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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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Book ChapterDOI
01 Jan 2022
TL;DR: In this article , the authors describe the recent developments in metal oxides for optoelectronic and photoelectronic applications, that is, dye-sensitized solar cells, photochromic and photo-electrochromic systems for digital display, optical sensor, etc.
Abstract: Metal oxides (MOs) play a vital role in the industrial and technological field including crystalline and amorphous transparent conductors (TCOs) and semiconductors. Since they are the most abundant materials in the Earth’s crust and are constituents of traditional ceramics, metal oxide semiconductors are complementing other unconventional organic and inorganic semiconductors such as silicon, CNTs, and 2D materials. The electronic and optical properties of the metal oxides can be tuned with respect to the synthesis techniques, morphology, electronic structure, defect states, charge transport mechanism, etc., for achieving the materials with completely new functions. These unique properties of metal oxides make them suitable for thin-film transistors, solar cells, flat panel displays, diodes, and memories. In particular, luminescent properties of the metal oxide were used in optoelectronic and photonic applications, that is, dye-sensitized solar cells, photochromic and photoelectrochromic systems for digital display, optical sensor, etc. In this chapter, we particularly describe the recent developments in metal oxides for optoelectronic and photoelectronic applications.

1 citations

Journal ArticleDOI
TL;DR: In this article , the authors presented an as-deposited IGZO/Ga2O3 TFT with high ON/OFF ratio of 1.2 and high mobility of 15.8 cm at a drain voltage of 1 V.
Abstract: High-performance thin-film transistors (TFTs) with amorphous indium gallium zinc oxide (IGZO)/Ga2O3 heterojunction and the reference TFTs with single-layer IGZO, Ga2O3, and stacked IGZO/Al2O3 layers are fabricated by sputtering. The as-deposited IGZO/Ga2O3 TFT shows high ON current of $0.97\,\,\mu \text{A}\cdot \mu \text{m}^{-{1}}$ at a drain voltage of 1 V, which is 7 orders of magnitude higher than that of the reference single layer TFTs and high mobility of 22.2 cm ${}^{{2}}{\cdot }\text{V}^{-{1}}{\cdot }\text{s}^{-{1}}$ , which is twice of that of the reference as-deposited IGZO/Al2O3 TFT (11.5 cm ${}^{{2}}{\cdot }\text{V}^{-{1}}{\cdot }\text{s}^{-{1}}$ ). Combining such superior conductivity of the IGZO/Ga2O3 TFT with the energy-level alignment, it indicates quasi-two-dimensional electron gas existed at the interface originated from the electrons confined in the potential well of IGZO. After annealing in air atmosphere, the IGZO/Ga2O3 TFT shows an effective gate modulation with high current ON/ OFF ratio of 1.2 $\times \,\,10^{{7}}$ and high mobility of 15.8 cm ${}^{{2}}{\cdot }\text{V}^{-{1}}\cdot \text{s}^{-{1}}$ comparing with that of the reference annealed IGZO/Al2O3 TFT (11.5 cm ${}^{{2}}{\cdot }\text{V}^{-{1}}{\cdot }\text{s}^{-{1}}$ ). In addition, the bias stability of the annealed IGZO/Ga2O3 TFT is enhanced due to the interface passivation. Our results indicate that amorphous IGZO/Ga2O3 heterostructure is an effective way to achieve high-mobility and stable TFTs, which have great potential in low-cost, large-area, and flexible high-definition displays.

1 citations

Proceedings ArticleDOI
15 Oct 2015
TL;DR: In this paper, the electrical properties of RF magnetron sputtered HfO 2 layers as dielectric and Hafnium-Indium-Zinc-Oxide HIZO as semiconductor in metal-insulator-semiconductor (MIS) structures are investigated.
Abstract: The electrical properties of RF magnetron sputtered HfO 2 layers as dielectric and Hafnium-Indium-Zinc-Oxide HIZO as semiconductor in metal-insulator-semiconductor (MIS) structures are investigated. The dielectric constant of the HfO 2 layer was around 9 measured at 10 kHz. The critical electric field was higher than 5×105 V/cm and the leakage current below 5×10−9 A/cm2. The effective charged density of interface states in the order of 5×1012 cm−2. Flat band shift due to polarization of the dielectric at voltage rage between −5 and 5 V is below 0.5 V. The RF deposited HIZO layer presents higher density of interface and bulk traps than similar layers deposited by other more complex techniques requiring higher processing temperature. However, results indicate that they can still be used in low voltage range amorphous oxide semiconductor thin film transistors AOSTFTs.

1 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of post-annealing treatment (PAT) on the properties of Ga-doped tin-oxide (Ga-SnOx) thin films grown at room temperature by using a radio-frequency magnetron sputtering technique were investigated.
Abstract: We investigated the effects of the post-annealing treatment (PAT) on the properties of Ga-doped tin-oxide (Ga-SnOx) thin films grown at room temperature by using a radio-frequency magnetron sputtering technique. On the basis of X-ray photoelectron spectroscopy (XPS), dynamic secondaryion mass spectrometry, X-ray diffraction (XRD), and Hall Effect measurements, we conclude that n-type SnO2 is the dominant phase in all samples regardless of PAT at low temperatures (25–200 °C). The Sn2+ area decreased to 32.5% with increasing temperature up to 150 °C, with a simultaneous increase in the Sn4+ area to 59%. This was attributed to a decrease and an increase in the Ga and the oxygen contents in the samples, respectively, which also caused a decrease in the number of oxygen vacancies in the samples treated at higher temperatures. In contrast, XPS on the samples post-annealed at temperatures higher than 150 °C showed results opposite to those of the samples treated at temperatures lower than 150 °C. This indicates that the Ga ions in Ga-doped SnOx films act as hole acceptors and that heat treatment is useful for controlling the number of oxygen vacancies, Sn2+ ions, and Sn4+ ions in Ga-doped SnOx films. In addition, XRD showed that post-annealing did not affect the amorphous phase in the samples.

1 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