Electronic Materials

For the first time, the hole mobility values for benzo[f]- and naphtho[1,2-f]-annelated [1,2,5]oxadiazolo[3,4-b]thieno[3,2-h]quinoxalines were determined experimentally by using the space-charge-limited current method. Analysis of the X-ray diffraction data for naphtho[1,2-f][1,2,5]oxadiazolo[3,4-b]thieno[3,2-h]quinoxaline revealed significant π–π stacking, which may be attributed to enhanced electron mobility. These findings are further supported by the observed low hole conductivity values, which reached 4.10 × 10⁻⁹ cm²·V⁻¹·s⁻¹. Therefore, polycyclic compounds based on the furazano[3,4-b]pyrazine core can be considered a convenient scaffold for developing both electron and hole transport materials in various organic photovoltaic devices. Full article

This manuscript investigates a biosensor based on a gadolinium (Gd)-doped hafnium oxide (HfO₂) ferroelectric–dielectric (FE-DE) heterostructure for high-sensitivity, low-power biomolecule detection. The sensing cavity consists of a dielectric layer and a biomolecule-filled region, where different filling conditions (0%, 50%, 75%, and 100%) emulate realistic sensing environments. The dielectric properties of the biomolecule changes, which results in changes of the dielectric capacitance, thus improving capacitance matching with the ferroelectric layer and stabilizing the negative-capacitance effect. This intrinsic voltage amplification enhances the electrical response of the biosensor. Electrical characteristics, including charge–voltage, energy–charge, capacitance–voltage, and voltage amplification, were analyzed for biomolecules with dielectric constants ranging from 1 to 12. Higher-dielectric-constant biomolecules exhibited superior sensing performance; for example, gelatin (K = 12) achieved the highest sensitivity of 1.9632 at 100% cavity filling, along with the maximum voltage amplification. To evaluate the impact of amplification, the amplified dielectric voltage was applied to the gate of a 50 nm NMOS transistor. The enhanced gate voltage improved the drain current and transconductance and enabled a subthreshold swing below the conventional thermal limit of 60 mV/dec. A feasible fabrication plan is demonstrated to show the possible realization of the sensor system. These outcomes indicate that the proposed Gd-doped HfO₂-based FE-DE heterostructure is capable of efficiently magnifying the dielectric changes caused by biomolecules, thus offering an encouraging framework for future low-power and high-sensitivity biosensing applications. Full article

Dissolved oxygen concentration is a key parameter determining the oxidation and corrosion behavior of structural materials in lead-based fast reactor coolants. Therefore, achieving high-precision in-situ oxygen measurement in LBE systems is a fundamental technical requirement for implementing oxygen-controlled corrosion protection. Currently, nuclear-grade Bi/Bi₂O₃ solid-state electrochemical oxygen sensors have a minimum effective operating temperature of 350 °C, which prevents them from meeting the real-time oxygen monitoring needs under low-temperature conditions. This temperature limitation has become a major bottleneck for the engineering application of oxygen control technology. To address these requirements and challenges, this study develops a novel electrochemical oxygen sensor based on an 8 mol% Y₂O₃-stabilized ZrO₂ (8YSZ) solid electrolyte and La_0.6Sr_0.4Co_0.2Fe_0.8O_3±δ (LSCF) electrode system. Comparative experiments with Bi/Bi₂O₃ sensors are conducted to quantitatively assess the advantages of the LSCF/Air sensor in low-temperature applications within 205~550 °C. Furthermore, considering the irradiation environment in nuclear reactors, oxygen ion irradiation was employed as an accelerated simulation method to preliminarily investigate the electrochemical transport properties of 8YSZ after irradiation. The effects of oxygen ion irradiation on the apparent impedance and apparent oxygen ion conductivity of 8YSZ were evaluated. The results show that the LSCF/Air oxygen sensor has the potential to extend the lower operating-temperature limit of 8YSZ-based oxygen sensors in static, oxygen-saturated LBE environments. Oxygen ion irradiation increased the apparent impedance and decreased the apparent ionic conductivity of the tested 8YSZ samples. These results provide preliminary experimental data for the development of oxygen sensors for oxygen monitoring and corrosion control in liquid-metal-cooled reactor systems over a wider temperature range. Full article

In this paper, the design and simulation of a monolithically integrated silicon carbide (SiC) MEMS piezoresistive accelerometer with an on-chip SiC field-effect transistor (SiC-FET) readout circuit are presented for applications in harsh environments. The proposed device can be fully realized on a single SiC platform, ensuring robust operation at a very high temperature (1000 K) and removing the bottlenecks associated with heterogeneous integration and silicon-based sensor electronics. Finite-element-method (FEM) simulations were performed to investigate the mechanical performance of the accelerometer, including sensitivity, cross-axis response, resonant frequency, and thermal stability. The designed accelerometer exhibits a z-axis sensitivity of 35.8 $\Omega$/g with low cross-axis sensitivities of 0.27% and 2.12% along the x- and y-axes, respectively. The eigen frequency analysis shows a fundamental resonance frequency of 1640 Hz and an operating bandwidth of 328 Hz. Thermal simulations indicate excellent stability performance from 300 K to 1000 K with resistance and displacement variations of less than 0.21% and 0.009%, respectively. A 4H-SiC MOSFET was designed and analyzed by the TCAD process and device simulations. It was shown to operate stably in a wide temperature range without breakdown. The FEM and TCAD results were incorporated into a Verilog-A model and implemented in Cadence Virtuoso to evaluate the complete sensor-readout system. The integrated SiC-FET common-source amplifier achieved a sensitivity of up to 100 mV/V at 1000 K with a non-linearity of approximately 1%. The results demonstrate the feasibility of a fully integrated all-SiC accelerometer platform for high-temperature sensing applications in aerospace, automotive, energy, and industrial environments. Full article

Electromagnetic interference (EMI) shielding is essential in modern electronics, telecommunications, and aerospace systems. Graphite-based materials are promising shielding candidates due to their tunable electrical conductivity, low density, corrosion resistance, and thermal stability. However, numerical studies investigating the combined effects of conductivity and thickness on shielding effectiveness (SE) across the X-band remain limited. This study presents a parametric finite element analysis of EMI shielding performance for graphite materials with electrical conductivities of 1, 10, 100, 1000, and 3000 S/m, representing structures ranging from highly porous to dense graphite. Thicknesses from 1 to 10 mm are simulated in a WR90 rectangular waveguide using finite element simulations. The Transition Boundary Condition (TBC) is employed to efficiently model conductive slabs without resolving the skin depth via volumetric meshing. Shielding effectiveness is evaluated from S-parameters and decomposed into total (SET), absorption (SEA), and reflection (SER) components. Results show that SET increases with both conductivity and thickness, and that shielding behavior is strongly dependent on conductivity. Low-conductivity graphite (σ = 1 S/m) exhibits absorption-dominated shielding, reaching an absorbed power fraction of 89% at 5 mm thickness. At σ = 10 S/m, the material enters a transitional regime where absorption and reflection contribute comparably. For highly conductive graphite (σ ≥ 100 S/m), reflection becomes dominant, with the reflected power fraction approaching 0.97 at σ = 3000 S/m. A conductivity-dependent saturation thickness is identified, beyond which additional thickness provides negligible shielding improvement. Dense graphite materials (σ ≥ 1000 S/m) reach saturation at approximately 1 mm thickness. Finally, a conductivity–thickness design heatmap is developed to guide the optimization of graphite-based EMI shielding materials. Full article

Reliable solder joint formation in electronic packaging depends on the coupled effects of solder composition and pad finish on molten solder wetting, yet direct comparisons of Bi-modified SAC305 and SAC405 solders on common surface finishes remain limited. In this study, nominal SAC305- and SAC405-based solders with Bi additions up to 3 wt.% were evaluated on ENIG and Cu-OSP finishes at 250 °C under forming gas. Sessile drop testing was used to measure contact angles, and atomic force microscopy and surface free energy measurements were used to characterize the substrates. The work of adhesion was calculated using the Young–Dupré relationship from contact angle and liquid surface tension values. For both alloy series, contact angle generally decreased with increasing Bi content, indicating improved spreading, with a stronger effect for SAC305 on Cu-OSP. ENIG produced lower contact angles and higher calculated work of adhesion than Cu-OSP. SAC405-based solders generally showed higher calculated work of adhesion than SAC305-based solders because of their higher liquid surface tension. However, the lowest contact angle did not always correspond to the highest calculated work of adhesion. These results show that Bi content, Ag level, and pad finish jointly influence the apparent wettability and calculated solder–substrate interaction of SAC-Bi solders. Full article

Oxide systems with the nominal composition LaCaCuVMnO_7.5 and composites modified with the YBa₂Cu₃O_x phase were synthesized by the solid-state reaction method. The phase composition and structural features were systematically investigated by X-ray diffraction (XRD), Rietveld refinement, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX). The parent oxide was found to form a two-phase system, consisting of an orthorhombic perovskite-like phase and a cubic manganite–vanadate phase, whereas the introduction of 10 wt.% YBa₂Cu₃O_x resulted in the formation of a three-phase composite containing an additional cuprate phase. Thermophysical investigations in the 298–673 K range revealed λ-type-like anomalies in the heat capacity, which may be associated with possible structural or interphase transformations in the investigated oxide systems. The incorporation of YBa₂Cu₃O_x significantly modified the temperature dependence of heat capacity and increased its values over both low- and high-temperature regions. Electrophysical measurements in the 293–483 K range confirmed the semiconducting nature of conductivity, while the addition of YBa₂Cu₃O_x reduced electrical resistance and enhanced dielectric permittivity. These findings demonstrate that YBa₂Cu₃O_x modification provides an effective route for tuning the thermophysical and electrophysical properties of LaCaCuVMnO_7.5-based oxide systems, suggesting their potential as promising candidates for multifunctional oxide materials with possible electronic and sensor-related applications. Full article

Two-dimensional (2D) group-IV materials are promising for spintronics due to their silicon compatibility and tunable properties. In this work, we investigate the structural, electronic, magnetic, and optical properties of semi-hydrogenated 2D SiGe random alloys—where hydrogen atoms saturate only one side of the atomic plane—using density functional theory and many-body perturbation theory ($G{W}_0$). Substitutional disorder is modeled via representative high-symmetry configurations introduced by Baldereschi and co-workers to enable quasiparticle and optical simulations in large supercells. We demonstrate that these semi-hydrogenated alloys possess an intrinsic magnetic semiconducting ground state, arising from the electronic structure of the system, with an integer magnetic moment of $1{\mathsf{\mu }}_{\mathrm{B}}$ per primitive cell. The spin-resolved electronic structure features nearly flat frontier bands and a finite energy gap, which is significantly renormalized by quasiparticle corrections while maintaining robust spin polarization. These properties remain remarkably stable across different realizations of chemical disorder and over a wide range of alloy compositions considered in this work. Optical spectra calculated within the random phase approximation reveal a composition-dependent red-shift of the low-energy onset in the imaginary part of the dielectric function, consistent with the evolution of the quasiparticle electronic structure and the persistence of flat spin-polarized frontier bands. Our findings establish semi-hydrogenated 2D SiGe random alloys as a resilient model platform to explore interaction-driven magnetism in disordered two-dimensional systems, while simultaneously offering realistic prospects for spintronic and magneto-optoelectronic applications in the presence of chemical disorder. Full article

To meet the requirements of wide-temperature reliability and fast transient response in power management ICs for automotive, aerospace, and industrial applications, this paper presents a fast-response low-dropout regulator (LDO) based on a 0.18 μm high-temperature SOI process. Benefiting from the buried oxide isolation structure of the SOI technology, leakage current and parasitic effects under high-temperature conditions are effectively suppressed. The proposed LDO employs an NMOS power transistor, with an on-chip charge pump used to enhance the gate driving capability. In addition, a triple-loop regulation scheme consisting of a main negative feedback loop, an auxiliary positive feedback loop, and a current-mode feedback loop is adopted to improve transient performance and enhance loop stability. The fabricated chip occupies an area of 2840 μm × 1490 μm and supports an input voltage range of 3–5.5 V and an output voltage range of 1.2–3.3 V. Over a temperature range of −55 °C to 175 °C, the LDO can deliver a maximum load current of 400 mA. At 175 °C, the measured overshoot and undershoot voltages are 64 mV and 94 mV, respectively, with a maximum recovery time of 336 μs. Moreover, the power supply rejection ratio (PSRR) reaches 56.8 dB at 100 Hz. Experimental results demonstrate that the proposed LDO exhibits excellent high-temperature adaptability, strong load-driving capability, and superior transient response performance. Full article

In this work, the structural, electronic, optical, and vibrational properties of gallium nitride (Ga_xN_x) nanostructures were systematically investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT). A series of nanoparticles was constructed starting from a cubic-like Ga₄N₄ building unit, leading to one-dimensional (1D), two-dimensional (2D), three-dimensional (3D), and hexagonal configurations. Geometry optimizations and vibrational frequency calculations were performed at the B3LYP/def2-TZVP level, while optical properties were investigated using TD-DFT with the CAM-B3LYP functional. Only dynamically stable structures without imaginary vibrational frequencies were considered for spectroscopic analysis. The results reveal a strong dependence of the optical and vibrational behavior on nanoparticle size and geometry. Larger and lower-symmetry systems exhibit broader and red-shifted UV–Vis absorption spectra together with richer IR vibrational features. In contrast, elongated low-dimensional configurations such as Ga₁₂N₁₂–1D and Ga₁₆N₁₆–1D/2D were found to be dynamically unstable. The investigated nanostructures also show a clear tendency toward structural reorganization from cubic-like motifs to compact hexagonal arrangements related to the wurtzite phase of bulk GaN. Benchmark analysis demonstrates that CAM-B3LYP provides reliable excitation energies at moderate computational cost. Overall, the obtained results highlight the strong coupling between structure and optoelectronic properties in Ga_xN_x nanostructures and indicate their potential for nanoscale optoelectronic and photonic applications. Full article

Monolayer and few-layer MoS₂ are promising two-dimensional electronic materials, but proton irradiation can trigger ultrafast electronic excitation and charge transfer before defect formation. Here, real-time time-dependent density functional theory (RT-TDDFT) is used to investigate proton-induced electronic stopping and localized charge capture in monolayer and bilayer MoS₂ under normal incidence. Four impact positions are examined in monolayer MoS₂, namely, the hollow channel, the Mo–S bond center, and two trajectories close to Mo and S atoms. Under hollow channel incidence, the stopping power shows a non-monotonic dependence on proton velocity. When comparing the different trajectories, the hollow channel path gives the lowest stopping power, whereas the Mo–S bond center path gives the highest values, indicating strong sensitivity to the in-plane valence charge distribution. By contrast, the time-averaged localized captured charge decreases with increasing velocity and is generally largest for the close to Mo trajectory. Under the same hollow channel condition, the monolayer stopping power exceeds the bilayer value in the main stopping region, whereas the bilayer generally shows slightly enhanced localized charge capture. These results show that electronic stopping and localized charge capture are distinct but coupled microscopic components of proton-induced electronic response in MoS₂ and provide first-principles insight relevant to ion-beam processing and radiation-tolerant two-dimensional devices. Full article

Pd-decorated Janus ZrSSe monolayers provide a promising platform for adsorption-coupled electronic modulation in two-dimensional materials. Using first-principles density functional theory, we systematically investigate the structural stability, electronic properties, and adsorbate-induced electronic response of Pd-modified Janus ZrSSe. The results show that Pd is most stably anchored at the hollow site on the S-terminated surface, with a formation energy of $-1.45$ eV, while substitutional incorporation remains energetically unfavorable even after HSE06 refinement. Compared with pristine ZrSSe, Pd decoration markedly strengthens the interaction with adsorbates, leading to strong chemisorption for CO ($-1.026$ eV) and C₂H₂ ($-0.748$ eV), whereas H₂ remains comparatively weakly bound ($-0.258$ eV). Electronic-structure analysis reveals that CO induces the most pronounced perturbation because of strong orbital hybridization between Pd 4d states and C/O 2p states, resulting in the largest band-edge modulation among the three adsorbates. More importantly, biaxial strain provides an effective external degree of freedom for continuously tuning the electronic structure: tensile strain widens the band gap, whereas compressive strain systematically narrows it and ultimately drives a semiconductor-to-metal transition at sufficiently large compression. These findings establish Pd-decorated Janus ZrSSe as a strain-tunable electronic material in which adsorption, orbital hybridization, and band-edge evolution are intimately coupled, offering fundamental insights into controllable electronic modulation in polar two-dimensional systems. Full article

This study investigated the optoelectronic synaptic properties of amorphous gallium oxide (GaO_x) thin films for low-power physical reservoir computing (PRC) applications. The fabricated devices were irradiated with time series UV-C light to characterize the paired pulse facilitation (PPF) index, a fundamental synaptic property governed by transient photocurrent dynamics. Furthermore, the short-term memory (STM) capacity and parity check (PC) nonlinearity were quantitatively evaluated as essential PRC performance metrics, alongside a practical demonstration using a handwritten digit recognition task. The experimental results revealed a high PPF index when the width and interval of the input light pulses were comparable to or shorter than the inherent photocurrent time constants of the device. Although the evaluated nonlinearity was lower than that of conventional optoelectronic artificial synapses based on other semiconductor materials, the GaO_x device exhibited a comparable short-term memory capacity. Consequently, the reservoir layer achieved a high classification accuracy of approximately 90% in the handwritten digit recognition task. As these performance metrics were higher than those of the annealed sample, the device without annealing proved to be more suitable for PRC applications. These findings indicate that the amorphous GaO_x thin film device holds significant potential to serve as a robust, UV-C-responsive edge artificial intelligence (AI) sensor in harsh environments, such as outer space. Full article

With parylene coatings, conventional layer thickness measurement methods such as gravimetry, reflectometry, and cross-sectional microscopy are performed post-process and do not allow real-time monitoring or control. This paper presents a novel in situ measurement method based on the capacitance change in interdigitated copper electrodes fabricated on a printed circuit board (PCB). As parylene deposits on this sensor, the effective permittivity above the electrodes increases from ${ϵ}_{\mathrm{r}}\approx 1$ (vacuum) to ${ϵ}_{\mathrm{r}}=2.1\text{–}3.2$ (parylene), causing a measurable capacitance change. Finite element simulations were performed to model the relationship between layer thickness and sensor capacitance. Experimental validation with parylene C and F-VT4 demonstrated good agreement between simulation and measurement. Four consecutive parylene C runs with 60 g raw material showed reproducible capacitance increases of 49–53 pF, corresponding to layer thicknesses of 20–25 µm, verified by cross-sectional microscopy. Two coating runs were performed with parylene F-VT4 with target layer thicknesses of 2.5 µm and 5 µm. They show particularly good agreement with the simulation. The proposed method enables real-time process monitoring and provides a foundation for closed-loop control of parylene CVD processes. Full article

Gallium oxide is an ultra-wide bandgap semiconductor with excellent opto-electronic properties, making it a highly promising material for a wide range of applications and devices. In this article, we report how the optical, morphological, structural, and compositional properties of $\beta$-Ga₂O₃ thin films deposited by RF Sputtering on silicon substrates are affected by thermal treatments. Ellipsometric spectra recorded at multiple angles of incidence from several samples subjected to thermal annealing in the range of 550–1000 °C were analyzed to extract the optical functions using appropriate multilayer models. This analysis is complemented by compositional, structural, and morphological characterization techniques. We observed two main stages of crystallization with increasing annealing temperature; up to 700 °C, there is an increase in density and then, for 700–1000 °C, there is an improvement in crystallinity. While the refractive index increases continuously throughout this process, we found that the polarizability of the samples decreases in the first stage and increases in the second. These observations demonstrate that thermal treatments are a powerful tool to tune the optical properties of Ga₂O₃ thin films for device applications. Full article

This work investigates the performance improvement of a four-probe ballistic rectifier on bilayer graphene (BLG) through the formation of an energy gap under a perpendicular electric field. For this purpose, exfoliated BLG was deposited on oxidized n⁺-Si and structured into an asymmetric cross junction with 90 nm wide channels. The junction consists of a straight voltage stem (contacts U, L) and slanted current injectors (contacts 1, 2). The differential conductance of the stem, g_UL, as a function of back-gate bias, V_BG, reveals clear indications of energy gap formation and lateral depletion zones at the edges of the channel. The DC characteristic of the ballistic rectifier, V_UL(I₁₂), shows an increase in the output voltage V_UL with increasing V_BG. We attribute this to reduced diffuse scattering at the rough edges when the lateral depletion zones form smooth barriers. Full article

The von Neumann architecture faces a “memory wall” problem due to the physical separation of memory and processor, posing major challenges to energy efficiency and latency in the era of artificial intelligence. To overcome these bottlenecks, artificial synaptic devices inspired by biological systems have emerged as an important research direction. By integrating sensing and computing functions at the device level, these architectures provide a promising approach for the efficient processing of natural physical signals. Supported by advances in functional materials and artificial neural network (ANN) algorithms, artificial synaptic devices are capable of perceiving and processing various external stimuli, showing strong potential for applications in intelligent electronic skins, robotics, and edge computing. This review provides a comprehensive overview of recent advances in artificial synaptic devices, with particular emphasis on tactile and visual sensing applications. We discuss representative device types and operating mechanisms, analyze critical challenges from the perspectives of material engineering and functional integration, and further summarize potential solutions and future trends toward multimodal sensory–memory–computing systems. Full article

With the intensification of the energy crisis and environmental issues, thermoelectric conversion technology has become a research focus due to its ability to directly convert thermal and electrical energy. β-Cu₂Se thermoelectric materials have garnered considerable attention owing to their distinctive physical and chemical characteristics. However, their practical implementation is hindered by the inherent imbalance between electrical and thermal transport properties. In this work, β-Cu₂Se/SnSe composite thermoelectric materials were successfully synthesized via a facile and scalable in situ compositing strategy by introducing SnSe micro-flakes as the secondary phase. The results demonstrate that the introduced SnSe secondary phase effectively modulates the carrier concentration and enhances the density-of-states effective mass through the energy filtering effect and resonant energy level regulation, thereby significantly optimizing the electrical transport properties. Meanwhile, the abundant heterointerfaces formed between the β-Cu₂Se matrix and introduced SnSe secondary phase induce intense phonon scattering, which efficiently suppresses the lattice thermal conductivity of the β-Cu₂Se/SnSe composites. Benefiting from the synergistic optimization of electrical and thermal transport behaviors, the β-Cu₂Se/5 mol% SnSe composite sample achieves a maximum figure of merit (ZT) value of ~0.51 at 750 K, which represents a 70% enhancement compared with the pristine β-Cu₂Se and a 60% improvement compared with the direct composite sample. This study provides a simple and effective in situ composite strategy for designing and synthesizing high-performance thermoelectric materials. Full article

Additive Manufacturing (AM) and printing-based fabrication technologies have emerged as powerful enablers for next-generation electronic integration and packaging, addressing the growing limitations of conventional subtractive manufacturing techniques. As electronic systems continue to scale toward higher operating frequencies (10–110 GHz and beyond) and increased functional density (>10⁴ interconnects/cm²), traditional packaging approaches struggle with rigid design constraints, complex processing steps (>15–25 fabrication steps), high tooling costs ($10,000–$100,000 for mask and molds) and limited compatibility with heterogeneous integration. In this review, a comprehensive and critical overview of major additive manufacturing and printing technologies including aerosol jet printing, inkjet printing, vat polymerization, fused filament fabrication (FFF) and nScrypt printing is presented from the perspective of electronic assembly and packaging. The fundamental working mechanisms, material compatibility, resolution limits, scalability, and reliability considerations of each technique are systematically discussed. From a manufacturing standpoint, AM reduces material waste by 50–90% compared to subtractive PCB processing and eliminates tooling costs, enabling low-volume prototyping with per-unit fabrication costs reduced by 30–70% for small batches (<100 units). Production throughput varies widely, from 1 to 20 cm²/min for high-resolution direct write systems to >100 cm²/min for scalable inkjet systems. Moreover, it is discussed how these technologies enable advanced packaging architectures such as printed signal crossovers, three-dimensional interconnects, ramps, and embedded chip assemblies. Recent research efforts and reported demonstrations are analyzed to highlight the advantages and current limitations of additive manufacturing for high-frequency, RF, and system-on-package (SoP) applications. Finally, future directions and remaining challenges are discussed, including advances in materials, custom and on-demand manufacturing, enhanced design freedom, integration of multifunctionality, cost-effectiveness, and smart packaging solutions. This review aims to serve as a reference for researchers and engineers seeking to leverage additive manufacturing for high-performance electronic integration and next-generation electronic packaging solutions. Full article