Search Results (86)

The optical, electrical, and material properties of In–Zn–O (IZO) films were optimized by adjusting the deposition power and annealing temperature. Films deposited at 125 W and annealed at 300 °C exhibited the best performance, with the lowest resistivity (1.43 × 10⁻³ Ω·cm), highest mobility (11.12 cm²/V·s), and highest carrier concentration (4.61 × 10²⁰ cm⁻³). The average transmittance and optical energy gap were 82.57% and 3.372 eV, respectively. The electrical characteristics of amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) using IZO source-drain (S–D) electrodes with various sputtering powers and annealing temperatures were investigated. The optimal sputtering power of 125 W and annealing temperature of 300 °C for the IZO S–D electrodes resulted in the highest field-effect mobility (~12.31 cm²/V·s) and on current (~2.09 × 10⁻⁶ A). This improvement is attributed to enhanced carrier concentration and mobility, which result from the high In/Zn ratio, the larger grain size, and low RMS roughness in the IZO films. The parasitic contact resistance (R_SD) and channel resistance (R_CH) were analyzed using the total resistance method. R_SD decreased with increasing IZO S–D sputtering power, while R_CH reached a minimum at 125 W. Both resistances decreased significantly as the annealing temperature increased from 200 °C to 300 °C. Full article

The advancement of portable high-definition organic light-emitting diode (OLED) displays necessitates thin film transistors (TFTs) with low power consumption and high pixel density. Amorphous indium gallium zinc oxide (a-IGZO) TFTs are promising candidates to meet these requirements. However, conventional silicon dioxide gate insulators provide limited channel modulation due to their low dielectric constant, while alternative high-k dielectrics often suffer from high leakage currents and poor surface quality. Plasma-enhanced atomic layer deposition (PEALD) enables the atomic-level control of film thickness, resulting in high-quality films with superior conformality and uniformity. In this work, a systematic investigation was conducted on the properties of HfO₂ films and the electrical characteristics of a-IGZO TFTs with different HfO₂ thicknesses. A Vth of −0.9 V, μ_sat of 6.76 cm²/Vs, SS of 0.084 V/decade, and I_on/I_off of 1.35 × 10⁹ are obtained for IGZO TFTs with 40 nm HfO₂. It is believed that the IGZO TFTs based on a HfO₂ gate insulating layer and prepared by PEALD can improve electrical performance. Full article

The surface morphology of porous source electrodes plays a significant role in the performance of vertical channel indium–gallium–zinc oxide thin-film transistors (VC-IGZO-TFTs). This study systematically investigates the properties of porous MXene-based source electrodes and their impact on VC-IGZO-TFTs fabricated with varying MXene concentrations. As the MXene concentration increases, both the sheet resistance and porosity of the electrodes decrease. VC-IGZO-TFTs based on a 3.0 mg/mL MXene concentration exhibit optimal electrical performance, with a threshold voltage (V_th) of 0.16 V, a subthreshold swing (SS) of 0.20 V/decade, and an on/off current ratio (I_on/I_off) of 4.90 × 10⁵. Meanwhile, the VC-IGZO-TFTs exhibit excellent electrical reliability and mechanical stability. This work provides a way to analyze the influence of sheet resistance and porosity on the performance of VC-IGZO-TFTs, offering a viable approach for enhancing device efficiency through porous MXene electrode engineering. Full article

As the typical representative of amorphous oxide semiconductors (AOS), quaternary indium gallium zinc oxide (IGZO) has been applied as the active layer of thin-film transistors (TFTs), but their mobility is still low (usually ~10 cm²/Vs). IGTO is reported to have larger mobility owing to the addition of Tin (Sn) in IZO. So, whether Sn doping can increase the optoelectronic properties of IGZO is a new topic worth studying. In this study, four series of quinary InGaZnSnO (IGZTO) oxide thin films were deposited on glass substrates using a high-purity IGZTO (In:Ga:Zn:Sn:O = 1:0.5:1.5:0.25:x, atomic ratio) ceramic target by RF magnetron sputtering. The effects of fabrication parameters (sputtering power, argon gas flow, and target-to-substrate distance) and film thickness on the microstructure, optical, and electrical properties of IGZTO thin films were investigated. The results show that all IGZTO thin films deposited at room temperature (RT) are amorphous and have a smooth and uniform surface with a low roughness (RMS of 0.441 nm, RA of 0.332 nm). They exhibit good average visible light transmittance (89.02~90.69%) and an optical bandgap of 3.47~3.56 eV. When the sputtering power is 90 W, the argon gas flow rate is 50 sccm, and the target-to-substrate distance is 60 mm, the IGZTO films demonstrate optimal electrical properties: carrier concentration (3.66 × 10¹⁹ cm⁻³), Hall mobility (29.91 cm²/Vs), and resistivity (0.54 × 10⁻² Ω·cm). These results provide a valuable reference for the property modulation of IGZTO films and the potential application in optoelectronic devices such as TFTs. Full article

Brain-inspired neuromorphic computing is expected to overcome the von Neumann bottleneck by eliminating the memory wall between processing and memory units. Nevertheless, critical challenges persist in synaptic device implementation, particularly regarding nonlinear/asymmetric conductance modulation and multilevel conductance states, which substantially impede the realization of high-performance neuromorphic hardware. This study demonstrates a novel advancement in photonic–electronic modulated synaptic devices through the development of an amorphous indium–gallium–zinc oxide (a-IGZO) synaptic transistor. The device demonstrates biological synaptic functionalities, including excitatory/inhibitory post-synaptic currents (EPSCs/IPSCs) and spike-timing-dependent plasticity, while achieving excellent conductance modulation characteristics (nonlinearity of 0.0095/−0.0115 and asymmetric ratio of 0.247) and successfully implementing Pavlovian associative learning paradigms. Notably, systematic neural network simulations employing the experimental parameters reveal a 93.8% recognition accuracy on the MNIST handwritten digit dataset. The a-IGZO synaptic transistor with photonic–electronic co-modulation serves as a potential critical building block for constructing neuromorphic architectures with human-brain efficiency. Full article

We report an ion-gel-gated amorphous indium gallium zinc oxide (a-IGZO) optoelectronic neuromorphic transistors capable of synaptic emulation in both photoelectric dual modes. The ion-gel dielectric in the coplanar-structured transistor, fabricated via ink-jet printing, exhibits excellent double-layer capacitance (>1 μF/cm²) and supports low-voltage operation through lateral gate coupling. The integration of ink-jet printing technology enables scalable and large-area fabrication, highlighting its industrial feasibility. Electrical stimulation-induced artificial synaptic behaviors were successfully demonstrated through ion migration in the gel matrix. Through a simple and controllable oxygen vacancy engineering process involving low-temperature oxygen-free growth and post-annealing process, a sufficient density of stable subgap states was generated in IGZO, extending its responsivity spectrum to the visible-red region and enabling wavelength-discriminative photoresponses to 450/532/638 nm visible light. Notably, the subgap states exhibited unique interaction dynamics with low-energy photons in optically triggered pulse responses. Critical synaptic functionalities—including short-term plasticity (STP), long-term plasticity (LTP), and paired-pulse facilitation (PPF)—were successfully simulated under both optical and electrical stimulations. The device achieves low energy consumption while maintaining compatibility with flexible substrates through low-temperature processing (≤150 °C). This study establishes a scalable platform for multimodal neuromorphic systems utilizing printed iontronic architectures. Full article

Dual-gate metal-oxide-semiconductor transistors have attracted considerable interest due to their high threshold voltage control capability, higher drain current, and the ability to alleviate the impact of carrier surface scattering at the channel/dielectric interface. However, their applications in the monolithic integration of scaled devices encounter challenges stemming from the interaction between the pre-treated channel layer and its covering dielectric. Here, we demonstrate the successful realization of a scaled back-end-of-line (BEOL) compatible dual-gate indium–gallium–zinc oxide (IGZO) transistor with a channel length (L_ch) scaled down to 150 nm and a channel thickness (T_ch) of 4.2 nm. After precisely adjusting the metal ratio to In_0.24Ga_0.58Zn_0.18O and employing O₃ as an oxygen precursor for the deposition of Al₂O₃ as the top-gate dielectric layer, a high maximum current of 1.384 mA was attained under top-gate control, while a high current of 1.956 mA was achieved under bottom-gate control. Additionally, a high current on/off ratio (I_on/off > 10⁹) was achieved for the dual gate. Careful calculations reveal that the field-effective mobility (μ_eff) reaches 11.68 cm²V⁻¹s⁻¹ under top-gate control and 22.46 cm²V⁻¹s⁻¹ under bottom-gate control. We demonstrate excellent dual-gate low-voltage modulation performance, with a high current switch ratio of 3 × 10⁵ at L_ch = 300 nm and 2 × 10⁴ at L_ch = 150 nm achieved by only 1 V modulation voltage, accompanied by a normalized current variation higher than 10⁶. Overall, our devices show the remarkable electrical performance characteristics, highlighting their potential applications in high-performance electronic circuits. Full article

Amorphous oxide semiconductor transistors with a high current density output are highly desirable for large-area electronics. In this study, wrapping amorphous indium-gallium-zinc-oxide (a-IGZO) transistors are proposed to enhance the current density output relative to a-IGZO source-gated transistors (SGTs). Device performances are analyzed using technology computer-aided design (TCAD) simulations. The TCAD simulation results reveal that, with an optimized device structure, the current density of the wrapping a-IGZO transistor can reach 7.34 μA/μm, representing an approximate two-fold enhancement compared to that of the a-IGZO SGT. Furthermore, the optimized wrapping a-IGZO transistor exhibits clear flat saturation and pinch-off behavior. The proposed wrapping a-IGZO transistors show significant potential for applications in large-area electronics. Full article

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. Full article

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. Full article

This study investigated the potential of indium tungsten oxide (IWO) channel-based inorganic electrolyte transistors as synaptic devices. We comparatively analyzed the electrical characteristics of indium gallium zinc oxide (IGZO) and IWO channels using phosphosilicate glass (PSG)-based electrolyte transistors, focusing on the effects of electric-double-layer (EDL) and electrochemical doping. The results showed the superior current retention characteristics of the IWO channel compared to the IGZO channel. To validate these findings, we compared the DC bias characteristics of SiO₂-based field-effect transistors (FETs) with IGZO and IWO channels. Furthermore, by examining the transfer curve characteristics under various gate voltage (V_G) sweep ranges for PSG transistors based on IGZO and IWO channels, we confirmed the reliability of the proposed mechanisms. Our results demonstrated the superior short-term plasticity of the IWO channel at V_G = 1 V due to EDL operation, as confirmed by excitatory post-synaptic current measurements under pre-synaptic conditions. Additionally, we observed superior long-term plasticity at V_G ≥ 2 V due to proton doping. Finally, the IWO channel-based FETs achieved a 92% recognition rate in pattern recognition simulations at V_G = 4 V. IWO channel-based inorganic electrolyte transistors, therefore, have remarkable applicability in neuromorphic devices. Full article

Amorphous indium gallium zinc oxide (a-IGZO) is becoming an increasingly important technological material. Transport in this material is conceptualized as the heavy disorder of the material causing a conduction or mobility band-edge that randomly varies and undulates in space across the entire system. Thus, transport is envisioned as being dominated by percolation physics as carriers traverse this varying band-edge landscape of “hills” and “valleys”. It is then something of a missed opportunity to model such a system using only a compact approach—despite this being the primary focus of the existing literature—as such a system can easily be faithfully reproduced as a true microscopic TCAD model with a real physically varying potential. Thus, in this work, we develop such a “microscopic” TCAD model of a-IGZO and detail a number of key aspects of its implementation. We then demonstrate that it can accurately reproduce experimental results and consider the issue of the addition of non-conducting band-tail states in a numerically efficient manner. Finally, two short studies of 3D effects are undertaken to illustrate the utility of the model: specifically, the cases of variation effects as a function of device size and as a function of surface roughness scattering. Full article

In this study, a KrF excimer laser with a high-absorption coefficient in metal oxide films and a wavelength of 248 nm was selected for the post-processing of a film and metal oxide thin film transistor (MOTFT). Due to the poor negative bias illumination stress (NBIS) stability of indium gallium zinc oxide thin film transistor (IGZO-TFT) devices, terbium-doped Tb:In₂O₃ material was selected as the target of this study. The XPS test revealed the presence of both Tb³⁺ and Tb⁴⁺ ions in the Tb:In₂O₃ film. It was hypothesized that the peak of the laser thermal effect was reduced and the action time was prolonged by the f-f jump of Tb³⁺ ions and the C-T jump of Tb⁴⁺ ions during the laser treatment. Studies related to the treatment of Tb:In₂O₃ films with different laser energy densities have been carried out. It is shown that as the laser energy density increases, the film density increases, the thickness decreases, the carrier concentration increases, and the optical band gap widens. Terbium has a low electronegativity (1.1 eV) and a high Tb-O dissociation energy (707 kJ/mol), which brings about a large lattice distortion. The Tb:In₂O₃ films did not show significant crystallization even under laser energy density treatment of up to 250 mJ/cm². Compared with pure In₂O₃-TFT, the doping of Tb ions effectively reduces the off-state current (1.16 × 10⁻¹¹ A vs. 1.66 × 10⁻¹² A), improves the switching current ratio (1.63 × 10⁶ vs. 1.34 × 10⁷) and improves the NBIS stability (ΔV_ON = −10.4 V vs. 6.4 V) and positive bias illumination stress (PBIS) stability (ΔV_ON = 8 V vs. 1.6 V). Full article

Perovskite-based metal oxide phototransistors have emerged as promising photodetection devices owing to the superior optoelectronic properties of perovskite materials and the high carrier mobility of metal oxides. However, high dark current has been one major problem for this type of device. Here, we studied the dark current behaviors of phototransistors fabricated based on the Indium Gallium Zinc Oxide (IGZO) channel and different perovskite materials. We found that depositing organic–inorganic hybrid perovskites materials (MAPbI₃/FAPbI₃/FA_0.2MA_0.8PbI₃) on top of IGZO transistor can increase dark current from ~10⁻⁶ mA to 1~10 mA. By contrast, we observed depositing an inorganic perovskite material, CsPbI₃, incorporated with PCBM additive can suppress the dark current down to ~10⁻⁶ mA. Our study of ion migration reveals that ion migration is pronounced in organic–inorganic perovskite films but is suppressed in CsPbI₃, particularly in CsPbI₃ mixed with PCBM additive. This study shows that ion migration suppression by the exclusion of organic halide and the incorporation of PCBM additive can benefit low dark current in perovskite phototransistors. Full article

The effect of high- and low-temperature conditions on the performance of IGZO TFT and logic circuits were investigated in this work. In the temperature range of 250−350 K, the performance of the IGZO TFT did not show significant changes and exhibited a certain degree of high- and low-temperature resistance. When the temperature was below 250 K, as the temperature decreased, the threshold voltage (V_TH) of the IGZO TFT significantly increased, the field effect mobility (μ_FE) and the on state current (I_ON) significantly decreased. This is attributed to the lower excitation degree of charge carriers at extremely low temperatures, resulting in fewer charge carriers transitioning to the conduction or valence bands, and the formation of defects also limits carrier migration. When the temperature exceeded 350 K, as the temperature increased, more electrons could escape from the bandgap trap state and become free charge carriers, and the IGZO layer was thermally excited to produce more oxygen vacancies, resulting in higher μ_FE and lower V_TH. In addition, the drain current noise spectral density of IGZO TFT conformed to the 1/ƒ noise characteristic, and the degradation mechanism of IGZO TFT over a wide temperature range was confirmed based on the changes in noise spectral density at different temperatures. In addition, an inverter logic unit circuit was designed based on IGZO TFT, and the performance changes over a wide temperature range were analyzed. This lays the foundation for IGZO TFT to be applied in integrated circuits with harsh environments. Full article