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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: The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed in this article.
Abstract: Gallium oxide (Ga2O3) is emerging as a viable candidate for certain classes of power electronics, solar blind UV photodetectors, solar cells, and sensors with capabilities beyond existing technologies due to its large bandgap. It is usually reported that there are five different polymorphs of Ga2O3, namely, the monoclinic (β-Ga2O3), rhombohedral (α), defective spinel (γ), cubic (δ), or orthorhombic (e) structures. Of these, the β-polymorph is the stable form under normal conditions and has been the most widely studied and utilized. Since melt growth techniques can be used to grow bulk crystals of β-GaO3, the cost of producing larger area, uniform substrates is potentially lower compared to the vapor growth techniques used to manufacture bulk crystals of GaN and SiC. The performance of technologically important high voltage rectifiers and enhancement-mode Metal-Oxide Field Effect Transistors benefit from the larger critical electric field of β-Ga2O3 relative to either SiC or GaN. However, the absence of clear demonstrations of p-type doping in Ga2O3, which may be a fundamental issue resulting from the band structure, makes it very difficult to simultaneously achieve low turn-on voltages and ultra-high breakdown. The purpose of this review is to summarize recent advances in the growth, processing, and device performance of the most widely studied polymorph, β-Ga2O3. The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed. Areas where continued development is needed to fully exploit the properties of Ga2O3 are identified.

1,535 citations

Journal ArticleDOI
TL;DR: This Review surveys the uniqueness and universality of MOs versus other unconventional electronic materials in terms of materials chemistry and physics, electronic characteristics, thin-film fabrication strategies and selected applications in thin- film transistors, solar cells, diodes and memories.
Abstract: Optical transparency, tunable conducting properties and easy processability make metal oxides key materials for advanced optoelectronic devices. This Review discusses recent advances in the synthesis of these materials and their use in applications. Metal oxides (MOs) are the most abundant materials in the Earth's crust and are ingredients in traditional ceramics. MO semiconductors are strikingly different from conventional inorganic semiconductors such as silicon and III–V compounds with respect to materials design concepts, electronic structure, charge transport mechanisms, defect states, thin-film processing and optoelectronic properties, thereby enabling both conventional and completely new functions. Recently, remarkable advances in MO semiconductors for electronics have been achieved, including the discovery and characterization of new transparent conducting oxides, realization of p-type along with traditional n-type MO semiconductors for transistors, p–n junctions and complementary circuits, formulations for printing MO electronics and, most importantly, commercialization of amorphous oxide semiconductors for flat panel displays. This Review surveys the uniqueness and universality of MOs versus other unconventional electronic materials in terms of materials chemistry and physics, electronic characteristics, thin-film fabrication strategies and selected applications in thin-film transistors, solar cells, diodes and memories.

1,098 citations

Journal ArticleDOI
TL;DR: This Review focuses on the analysis of new approaches and results in the field of solution combustion synthesis (SCS) obtained during recent years, emphasizing the chemical mechanisms that are responsible for rapid self-sustained combustion reactions.
Abstract: Solution combustion is an exciting phenomenon, which involves propagation of self-sustained exothermic reactions along an aqueous or sol–gel media. This process allows for the synthesis of a variety of nanoscale materials, including oxides, metals, alloys, and sulfides. This Review focuses on the analysis of new approaches and results in the field of solution combustion synthesis (SCS) obtained during recent years. Thermodynamics and kinetics of reactive solutions used in different chemical routes are considered, and the role of process parameters is discussed, emphasizing the chemical mechanisms that are responsible for rapid self-sustained combustion reactions. The basic principles for controlling the composition, structure, and nanostructure of SCS products, and routes to regulate the size and morphology of the nanoscale materials are also reviewed. Recently developed systems that lead to the formation of novel materials and unique structures (e.g., thin films and two-dimensional crystals) with unusual...

841 citations

Journal ArticleDOI
TL;DR: In this review, recent progress in materials and devices for future wearable sensor technologies for bio and medical applications are reported.
Abstract: Printable electronics present a new era of wearable electronic technologies. Detailed technologies consisting of novel ink semiconductor materials, flexible substrates, and unique processing methods can be integrated to create flexible sensors. To detect various stimuli of the human body, as well as specific environments, unique electronic devices formed by "ink-based semiconductors" onto flexible and/or stretchable substrates have become a major research trend in recent years. Materials such as inorganic, organic, and hybrid semiconductors with various structures (i.e., 1D, 2D and 3D) with printing capabilities have been considered for bio and medical applications. In this review, we report recent progress in materials and devices for future wearable sensor technologies.

589 citations

Journal ArticleDOI
TL;DR: In this article, 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 summarized.
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.

529 citations

References
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Journal ArticleDOI
TL;DR: In this article, sulfur (S) segregation was exploited to attain a record-low electron barrier height (PhiB N) of 110 meV for platinum-based silicide contacts.
Abstract: In this letter, sulfur (S) segregation was exploited to attain a record-low electron barrier height (PhiB N) of 110 meV for platinum-based silicide contacts. Sulfur-incorporated PtSi:C/Si:C contacts were also demonstrated in strained FinFETs with Si:C source/drain stressors. Incorporation of sulfur at the PtSi:C/Si:C interface in the source/drain regions of FinFETs provides a 51% improvement in external resistances and a 45% enhancement in drive current as compared to devices without S segregation. The remarkable reduction in PhiB N is explained using charge transfer and dipole formation at the silicide/semiconductor interface with S segregation.

93 citations

Journal ArticleDOI
TL;DR: In this paper, a nonvacuum and low temperature process for passivating transparent metal oxides based thin-film transistors is presented, which uses the epoxy-based SU-8 resist which prevents device degradation against environmental conditions, vacuum or sputtering surface damage.
Abstract: A nonvacuum and low temperature process for passivating transparent metal oxides based thin-film transistors is presented. This process uses the epoxy-based SU-8 resist which prevents device degradation against environmental conditions, vacuum or sputtering surface damage. The incorporation of SU-8 as a passivation layer is based on the ability of this polymer to provide features with high mechanical and chemical stability. With this approach, lithography is performed to pattern the resist over the active area of the device in order to form the passivation layer. The resulting transistors demonstrate very good electrical characteristics, such as μFE=61 cm2/V s, VON=−3 V, ON/OFF=4.4×109, and S=0.28 V/dec. Electrical behavior due to the SU-8/metal oxide interface characteristics is also reported on the basis of Fourier transform infrared analysis. In contrast, we demonstrate how sputtering of SiO2 as a passivation layer results in severely degraded devices that cannot be switched-off. In order to obtain pro...

93 citations

Journal ArticleDOI
Xiao Zou1, Guojia Fang1, Longyan Yuan1, Meiya Li1, Wenjie Guan1, Xingzhong Zhao1 
TL;DR: In this article, the p-channel pure polycrystalline Cu2O TFTs (W/L = 500 μm/20 μm) exhibited a low threshold voltage of -0.8 V, an on-off current ratio of 3 x 106, a saturation mobility of 4.3 cm2/V s, and a subthreshold swing of 0.18 V/decade.
Abstract: Copper oxide (CuxO) thin films were grown on SiO2/Si substrate by pulsed laser deposition under different substrate temperatures. Top-gate Cux O semiconductor thin-film transistors (TFTs) were fabricated with high- κ HfON as gate dielectric. The performance of Cu2O TFTs was improved due to increased Hall mobility resulting from the decreased scattering of both the ionized defects and the grain boundary for Cu2O channel films. The p-channel pure polycrystalline Cu2O TFTs (W/L = 500 μm/20 μm) exhibited a low threshold voltage of -0.8 V, an on-off current ratio of 3 x 106, a saturation mobility of 4.3 cm2/ V s, and a subthreshold swing of 0.18 V/decade.

93 citations

Journal ArticleDOI
Edward Namkyu Cho1, Jung Han Kang1, Chang Eun Kim1, Pyung Moon1, Ilgu Yun1 
TL;DR: In this article, an analysis of electrical bias stress instability in amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) is presented.
Abstract: In this paper, we report an analysis of electrical bias stress instability in amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs). Understanding the variations of TFT characteristics under an electrical bias stress is important for commercial goals. In this experiment, the positive gate bias is initially applied to the tested a-IGZO TFTs, and subsequently, the negative gate bias is applied to the TFTs. For comparison with the subsequently negative-gate-bias-applied TFTs, another experiment is performed by directly applying the negative gate bias to the tested TFTs. For the positive gate bias stress, a positive shift in the threshold voltage (Vth) with no apparent change in the subthreshold swing (SSUB) is observed. On the other hand, when the negative gate bias is subsequently applied, the TFTs exhibit higher mobility with no significant change in SSUB, whereas the shift of the Vth is much smaller than that in the positive gate bias stress case. These phenomena are most likely induced by positively charged donor-like subgap density of states and the detrapping of trapped interface charge during the positive gate bias stress. The proposed mechanism was verified by device simulation. Thus, the proposed model can explain the instability for both positive and negative bias stresses in a-IGZO TFTs.

92 citations

Journal ArticleDOI
TL;DR: In this paper, the role of gate insulators in oxide thin-film transistors has been investigated and the results show that ZrO2 is more suitable than HfO2 for the gate-dielectric material which can be fabricated at room temperature.

90 citations