this paper the recent progress in n- and p-type oxide based thin-film transistors (TFT) is reviewed, with special emphasis on solution-processed and p-type, and the major milestones already achieved with this emerging and very promising technology are summarizeed. After a short introduction where the main advantages of these semiconductors are presented, as well as the industry expectations, the beautiful history of TFTs is revisited, including the main landmarks in the last 80 years, finishing by referring to some papers that have played an important role in shaping transparent electronics. Then, an overview is presented of state of the art n-type TFTs processed by physical vapour deposition methods, and finally one of the most exciting, promising, and low cost but powerful technologies is discussed: solution-processed oxide TFTs. Moreover, a more detailed focus analysis will be given concerning p-type oxide TFTs, mainly centred on two of the most promising semiconductor candidates: copper oxide and tin oxide. The most recent data related to the production of complementary metal oxide semiconductor (CMOS) devices based on n- and p-type oxide TFT is also be presented. The last topic of this review is devoted to some emerging applications, finalizing with the main conclusions. Related work that originated at CENIMAT|I3N during the last six years is included in more detail, which has led to the fabrication of high performance n- and p-type oxide transistors as well as the fabrication of CMOS devices with and on paper.
Citations
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Journal ArticleDOI
TL;DR: In this article, the electrical properties of polyvinyl alcohol (PVA)/ZnO films under the influence of electric field through photoluminescence (PL) analysis were verified.

11 citations

Journal ArticleDOI
TL;DR: A static modeling methodology for amorphous Gallium–Indium–Zinc-Oxide – Thin Film Transistor (a-GIZO TFT), with different ANNs, revealing that MLP is the most suitable approach for circuit simulations among the three ANNs.
Abstract: Development time and accuracy are measures that need to be taken into account when devising device models for a new technology. If complex circuits need to be designed immediately, then it is very important to reduce the time taken to realize the model. Solely based on data measurements, artificial neural networks (ANNs) modeling methodologies are capable of capturing small and large signal behavior of the transistor, with good accuracy, thus becoming excellent alternatives to more strenuous modeling approaches, such as physical and semi-empirical. This paper then addresses a static modeling methodology for amorphous Gallium–Indium–Zinc-Oxide – Thin Film Transistor (a-GIZO TFT), with different ANNs, namely: multilayer perceptron (MLP), radial basis functions (RBF) and least squares-support vector machine (LS-SVM). The modeling performance is validated by comparing the model outcome with measured data extracted from a real device. In case of a single transistor modeling and under the same training conditions, all the ANN approaches revealed a very good level of accuracy for large- and small-signal parameters ( g m and g d ), both in linear and saturation regions. However, in comparison to RBF and LS-SVM, the MLP achieves a very acceptable degree of accuracy with lesser complexity. The impact on simulation time is strongly related with model complexity, revealing that MLP is the most suitable approach for circuit simulations among the three ANNs. Accordingly, MLP is then extended for multiple TFTs with different aspect ratios and the network implemented in Verilog-A to be used with electric simulators. Further, a simple circuit (inverter) is simulated from the developed model and then the simulation outcome is validated with the fabricated circuit response.

11 citations

Journal ArticleDOI
TL;DR: It is found that thin films with optimal electrical properties can be achieved with a reduction in the number of laser irradiations from 20 to 6, as well as the preservation of the interface between the poly-Si and the SiO2 gate insulator.
Abstract: We report a method to improve the performance of polycrystalline Si (poly-Si) thin-film transistors (TFTs) via pressure-induced nucleation (PIN). During the PIN process, spatial variation in the local solidification temperature occurs because of a non-uniform pressure distribution during laser irradiation of the amorphous Si layer, which is capped with an SiO2 layer. This leads to a four-fold increase in the grain size of the poly-Si thin-films formed using the PIN process, compared with those formed using conventional excimer laser annealing. We find that thin films with optimal electrical properties can be achieved with a reduction in the number of laser irradiations from 20 to 6, as well as the preservation of the interface between the poly-Si and the SiO2 gate insulator. This interface preservation becomes possible to remove the cleaning process prior to gate insulator deposition, and we report devices with a field-effect mobility greater than 160 cm2/Vs.

11 citations

Journal ArticleDOI
TL;DR: In this article, the general aspects of source-gated transistors (SGT) structure, fabrication, and operation mechanisms are discussed, followed by a detailed property comparison with conventional TFTs.
Abstract: Source-gated transistors (SGTs), which are typically realized by introducing a source barrier in staggered thin-film transistors (TFTs), exhibit many advantages over conventional TFTs, including ultrahigh gain, lower power consumption, higher bias stress stability, immunity to short-channel effects, and greater tolerance to geometric variations. These properties make SGTs promising candidates for readily fabricated displays, biomedical sensors, and wearable electronics for the Internet of Things, where low power dissipation, high performance, and efficient, low-cost manufacturability are essential. In this review, the general aspects of SGT structure, fabrication, and operation mechanisms are first discussed, followed by a detailed property comparison with conventional TFTs. Next, advances in high-performance SGTs based on silicon are first discussed, followed by recent advances in emerging metal oxides, organic semiconductors, and 2D materials, which are individually discussed, followed by promising applications that can be uniquely realized by SGTs and their circuitry. Lastly, this review concludes with challenges and outlook overview.

11 citations

Journal ArticleDOI
TL;DR: In this article, a double fluorine based remote plasma treatment process is proposed for the high electronegativity of fluorine element and its similar radius as oxygen, which can be used to terminate the donor-like oxygen vacancy.

11 citations

References
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Journal ArticleDOI
25 Nov 2004-Nature
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

Book
04 Jul 1990
TL;DR: In this article, the authors present a characterization of the resistivity of a two-point-versus-four-point probe in terms of the number of contacts and the amount of contacts in the probe.
Abstract: Preface to Third Edition. 1 Resistivity. 1.1 Introduction. 1.2 Two-Point Versus Four-Point Probe. 1.3 Wafer Mapping. 1.4 Resistivity Profiling. 1.5 Contactless Methods. 1.6 Conductivity Type. 1.7 Strengths and Weaknesses. Appendix 1.1 Resistivity as a Function of Doping Density. Appendix 1.2 Intrinsic Carrier Density. References. Problems. Review Questions. 2 Carrier and Doping Density. 2.1 Introduction. 2.2 Capacitance-Voltage (C-V). 2.3 Current-Voltage (I-V). 2.4 Measurement Errors and Precautions. 2.5 Hall Effect. 2.6 Optical Techniques. 2.7 Secondary Ion Mass Spectrometry (SIMS). 2.8 Rutherford Backscattering (RBS). 2.9 Lateral Profiling. 2.10 Strengths and Weaknesses. Appendix 2.1 Parallel or Series Connection? Appendix 2.2 Circuit Conversion. References. Problems. Review Questions. 3 Contact Resistance and Schottky Barriers. 3.1 Introduction. 3.2 Metal-Semiconductor Contacts. 3.3 Contact Resistance. 3.4 Measurement Techniques. 3.5 Schottky Barrier Height. 3.6 Comparison of Methods. 3.7 Strengths and Weaknesses. Appendix 3.1 Effect of Parasitic Resistance. Appendix 3.2 Alloys for Contacts to Semiconductors. References. Problems. Review Questions. 4 Series Resistance, Channel Length and Width, and Threshold Voltage. 4.1 Introduction. 4.2 PN Junction Diodes. 4.3 Schottky Barrier Diodes. 4.4 Solar Cells. 4.5 Bipolar Junction Transistors. 4.6 MOSFETS. 4.7 MESFETS and MODFETS. 4.8 Threshold Voltage. 4.9 Pseudo MOSFET. 4.10 Strengths and Weaknesses. Appendix 4.1 Schottky Diode Current-Voltage Equation. References. Problems. Review Questions. 5 Defects. 5.1 Introduction. 5.2 Generation-Recombination Statistics. 5.3 Capacitance Measurements. 5.4 Current Measurements. 5.5 Charge Measurements. 5.6 Deep-Level Transient Spectroscopy (DLTS). 5.7 Thermally Stimulated Capacitance and Current. 5.8 Positron Annihilation Spectroscopy (PAS). 5.9 Strengths and Weaknesses. Appendix 5.1 Activation Energy and Capture Cross-Section. Appendix 5.2 Time Constant Extraction. Appendix 5.3 Si and GaAs Data. References. Problems. Review Questions. 6 Oxide and Interface Trapped Charges, Oxide Thickness. 6.1 Introduction. 6.2 Fixed, Oxide Trapped, and Mobile Oxide Charge. 6.3 Interface Trapped Charge. 6.4 Oxide Thickness. 6.5 Strengths and Weaknesses. Appendix 6.1 Capacitance Measurement Techniques. Appendix 6.2 Effect of Chuck Capacitance and Leakage Current. References. Problems. Review Questions. 7 Carrier Lifetimes. 7.1 Introduction. 7.2 Recombination Lifetime/Surface Recombination Velocity. 7.3 Generation Lifetime/Surface Generation Velocity. 7.4 Recombination Lifetime-Optical Measurements. 7.5 Recombination Lifetime-Electrical Measurements. 7.6 Generation Lifetime-Electrical Measurements. 7.7 Strengths and Weaknesses. Appendix 7.1 Optical Excitation. Appendix 7.2 Electrical Excitation. References. Problems. Review Questions. 8 Mobility. 8.1 Introduction. 8.2 Conductivity Mobility. 8.3 Hall Effect and Mobility. 8.4 Magnetoresistance Mobility. 8.5 Time-of-Flight Drift Mobility. 8.6 MOSFET Mobility. 8.7 Contactless Mobility. 8.8 Strengths and Weaknesses. Appendix 8.1 Semiconductor Bulk Mobilities. Appendix 8.2 Semiconductor Surface Mobilities. Appendix 8.3 Effect of Channel Frequency Response. Appendix 8.4 Effect of Interface Trapped Charge. References. Problems. Review Questions. 9 Charge-based and Probe Characterization. 9.1 Introduction. 9.2 Background. 9.3 Surface Charging. 9.4 The Kelvin Probe. 9.5 Applications. 9.6 Scanning Probe Microscopy (SPM). 9.7 Strengths and Weaknesses. References. Problems. Review Questions. 10 Optical Characterization. 10.1 Introduction. 10.2 Optical Microscopy. 10.3 Ellipsometry. 10.4 Transmission. 10.5 Reflection. 10.6 Light Scattering. 10.7 Modulation Spectroscopy. 10.8 Line Width. 10.9 Photoluminescence (PL). 10.10 Raman Spectroscopy. 10.11 Strengths and Weaknesses. Appendix 10.1 Transmission Equations. Appendix 10.2 Absorption Coefficients and Refractive Indices for Selected Semiconductors. References. Problems. Review Questions. 11 Chemical and Physical Characterization. 11.1 Introduction. 11.2 Electron Beam Techniques. 11.3 Ion Beam Techniques. 11.4 X-Ray and Gamma-Ray Techniques. 11.5 Strengths and Weaknesses. Appendix 11.1 Selected Features of Some Analytical Techniques. References. Problems. Review Questions. 12 Reliability and Failure Analysis. 12.1 Introduction. 12.2 Failure Times and Acceleration Factors. 12.3 Distribution Functions. 12.4 Reliability Concerns. 12.5 Failure Analysis Characterization Techniques. 12.6 Strengths and Weaknesses. Appendix 12.1 Gate Currents. References. Problems. Review Questions. Appendix 1 List of Symbols. Appendix 2 Abbreviations and Acronyms. Index.

6,573 citations

Journal ArticleDOI
TL;DR: In this paper, a review of the literature in the area of alternate gate dielectrics is given, based on reported results and fundamental considerations, the pseudobinary materials systems offer large flexibility and show the most promise toward success.
Abstract: Many materials systems are currently under consideration as potential replacements for SiO2 as the gate dielectric material for sub-0.1 μm complementary metal–oxide–semiconductor (CMOS) technology. A systematic consideration of the required properties of gate dielectrics indicates that the key guidelines for selecting an alternative gate dielectric are (a) permittivity, band gap, and band alignment to silicon, (b) thermodynamic stability, (c) film morphology, (d) interface quality, (e) compatibility with the current or expected materials to be used in processing for CMOS devices, (f) process compatibility, and (g) reliability. Many dielectrics appear favorable in some of these areas, but very few materials are promising with respect to all of these guidelines. A review of current work and literature in the area of alternate gate dielectrics is given. Based on reported results and fundamental considerations, the pseudobinary materials systems offer large flexibility and show the most promise toward success...

5,711 citations

Journal ArticleDOI
TL;DR: In this article, the authors present new insight into conduction mechanisms and performance characteristics, as well as opportunities for modeling properties of organic thin-film transistors (OTFTs) and discuss progress in the growing field of n-type OTFTs.
Abstract: Organic thin-film transistors (OTFTs) have lived to see great improvements in recent years. This review presents new insight into conduction mechanisms and performance characteristics, as well as opportunities for modeling properties of OTFTs. The shifted focus in research from novel chemical structures to fabrication technologies that optimize morphology and structural order is underscored by chapters on vacuum-deposited and solution-processed organic semiconducting films. Finally, progress in the growing field of the n-type OTFTs is discussed in ample detail. The Figure, showing a pentacene film edge on SiO2, illustrates the morphology issue.

4,804 citations

Journal ArticleDOI
TL;DR: An outlook is presented on what will be required to drive this young photovoltaic technology towards the next major milestone, a 10% power conversion efficiency, considered by many to represent the efficiency at which OPV can be adopted in wide-spread applications.
Abstract: Solution-processed bulk-heterojunction solar cells have gained serious attention during the last few years and are becoming established as one of the future photovoltaic technologies for low-cost power production. This article reviews the highlights of the last few years, and summarizes today's state-of-the-art performance. An outlook is given on relevant future materials and technologies that have the potential to guide this young photovoltaic technology towards the magic 10% regime. A cost model supplements the technical discussions, with practical aspects any photovoltaic technology needs to fulfil, and answers to the question as to whether low module costs can compensate lower lifetimes and performances.

3,084 citations