Fully solution-processed low-voltage aqueous In2O3 thin-film transistors using an ultrathin ZrO(x) dielectric

Solution-Processed Metal Oxide Thin-Film Transistor at Low Temperature via A Combination Strategy of H2 O2 -Inducement Technique and Infrared Irradiation Annealing

Solution processing has emerged as a promising technique for the fabrication of oxide thin-film transistors (TFTs), offering advantages such as low cost, high throughput, and exceptional compositional control. However, achieving reasonable electrical properties typically demands high annealing temperatures in the fabrication process. In addressing this challenge, a novel combination strategy is proposed that involves integrating the H2 O2 inducement technique with infrared (IR) irradiation annealing. The study investigates the effects of precursors and IR irradiation annealing temperatures on the electrical properties of In2 O3 TFTs. It is found that H2 O2 can help accelerate the decomposition of organic residues, while IR irradiation annealing could enhance the film densification. By employing the proposed strategy, metal oxide TFTs consisting of a Zr-Al-O dielectric fabricated at 230 °C and an In2 O3 channel layer fabricated at 185 °C demonstrated high performance with field-effect mobility = 31.7 cm2  V-1 ·s-1 , threshold voltage = 1.3 V, subthreshold swing = 0.13 V per decade, and on-to-off current ratio = 1.1 × 105 . This work demonstrates the proposed combinational strategy is a general method to fabricate not only metal oxide semiconductors but also dielectrics.

Printable Epsilon-Type Structure Transistor Arrays with Highly Reliable Physical Unclonable Functions

Printed electronics promises to drive the future data-intensive technologies, with its potential to fabricate novel devices over a large area with low cost on nontraditional substrates. In these emerging technologies, there exists a large digital information flow, which requires secure communication and authentication. Physical unclonable functions (PUFs) offer a promising built-in hardware-security system comparable to biometrical data, which can be constructed by device-specific intrinsic variations in the additive manufacturing process of active devices. However, printed PUFs typically exploit the inherent variation in layer thickness and roughness of active devices. The current in devices with enough significant changes to increase the robustness to external environment noise is still a challenge. Here, printable epsilon-type-structure indium tin oxide transistor arrays are demonstrated to construct high-reliability PUFs by modifying the coffee-ring structure. The epsilon-type structure improves the printing scalability, film quality, and device reliability. Furthermore, the print-induced uncertainty along the channel thickness and length can lead to changes in the carrier concentration. Notably, the randomly distributed printing droplets in a small area significantly increase this uncertainty. As a result, the PUFs exhibit near-ideal uniformity, uniqueness, randomness, and reliability. Additionally, the PUFs are resilient against machine-learning-based attacks with a prediction accuracy of only 55% without postprocessing.

All-Water-Driven High-k HfO2 Gate Dielectrics and Applications in Thin Film Transistors

In this article, we used a simple, non-toxic, environmentally friendly, water-driven route to fabricate the gate dielectric on the Si substrate and successfully integrate the In₂O₃/HfO₂ thin film transistor (TFT). All the electrical properties of In₂O₃ based on HfO₂ were systematically analyzed. The In₂O₃/HfO₂ device exhibits the best electrical performance at an optimized annealing temperature of 500 °C, including a high µ_FE of 9 cm² V^-1 s^-1, a high I_ON/I_OFF of 10⁵, a low threshold voltage of 1.1 V, and a low sub-threshold of 0.31 V dec^-1. Finally, test the stability of the bias under positive bias stress (PBS) and negative bias stress (NBS) with threshold shifts (V_TH) of 0.35 and 0.13 V while these optimized properties are achieved at a small operating voltage of 2 V. All experimental results demonstrate the potential application of aqueous solution technology for future low-cost, energy-efficient, large-scale, and high-performance electronics.

Enhanced Electrical Performance and Stability of Solution-Processed Thin-Film Transistors with In2O3/In2O3:Gd Heterojunction Channel Layer

The use of the semiconductor heterojunction channel layer has been explored as a method for improving the performance of metal oxide thin-film transistors (TFTs). The excellent electrical performance and stability of heterojunction TFTs is easy for vacuum-based techniques, but difficult for the solution process. Here, we fabricated In₂O₃/In₂O₃:Gd (In₂O₃/InGdO) heterojunction TFTs using a solution process and compared the electrical properties with single-layer In₂O₃ TFTs and In₂O₃:Gd (InGdO) TFTs. The In₂O₃/InGdO TFT consisted of a highly conductive In₂O₃ film as the primary transmission layer and a subconductive InGdO film as the buffer layer, and exhibited excellent electrical performance. Furthermore, by altering the Gd dopant concentration, we obtained an optimal In₂O₃/InGdO TFT with a higher saturation mobility (µ) of 4.34 cm²V^-1s^-1, a near-zero threshold voltage (V_th), a small off-state current (I_off) of 1.24×10-9 A, a large on/off current ratio (I_on/I_off) of 3.18×105, a small subthreshold swing (SS), and an appropriate positive bias stability (PBS). Finally, an aging test was performed after three months, indicating that In₂O₃/InGdO TFTs enable long-term air stability while retaining a high-mobility optimal switching property. This study suggests that the role of a high-performance In₂O₃/InGdO heterojunction channel layer fabricated by the solution process in the TFT is underlined, which further explores a broad pathway for the development of high-performance, low-cost, and large-area oxide electronics.

High-Performance Deep Red Colloidal Quantum Well Light-Emitting Diodes Enabled by the Understanding of Charge Dynamics

Colloidal quantum wells (CQWs) have emerged as a promising family of two-dimensional (2D) optoelectronic materials with outstanding properties, including ultranarrow luminescence emission, nearly unity quantum yield, and large extinction coefficient. However, the performance of CQWs-based light-emitting diodes (CQW-LEDs) is far from satisfactory, particularly for deep red emissions (≥660 nm). Herein, high efficiency, ultra-low-efficiency roll-off, high luminance, and extremely saturated deep red CQW-LEDs are reported. A key feature for the high performance is the understanding of charge dynamics achieved by introducing an efficient electron transport layer, ZnMgO, which enables balanced charge injection, reduced nonradiative channels, and smooth films. The CQW-LEDs based on (CdSe/CdS)@(CdS/CdZnS) ((core/crown)@(colloidal atomic layer deposition shell/hot injection shell)) show an external quantum efficiency of 9.89%, which is a record value for 2D nanocrystal LEDs with deep red emissions. The device also exhibits an ultra-low-efficiency roll-off and a high luminance of 3853 cd m^-2. Additionally, an exceptional color purity with the CIE coordinates of (0.719, 0.278) is obtained, indicating that the color gamut covers 102% of the International Telecommunication Union Recommendation BT 2020 (Rec. 2020) standard in the CIE 1931 color space, which is the best for CQW-LEDs. Furthermore, an active-matrix CQW-LED pixel circuit is demonstrated. The findings imply that the understanding of charge dynamics not only enables high-performance CQW-LEDs and can be further applied to other kinds of nanocrystal LEDs but also is beneficial to the development of CQW-LEDs-based display technology and related integrated optoelectronics.

Role of Fluoride Doping in Low-Temperature Combustion-Synthesized ZrOx Dielectric Films

Zirconium oxide (ZrO_x) is an attractive metal oxide dielectric material for low-voltage, optically transparent, and mechanically flexible electronic applications due to the high dielectric constant (κ ∼ 14-30), negligible visible light absorption, and, as a thin film, good mechanical flexibility. In this contribution, we explore the effect of fluoride doping on structure-property-function relationships in low-temperature solution-processed amorphous ZrO_x. Fluoride-doped zirconium oxide (F:ZrO_x) films with a fluoride content between 1.7 and 3.2 in atomic (at) % were synthesized by a combustion synthesis procedure. Irrespective of the fluoride content, grazing incidence X-ray diffraction, atomic-force microscopy, and UV-vis spectroscopy data indicate that all F:ZrO_x films are amorphous, atomically smooth, and transparent in visible light. Impedance spectroscopy measurements reveal that unlike solution-processed fluoride-doped aluminum oxide (F:AlO_x), fluoride doping minimally affects the frequency-dependent capacitance instability of solution-processed F:ZrO_x films. This result can be rationalized by the relatively weak Zr-F versus Zr-O bonds and the large ionic radius of Zr⁺⁴, as corroborated by EXAFS analysis and MD simulations. Nevertheless, the performance of pentacene thin-film transistors (TFTs) with F:ZrO_x gate dielectrics indicates that fluoride incorporation reduces I-V hysteresis in the transfer curves and enhances bias stress stability versus TFTs fabricated with analogous, but undoped ZrO_x films as gate dielectrics, due to reduced trap density.

Sublimation-doping with super bases for high-performance solution-processed heterojunction oxide thin film transistors

We elucidate how non-destructive sublimation-doping of In₂O₃/ZnO heterojunctions with various amidine-based organic dopants affects the degree of band bending of the heterojunction and thus the overall performance of solution-processed heterojunction oxide thin-film transistors (TFTs). Ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy analyses show that the stronger the basicity of the dopant, the smaller the E_C - E_F of ZnO that can be induced within a short doping time, resulting in a high electron mobility due to the increased electron density of the In₂O₃ layer at the vicinity of the heterointerface. Mott-Schottky analysis combined with secondary ion mass spectroscopy shows the preferential modification of E_C - E_F selectively for the ZnO layer. The use of a super base with the highest basicity exhibits a high electron mobility of 17.8 cm² V^-1 s^-1 for the SiO₂ and 37.8 cm² V^-1 s^-1 on average (46.6 cm² V^-1 s^-1 maximum) for the ZrO₂ dielectric layers and enhanced operational bias-stress stability via sublimation-doping for 6 min, which can be attributed to the trap-filled, percolation-limited charge transport behavior. Reproducibility tests are conducted for more than 50 independently fabricated TFTs using the optimized doping technique, and electron mobility distributions with deviations <±10% are demonstrated. This study shows that sublimation doping with super bases can be a good solution for high mobility oxide TFTs with stability and reliability.

High-Performance and Radiation-Hardened Solution-Processed ZrLaO Gate Dielectrics for Large-Area Applications

Radiation hardness is important for electronics operating in harsh radiation environments such as outer space and nuclear energy industries. In this work, radiation-hardened solution-processed ZrLaO thin films are demonstrated. The radiation effects on solution-processed ZrLaO thin films and InO_x/ZrLaO thin-film transistors (TFTs) were systemically investigated. The Zr_0.9La_0.1O_y thin films demonstrated excellent radiation hardness with negligible roughness, composition, electrical property, and bias-stress stability degradation after radiation exposure. The metal-oxide-semiconductor capacitors (MOSCAPs) based on Zr_0.9La_0.1O_y gate dielectrics exhibited an ultralow flat band-voltage (V_FB) sensitivity of 0.11 mV/krad and 0.19 mV/krad under low dose and high dose gamma irradiation conditions, respectively. The low dose condition had a 103 krad (SiO₂) total dose and a 0.12 rad/s low dose rate, whereas the high dose condition had a 580 krad total dose and a 278 rad/s high dose rate. Furthermore, InO_x/Zr_0.9La_0.1O_y thin-film transistors (TFTs) exhibited a large I_on/I_off of 2 × 10⁶, a small subthreshold swing (SS) of 0.11 V/dec, a small interface trap density (D_it) of 1 × 10¹² cm^-2, and a 0.16 V threshold shift (ΔV_TH) under 3600 s positive bias-stress (PBS). InO_x/Zr_0.9La_0.1O_y TFT-based resistor-loaded inverters demonstrated complete swing behavior, a static output gain of 13.3 under 4 V V_DD, and an ∼9% radiation-induced degradation. Through separate investigation of the radiation-induced degradation on the semiconductor layer and dielectric layer of TFTs, it was found that radiation exposure mainly generated oxygen vacancies (V_o) and increased electron concentration among gate oxide. Nevertheless, the radiation-induced TFT instability was mainly related to the semiconductor layer degradation, which could be possibly suppressed by back-channel passivation. The demonstrated results indicate that solution-processed ZrLaO is a high-potential candidate for large-area electronics and circuits applied in harsh radiation environments. In addition, the detailed investigation of radiation-induced degradation on solution-processed high-k dielectrics in this work provided clear inspiration for developing novel flexible rad-hard dielectrics.

High Performance of Solution-Processed Amorphous p-Channel Copper-Tin-Sulfur-Gallium Oxide Thin-Film Transistors by UV/O3 Photocuring

The development of p-type metal-oxide semiconductors (MOSs) is of increasing interest for applications in next-generation optoelectronic devices, display backplane, and low-power-consumption complementary MOS circuits. Here, we report the high performance of solution-processed, p-channel copper-tin-sulfide-gallium oxide (CTSGO) thin-film transistors (TFTs) using UV/O₃ exposure. Hall effect measurement confirmed the p-type conduction of CTSGO with Hall mobility of 6.02 ± 0.50 cm² V^-1 s^-1. The p-channel CTSGO TFT using UV/O₃ treatment exhibited the field-effect mobility (μ_FE) of 1.75 ± 0.15 cm² V^-1 s^-1 and an on/off current ratio (I_ON/I_OFF) of ∼10⁴ at a low operating voltage of -5 V. The significant enhancement in the device performance is due to the good p-type CTSGO material, smooth surface morphology, and fewer interfacial traps between the semiconductor and the Al₂O₃ gate insulator. Therefore, the p-channel CTSGO TFT can be applied for CMOS MOS TFT circuits for next-generation display.

Ecofriendly Solution-Combustion-Processed Thin-Film Transistors for Synaptic Emulation and Neuromorphic Computing

The ecofriendly combustion synthesis (ECS) and self-combustion synthesis (ESCS) have been successfully utilized to deposit high-k aluminum oxide (AlO_x) dielectrics at low temperatures and applied for aqueous In₂O₃ thin-film transistors (TFTs) accordingly. The ECS and ESCS processes facilitate the formation of high-quality dielectrics at lower temperatures compared to conventional methods based on an ethanol precursor, as confirmed by thermal analysis and chemical composition characterization. The aqueous In₂O₃ TFTs based on ECS and ESCS-AlO_x show enhanced electrical characteristics and counterclockwise transfer-curve hysteresis. The memory-like counterclockwise behavior in the transfer curve modulated by the gate bias voltage is comparable to the signal modulation by the neurotransmitters. ECS and ESCS transistors are employed to perform synaptic emulation; various short-term and long-term memory functions are emulated with low operating voltages and high excitatory postsynaptic current levels. High stability and reproducibility are achieved within 240 pulses of long-term synaptic potentiation and depression. The synaptic emulation functions achieved in this work match the demand for artificial neural networks (ANN), and a multilayer perceptron (MLP) is developed using an ECS-AlO_x synaptic transistor for image recognition. A superior recognition rate of over 90% is achieved based on ECS-AlO_x synaptic transistors, which facilitates the implementation of the metal-oxide synaptic transistor for future neuromorphic computing via an ecofriendly route.

Highly Reliable Organic Field-Effect Transistors with Molecular Additives for a High-Performance Printed Gas Sensor

Organic semiconductors (OSCs) are promising sensing materials for printed flexible gas sensors. However, OSCs are unstable in the humid air, which limits the realization of gas sensors for multiple usages. In this paper, we report a facile and effective way to improve the air stability of an OSC film to realize multiple reversibly used printed gas sensors by adding molecular additives. The tetracyanoquinodimethane (TCNQ) or 4-aminobenzonitrile (ABN) additives effectively prevent adsorption of moisture from the air on the OSC layer, thereby providing a stable gas sensor operation. The organic field-effect transistor (OFET)-based indacenodithiophene-co-benzothiadiazole with TCNQ or ABN shows highly reliable ammonia (NH₃) gas sensing up to 10 ppm in air, with 23.14% sensitivity, and the gas sensor signal can recover up to 100%. In particular, the stability of gas detection is greatly improved by the additives, which can be performed in the air for 16 days. The result indicates that the elimination of moisture trapped in OSCs with molecule additives is critical in the improvement of device air/operational stabilities and the achievement of high-performance OFET-based gas sensors.

High-Intensity Ultrasound-Assisted Low-Temperature Formulation of Lanthanum Zirconium Oxide Nanodispersion for Thin-Film Transistors

The process complexity, limited stability, and distinct synthesis and dispersion steps restrict the usage of multicomponent metal oxide nanodispersions in solution-processed electronics. Herein, sonochemistry is employed for the in situ synthesis and formulation of a colloidal nanodispersion of high-permittivity (κ) multicomponent lanthanum zirconium oxide (LZO: La₂Zr₂O₇). The continuous propagation of intense ultrasound waves in the aqueous medium allows the generation of oxidant species which, on reaction, form nanofragments of crystalline LZO at ∼80 °C. Simultaneously, the presence of acidic byproducts in the vicinity promotes the formulation of a stable as-prepared LZO dispersion. The LZO thin film exhibits a κ of 16, and thin-film transistors (TFTs) based on LZO/indium gallium zinc oxide operate at low input voltages (≤4 V), with the maximum mobility (μ) and on/off ratio (I_on/I_off) of 5.45 ± 0.06 cm² V^-1 s^-1 and ∼10⁵, respectively. TFTs based on the compound dielectric LZO/Al₂O₃ present a marginal reduction in leakage current, along with enhancement in μ (6.16 ± 0.04 cm² V^-1 s^-1) and I_on/I_off (∼10⁵). Additionally, a 3 × 3 array of the proposed TFTs exhibits appreciable performance, with a μ of 3-6 cm² V^-1 s^-1, a threshold voltage of -0.5 to 0.8 V, a subthreshold swing of 0.3-0.6 V dec^-1, and an I_on/I_off of 1-2.5 (×10⁶).

Frequency-Agile Low-Temperature Solution-Processed Alumina Dielectrics for Inorganic and Organic Electronics Enhanced by Fluoride Doping

The frequency-dependent capacitance of low-temperature solution-processed metal oxide (MO) dielectrics typically yields unreliable and unstable thin-film transistor (TFT) performance metrics, which hinders the development of next-generation roll-to-roll MO electronics and obscures intercomparisons between processing methodologies. Here, capacitance values stable over a wide frequency range are achieved in low-temperature combustion-synthesized aluminum oxide (AlO_x) dielectric films by fluoride doping. For an optimal F incorporation of ∼3.7 atomic % F, the F:AlO_x film capacitance of 166 ± 11 nF/cm² is stable over a 10^-1-10⁴ Hz frequency range, far more stable than that of neat AlO_x films (capacitance = 336 ± 201 nF/cm²) which falls from 781 ± 85 nF/cm² to 104 ± 4 nF/cm² over this frequency range. Importantly, both n-type/inorganic and p-type/organic TFTs exhibit reliable electrical characteristics with minimum hysteresis when employing the F:AlO_x dielectric with ∼3.7 atomic % F. Systematic characterization of film microstructural/compositional and electronic/dielectric properties by X-ray photoelectron spectroscopy, time-of-fight secondary ion mass spectrometry, cross-section transmission electron microscopy, solid-state nuclear magnetic resonance, and UV-vis absorption spectroscopy reveal that fluoride doping generates AlOF, which strongly reduces the mobile hydrogen content, suppressing polarization mechanisms at low frequencies. Thus, this work provides a broadly applicable anion doping strategy for the realization of high-performance solution-processed metal oxide dielectrics for both organic and inorganic electronics applications.

Effect of Zirconium Doping on Electrical Properties of Aluminum Oxide Dielectric Layer by Spin Coating Method with Low Temperature Preparation

In recent years, significant efforts have been devoted to the research and development of spin-coated Al2O3 thin films, due to their large band gaps, high breakdown voltage and stability at high annealing temperature. However, as the alumina precursor has a large surface energy, substrates need to be treated by plasma before spin coating. Therefore, to avoid the expensive and process-complicated plasma treatment, we incorporated zirconium nitrate into the aluminum nitrate solution to decrease the surface energy of the precursor which improve the spreadability. Then, the electrical performances and the surface morphologies of the films were measured. For comparison, the pure Al2O3 films with plasma treatments were also prepared. As a result, after low temperature annealing (200 °C), the relative dielectric constant of Zr–AlOx spin-coated thin-film MIM (Metal-Insulator-Metal) devices can reach 12 and the leakage current density is not higher than 7.78 × 10−8 A/cm2 @ 1 MV/cm when the concentration of zirconium nitrate is 0.05 mol/L. The Aluminum oxide film prepared by zirconium doping has higher stability and better electrical properties than the pure films with plasma treatments and high performance can be attained under low-temperature annealing, which shows its potential application in printing and flexible electronic devices.

Proton Conducting Perhydropolysilazane-Derived Gate Dielectric for Solution-Processed Metal Oxide-Based Thin-Film Transistors

Perhydropolysilazane (PHPS), an inorganic polymer composed of Si-N and Si-H, has attracted much attention as a precursor for gate dielectrics of thin-film transistors (TFTs) due to its facile processing even at a relatively low temperature. However, an in-depth understanding of the tunable dielectric behavior of PHPS-derived dielectrics and their effects on TFT device performance is still lacking. In this study, the PHPS-derived dielectric films formed at different annealing temperatures have been used as the gate dielectric layer for solution-processed indium zinc oxide (IZO) TFTs. Notably, the IZO TFTs fabricated on PHPS annealed at 350 °C exhibit mobility as high as 118 cm² V^-1 s^-1, which is about 50 times the IZO TFTs made on typical SiO₂ dielectrics. The outstanding electrical performance is possible because of the exceptional capacitance of PHPS-derived dielectric caused by the limited hydrolysis reaction of PHPS at a low processing temperature (<400 °C). According to our analysis, the exceptional dielectric behavior is originated from the electric double layer formed by mobile of protons in the low temperature-annealed PHPS dielectrics. Furthermore, proton conduction through the PHPS dielectric occurs through a three-dimensional pathway by a hopping mechanism, which allows uniform polarization of the dielectric even at room temperature, leading to amplified performance of the IZO TFTs.

Suppression of Interfacial Disorders in Solution-Processed Metal Oxide Thin-Film Transistors by Mg Doping

The fabrication of high-performance metal oxide thin-film transistors (TFTs) using a low-temperature solution process may facilitate the realization of ultraflexible and wearable electronic devices. However, the development of highly stable oxide gate dielectrics at a low temperature has been a challenging issue since a considerable amount of residual impurities and defective bonding states is present in low-temperature-processed gate dielectrics causing a large counterclockwise hysteresis and a significant instability. Here, we report a new approach to effectively remove the residual impurities and suppress the relevant dipole disorder in a low-temperature-processed (180 °C) AlO_x gate dielectric layer by magnesium (Mg) doping. Mg is well known as a promising material for suppression of oxygen vacancy defects and improvement of operational stability due to a high oxygen vacancy formation energy (E_vo = 9.8 eV) and a low standard reduction potential (E⁰ = -2.38 V). Therefore, with an adequate control of Mg concentration in metal oxide (MO) films, oxygen-related defects could be easily suppressed without additional treatments and then stable metal-oxygen-metal (M-O-M) network formation could be achieved, causing excellent operational stability. By optimal Mg doping (10%) in the InO_x channel layer, Mg:InO_x TFTs exhibited negligible clockwise hysteresis and a field-effect mobility of >4 cm² V^-1 s^-1. Furthermore, the electric characteristics of the low-temperature-processed AlO_x gate dielectric with high impurities were improved by Mg diffusion originating in Mg doping, resulting in stable threshold voltage shift in the bias stability test.

Synthesis, oxide formation, properties and thin film transistor properties of yttrium and aluminium oxide thin films employing a molecular-based precursor route

Combustion synthesis of dielectric yttrium oxide and aluminium oxide thin films is possible by introducing a molecular single-source precursor approach employing a newly designed nitro functionalized malonato complex of yttrium (Y-DEM-NO21) as well as defined urea nitrate coordination compounds of yttrium (Y-UN 2) and aluminium (Al-UN 3). All new precursor compounds were extensively characterized by spectroscopic techniques (NMR/IR) as well as by single-crystal structure analysis for both urea nitrate coordination compounds. The thermal decomposition of the precursors 1-3 was studied by means of differential scanning calorimetry (DSC) and thermogravimetry coupled with mass spectrometry and infrared spectroscopy (TG-MS/IR). As a result, a controlled thermal conversion of the precursors into dielectric thin films could be achieved. These oxidic thin films integrated within capacitor devices are exhibiting excellent dielectric behaviour in the temperature range between 250 and 350 °C, with areal capacity values up to 250 nF cm-2, leakage current densities below 1.0 × 10-9 A cm-2 (at 1 MV cm-1) and breakdown voltages above 2 MV cm-1. Thereby the increase in performance at higher temperatures can be attributed to the gradual conversion of the intermediate hydroxy species into the respective metal oxide which is confirmed by X-ray photoelectron spectroscopy (XPS). Finally, a solution-processed Y x O y based TFT was fabricated employing the precursor Y-DEM-NO21. The device exhibits decent TFT characteristics with a saturation mobility (μ sat) of 2.1 cm2 V-1 s-1, a threshold voltage (V th) of 6.9 V and an on/off current ratio (I on/off) of 7.6 × 105.

Inkjet-Printed Oxide Thin-Film Transistors Based on Nanopore-Free Aqueous-Processed Dielectric for Active-Matrix Quantum-Dot Light-Emitting Diode Displays

Inkjet-printed thin-film transistors (TFTs) for active-matrix light-emitting diode display are drawing much attention for the advantages of low material waste and simple fabrication processes without vacuum deposition and photolithography steps. Herein, for the first time, solution-processed quantum-dot light-emitting diode (QLED) array displays driven with the inkjet-printed oxide TFT backplane were realized and demonstrated using a general "solvent printing" method. To suppress nanopore formation in the thick oxide films, carbon-free aqueous inks were employed for gate dielectrics. No nanopore was found in the whole 120 nm-thick gate dielectrics. However, compared to the organic inks, the aqueous inks have very low viscosity, resulting in uncontrollable ink spreading especially in transline printing. The ink easily shrinks on the low-surface-energy area and spreads on the high-surface-energy area, leading to serious uniformity problems (the upper lines even break at the top of underlying lines). To solve the problem, a "solvent printing" method was employed to form coffee-line surface-energy patterns, which were uniform without shape distortion. The surface-energy patterns can restrain the ink spreading and tune the morphology of the printed films. As a result, multilayer TFT arrays with ideal shapes were achieved. The mobilities of the printed top-gate TFTs in the backplane array were 3.13 ± 0.87 cm² V^-1 s^-1 for switching TFTs and 2.22 ± 0.38 cm² V^-1 s^-1 for driving TFTs. Finally, an active-matrix red QLED character display based on the printed oxide TFT backplane and solution-processed QLEDs was demonstrated. The "solvent printing" method opens a general route for inkjet-printed multilayer electronic devices.

Recent Progress in Inkjet-Printed Thin-Film Transistors

Drop-on-demand inkjet printing is one of the most attractive techniques from a manufacturing perspective due to the possibility of fabrication from a digital layout at ambient conditions, thus leading to great opportunities for the realization of low-cost and flexible thin-film devices. Over the past decades, a variety of inkjet-printed applications including thin-film transistors (TFTs), radio-frequency identification devices, sensors, and displays have been explored. In particular, many research groups have made great efforts to realize high-performance TFTs, for application as potential driving components of ubiquitous wearable electronics. Although there are still challenges to enable the commercialization of printed TFTs beyond laboratory-scale applications, the field of printed TFTs still attracts significant attention, with remarkable developments in soluble materials and printing methodology. Here, recent progress in printing-based TFTs is presented from materials to applications. Significant efforts to improve the electrical performance and device-yield of printed TFTs to match those of counterparts fabricated using conventional deposition or photolithography methods are highlighted. Moreover, emerging low-dimension printable semiconductors, including carbon nanotubes and transition metal dichalcogenides as well as mature semiconductors, and new-concept printed switching devices, are also discussed.

Investigation of direct inkjet-printed versus spin-coated ZrO2 for sputter IGZO thin film transistor

In this work, a low leakage current ZrO2 was fabricated for sputter indium gallium zinc oxide (IGZO) thin-film transistor using direct inkjet-printing technology. Spin-coated and direct inkjet-printed ZrO2 were prepared to investigate the film formation process and electrical performance for different process. Homogeneous ZrO2 films were observed through the high-resolution TEM images. The chemical structure of ZrO2 films were investigated by XPS measurements. The inkjet-printed ZrO2 layer upon IGZO showed a superior performance on mobility and off state current, but a large Vth shift under positive bias stress. As a result, the TFT device based on inkjet-printed ZrO2 exhibited a saturation mobility of 12.4 cm2/Vs, an Ion/Ioff ratio of 106, a turn on voltage of 0 V and a 1.4-V Vth shift after 1-h PBS strain. Higher density films with less oxygen vacancy were responsible for low off state current for the printed ZrO2 device. The mechanism of deteriorated performance on PBS test can be ascribed to the In-rich region formed at the back channel which easily absorbs H2O and oxygen. The absorbed H2O and oxygen capture electrons under positive bias stress, serving as acceptors in TFT device. This work demonstrates the film formation process of direct inkjet-printed and spin-coated oxide films and reveals the potential of direct inkjet-printed oxide dielectric in high-performance oxide TFT device.

High performance electronic devices based on nanofibers via a crosslinking welding process

Recently, metal oxide nanofibers fabricated by electrospinning have been considered as promising components for next-generation electronic devices. Unfortunately, the nanofiber-based electronic devices usually exhibited inferior electrical performance, due to the high contact resistance between the nanofibers and the inferior interfacial adhesion between the nanofibers and the substrate. In this report, an amine-hardened epoxy resin was selected as an adhesion agent to weld nanofiber junctions and improve the interfacial adhesion performance. It was confirmed that the physical properties of the nanofibers were greatly improved after the crosslinking welding process. Taking advantage of the welding process, field-effect transistors (FETs) based on In₂O₃ nanofiber networks (NFNs) with various nanofiber densities were integrated and investigated. It was found that the FETs based on In₂O₃ NFNs with a nanofiber density of 0.4 μm^-1 exhibited the optimal electrical performance. When high-k ZrO_x was integrated into the FETs as the dielectric layer, the FETs based on In₂O₃ NFNs/ZrO_x exhibited superior performance, including a μ_FE of 13.2 cm² V^-1 s^-1, an I_on/I_off of 10⁷, and an SS of 90 mV per decade. The crosslinking welding process is a simple, versatile and low-cost technique, which has great possibility for various applications.

Potential solution-induced HfAlO dielectrics and their applications in low-voltage-operating transistors and high-gain inverters

Recently, much attention has been paid to the investigation of solution-driven oxides for application in thin film transistors (TFTs). In current study, a fully solution-based method, using 2-methoxyethanol as solvent, has been adopted to prepare InZnO thin films and HfAlO _x gate dielectrics. Amorphous HfAlO _x thin films annealed at 600 °C have shown a high transparency (>85%), low leakage current density (6.9 × 10^-9 A cm^-2 at 2 MV cm^-1), and smooth surface. To verify the potential applications of HfAlO _x gate dielectrics in oxide-based TFTs, fully solution-induced InZnO/HfAlO _x TFTs have been integrated. Excellent electrical performance for InZnO/HfAlO _x TFTs annealed at 450 °C has been observed, including a low operating voltage of 3 V, a saturated mobility of 5.17 cm² V^-1 s^-1, a high I _on/I _off of ∼10⁶, a small subthreshold swing of 87 mV per decade, and a threshold voltage shift of 0.52 V under positive bias stress (PBS) for 7200 s, respectively. In addition, time dependent threshold voltage shift under PBS could be described by a stretched-exponential model, which can be due to charge trapping in the semiconductor/dielectric interface. Finally, to explore the possible application in logic operation, a resistor-loaded inverter based on InZnO/HfAlO _x TFTs has been built and excellent swing characteristic and well dynamic behavior have been obtained. Therefore, it can be concluded that fully solution-driven InZnO/HfAlO _x TFTs have demonstrated potential application in nontoxic, eco-friendly and low-power consumption oxide-based flexible electronics.

Improving Thermal Stability of Solution-Processed Indium Zinc Oxide Thin-Film Transistors by Praseodymium Oxide Doping

Praseodymium-doped indium zinc oxide (PrIZO) channel materials have been fabricated by a solution process with conventional chemical precursor. The PrIZO-based thin-film transistors (TFTs) exhibited a field-effect mobility of 10.10 cm²/V s, a subthreshold swing value of 0.25 V/decade, and an I_on/ I_off ratio of 10⁸. The as-fabricated PrIZO-TFTs showed an improved device performance against positive bias temperature stress (PBTS shift of 1.97 V for 7200 s), which was evidently better than the undoped IZO-TFTs (PBTS shift of 9.52 V). This result indicates that the organic residual (-OCH₃ and -CH₂-) in metal-oxide semiconductor, which is confirmed to be a dominant effect on the performance of PBTS, can be passivated by the rare earth of praseodymium element. The residual is intended to be oxidized with a more stable ester group with the assistant of PrOx, weakening the electron-withdrawing characteristic during the thermal bias stress.

Recent Advances of Solution-Processed Metal Oxide Thin-Film Transistors

Solution-processed metal oxide thin-film transistors (TFTs) are considered as one of the most promising transistor technologies for future large-area flexible electronics. This work surveys the recent advances in solution-processed metal oxide TFTs, including n-type oxide semiconductors, oxide dielectrics, and p-type oxide semiconductors. We first deliver a review on the history and present status of metal oxide TFTs. Then, we present the recent progress in solution-processed n-type oxide semiconductors, with a special focus on low-temperature and large-area solution-based approaches as well as emerging nondisplay applications. Next, we give a detailed analysis of the state-of-the-art solution-processed oxide dielectrics for low-power electronics. We further discuss the recent advances in solution-based p-type oxide semiconductors, which will enable the highly desirable future low-cost large-area complementary circuits. Finally, we draw conclusions and outline the perspectives over the research field.

Electrospun p-Type Nickel Oxide Semiconducting Nanowires for Low-Voltage Field-Effect Transistors

One-dimensional metal-oxide nanowires are regarded as important building blocks in nanoscale electronics, because of their unique mechanical and electrical properties. In this work, p-type nickel oxide nanowires (NiO NWs) were fabricated by combining sol-gel and electrospinning processes. The poly(vinylpyrrolidone) (PVP) with a molecular weight of 1 300 000 was used as the polymer matrix to increase the viscosity of a NiO precursor solution. The formation and properties of the as-spun NiO/PVP composite NWs before/after calcination treatment were investigated using various techniques. Because of the enhanced adhesion properties between ultraviolet (UV)-treated NiO NWs and the substrate, the field-effect transistors (FETs) based on NiO NWs were found to exhibit satisfying p-channel behaviors. For the fabrication of aligned NiO NW arrays, two parallel conducting Si strips were grounded as NW collector. The integrated FETs based on aligned NiO NWs were demonstrated to exhibit superior electrical performance, compared to the disordered counterparts with the comparable NW coverage. By employing high- k aluminum oxide (Al₂O₃) as a dielectric layer, instead of conventional SiO₂, the devices with an aligned NiO NW array exhibit a high hole mobility of 2.8 cm²/(V s) with a low operating voltage of 5 V, fast switching speed, and successful modulation of light emission over external light-emitting diodes. To the best of our knowledge, this is the first work demonstrating the low-voltage transistors based on p-type oxide NWs, which represents a great step toward the development of sensors and CMOS logic circuits.

Low-voltage and high-performance field-effect transistors based on ZnxSn1-xO nanofibers with a ZrOx dielectric

One-dimensional (1D) nanofibers have been considered to be important building blocks for nano-electronics due to their superior physical and chemical properties. In this report, high-performance zinc tin oxide (ZnSnO) nanofibers with various composition ratios were prepared by electrospinning. The surface morphology, crystallinity, grain size distribution, and chemical composition of the nanofibers were investigated. Meanwhile, field-effect transistors (FETs) based on ZnSnO nanofiber networks (NFNs) with various composition ratios were integrated and investigated. For optimized Zn0.3Sn0.7O NFNs FETs, the device based on an SiO2 dielectric exhibited a high electrical performance, including a high on/off current ratio (Ion/off) of 2 × 107 and a field-effect mobility (μFE) of 0.17 cm2 V-1 s-1. When a high-permittivity (κ) ZrOx thin film was employed as the dielectric in Zn0.3Sn0.7O NFNs FETs, the operating voltage was substantially reduced and a high μFE of 7.8 cm2 V-1 s-1 was achieved. These results indicate that the Zn0.3Sn0.7O NFNs/ZrOx FETs exhibit great potency in low-cost and low-voltage devices.

Printed Electronics Based on Inorganic Semiconductors: From Processes and Materials to Devices

Following the ever-expanding technological demands, printed electronics has shown palpable potential to create new and commercially viable technologies that will benefit from its unique characteristics, such as, large-area and wide range of substrate compatibility, conformability and low-cost. Through the last few decades, printed/solution-processed field-effect transistors (FETs) and circuits have witnessed immense research efforts, technological growth and increased commercial interests. Although printing of functional inks comprising organic semiconductors has already been initiated in early 1990s, gradually the attention, at least partially, has been shifted to various forms of inorganic semiconductors, starting from metal chalcogenides, oxides, carbon nanotubes and very recently to graphene and other 2D semiconductors. In this review, the entire domain of printable inorganic semiconductors is considered. In fact, thanks to the continuous development of materials/functional inks and novel design/printing strategies, the inorganic printed semiconductor-based circuits today have reached an operation frequency up to several hundreds of kilohertz with only a few nanosecond time delays at the individual FET/inverter levels; in this regard, often circuits based on hybrid material systems have been found to be advantageous. At the end, a comparison of relative successes of various printable inorganic semiconductor materials, the remaining challenges and the available future opportunities are summarized.

Solution Processed Metal Oxide High-κ Dielectrics for Emerging Transistors and Circuits

The electronic functionalities of metal oxides comprise conductors, semiconductors, and insulators. Metal oxides have attracted great interest for construction of large-area electronics, particularly thin-film transistors (TFTs), for their high optical transparency, excellent chemical and thermal stability, and mechanical tolerance. High-permittivity (κ) oxide dielectrics are a key component for achieving low-voltage and high-performance TFTs. With the expanding integration of complementary metal oxide semiconductor transistors, the replacement of SiO2 with high-κ oxide dielectrics has become urgently required, because their provided thicker layers suppress quantum mechanical tunneling. Toward low-cost devices, tremendous efforts have been devoted to vacuum-free, solution processable fabrication, such as spin coating, spray pyrolysis, and printing techniques. This review focuses on recent progress in solution processed high-κ oxide dielectrics and their applications to emerging TFTs. First, the history, basics, theories, and leakage current mechanisms of high-κ oxide dielectrics are presented, and the underlying mechanism for mobility enhancement over conventional SiO2 is outlined. Recent achievements of solution-processed high-κ oxide materials and their applications in TFTs are summarized and traditional coating methods and emerging printing techniques are introduced. Finally, low temperature approaches, e.g., ecofriendly water-induced, self-combustion reaction, and energy-assisted post treatments, for the realization of flexible electronics and circuits are discussed.

Low-Voltage Solution-Processed Hybrid Light-Emitting Transistors

We report the development of low operating voltages in inorganic-organic hybrid light-emitting transistors (HLETs) based on a solution-processed ZrO _x gate dielectric and a hybrid multilayer channel consisting of the heterojunction In₂O₃/ZnO and the organic polymer "Super Yellow" acting as n- and p-channel/emissive layers, respectively. Resulting HLETs operate at the lowest voltages reported to-date (<10 V) and combine high electron mobility (22 cm²/(V s)) with appreciable current on/off ratios (≈10³) and an external quantum efficiency of 2 × 10^-2% at 700 cd/m². The charge injection, transport, and recombination mechanisms within this HLET architecture are discussed, and prospects for further performance enhancement are considered.

High-Mobility and Hysteresis-Free Flexible Oxide Thin-Film Transistors and Circuits by Using Bilayer Sol-Gel Gate Dielectrics

In this paper, we demonstrate high-performance and hysteresis-free solution-processed indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs) and high-frequency-operating seven-stage ring oscillators using a low-temperature photochemically activated Al₂O₃/ZrO₂ bilayer gate dielectric. It was found that the IGZO TFTs with single-layer gate dielectrics such as Al₂O₃, ZrO₂, or sodium-doped Al₂O₃ exhibited large hysteresis, low field-effect mobility, or unstable device operation owing to the interfacial/bulk trap states, insufficient band offset, or a substantial number of mobile ions present in the gate dielectric layer, respectively. To resolve these issues and to explain the underlying physical mechanisms, a series of electrical analyses for various single- and bilayer gate dielectrics was carried out. It is shown that compared to single-layer gate dielectrics, the Al₂O₃/ZrO₂ gate dielectric exhibited a high dielectric constant of 8.53, low leakage current density (∼10^-9 A cm^-2 at 1 MV cm^-1), and stable operation at high frequencies. Using the photochemically activated Al₂O₃/ZrO₂ gate dielectric, the seven-stage ring oscillators operating at an oscillation frequency of ∼334 kHz with a propagation delay of <216 ns per stage were successfully demonstrated on a polymeric substrate.

Fully solution-induced high performance indium oxide thin film transistors with ZrOx high-k gate dielectrics

Solution based deposition has been recently considered as a viable option for low-cost flexible electronics.

Boosting Electrical Performance of High-κ Nanomultilayer Dielectrics and Electronic Devices by Combining Solution Combustion Synthesis and UV Irradiation

In the past decade, solution-based dielectric oxides have been widely studied in electronic applications enabling the use of low-cost processing technologies and device improvement. The most promising are the high-κ dielectrics, like aluminum (AlO_x) and hafnium oxide (HfO_x), that allow an easier trap filling in the semiconductor and the use of low operation voltage. However, in the case of HfO_x, a high temperature usually is needed to induce a uniform and condensed film, which limits its applications in flexible electronics. This paper describes how to obtain HfO_x dielectric thin films and the effect of their implementation in multilayer dielectrics (MLD) at low temperatures (150 °C) to apply in thin film transistors (TFTs) using the combination of solution combustion synthesis (SCS) and ultraviolet (UV) treatment. The single layers and multilayers did not show any trace of residual organics and exhibited a small surface roughness (<1.2 nm) and a high breakdown voltage (>2.7 MV·cm^-1). The resulting TFTs presented a high performance at a low operation voltage (<3 V), with high saturation mobility (43.9 ± 1.1 cm²·V^-1·s^-1), a small subthreshold slope (0.066 ± 0.010 V·dec^-1), current ratio of 1 × 10⁶ and a good idle shelf life stability after 2 months. To our knowledge, the results achieved surpass the actual state-of-the-art. Finally, we demonstrated a low-voltage diode-connected inverter using MLD/IGZO TFTs working with a maximum gain of 1 at 2 V.

High-κ Lanthanum Zirconium Oxide Thin Film Dielectrics from Aqueous Solution Precursors

Metal oxide thin films are critical components in modern electronic applications. In particular, high-κ dielectrics are of interest for reducing power consumption in metal-insulator-semiconductor (MIS) field-effect transistors. Although thin-film materials are typically produced via vacuum-based methods, solution deposition offers a scalable and cost-efficient alternative. We report an all-inorganic aqueous solution route to amorphous lanthanum zirconium oxide (La₂Zr₂O₇, LZO) dielectric thin films. LZO films were spin-cast from aqueous solutions of metal nitrates and annealed at temperatures between 300 and 600 °C to produce dense, defect-free, and smooth films with subnanometer roughness. Dielectric constants of 12.2-16.4 and loss tangents <0.6% were obtained for MIS devices utilizing LZO as the dielectric layer (1 kHz). Leakage currents <10^-7 A cm^-2 at 4 MV cm^-1 were measured for samples annealed at 600 °C. The excellent surface morphology, high dielectric constants, and low leakage current densities makes these LZO dielectrics promising candidates for thin-film transistor devices.

Direct transfer of graphene and application in low-voltage hybrid transistors

Scotch tape assisted direct transfer of graphene is presented. Transferred graphene can act as a carrier transport layer in In₂O₃/graphene/ZrO₂transistor.

Tunable high-κ ZrxAl1−xOy thin film dielectrics from all-inorganic aqueous precursor solutions

An all-inorganic, aqueous solution route enables facile control of composition and optimization of zirconium aluminum oxide thin film dielectric properties.

Nondestructive Method for Mapping Metal Contact Diffusion in In2O3 Thin-Film Transistors

The channel width-to-length ratio is an important transistor parameter for integrated circuit design. Contact diffusion into the channel during fabrication or operation alters the channel width and this important parameter. A novel methodology combining atomic force microscopy and scanning Kelvin probe microscopy (SKPM) with self-consistent modeling is developed for the nondestructive detection of contact diffusion on active devices. Scans of the surface potential are modeled using physically based Technology Computer Aided Design (TCAD) simulations when the transistor terminals are grounded and under biased conditions. The simulations also incorporate the tip geometry to investigate its effect on the measurements due to electrostatic tip-sample interactions. The method is particularly useful for semiconductor- and metal-semiconductor interfaces where the potential contrast resulting from dopant diffusion is below that usually detectable with scanning probe microscopy.

Identification of dipole disorder in low temperature solution processed oxides: its utility and suppression for transparent high performance solution-processed hybrid electronics

Identification of long-lived dipole disorder in low-temp solution processed dielectrics, and it's suppression.

The ability to deposit high-quality inorganic semiconductors and dielectrics from solution at low process temperatures (∼200 °C) has become a very important research focus. During the course of our investigation, we identify the presence of an induced dipole present in solid state solution processed inorganic oxide insulator layers processed at reduced temperature (200–350 °C) from either molecular precursors, or well-dispersed metal oxide nanoparticles. Chemical composition analysis coupled with electrical measurements shows that the dielectric instability occurs due to proton migration via the Grotthuss mechanism inducing a long lived dipole disorder. Thus we established conditions for suppressing this effect to afford “ideal” high-k dielectric layer. Using this methodology, solution processed all inorganic thin film transistors (TFTs) with charge carrier mobilities exceeding 6 cm² V^–1 s^–1 operating at low voltage (5 V) have been achieved. In addition, we show the broad utility of the perovskite high-k dielectric when processed with state of the art polymer and single crystal organic semiconductors yielding mobilities of approx. 7 cm² V^–1 s^–1 at only 4 V. These transparent devices demonstrate excellent electrical device stability and a threshold voltage shift of only 0.41 V over 14 h, which is comparable, or better than sputtered oxide films.

Aqueous Solution-Deposited Gallium Oxide Dielectric for Low-Temperature, Low-Operating-Voltage Indium Oxide Thin-Film Transistors: A Facile Route to Green Oxide Electronics

We reported a novel aqueous route to fabricate Ga2O3 dielectric at low temperature. The formation and properties of Ga2O3 were investigated by a wide range of characterization techniques, revealing that Ga2O3 films could effectively block leakage current even after annealing in air at 200 °C. Furthermore, all aqueous solution-processed In2O3/Ga2O3 TFTs fabricated at 200 and 250 °C showed mobilities of 1.0 and 4.1 cm2 V(-1) s(-1), on/off current ratio of ∼10(5), low operating voltages of 4 V, and negligible hysteresis. Our study represents a significant step toward the development of low-cost, low-temperature, and large-area green oxide electronics.

High-Quality Solution-Processed Silicon Oxide Gate Dielectric Applied on Indium Oxide Based Thin-Film Transistors

A silicon oxide gate dielectric was synthesized by a facile sol-gel reaction and applied to solution-processed indium oxide based thin-film transistors (TFTs). The SiOx sol-gel was spin-coated on highly doped silicon substrates and converted to a dense dielectric film with a smooth surface at a maximum processing temperature of T = 350 °C. The synthesis was systematically improved, so that the solution-processed silicon oxide finally achieved comparable break downfield strength (7 MV/cm) and leakage current densities (<10 nA/cm(2) at 1 MV/cm) to thermally grown silicon dioxide (SiO2). The good quality of the dielectric layer was successfully proven in bottom-gate, bottom-contact metal oxide TFTs and compared to reference TFTs with thermally grown SiO2. Both transistor types have field-effect mobility values as high as 28 cm(2)/(Vs) with an on/off current ratio of 10(8), subthreshold swings of 0.30 and 0.37 V/dec, respectively, and a threshold voltage close to zero. The good device performance could be attributed to the smooth dielectric/semiconductor interface and low interface trap density. Thus, the sol-gel-derived SiO2 is a promising candidate for a high-quality dielectric layer on many substrates and high-performance large-area applications.

Facile and environmentally friendly solution-processed aluminum oxide dielectric for low-temperature, high-performance oxide thin-film transistors

We developed a facile and environmentally friendly solution-processed method for aluminum oxide (AlOx) dielectrics. The formation and properties of AlOx thin films under various annealing temperatures were intensively investigated by thermogravimetric analysis-differential scanning calorimetry (TGA-DSC), X-ray diffraction (XRD), spectroscopic ellipsometry, atomic force microscopy (AFM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), impedance spectroscopy, and leakage current measurements. The sol-gel-derived AlOx thin film undergoes the decomposition of organic residuals and nitrate groups, as well as conversion of aluminum hydroxides to form aluminum oxide, as the annealing temperature increases. Finally, the AlOx film is used as gate dielectric for a variety of low-temperature solution-processed oxide TFTs. Above all, the In2O3 and InZnO TFTs exhibited high average mobilities of 57.2 cm(2) V(-1) s(-1) and 10.1 cm(2) V(-1) s(-1), as well as an on/off current ratio of ∼10(5) and low operating voltages of 4 V at a maximum processing temperature of 300 °C. Therefore, the solution-processable AlOx could be a promising candidate dielectric for low-cost, low-temperature, and high-performance oxide electronics.

Eco-friendly water-induced aluminum oxide dielectrics and their application in a hybrid metal oxide/polymer TFT

Eco-friendly water-inducement method was used to fabricate hybrid metal oxide/polymer TFTs based on high-k AlO_x dielectric with high electrical performance.

Low-temperature fabrication of high performance indium oxide thin film transistors

In this study, indium oxide (In₂O₃) thin-film transistors (TFTs) were fabricated by a fully-solution process at low temperature.