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Amorphous oxide semiconductors have garnered significant attention in recent years for their potential in flat-panel displays and back-end-of-line-compatible monolithic 3D (M3D) integration applications. This study explores amorphous InSnZnO thin films deposited via plasma-enhanced atomic layer deposition (PEALD) and the development of high-performance PEALD ITZO thin-film transistors (TFTs) with different active layer thicknesses, fabricated under a low thermal budget of 200 °C. By optimizing the deposition process of binary oxides InOx, SnOx, and ZnOx, a shared temperature window of 170–180 °C was identified for ITZO thin-film deposition. The deposited ITZO films, irrespective of thickness, exhibit an amorphous phase. Moreover, a reduction in ITZO film thickness from 24 to 4.8 nm leads to an increase in the optical bandgap from 3.35 to 3.65 eV. The channel thickness significantly impacts the threshold voltage and carrier density of ITZO TFTs. Optimized ITZO TFTs with a 16 nm channel thickness demonstrate excellent electrical performance, including a threshold voltage of −0.58 V, a field-effect mobility of 29 cm2/V s, an on/off ratio exceeding 108, and a subthreshold swing of 74 mV/dec. Furthermore, the optimized ITZO TFT exhibits excellent stability under positive bias stress at 2 MV/cm, with a threshold voltage shift of 0.15 V after 3600 s. Consequently, ALD-based ITZO emerges as a promising channel material for future applications in transparent electronics and flat-panel displays. [ABSTRACT FROM AUTHOR]

In this study, we integrated an Indium Gallium Zinc Oxide (IGZO) channel with a superlattice of HfO2/ZrO2 (HZO) under low-thermal-budget microwave annealing to produce nearly wake-up-free ferroelectric capacitors. To eliminate the impact of trap-charges during the atomic layer deposition process, we conducted H2 plasma treatment to eliminate leak defects induced by carbon contamination and maintain neutrality to achieve high-quality IGZO/HZO interfaces, confirmed by x-ray photoelectron spectroscopy. The H2 plasma treatment improved polarization (Pr) and coercive field (Ec), reaching 2Pr: 40 μC/cm2 and Ec: 2.33 MV/cm, enabling a low-power writing speed of 30 ns with eight states (three bits per cell). The defect engineering method ensures endurance of up to 108 cycles and retains ten-year data storage at 90 °C. This research provides a new avenue for improving emerging oxide interfaces controlled by ferroelectric polarization. [ABSTRACT FROM AUTHOR]

Metal oxide transistors have garnered substantial attention for their potential in low-power electronics, yet challenges remain in achieving both high performance and low operating voltages through solution-based fabrication methods. Optimizing interfacial engineering at the dielectric/semiconductor interface is of utmost importance in the fabrication of high-performance thin film transistors (TFTs). In the present article, a bilayer Ti3C2Tx-MXene/SnO2–semiconductor (Tx stands for surface termination) configuration is used to fabricate a high-performance n-type thin film transistor by using an ion-conducting Li-Al2O3 gate dielectric on a p+-Si substrate, where electrical charges are formed and modulated at the Li-Al2O3/SnO2 interface, and Ti3C2Tx-MXene nanosheets serve as the primary electrical charge channel due to their long lateral size and high mobility. A comparative characterization of two distinct TFTs is conducted, one featuring Ti3C2Tx MXene and SnO2 semiconductor layer and the other with SnO2 only. Notably, the TFT with the Ti3C2Tx MXene layer has shown a significant boost in the carrier mobility (10.6 cm2/V s), leading to remarkable improvements in the on/off ratio (1.3 × 105) and subthreshold swing (194 mV/decade), whereas the SnO2 TFT without the Ti3C2Tx MXene layer shows a mobility of 1.17 cm2/V s with 8.1 × 102 on/off ratio and 387 mV/decade subthreshold swing. This investigation provides a possible way toward the development of high-performance, low-voltage TFT fabrication with the MXene/semiconductor combination. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate a hydrogen-terminated diamond (H-diamond) field-effect transistor (FET) with Al2O3/CeB6 gate materials. The CeB6 and Al2O3 films have been deposited by electron beam evaporation technique, sequentially. For the 4/8/12/15 μm gate length (LG) devices, the whole devices demonstrate distinct p-type normally off characteristics, and all the threshold voltage are negative; all the absolute values of leakage current density are 10−4 A/cm2 at a VGS of −11 V, exhibiting a relatively low leakage current density compared with CeB6 FETs, and this further demonstrates the feasibility of the introduction of Al2O3 to reduce the leakage current density; the maximum drain–source current density is −114.6, −96.0, −80.9, and −73.7 mA/mm, which may be benefited from the well-protected channel. For the 12 μm LG devices, the saturation carrier mobility is 593.6 cm2/V s, demonstrating a good channel transport characteristic. This work may provide a promising strategy for the application of normally off H-diamond FETs significantly. [ABSTRACT FROM AUTHOR]

In this work, bottom-Schottky-structure InGaZnOx (IGZO) Schottky barrier diodes (SBDs) with sputtered PtOx anodes were fabricated and annealed in oxygen at different temperatures. Critical parameters and negative bias stress (NBS) stability of SBDs with different annealing temperatures are investigated. With the annealing temperature increases, the barrier height and rectification ratio of the SBDs exhibited a rising-then-declining trend, while the ideality factor slightly increased until 200 °C. The SBDs show up overall reliability except for a leakage current rising trend under light, which can be attributed to free electron generation from the ionized oxygen vacancy. Among all the SBDs, the 175 °C annealed ones exhibited the best overall performance, including a high barrier height of 0.89 eV, an ideality factor of 1.14, and a large rectification ratio of over 108. Compared to the initial SBDs, the annealed ones showed up great improvement in NBS stability except for the 200 °C annealed ones, which was permanently degraded and not able to recover to original states. According to experimental result analysis and IGZO material characteristics, a stability model based on the subgap trap transition from V O 2 + to VO and new V O 2 + creation was proposed, which applies to both the short-term and long-term NBS tests. The results above demonstrate that oxygen annealing at appropriate temperature is an effective method to improve both device performance and NBS stability for PtOx–IGZO SBDs. [ABSTRACT FROM AUTHOR]

In this work, three atomic layer deposition (ALD) approaches are used to deposit an Al2O3 gate insulator on n-GaN for application in vertical GaN power switches: thermal ALD (ThALD), plasma-enhanced ALD (PEALD), and their stacked combination. The latter is a novel method to yield the most ideal insulating layer. Also, the influence of an in situ NH3 or H2 plasma pre-treatment is studied. Planar MIS capacitors are used to investigate the electrical properties and robustness of the gate insulators. In vacuo x-ray photoelectron spectroscopy (XPS) is used to study the changes in chemical composition after every surface treatment. XPS shows that all plasma pre-treatments efficiently remove all carbon contamination from the surface, but only NH3 plasma is observed to additionally remove the native oxide from the n-GaN surface. The water precursor step in the ThALD process does not completely remove the CH3 ligands of the trimethylaluminum precursor step, which might electrically be associated with a reduced forward bias robustness. The O2 plasma step in the PEALD process is associated with the removal of carbon and a tremendous increase of the O content in the GaN surface region. Electrically, this strongly correlates to an enhanced forward bias robustness and an increased forward bias hysteresis, respectively. The ThALD/PEALD stack method mitigates the shortcomings of both ALD processes while maintaining its advantages. Electrical measurements indicate that the stack method alongside NH3 plasma pretreatment provides the best characteristics in terms of hysteresis, threshold voltage, forward bias robustness, and interface trap density of states. [ABSTRACT FROM AUTHOR]

Information processing and memorizing in the brain take place in a neural network consisting of neurons connected with each other by synapses. Meanwhile, the neural network is immersed in a common electrochemical environment with global parameters regulating the overall functions, which is barely discussed in neuromorphic devices. In this study, organic/inorganic hybrid transistors with sodium alginate as the gate dielectric layer and indium tin oxide as the channel were successfully prepared. We have not only simulated the basic properties of synapses in a single device, but, on top of that, also simulated the global regulation of information processing in the brain due to the incorporation of global grids, achieving excitatory and inhibitory synaptic weight. Moreover, the construction of a 3 × 3 synaptic array enables image learning and memorizing functions. These results demonstrate the significant advantages of electrolyte-gated transistors in enabling complex neural network connectivity and offer a promising opportunity for future artificial synapses. [ABSTRACT FROM AUTHOR]

To achieve progressive resistance modulation with memristors, we utilized InGaZnO (IGZO) films with a Pd top electrode to form a Schottky barrier at the interface. As oxygen vacancies (V O) were ionized and recombined in the IGZO layer depending on the applied voltage polarity, the magnitude of the barrier was smoothly adjusted, enabling analogous modulation of current. Because a native SiO 2 layer was invariably formed on the Si bottom electrode (BE) during fabrication, we analyzed the impact of the SiO 2 layer on the memristive characteristics of the IGZO layer through a comparison between memristors with differently formed SiO 2 layers. Even when the native oxide was removed via wet etching, the subsequent IGZO sputtering induced oxidation at the Si BE interface by scavenging oxygen ions, resulting in a non-stoichiometric IGZO layer. Contrarily, when the interfacial SiO 2 was intentionally deposited using an e-beam evaporator after wet etching, physical analysis showed that the scavenging of oxygen ions from the IGZO layer was inhibited. Among the fabricated samples, the memristor with the V O -rich non-stoichiometric IGZO layer exhibited improved state stability over time. These optimized IGZO memristors also displayed analogously tunable weight-update behavior when incorporated into neuromorphic synaptic devices, enabling artificial neural networks to achieve high pattern-recognition accuracy. [ABSTRACT FROM AUTHOR]

Flexible integrated circuits (FlexICs) have drawn increasing attention, particularly in remote sensors and wearables operating in a limited power budget. Here, we present an ultra-low power timer designed to wake-up an external circuit periodically, from a deep-sleep state into an active state, thereby largely reducing the system power consumption. We achieved this with a circuit topology that exploits the transistor's leakage current to generate a low frequency wake-up signal. This topology is compatible with IC technologies where only n-type transistors are available. The design was implemented with the sustainable FlexIC process of PragmatIC, that is based on Indium Gallium Zinc Oxide (IGZO) thin-film transistors. Our timer generates mean wake-up frequency of 0.24 ± 0.15 Hz, with a mean power consumption of 26.7 ± 14.1 nW. In this paper, we provide details of the Wake-Up timer's design and performance at different supply voltages, under temperature variations and different light conditions. [ABSTRACT FROM AUTHOR]

The growing demand for high-performance oxide transistors in advanced integrated circuits (ICs) underscores the need for innovative device structures, with heterojunctions emerging as a promising approach. This study presents high-performance ITO/ZnO transistors, which outperform individual ITO or ZnO transistors by achieving an on-state current of 19.2 μA/μm at a drain voltage of 1 V and exhibiting a minimal threshold voltage shift of −0.16 V under negative bias illumination stress. Band structure analysis reveals that the differences in the conduction band minimum and Fermi level between the ZnO and ITO films lead to the formation of a potential well at the ITO/ZnO interface. Furthermore, the increase in the on-state current is attributed to electron confinement at the ITO/ZnO interface, while the enhanced NBIS stability is ascribed to both the band structure and ZnO passivation. These findings make significant contributions to both optimizing the performance and analyzing the mechanisms of oxide devices, highlighting the potential of high-performance ITO/ZnO transistors in 3D integrated circuits, advanced memory devices, and back-end-of-line (BEOL) processes. [ABSTRACT FROM AUTHOR]

This study explores the impact of oxygen vacancy defects on elevated-metal metal-oxide (EMMO) IGZO TFTs under positive bias stress (PBS) using TCAD and DFT simulation. Findings reveal that oxygen vacancies accumulating at the channel/passivation layer interface and within the channel under PBS lead to negative threshold voltage shifts and reduced mobility. Additionally, higher tail state densities contribute to a positive Vth shift. These results provide important insights into the defect-related reliability of EMMO IGZO TFTs, guiding the design of more reliable devices. [ABSTRACT FROM AUTHOR]

Metal oxide semiconductors, such as indium gallium zinc oxide (IGZO), have attracted significant attention from researchers in the fields of liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs) for decades. This interest is driven by their high electron mobility of over ~10 cm2/V·s and excellent transmittance of more than ~80%. Amorphous IGZO (a-IGZO) offers additional advantages, including compatibility with various processes and flexibility making it suitable for applications in flexible and wearable devices. Furthermore, IGZO-based thin-film transistors (TFTs) exhibit high uniformity and high-speed switching behavior, resulting in low power consumption due to their low leakage current. These advantages position IGZO not only as a key material in display technologies but also as a candidate for various next-generation electronic devices. This review paper provides a comprehensive overview of IGZO-based electronics, including applications in gas sensors, biosensors, and photosensors. Additionally, it emphasizes the potential of IGZO for implementing logic gates. Finally, the paper discusses IGZO-based neuromorphic devices and their promise in overcoming the limitations of the conventional von Neumann computing architecture. [ABSTRACT FROM AUTHOR]

A high mobility crystallized stacked-channel thin-film transistor (TFT) was fabricated and characterized. The stacked IGO/IGZO channel film consisting of an In-rich IGO layer and a conventional IGZO layer was fabricated by atomic layer deposition technology, where the upper layer of amorphous IGZO is induced into nanocrystals by the lower layer of preferentially oriented polycrystalline IGO during thermal annealing at a low temperature of 300 °C. The preferential growth of nanocrystalline IGZO with matched crystal structure in the channel favors the transport of electrons. In addition, the accumulation of a large number of electrons at the heterojunction due to energy band bending provides a strong guarantee for high mobility. The crystallized stacked IGO/IGZO TFT exhibits a superior field effect mobility of 95.7 cm2 V−1 s−1, which is 55.9% higher than that of single-layer IGO TFT. At the same time, the stability of the device was also dramatically improved. The proposed strategy is a simple and promising approach to prepare high performance TFTs for future display and semiconductor applications. [ABSTRACT FROM AUTHOR]

The document from Applied Physics Letters discusses the advancements in organic and hybrid photodetectors (OHPDs) and their potential applications in various fields. Researchers have made significant progress in improving OHPDs' performance, making them comparable or even superior to traditional inorganic photodetectors. The document highlights various studies on OHPDs, including strategies to enhance detectivity, achieve high responsivity, and address specific challenges in photodetection. The research presented in this special issue showcases the diverse and innovative approaches being taken to advance OHPDs and their potential impact on future technologies. [Extracted from the article]

In this paper, we delve into recent advancements in the fabrication of high-performance n-type oxide semiconductor thin-film transistors (TFTs) through crystallization pathways. The last two decades have seen a rapid proliferation of applications employing amorphous oxide semiconductor (AOS) transistors, from display technologies to semiconductor chips. However, with the growing demand for ultra-high-resolution organic light-emitting diodes, flexible electronics, and next-generation electronic devices, interest in oxide semiconductors exhibiting high mobility and exceptional reliability has grown. However, AOS TFTs must balance the competing demands of mobility and stability. Here, we explore various crystallization methods of enhancing the device performance of oxide semiconductors, alongside the intrinsic challenges associated with crystalline oxide semiconductors. Our discussion highlights the potential solutions presented by controlling crystalline quality in terms of grain size and orientation. We propose that advanced manufacturing techniques coupled with a profound understanding of materials science are needed to effectively address these issues. [ABSTRACT FROM AUTHOR]

The praseodymium-doped indium zinc oxide (PrIZO) thin-film transistor (TFT) is promising for applications in flat-panel displays, due to its high carrier mobility and stability. Nevertheless, there are few studies on the mechanism of annealing on PrIZO films and the fabrication of flexible devices. In this work, we first optimized the annealing-process parameters on the glass substrate. As the annealing temperature rises, the film tends to be denser and obtains a lower surface roughness, a narrower optical-band gap and less oxygen-vacancy content. However, the μ-PCD test shows the 250 °C-annealed film obtains the least defects. And the PrIZO TFT annealed at 250 °C exhibited a desired performance with a saturation mobility (μsat) of 14.26 cm2·V−1·s−1, a subthreshold swing (SS) of 0.14 V·dec−1, an interface trap density (Dit) of 3.17 × 1011, an Ion/Ioff ratio of 1.83 × 108 and a threshold voltage (Vth) of −1.15 V. The flexible devices were prepared using the optimized parameters on the Polyimide (PI) substrate and subjected to static bending tests. After bending at a radius of 5 mm, the mobility of devices decreases slightly from 12.48 to 10.87 cm2·V−1·s−1, demonstrating the great potential of PrIZO for flexible displays. [ABSTRACT FROM AUTHOR]

Electronics today has evolved significantly, including its application in transparent and flexible devices. Flexible electronics offers new product concepts, including low production cost, low energy consumption, and sustainable and environmentally friendly materials. This concept leads to the development of novel materials that realize today's requirements. Incorporating optically transparent and flexible thin-film-based devices into the electronic circuitry helps in maintaining high conductivity along with achieving the similar electronic behavior of the conventional electronic gadgets. Thin-film diodes (TFDs) and thin-film transistors (TFTs) are the core materials to be incorporated as building blocks for flexible devices. Among them, oxide-based thin films have been marked to be significant because of their efficient electrical performance, low temperature processing, and device flexibility. The present article reviews the concepts and application of zinc oxide (ZnO) as the semiconducting material for flexible thin-film devices. We also review flexible and transparent TFDs and TFTs that are based prominently on ZnO as the semiconducting material. Furthermore, the present issues have also been addressed. [ABSTRACT FROM AUTHOR]

Synaptic behavior simulation in transistors based on MoS2 has been reported. MoS2 was utilized as the active layer to prepare ambipolar thin-film transistors. The excitatory postsynaptic current phenomenon was simulated, observing a gradual voltage decay following the removal of applied pulses, ultimately resulting in a response current slightly higher than the initial current. Subsequently, ±5 V voltages were separately applied for ten consecutive pulse voltage tests, revealing short-term potentiation and short-term depression behaviors. After 92 consecutive positive pulses, the device current transitioned from an initial value of 0.14 to 28.3 mA. Similarly, following 88 consecutive negative pulses, the device current changed, indicating long-term potentiation and long-term depression behaviors. We also employed a pair of continuous triangular wave pulses to evaluate paired-pulse facilitation behavior, observing that the response current of the second stimulus pulse was ∼1.2× greater than that of the first stimulus pulse. The advantages and prospects of using MoS2 as a material for thin-film transistors were thoroughly displayed. [ABSTRACT FROM AUTHOR]

The mechanism of gate threshold voltage (VT) shifts observed in high κ/metal gate stacks is investigated by a density functional theory. This finds that VT depends on the band alignments and the chemical trends between the component oxide layers, such as HfO2, SrO, La2O3, Al2O3, and SiO2. Based on the electron counting rule, we have built three insulating SiO2/SrO, SiO2/La2O3, and SiO2/Al2O3 interfaces, all of which feature a clean bandgap. Two methods have been adopted to derive the band alignments between these four oxides, which are consistent with each other. The results show staggered, "staircase" band alignments and enable La2O3 and Al2O3 layers to shift the metal electrode Fermi level in opposite directions and to approach the Si conduction band and valence band edge positions, respectively. This analysis updates previous empirical models of this effect based on metal oxide ion densities or electronegativity scales and confirms that the oxide layer scheme is suitable for controlling the effective metal work functions in metal–oxide–semiconductor field-effect transistors. [ABSTRACT FROM AUTHOR]

This study optimizes VT and ΔVT in amorphous indium-gallium-zinc-oxide (a-IGZO) field-effect transistors (FETs) by examining the influence of both channel length (L) and Ga composition. It was observed that as the ratio of In: Ga: Zn changed from 1:1:1 to 0.307:0.39:0.303 in the IGZO film, both VT and ΔVT decreased by 0.1 V at the shortest channel length (L = 0.5 μm). This reduction was attributed to the change in the oxygen concentration in IGZO due to the variation in Ga composition. In addition, as the channel length decreased from 10 μm to 0.5 μm, VT decreased by up to 0.7 V, and ΔVT decreased by up to 0.4 V. This observation was due to diffusion of oxygen vacancies (VO) from the source and drain into the main channel. To provide a comprehensive understanding, we quantitatively modeled the doping concentration of IGZO and the trap density of gate insulator (GI) traps using TCAD simulation based on Ga composition and diffusion of VO. Using this approach, we propose a method to optimize the design of a-IGZO FETs with high VT and low ΔVT in short-channel devices by adjusting the Ga composition. [ABSTRACT FROM AUTHOR]

pH sensing technology is pivotal for monitoring aquatic ecosystems and diagnosing human health conditions. Indium–gallium–zinc oxide electrolyte-gated thin-film transistors (IGZO EGTFTs) are highly regarded as ion-sensing devices due to the pH-dependent surface chemistry of their sensing membranes. However, applying EGTFT-based pH sensors in complex biofluids containing diverse charged species poses challenges due to ion interference and inherently low sensitivity constrained by the Nernst limit. Here, we propose a dual-biased (DB) EGTFT pH sensing platform, acquiring back-gate-assisted sensitivity enhancement and recyclable redox-coupled protonation at the semiconductor-biofluid interface. A solution-processed amorphous IGZO film, used as the proton-sensitive membrane, ensures scalable uniformity across a 6-inch wafer. These devices demonstrate exceptional pH resistivity over several hours when submerged in solutions with pH levels of 4 and 8. In-depth electrochemical investigations reveal that back-gate bias significantly enhances sensitivity beyond the Nernst limit, reaching 85 mV/pH. This improvement is due to additional charge accumulation in the channel, which expands the sensing window. As a proof of concept, we observe consistent variations in threshold voltage during repeated pH cycles, not only in standard solutions but also in physiological electrolytes such as phosphate-buffered saline (PBS) and artificial urine, confirming the potential for reliable operation in complex biological environments. [ABSTRACT FROM AUTHOR]

Inductively coupled plasma–reactive etching (ICP-RIE) of InGaZnO (IGZO) thin films was studied with variations in gas mixtures of hydrochloride (HCl) and argon (Ar). The dry etching characteristics of the IGZO films were investigated according to radiofrequency bias power, gas mixing ratio, and chamber pressure. The IGZO film showed an excellent etch rate of 83.2 nm/min from an optimized etching condition such as a plasma power of 100 W, process pressure of 3 mTorr, and HCl ratio of 75% (HCl:Ar at 30 sccm:10 sccm). In addition, this ICP-RIE etching condition with a high HCl composition ratio at a moderate RIE power of 100 W showed a low etched pattern skew and low photoresist damage on the IGZO patterns. It also provided excellent surface morphology of the SiO2 film underneath after the entire dry etching of the IGZO layer. The IGZO thin film as an active layer was successfully patterned under the ICP-RIE dry etching under the HCl-Ar gas mixture, affording an excellent electrical characteristic in the resultant top-gate IGZO thin-film transistor. [ABSTRACT FROM AUTHOR]

To enhance the efficiency of machine vision system, physical hardware capable of sensing and encoding is essential. However, sensing and encoding color information has been overlooked. Therefore, this work utilizes an indium‐gallium‐zinc oxide (IGZO) phototransistor to detect varying densities of red, green, and blue (RGB) light, converting them into corresponding drain current (ID) states. By applying stochastic gate voltage (VG) pulses to the IGZO phototransistor, the fluctuations are generated in these ID states. When the ID exceeds the threshold current (ITC), a spike signal is generated. This approach enables the conversion of light densities into spike signals, achieving spike‐rate encoding. Moreover, adjusting the standard deviation (σ) of the VG pulses controls the range of light densities converted into spike rates, while altering the mean (μ) of the VG pulses changes the baseline level of spike rates. Remarkably, separate RGB channels offer a tunable encoding process, which can emphasize individual colors and correct color bias. The encoded spike rates are also fed into a spiking neural network (SNN) for CIFAR‐10 pattern recognition, achieving an accuracy of 86%. The method allows the operation of SNN and shows the tunability in the process of light‐to‐spike encoding, opening possibilities for color image processing. [ABSTRACT FROM AUTHOR]

Nanometer-thick-TiO2-channel thin-film transistors (TFTs) are examined as oxidizing-agent monitors for room-temperature atomic layer deposition (RTALD). RTALD is a plasma-based process using plasma-excited humidified argon where OH radicals oxidize the precursor-gas adsorbed surface. In the TFT, the anatase TiO2 channel, with a thickness of 16 nm, is attached to a 300 nm thick gate capacitor of SiO2, while the channel surface is exposed to the ALD ambient. A heavily doped n-type Si substrate attached to the gate SiO2 is used as the gate electrode. The gate width and length are 1000 and 60 μm, respectively. When the TFT is installed in the RTALD chamber, the drain-current waveform is recorded in the course of the metal organic gas adsorption, evacuation of the residual gas, oxidization, and evacuation. In the present study, three kinds of metal organic (MO) precursors, tetrakis(dimethyl)amino titanium, tris(dimethyl)amino silane, and trimethyl aluminum are examined. The drain current exhibits strong responses upon the exposure of the plasma excited humidified argon. This suggests that OH radicals in the plasma might oxidize the adsorbed MO precursors to produce the OH moieties, where the surface polarization of OH moieties might enhance channel conductivity. The experimental results suggest the applicability of the present TFT as a plasma monitor in RTALD. [ABSTRACT FROM AUTHOR]

A phototransistor with a sol–gel‐based Cd‐doped indium‐gallium‐zinc‐oxide (IGZO) photoactive sensing channel on a dual‐purpose indium‐tin‐oxide (ITO) substrate (gate electrode and embedded transparent heater) is reported for the first time. The Cd‐doped IGZO layer is fabricated in situ by a one‐step microwave‐assisted sol–gel process with reduced temperature (<125 °C) and time (<15 min). Despite the wide bandgap of the IGZO (≈3.83 eV) channel, visible‐light (≈2 eV) photosensing is achieved in the developed phototransistor upon Cd doping owing to the reduced bandgap (≈3.71 eV) and increased density of subgap states associated with oxygen vacancies in the metal–oxygen bonding structure. In addition, the Cd‐doped IGZO phototransistor exhibits excellent operational stability (up to 10 000 cycles) and long‐term reliability (up to 30 days). Finally, the embedded Joule heater, based on the inherent transparent ITO substrate, significantly improves the recovery characteristics of the IGZO phototransistor owing to relaxation of the photoexcited charges at the oxygen‐vacancy‐related trap states upon heating, resulting in 100% recovery in a significantly reduced timeframe (≈10 s). These findings pave the way for the development of high‐performance, stable, and reliable visible‐light phototransistors based on wide‐bandgap IGZO active sensing channels with fast and full recovery, expanding their practical applicability of optoelectronics. [ABSTRACT FROM AUTHOR]

Optoelectronic synapses are inevitable for realizing neuromorphic vision systems, which require the integration of image recognition, memory and image processing into a single platform. In this work, we present a three terminal optoelectronic synapse created using zinc oxide (ZnO) thin film transistor. The persistent photoconductivity (PPC) of ZnO thin film is utilized to demonstrate the synaptic behavior. The change in conductance of the device under UV illumination has been interpreted as the weight change in the synapse. The basic synaptic functions such as sensory memory, short term memory, long term memory, duration-time-dependent plasticity and paired pulse facilitation (PPF) have been successfully demonstrated. The device shows a PPF index of 160%, comparable to other optoelectronic synapses reported in literature. Further, to corroborate the existing theory that PPC is caused by oxygen vacancies, additional characterizations are carried out and the presence of oxygen vacancies is detected in the fabricated ZnO device. Subsequently, pattern recognition of MNIST handwritten dataset has been performed using the conductance tuning curves of the proposed ZnO TFT based synapses in a neural network architecture, thereby demonstrating their feasibility to be used in neuromorphic applications. [ABSTRACT FROM AUTHOR]

Multi‐phenyl and multi‐thiophene rod‐like molecules are typically used for weak epitaxial growth (WEG) of highly ordered organic semiconductor films enabling controllable microstructure properties and improved device performance. However, very few templating molecules have been reported, making it challenging to establish structure‐property relationships. As semiconductors are integrated into organic thin film transistors (OTFTs), the impact of templating layers on semiconductor microstructure and device performance must be established. Herein, four aromatic molecules with similar structure to para‐sexiphenyl (p‐6P) are synthesized and incorporated as the template layer in bis (pentafluoro phenoxy) silicon phthalocyanine (F10‐SiPc) OTFTs. The use of fluorinated p‐6P (p‐6PF) yields devices with the highest electron field‐effect mobility of 0.14 cm2 V−1 s−1 while a partially fluorinated p‐6P (p‐6PF4) results in improved threshold voltage. X‐ray diffraction (XRD) demonstrates varying F10‐SiPc crystallinity with choice of templating layer with the most crystalline films resulting from the use of p‐6PF. By grazing incidence wide angle X‐ray scattering (GIWAXS) and polarized Raman microscopy, all templating layers yield films with F10‐SiPc molecules predominantly aligned face‐on to the substrate. However, rod‐like p‐6P derivatives increased the face‐on orientation of F10‐SiPc. This study highlights the importance of template layer selection and deposition optimization in WEG‐based OTFTs. [ABSTRACT FROM AUTHOR]

In this paper, we optimized IGZO/Ag/IGZO (IAI) multilayer films by post-rapid thermal annealing (RTA) to enhance the electrical conductivity and optical transmittance in visible wavelengths for solar cell applications. Our optimized device showed an average transmittance of 85% in the visible range, with a lowest sheet resistance of 6.03 Ω/□ when annealed at 500 °C for 60 s. Based on these results, we assessed our device with photo-generated short circuit current density (JSC) using a solar cell simulator to confirm its applicability in the solar cell. IAI multilayer RTA at 500 °C for 60 s showed a highest JSC of 40.73 mA/cm2. These results show that our proposed IAI multilayer film, which showed a high optical transparency and electrical conductivity optimized with post RTA, seems to be excellent transparent electrode for solar cell applications. [ABSTRACT FROM AUTHOR]

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Active materials play a crucial role in the performance of phototransistors. However, the discovery of a novel and versatile active material is a big challenge. For the first time, phototransistors with ultrathin niobium‐doped indium oxide (InNbO) active layer are fabricated. The InNbO phototransistors without additional light‐absorbing layers exhibit the performance with a high average mobility of 22.86 cm2 V−1s−1, a turn‐on voltage of −0.75 V, a low sub threshold swing of 0.18 V/decade, and a high on/off current ratio of 5.74 × 108. Detailed studies show that Nb is the key to suppress the free carrier generation due to the strong bonding strength of Nb─O. In addition, the InNbO phototransistors exhibit a very broad spectral responsivity with a photocurrent of 4.72 × 10−4 A, a photosensitivity of 1.69 × 108, and a high detectivity of 3.33 × 1013 Jones under violet (405 nm) light illumination, which is significantly higher than that of the IGZO phototransistors. Furthermore, an active‐matrix quantum‐dot light‐emitting diode pixel circuit based on InNbO phototransistors is demonstrated. The findings not only indicate that InNbO is a new active material for phototransistors, but also suggest that InNbO‐based phototransistors have a great potential for the next‐generation interactive display technology. [ABSTRACT FROM AUTHOR]

The drain current (ID) of indium gallium zinc oxide thin-film transistors (IGZO-TFTs), fabricated by spin coating, decreases even when they are exposed to ozone gas at a concentration equal to or lower than 5 ppm. The ID reduction rate increases when the film thickness and the firing temperature in the spin-coating process of IGZO layer decreases. In these samples, the peak intensity ratio of the O 1s X-ray photoelectron spectroscopy (XPS) peak due to the OH group and the intensity of the infrared (IR) absorption band at 3000 cm−1–3500 cm−1 due to the OH stretching vibration increase. This indicates that OH groups within the IGZO film contribute to the ozone reaction mechanism. These findings are significant for developing high-sensitivity ozone sensors using a simpler process. [ABSTRACT FROM AUTHOR]

Indium–gallium–zinc oxide (IGZO) as a star material has been broadly applied in multiple functional devices, including planar displays, flexible electronic devices, and photoelectronics. In recent years, the development of artificial intelligence and great data also extends the application of IGZO-based thin film transistors (TFTs) to memory, memristors, and neuromorphic computing. Thus, the research of high performance and reliable IGZO TFTs attracts tremendous attention worldwide. Herein, a high-quality IGZO thin film was deposited via atomic layer deposition, and a dual-gate (DG) IGZO TFT was fabricated. Comprehensive electrical characterization was conducted on the fabricated DG IGZO TFTs, revealing that DG IGZO TFTs exhibited good performance for reliability analysis. The reliability and degradation mechanism of the DG IGZO TFT was systematically investigated under bias stress at room temperature and elevated temperatures of 350, 400, and 450 K by the comprehensive electrical characterization. Results indicate that the defects of the dual gate insulators and the interfaces majorly influence the degradation under bias stresses, while the carrier scattering of the IGZO channel is the major degradation mechanism under elevated temperatures. These findings highlight the degradation mechanism of the DG IGZO TFT under bias stress and elevated temperatures from a novel viewpoint, which provides a utilizable reference to its application in circuits. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the resistive switching (RS) behavior of Cu/ZnO/ITO devices subjected to various rapid thermal annealing (RTA) temperatures under vacuum. Current–voltage characteristics reveal that following the application of a positive electroforming voltage, both unannealed ZnO films and those annealed at 200 °C exhibit bipolar RS, consistent with the electrochemical metallization mechanism (ECM). However, films annealed at higher temperatures exhibit RS with both positive and negative electroforming threshold voltages and coexistence of switching in both polarities. Ultimately, these films display RS behavior aligned with the valence change mechanism (VCM), dominated by a negative electroforming voltage and RS on the negative bias side, while positive electroforming voltage and RS vanish for films annealed at 600 °C. Curve fitting analysis was conducted for Schottky emission (SE), space-charge limited current, and Poole–Frenkel (PF) emission mechanisms, with SE and PF emission providing better fits. These results demonstrate the tunability of ECM and VCM RS modes and the polarity of the forming bias, underscoring the potential of vacuum RTA in advancing ZnO-based memory device development. [ABSTRACT FROM AUTHOR]

This study delves into the characterization of IGZO/ZnO bilayer memristors, examining the impact of ZnO thickness and voltage scan rate on device performance. Bilayer memristors with varying ZnO thicknesses were prepared using magnetron sputtering, and their electrical properties were evaluated. The results indicate that a ZnO thickness of 17.3 nm yields optimal device performance, characterized by lower Forming and RESET voltages, reduced operating voltage volatility, higher switching ratios, and excellent cycling endurance and state retention. As the ZnO thickness increases, the Forming and RESET voltages of the devices also increase, the high resistance state volatility increases, and the switching ratio improves, although this is accompanied by greater operating voltage volatility. I–V characteristic measurements conducted at different scan rates revealed that the devices are insensitive to voltage scan rates, exhibiting stable resistive behavior within the range of 0.125–1.0 V/s. Furthermore, the study explores the multi-value storage capability of the bilayer device. To understand the resistive switching mechanism, current conduction mechanism fitting and resistive switching modeling were performed. The findings demonstrate that the device's current conduction mechanism primarily involves the space-charge-limited current mechanism and Schottky emission mechanism. This research presents a novel approach to developing high-performance memristors, paving the way for their applications in nonvolatile storage and neuromorphic computing. [ABSTRACT FROM AUTHOR]

At present, amorphous indium–gallium–zinc oxide (IGZO) semiconductor has become the most commonly used semiconductor material and is widely used in flat panel displays and various sensors, but its performance is greatly affected by environmental factors, especially water. This study investigates the instability of IGZO thin‐film transistors (TFTs) soaked in deionized water. After 24 h bathing, the field‐effect mobility and threshold voltage change a little, but the subthreshold swing, positive bias stress and negative bias stress stability undergo clear degradation. Through comprehensive examination of the changes in the chemical composition, surface morphology and thickness of the IGZO films, it's found that IGZO experiences selective etching by deionized water, and consequently the film surface becomes rough and rich of In and oxygen vacancies, which can explain the variations on device performance well. In addition to the bathing experiment performed on In2O3, Ga2O3, and ZnO TFTs, a schematic image of the reaction between water and IGZO is depicted, showing the preferential loss of Ga and Zn located next to the oxygen vacancy. [ABSTRACT FROM AUTHOR]

Analog reservoir computing (ARC) systems have attracted attention owing to their efficiency in processing temporal information. However, the distinct functionalities of the system components pose challenges for hardware implementation. Herein, we report a fully integrated ARC system that leverages material versatility of the ferroelectric-to-mixed phase boundary (MPB) hafnium zirconium oxides integrated onto indium–gallium–zinc oxide thin-film transistors (TFTs). MPB-based TFTs (MPBTFTs) with nonlinear short-term memory characteristics are utilized for physical reservoirs and artificial neuron, while nonvolatile ferroelectric TFTs mimic synaptic behavior for readout networks. Furthermore, double-gate configuration of MPBTFTs enhances reservoir state differentiation and state expansion for physical reservoir and processes both excitatory and inhibitory pulses for neuronal functionality with minimal hardware burden. The seamless integration of ARC components on a single wafer executes complex real-world time-series predictions with a low normalized root mean squared error of 0.28. The material-device co-optimization proposed in this study paves the way for the development of area- and energy-efficient ARC systems. Hardware implementation of analog reservoir computing is a challenge. The analog reservoir system in this work contains mixed phase boundary-based transistors with nonlinear short-term memory as physical reservoirs and artificial neuron, and nonvolatile ferroelectric transistors as readout networks. [ABSTRACT FROM AUTHOR]

In this study, the influence of the thickness of the channel layer on the electrical properties and stability of tungsten-doped indium oxide (IWO) thin-film transistors (TFTs) was investigated. Although oxide-semiconductor TFTs, particularly indium gallium zinc oxide, are promising, problems related to oxygen vacancies have led to their instability. In contrast, IWO has proven to be a compelling alternative because of its robust resistance to oxygen vacancies. IWO TFTs with varying channel thicknesses (10, 20, and 30 nm) were fabricated, and the device parameters, such as threshold voltage (Vth), subthreshold swing (SS), field-effect mobility (μFE), and on/off current ratio (Ion/Ioff), were analyzed. It was found that as the channel thickness increased, Vth exhibited a negative shift and SS increased, indicating an increase in carrier concentration. This phenomenon is attributed to the bulk trap density, in particular to oxygen vacancies. Negative bias stress tests confirmed the influence of the oxygen vacancies, with thicker channels showing more pronounced shifts. Low-frequency noise measurements were consistent with the carrier number fluctuation model, indicating that defects within the channel region contribute to the observed noise. The study concludes that identifying an optimal channel thickness during device manufacturing is crucial for improved TFT performance, with 20 nm devices characterized by high μFE and comparable trap density to 10 nm. This study provides valuable insight into the nuanced relationship between the channel thickness, trap density, and electrical performance of IWO TFTs. [ABSTRACT FROM AUTHOR]

Although the irreplaceable position of silicon (Si) semiconductor materials in the field of information has become a consensus, new materials continue to be sought to expand the application range of semiconductor devices. Among them, research on wide bandgap semiconductors has already achieved preliminary success, and the relevant achievements have been applied in the fields of energy conversion, display, and storage. However, similar to the history of Si, the immature material grown and device manufacturing processes at the current stage seriously hinder the popularization of wide bandgap semiconductor-based applications, and one of the crucial issues behind this is the defect problem. Here, we take amorphous indium gallium zinc oxide (a-IGZO) and 4H silicon carbide (4H-SiC) as two representatives to discuss physical/mechanical properties, electrical performance, and stability from the perspective of defects. Relevant experimental and theoretical works on defect formation, evolution, and annihilation are summarized, and the impacts on carrier transport behaviors are highlighted. State-of-the-art applications using the two materials are also briefly reviewed. This review aims to assist researchers in elucidating the complex impacts of defects on electrical behaviors of wide bandgap semiconductors, enabling them to make judgments on potential defect issues that may arise in their own processes. It aims to contribute to the effort of using various post-treatment methods to control defect behaviors and achieve the desired material and device performance. [ABSTRACT FROM AUTHOR]

The integration of molybdenum disulfide (MoS2) with other semiconductors to form heterojunction phototransistors demonstrates potential for optoelectronic applications due to their strong interaction with light and tunable bandgaps. Conventionally, bottom‐gate phototransistors based on MoS2 and amorphous indium–gallium–zinc oxide (a‐IGZO) are fabricated by deposition of the a‐IGZO film on the gate dielectric, followed by deposition of the MoS2 film, resulting in a MoS2/a‐IGZO heterojunction. In this study, an inverted MoS2/a‐IGZO (or denoted as a‐IGZO/MoS2) heterojunction integration for bottom‐gate phototransistors, where the MoS2 film is deposited on the gate dielectric first, followed by the deposition of the a‐IGZO film, is presented. This configuration is designed to enhance the processability and electrical properties of the phototransistor. Under visible light exposure with a low optical power density of 5.3 μW cm−2, the a‐IGZO/MoS2 heterojunction phototransistor demonstrates significantly improved photoresponsivity (1.6, 2.8, and 17 A W−1 at 635, 520, and 405 nm wavelengths, respectively) compared to the MoS2 single‐channel phototransistor. Time‐dependent photoresponse measurements reveal that the a‐IGZO/MoS2 heterojunction phototransistor responds more quickly to light changes and generates a tenfold‐greater photocurrent than that of the MoS2 single‐channel phototransistor. [ABSTRACT FROM AUTHOR]

The lateral carrier profile of amorphous indium gallium zinc oxide (IGZO) thin‐film transistors (TFTs) plays a significant role in determining the effective channel length (Leff) and length scalability even when the physical gate length (Lg) is the same. Especially, devices with high carrier concentration that have a high mobility of 14.54 cm2 V·s−1 suffer from severe short channel effects at Lg = 1 µm due to the reduced Leff. The current work proposes a systematic methodology for optimizing length scalability for a given Lg that involves engineering of the lateral carrier profile. Unique lateral carrier profiles are extracted using contour maps of ΔL and RSD as a function of carrier profile parameters, and they are validated by comparing the measured Leff, drain‐to‐source resistance, and current‐voltage characteristics with the results of simulations using the extracted carrier profiles. Further, to overcome the trade‐off between enhanced mobility and degraded VT roll‐off that occurs with increasing carrier concentration, an IGZO TFT with gate‐insulator shoulders is fabricated to structurally form negative ΔL and physically increase Leff, while also obtaining a high carrier concentration, ultimately achieving both optimal electrical performance, with mobility of 17.50 cm2 V·s−1, and complete control of the electrostatic integrity of the gate. [ABSTRACT FROM AUTHOR]

Active sensing matrices play a pivotal role in various electronic devices, including optical and X‐ray imaging arrays, electronic skins, and artificial tactile arrays, among others. These matrices function through a thin‐film active switching mechanism, allowing for the scanning of rows and columns by external circuitry to read the sensory signals of individual pixels. Recently, indium–gallium‐zinc oxide thin‐film transistors (IGZO TFTs) have emerged as highly promising technology in the realm of flexible electronics. They enable the large‐scale integration of functional circuits on flexible substrates. Shift registers are commonly employed as peripheral scanning circuits to sequentially address active‐matrix arrays. To enhance system compactness and minimize external electrical connections, it is imperative to seamlessly integrate shift registers within the active matrices. However, contemporary flexible IGZO‐based shift registers suffer from high operating voltages and low frequencies, which constrain their applicability in high‐performance flexible sensors and displays. In response to this challenge, a breakthrough is presented in the form of low‐voltage, high‐frequency bootstrap shift registers implemented with flexible IGZO technology. The approach involves utilizing SU‐8 buffered polyimide (PI) polymer foils as substrates. These foils boast an exceptional level of surface smoothness, significantly increasing the yield and performance of electronic components, including vias, IGZO TFTs, and capacitors used in the shift register circuitry. Additionally, HfO2/Al2O3/HfO2 sandwich structures are employed as high‐k dielectric layers to reduce the operational voltage. Thanks to the innovative circuit design and optimized fabrication methods, the 16‐stage shift register can operate at just 1.8 V with a frequency of 15 kHz. This breakthrough promises to have a profound impact on a wide range of applications for driving flexible active‐matrix electronic systems. [ABSTRACT FROM AUTHOR]

Solid–liquid interfaces made of functional inorganic materials and liquid electrolytes exhibit various interesting responses by applying an electric bias across the interface. Using an electric-double-layer device fabricated on a thin-film channel of magnetic Weyl semimetal Co3Sn2S2 with an ionic liquid gate electrolyte, we show that the conducting channel thickness can be effectively decreased by applying a negative gate voltage. The application of a gate voltage of −6 V at 250 K gives rise to an irreversible increase in the channel resistance. Transmission electron microscopy reveals that the thickness of the crystallized Co3Sn2S2 region is decreased by applying the negative bias, leaving a Co-poor disordered region on top of the Co3Sn2S2 layer. These results suggest that the preferential dissolution of Co is driven under the application of the negative bias, which leads to the disconnection of Co kagome-lattice layer that is mainly responsible for electrical conduction in Co3Sn2S2. Distinct from conventional bottom-up film growth approaches, this top-down thickness control enables us to examine the thickness dependence of the anomalous transport properties of Co3Sn2S2 in a single sample. The present finding will be useful for experimentally verifying the theoretically discussed ultrathin-film properties of the magnetic Weyl semimetal Co3Sn2S2. [ABSTRACT FROM AUTHOR]

Developing p-type oxide thin-film transistors (TFTs) is an essential path for further application in complementary metal oxide semiconductor (CMOS) components. However, the inferior electrical performance of p-type MO TFTs compared to n-type TFTs remains an ongoing challenge. Herein, for the first time, a low temperature, facile material engineering approach by incorporating n-type nanoparticles (NPs) was proposed for preparing p-type transparent NiOx TFTs. The characteristics of thin films blending NPs and the electrical performances of TFTs were investigated. The field effect mobility of TFTs with doping was nearly 20 times higher than pristine TFTs without doping, which was mainly beneficial from the suitable band alignment between NPs and p-type oxide, the increasing Ni3+ oxidation state in NiOx, as well as the improved dielectric/semiconductor interface quality. Electrons from drain electrode injected into metal oxide turn accepted in NPs rather than being trapped in the dielectric/semiconductor interface due to a strong surface electron depletion effect of NPs. NPs with small particle size and appropriate concentration would promote continuous hole transport by electrons transferring and reducing the interface trap state. The facile material engineering strategy is a promising technique for preparing p-type transparent MO-TFTs at low temperature, which showed great potential to be applicable in CMOS circuits on flexible substrates. [ABSTRACT FROM AUTHOR]

Hardware‐based reservoir computing (RC) systems provide benefits like energy efficiency and effective predictability. The implementation of different switching characteristics for the reservoir and readout layers requires the use of different types of devices or additional processing. However, an RC system with distinguishable switching characteristics obtained by changing stimulation on a single device is not identified yet, but it is appealing in terms of process simplicity and efficient processing costs. This study develops an RC system that uses ferroelectric thin‐film transistor (FeTFT) devices with an indium gallium zinc oxide channel and Hf0.5Zr0.5O2 ferroelectric layer for both networks. The nonvolatile FeTFT utilizes the remnant polarization properties of the ferroelectric layer through electrical stimulation, showing stable retention characteristics (104 s) and long‐term potentiation/depression. By using optical stimulation, the volatile FeTFT demonstrates short‐term characteristics, such as paired‐pulse facilitation, and a 4‐bit RC system. This proves that it is possible to meet the functional requirements of both the reservoir and readout networks by simply varying the type of stimulation applied to a single FeTFT. Finally, the fully FeTFT‐based RC system can recognize digit patterns from the Modified National Institute of Standards and Technology database with a high accuracy of 90.5%. [ABSTRACT FROM AUTHOR]

It seems impossible to use silicon oxide as a suitable gate dielectric material in metal-oxide-semiconductor field effect transistors. Many researchers have studied various metal oxides, nitrides, composite, and hybrid materials in search of dielectric materials that can replace silicon oxide. Each of these materials has advantages and disadvantages. In the present work, water-induced Lithium oxide (LiOx) with the organic PEIE (polyethylene imine ethoxylated) materials has been synthesized and studied. One advantage of the present work is using deionized water for getting (LiOx) precursor solution from lithium nitrate without the use of any toxic additives, resulting in a low cost-effective and eco-friendly synthesis. By fabricating three organic field effect transistors (OFETs) with LiOx/ PEIE nanocomposite materials with the same weight ratio (1:1), desirable electrical characteristics such as higher carrier mobility (μ) of 47.3 cm2V−1 S−1 , higher on-off current ratio (Ion/Ioff) of ∼105 , minima threshold voltage (Vth) shift of ∼ 0.6 (±0.2) V, lower subthreshold swing (SS) of 3.12 mV/decade and lower tunneling-, and leakage current density (J) of 2 (nA/cm2) could be found which demonstrated eco-friendly water-induced LiOx/ PEIE can be used as an alternative gate dielectric for the future of the OFET devices. [ABSTRACT FROM AUTHOR]