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Brain‐inspired neuromorphic computing has drawn significant attraction as a promising technology beyond von Neumann architecture by using the parallel structure of synapses and neurons. Various artificial synapse configurations and materials have been proposed to emulate synaptic behaviors for human brain functions such as memorizing, learning, and visual processing. Especially, the memory type indium‐gallium‐zinc‐oxide (IGZO) synaptic transistor adopting a charge trapping layer (CTL) has the advantages of high stability and a low leakage current of the IGZO channel. However, the CTL material should be carefully selected and optimized to overcome the low de‐trapping efficiency, resulting from difficulty in inducing holes in the IGZO channel. In this paper, IGZO is adopted as a CTL and found out that making it degenerated is crucial to improving de‐trapping efficiency. The degenerate CTL, where electrons remain as free electrons, induces Fowler‐Nordheim tunneling by increasing the electric field across the tunneling layer. As a result, the synaptic transistor represents a high linearity of potentiation (αp: −0.03) and depression (αd: −0.47) with 64 conductance levels, which enables the spiking neural network simulation to achieve high accuracy of 98.08%. These experimental results indicate that the synapse transistor can be one of the promising candidates for neuromorphic applications. [ABSTRACT FROM AUTHOR]

Sputtered amorphous indium-gallium-zinc-oxide (a-IGZO) Schottky barrier diodes (SBDs) were comparatively investigated without and with a passivation layer (PL). The a-IGZO SBDs without PLs were found to be highly unstable in the atmosphere and under electrical stress. During the implementation of silicon dioxide (SiO2) PL, the associated thermal oxidization and hydrogen doping resulted in high-performance metrics, including an ideality factor close to the unity, a high Schottky barrier of 0.82 eV, and a large current rectification ratio of over 108. Benefited from the PL protection and ideal Schottky contact, the environmental and electrical stabilities of SBDs were significantly enhanced. [ABSTRACT FROM AUTHOR]

Solution‐processed indium‐gallium‐zinc oxide (IGZO) thin film transistors (TFTs) have become well known in recent decades for their promising commercial potential. However, the unsatisfactory performance of small‐sized IGZO TFTs is limiting their applicability. To address this issue, this work introduces an interface engineering method of bi‐functional acid modification to regulate the interfaces between electrodes and the channels of IGZO TFTs. This method increases the interface oxygen vacancy concentration and reduces the surface roughness, resulting in higher mobility and enhanced contact at the interfaces. The TFT devices thus treated display contact resistance reduction from 9.1 to 2.3 kΩmm, as measured by the gated four‐probe method, as well as field‐effect mobility increase from 1.5 to 4.5 cm2 (V s)−1. Additionally, a 12 × 12 organic light emitting diode display constructed using the acid modified IGZO TFTs as switching and driving elements demonstrate the applicability of these devices. [ABSTRACT FROM AUTHOR]

Indium–gallium–zinc-oxide thin-film transistors gated with solution-processed, ultra-thin AlxOy have been fabricated on a plastic substrate. The effects of bending on the gate dielectric in terms of leakage current density and capacitance density have been studied. The devices show a low operating voltage of less than 1 V, a high current on/off ratio >105, and a low subthreshold swing <90 mV/decade. The devices maintain their high performance even when flexed to a curvature radius of 11 mm. As a result, such devices possess a great potential for low-power, flexible electronics. [ABSTRACT FROM AUTHOR]

Metal-oxide high- k dielectric films have received considerable attention in lowering the driving voltage and power consumption in semiconductor devices. Here, we demonstrate sub-volt operating metal-oxide thin-film transistors (TFTs) using solution-processed high- k gadolinium-doped hafnium oxide (HGO) dielectric films. Particularly, the HGO dielectric films were fabricated using a solution combustion synthesis (SCS) method using acetylacetone and 1,1,1-trifluoroacetylacetone as cofuels. The HGO dielectric films exhibited low leakage current of 2.7 × 10−6 A/cm2 at 1 MV/cm and dielectric constant of ∼17. It was found that the Gd doping had a significant impact on improving the leakage current characteristics compared to the undoped HfO 2 films (leakage current of ∼10−2 A/cm2 at 1 MV/cm). By employing the high- k HGO gate dielectric layer, we demonstrated 0.5 V-operating indium-gallium-zinc-oxide TFTs exhibiting field-effect mobility of 3.55 cm2/Vs, on/off ratio of 5.9 × 105, and subthreshold slope of 75 mV/decade. We investigated the effects of cofuel concentration on the film morphology and dielectric properties of HGO films to determine the optimal cofuel concentration for SCS. Furthermore, X-ray photoelectron spectroscopy was performed to reveal the role of Gd doping in improving the dielectric properties in correlation with the oxygen vacancy formation. Based on these results, we claim that the high- k HGO film fabricated through the SCS route can be a promising candidate for realizing sub-volt operating TFTs for low-power consumption. [Display omitted] • High- k Gd-doped HfO 2 dielectric films are fabricated using a solution process. • Influences of Gd doping and cofuel concentrations on the dielectric properties are investigated. • The effects of annealing time on oxygen binding states, crystalline structure, and dielectric properties are investigated. • Sub-volt IGZO TFTs are demonstrated using Gd-doped HfO 2 gate dielectric layer. [ABSTRACT FROM AUTHOR]

The quest for high-performance flexible circuits call for scaling of the minimum feature size in thin-film transistors (TFTs). Although reduced channel lengths can guarantee an improvement in the electrical properties of the devices, proper design rules also play a crucial role to minimize parasitics when designing fast circuits. In this letter, systematic computer-aided design simulations have guided the fabrication of high-performance flexible operational amplifiers (opamps) and logic circuits based on indium–gallium–zinc-oxide TFTs. In particular, the performance improvements due to the use of an additional third metal layer for the interconnections have been estimated for the first time. Encouraged by the simulated enhancements resulting by the decreased parasitic resistances and capacitances, both TFTs and circuits have been realized on a free-standing 50- \mu \textm -thick polymide foil using three metal layers. Despite the thicker layer stack, the TFTs have shown mechanical stability down to 5-mm bending radii. Moreover, the opamps and the logic circuits have yielded improved electrical performance with respect to the architecture with two metal layers: gain-bandwidth-product increased by 16.9%, for the first one, and propagation delay ( tpd ) decreased by 43%, for the latter one. [ABSTRACT FROM PUBLISHER]

The degradation of thin-film transistors (TFTs) caused by the self-heating effect constitutes a problem to be solved for the next generation of displays. Aluminum nitride (AlN) is a viable alternative for gate dielectric of TFTs due to its good thermal conductivity, matching coefficient of thermal expansion to indium–gallium–zinc-oxide, and excellent stability at high temperatures. Here, AlN thin films of different thicknesses were fabricated by a low temperature reactive radio-frequency magnetron sputtering process, using a low cost, metallic Al target. Their electrical properties have been thoroughly assessed. Furthermore, the 200 nm and 500 nm thick AlN layers have been integrated as gate-dielectric in transparent TFTs with indium–gallium–zinc-oxide as channel semiconductor. Our study emphasizes the potential of AlN thin films for transparent electronics, whilst the functionality of the fabricated field-effect transistors is explored and discussed. [ABSTRACT FROM AUTHOR]

Indium–gallium–zinc oxide (IGZO) thin films were prepared in a N 2 environment by varying the annealing pressure and then tested for NO 2 gas detection. These thin films, whose average thickness ranged between 5 and 100 nm, were deposited via the sputtering on alumina substrates equipped with interdigitated Au electrodes using an IGZO polycrystalline target (ZnO: Ga 2 O 3 :In 2 O 3 = 1:1:1 mol%). The effects of annealing pressure and environment were investigated. A superior sensor response (S) was observed when increasing the annealing pressure; the prepared IGZO thin film showed an S of –800 at an operating temperature of 250 °C for 25 ppm NO 2 gas. The recovery time decreased with increasing the annealing temperature. The sensor annealed at 400 °C at 3 atm showed superior selectivity to various gases and longtime stability of 60 days was attained. The role of the oxygen vacancies in the sensor performance was also investigated. • High pressure annealing (HPA) effect on Indium-Gallium-Zinc-Oxide (IGZO) films are demonstrated for high response to NO 2 gas. • Sensor response (S = R gas /R air) of S – 800 was achieved for 25 ppm concentration of NO 2 gas. • Modulation of Oxygen Vacancy (O vac) was observed by High pressure annealing on IGZO film. • IGZO Sensor show superior stability and selectivity. [ABSTRACT FROM AUTHOR]

Solution-processed metal oxides require a great deal of thermal budget in order to achieve the desired film properties. Here, we show that the deposition temperature of sprayed zirconium oxide (ZrOx) thin film can be lowered by exposing the film surface to an ultraviolet (UV) ozone treatment at room temperature. Atomic force microscopy reveals a smooth and uniform film with the root mean square roughness reduced from ~ 0.63 nm (UVO-O) to ~ 0.28 nm (UVO-120) in the UV–ozone treated ZrOx films. X-ray photoelectron spectroscopy analysis indicates the formation of a Zr–O network on the surface film, and oxygen vacancy is reduced in the ZrOx lattice by increasing the UV–ozone treatment time. The leakage current density in Al/ZrOx/p-Si structure was reduced by three orders of magnitude by increasing the UV-ozone exposure time, while the capacitance was in the range 290–266 nF/cm2, corresponding to a relative permittivity (k) in the range 5.8–6.6 at 1 kHz. An indium gallium zinc oxide (IGZO)-based thin film transistor, employing a UV-treated ZrOx gate dielectric deposited at 200 °C, exhibits negligible hysteresis, an Ion/Ioff ratio of 104, a saturation mobility of 8.4 cm2 V−1S−1, a subthreshold slope of 0.21 V.dec−1, and a Von of 0.02 V. These results demonstrate the potentiality of low-temperature sprayed amorphous ZrOx to be applied as a dielectric in flexible and low-power-consumption oxide electronics. [ABSTRACT FROM AUTHOR]