Search Results (377)

Near-surface geometric defects and local electrical nonuniformities in semiconductor wafers are difficult to identify simultaneously using conventional far-field inspection methods. In this study, a three-dimensional electromagnetic simulation model based on AFM tip-enhanced near-field coupling was developed to investigate the local defect responses of AlN wide-bandgap semiconductors at 110 GHz. A finite-conductivity Pt80Ir20 metallic AFM probe, a low-loss AlN sample, and a point field probe in CST were used to extract the localized electric-field response near the tip apex. Lateral scanning response and normalized response variation were introduced to evaluate near-field perturbations induced by different defects. The results show that the metallic AFM tip produces a strongly localized electric-field enhancement within the tip–sample gap. Surface cracks, subsurface voids, and local Drude-AlN electrical anomaly blocks all lead to distinguishable near-field response variations. Geometric defects mainly cause local field redistribution and abrupt changes in lateral scanning curves, whereas the Drude-AlN anomaly produces interface transition and depth-dependent attenuation without changing the surface morphology. These findings indicate that AFM-enhanced near-field electromagnetic responses can provide a useful simulation basis for potential nondestructive characterization and signal interpretation of near-surface defects in AlN and related wide-bandgap semiconductors. Full article

Group III-nitride semiconductors (GaN, AlN, InN) serve as foundational materials for modern optoelectronics, high-frequency microelectronics, and next-generation energy harvesting devices. However, traditional high-temperature epitaxy (>700 °C) introduces severe thermal stress, high dislocation densities, and fundamental incompatibility with flexible substrates or CMOS back-end-of-line (BEOL) processes. Plasma-enhanced atomic layer deposition (PEALD) provides a disruptive, ultra-low thermal budget (<300 °C) pathway for atomic-scale precision growth and conformal coating. This review systematically summarizes recent frontiers in PEALD-synthesized Group III-nitrides and 2D/3D polar heterostructures. First, we dissect the microscopic nucleation kinetics, surface bond reconstruction, and impurity suppression mechanisms across diverse substrates, including Si, sapphire, quartz, metals, and flexible polymers. Next, we highlight 2D template-assisted van der Waals epitaxy on graphene and MoS2, and elucidate polarization-driven dipole interactions and band alignment engineering at 2D/3D polar interfaces (e.g., α-In₂Se₃, Janus MoSSe). Furthermore, we comprehensively discuss innovative applications in advanced photovoltaics (as electron transport and passivation layers in perovskite and quantum dot-sensitized solar cells), silicon-based microcavity lasers, high-electron-mobility transistors (HEMTs), and flexible multimodal sensors. Finally, key technological challenges—including the low-thermal-budget paradox, wafer-scale uniformity, and deposition throughput—are addressed alongside future perspectives in area-selective ALD and neuromorphic computing, presenting a cohesive blueprint from underlying physics to macroscopic system integration. Full article

The ultra-wide bandgap semiconductor β-Ga₂O₃ is a promising material for next-generation optoelectronic systems and hybrid nanodevices. However, high interface state densities and anomalous trap-assisted leakage severely restrict its performance and signal transduction capabilities. To resolve these fundamental limitations, we investigated a two-dimensional h-BN interlayer to construct a high-quality heterogeneous metal/h-BN/β-Ga₂O₃ structure using experimentally calibrated Sentaurus TCAD simulations. Energy-band analysis and validated I–V simulations reveal that the low-dimensional h-BN interlayer reconstructs the interfacial barrier, suppresses interface-assisted recombination, and shifts the dominant carrier transport from thermionic emission to Fowler–Nordheim tunneling. These effects markedly reduce the interface-state density and effectively suppress the Shockley–Read–Hall recombination current, mechanisms that are critical for minimizing dark current and improving device sensitivity. After systematically examining the effects of key parameters on the electrical characteristics of this hybrid architecture, we quantify the tradeoff between threshold voltage and on-resistance using a comprehensive figure of merit. Specifically, our results indicate that maximum device efficiency is achieved only when an optimal h-BN thickness of 3.56–5.88 nm (10–17 atomic layers) is strategically integrated with the appropriate metal work function and semiconductor doping. Overall, this work suggests the potential advantage of 2D h-BN in mitigating the interfacial bottleneck of traditional β-Ga₂O₃ platforms, providing quantitative design guidelines and theoretical support for the heterogeneous integration of next-generation optoelectronic devices. Full article

Capacitive sensors implemented in complementary metal-oxide-semiconductor (CMOS) technology are widely used in lab-on-chip (LoC), biomedical, and microfluidic systems. While most capacitive sensor interfaces are designed for high-resolution capacitance quantification, many practical applications require only binary decisions, event detection, or state discrimination. In such scenarios, conventional readout architectures introduce unnecessary circuit complexity, power consumption, latency, and data-processing overhead. This paper presents a CMOS cross-coupled-based capacitance detector (CBCD) that directly converts the imbalance between a sensing capacitance and a reference capacitance into a digital output. By exploiting regenerative positive feedback in a dynamic latch architecture, the proposed detector integrates sensing, comparison, and digitization within a single stage, eliminating the need for analog amplification, analog-to-digital conversion, frequency-based readout, and external thresholding circuitry. Circuit-level simulations show the ability to detect extremely small capacitance differences, demonstrate robust operation across a wide range of input capacitances, and achieve negligible power consumption. Process-corner, noise, and Monte Carlo analyses further verify reliable operation in the presence of device mismatch and process variations. Owing to its compact structure, digital-native output, and energy-efficient operation, the proposed CBCD is well suited for decision-driven sensing applications, including droplet presence detection, bubble monitoring, threshold-based diagnostics, event detection, and time-of-evaporation (ToE) measurements. The proposed architecture provides a scalable and low-complexity front-end solution for next-generation CMOS-integrated sensing platforms. Full article

Recent developments in optoelectronics have led to the incorporation of metallic nanostructures into semiconductors and other active materials for tailoring optical confinement, carrier generation, energy transfer, and light emission. This review discusses the physical basis of these effects and their use in photovoltaic devices, light-emitting diodes, photodetectors, sensors, and flexible platforms. The mechanisms considered include localized surface plasmon resonance, near-field enhancement, light scattering, hot carrier injection, and plasmon–exciton coupling. The relative contributions of these processes often coexist within the same hybrid structure, being dependent on nanoparticle size and shape, the local dielectric environment, spectral overlap, interface properties, and device architecture. Particular attention is given to the difficulty of identifying the dominant enhancement pathways, emphasizing that similar improvements in device performance may originate from different physical mechanisms. Advances in hybrid perovskites, MXenes, metal–organic frameworks, polymeric composites, and other emerging material platforms further highlight the central role of interfacial engineering in controlling plasmonic functionality. Overall, this review highlights that understanding the interplay between plasmonic mechanisms, hybrid material design, and interfacial engineering is essential for the rational design and practical implementation of next-generation hybrid optoelectronic technologies. Full article

The degradation of organic pollutants through photocatalysis is currently a major research focus. Core–shell heterostructures of metal semiconductors have been widely recognized as an effective strategy for enhancing photocatalytic performance, particularly when alloy nanoparticles are incorporated due to their unique electronic and catalytic properties. However, conventional synthetic approaches typically rely on high-temperature and high-pressure conditions, which often induce undesirable particle overgrowth and aggregation. Herein, AuPt bimetallic alloy nanoparticles were successfully fabricated via two successive in situ redox processes under room-temperature and ambient-pressure conditions, which were in situ integrated with Cu₂O to form multilevel core–shell composite particles. Structurally, an octahedral Cu₂O crystal serves as the inner core (denoted as Cu₂O_(O)), sequentially coated with a Cu₂O nanoparticle (denoted as Cu₂O_(P)) interlayer and a AuPt alloy nanoparticle shell. Functionally, the enhanced photocatalytic activity of Cu₂O_(O)@Cu₂O_(P)@AuPt was proven to be attributed to a dual function of AuPt, which includes an adsorption-induced polarized interface and an efficient charge-transfer mediator with the ohmic contact. This work demonstrates a mild and versatile synthetic strategy for constructing semiconductor–alloy heterostructures, offering valuable insights into the rational design of highly efficient and stable photocatalysts. Full article

Recent demand for reliable, low-power, and cost-effective gas sensors has spurred research into chemiresistive materials that operate under ambient conditions. PEDOT and PEDOT:PSS combined with semiconductor metal oxides (SMOs) have attracted attention due to their complementary properties: polymer flexibility and stability, alongside oxide reactivity and robustness. This review highlights the integration of PEDOT and PEDOT:PSS with n- and p-type SMOs, concentrating on fabrication techniques, sensing mechanisms, and performance indicators, such as sensitivity, selectivity, and response time. Emphasis is placed on heterojunction engineering, morphology control, and the influence of particle size and environmental factors. Despite notable progress, challenges persist in long-term stability, selectivity in mixed gases, and performance under varying conditions. Interface engineering and composite optimisation show promise, with potential applications in environmental monitoring, industrial safety, and wearable diagnostics. Full article

The parameter degradation and failure mechanisms of 1200 V asymmetric trench-type (AT) silicon carbide (SiC) metal oxide semiconductor field-effect transistors (MOSFETs) under various single and repetitive surge currents, with various gate bias voltages (V_GS) of 0 V, −5 V, and −10 V, are systematically investigated in this work. It is indicated that V_GS has no impact on the single surge reliability, with the same maximum single surge current (SSC_max) under different V_GS. However, during repetitive surge stress (90% and 60% SSC_max), the maximum surge cycles have increased as V_GS increases from −10 V to 0 V. It may be caused by the enhancement of channel-assisted leakage conduction, allowing more surge current to flow through the channel. It is concluded from gate capacitance (Cg-Vg) and low-frequency noise (LFN) characterizations that lower V_GS increases SiC/SiO₂ interface defect density, accelerating parameter degradation during single and repetitive surge stress. Both chip and package failures are observed for single and repetitive surge stress. For single surge stress, the device failure has resulted from the melted source Al as the metal erodes and penetrates through the interlayer dielectric and the ohmic contact layer between the source metal and the SiC-doped region, respectively, leading to a three-terminal short circuit. For repetitive surge stress, the device failure has been caused by the penetration of Al metal into the interlayer dielectric, leading to a gate-source short circuit. This comprehensive research provides valuable guidance for enhancing the surge reliability of SiC MOSFETs. Full article

Two-dimensional transient electroluminescent devices have attracted considerable attention owing to their simple device architecture and reduced contact-barrier dependence. However, the influence of semiconductor transport polarity on transient electroluminescence (EL) remains unclear. Here, we compare four representative transition metal dichalcogenide (TMDC) semiconductors with different transport polarities and find that ambipolar WSe₂ exhibits a stronger transient EL signal under identical driving conditions, a trend that cannot be explained by relative photoluminescence quantum yield (PLQY) alone. Transfer characteristics and gate-modulated photoluminescence (PL) measurements were further used to analyze the gate-dependent carrier doping states and the local spectral response associated with interfacial carrier modulation near the metal/TMDC interface during abrupt gate-voltage switching. Based on these results, we propose a possible physical picture in which ambipolar WSe₂ is more likely to form a transient interfacial electron–hole distribution favorable for electron–hole radiative recombination, whereas predominantly n-type materials tend to form electron-rich interfacial carrier states. These findings suggest that semiconductor transport polarity is an important material factor for designing low-dimensional transient electroluminescent devices. Full article

Semiconductor–biological hybrid systems (SBHS) have emerged as a disruptive technology for solar-driven chemical manufacturing, effectively bypassing the thermodynamic bottlenecks of natural photosynthesis. However, the aggressive pursuit of record-breaking solar-to-chemical conversion efficiencies has inadvertently fostered an efficiency trap. A profound interdisciplinary schism exists wherein the acute environmental toxicity and long-term interfacial instability of these hybrid architectures are frequently overlooked. This review provides a critical appraisal of the oft-ignored environmental risks inherent in current SBHS designs. We systematically dissect the heavy metal leaching toxicity of first-generation inorganic photosensitizers and unveil the complex, bidirectional degradation mechanisms at the abiotic–biotic interface. Specifically, we highlight the dual threats of photogenerated reactive oxygen species inducing cellular oxidative stress and active, microbially induced material dismantling via reductive dissolution driven by extracellular electron transfer. To navigate beyond this purely performance-driven paradigm, we propose a multidimensional, standardized evaluation matrix that systematically balances catalytic efficiency with biological safety and life-cycle sustainability. Ultimately, this review offers a comprehensive roadmap to transition biohybrid platforms from fragile laboratory concepts into robust, scalable, and ecologically benign negative-emission technologies. Full article

In this work, plasmonic photoconductive antenna (PCA) structures with different grating-width and gap configurations were numerically investigated to evaluate their influence on transient-current generation and terahertz (THz) emission performance. Two geometrical scaling strategies were considered: a fixed-gap configuration with a constant 100 nm photoconductive gap and a proportional-gap configuration in which the gap size was equal to the grating width. Three-dimensional finite element method (FEM) simulations were performed to analyze transient carrier dynamics, THz pulse electric-field behavior, and frequency-domain spectral response under 800 nm optical excitation. The results demonstrate that reducing the inter-grating gap enhances plasmonic near-field confinement and carrier localization near the metal–semiconductor interface, leading to stronger transient-current responses and enhanced THz characteristics. Spatial field and carrier-distribution analyses further confirmed improved electric-field localization and carrier confinement for the fixed-gap structures. In addition, voltage-dependent investigations showed that increasing the applied bias voltage strengthens carrier acceleration and enhances the simulated THz response within the investigated operating range. The results further demonstrate that the observed enhancement is governed not only by grating periodicity but also by the grating-width/gap-size ratio, highlighting the importance of geometrical fill-factor optimization. Polarization-dependent simulations confirmed the plasmonic origin of the enhanced transient-current generation and THz emission. These findings demonstrate that optimal THz performance arises from a balanced interplay between plasmonic field localization, optical absorption, and carrier-transport dynamics, providing design guidelines for the optimization of plasmonic THz PCAs. Full article

Hydrogen is a promising clean-energy carrier, but its low ignition energy, high diffusivity, and wide flammability range demand reliable leak detection. Chemiresistive sensors based on n-type metal oxide semiconductors are attractive owing to their simple architecture, low cost, large resistance modulation, thermal robustness, and compatibility with miniaturized devices. This review focuses on n-type metal oxide semiconductor nanomaterials for hydrogen sensing, particularly ZnO, SnO₂, In₂O₃, WO₃, TiO₂, and related mixed oxides. The fundamental sensing mechanisms are examined, including oxygen chemisorption, electron-depletion-layer modulation, grain-boundary barrier control, catalytic hydrogen spillover, and hydrogen-induced surface reduction or metallization, together with the way these mechanisms compete and cooperate under different operating conditions. Recent performance-enhancement strategies are organized around morphology and porosity control, noble-metal sensitization, defect and dopant engineering, n–n heterojunctions, molecular sieving, and low-temperature activation. Density functional theory is discussed as a design tool for evaluating adsorption energetics, vacancy formation, work-function shifts, band alignment, and interfacial charge transfer, along with its current limitations for modeling humid surfaces. Finally, key challenges and future directions, including humidity tolerance, standardized reporting, device integration, and emerging materials, are summarized to guide the development of high-performance hydrogen sensors. Full article

To minimize the influence of interface states and surface damage, by inserting a gate oxide layer, the photoelectrochemical oxidation method was utilized to directly grow the gate oxide layer while simultaneously creating the gate-recessed regions onto gallium nitride (GaN)-based single-gate and dual-gate metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs). Compared to the single-gate structure, the two-dimensional electron gas (2DEG) channel layer was also modulated by the auxiliary gate, in addition to being modulated by the main gate. Consequently, a wider transconductance range, larger saturation drain-source current, lower gate leakage current, and higher drain-source breakdown voltage were the benefits derived from the auxiliary gate functionality in the dual-gate devices. Moreover, the low-frequency noise characteristics of the GaN-based MOS-HEMTs could also be improved by the dual-gate structure. These experimental results demonstrated that incorporating a dual-gate structure and directly grown gate oxide layers onto GaN-based MOS-HEMTs is a promising alternative for GaN-based low-noise, high-power, and high-frequency applications. Full article

To overcome the inherent limitations of 2D MXenes in photocatalysis, namely severe nanosheet restacking and rapid charge recombination, this study reports a synergistic dual-modification strategy. By integrating microwave-assisted in situ growth of carbon nanotubes (CNTs) with the hydrothermal incorporation of multivalent cobalt (Co) species, a 3D hierarchical Co-Ti₃C₂/CNT composite was successfully fabricated. Structural characterization reveals that the in situ grown CNTs act as robust spatial spacers and conductive highways, effectively preventing Ti₃C₂ agglomeration while providing a continuous electron-transfer network. The introduction of Co significantly enriches the surface with redox-active sites and facilitates the formation of an interfacial Schottky junction. Under visible-light irradiation, the optimized Co_10%-Ti₃C₂/CNT composite achieved a superior methylene blue degradation efficiency of 90.3% within 120 min. Mechanistic insights, supported by EPR and electrochemical analyses, confirm that the Schottky barrier at the semiconductor-metal interface acts as a potent electron trap, significantly suppressing e⁻/h⁺ recombination and accelerating surface-mediated radical generation (•OH, •O₂⁻). This work provides a sophisticated template for designing high-performance, dimensionally stable MXene-based heterostructures for advanced environmental remediation. Full article

In extreme scenarios such as nuclear explosions and high-energy radiation detection in space, UV-cured adhesives are usually used as coupling media to bind tapered optic fiber arrays with intensified charge-coupled devices or complementary metal–oxide semiconductors and a tapered optic fiber array for effective optical signal transmission. To address the issue of weak bonding strength caused by the small binding area between charge-coupled devices or complementary metal–oxide semiconductors and TOFA, a stage-wise curing process was investigated and proved to be efficient through comparison with the single curing process. The effect of interval time between the initial and final curing on coupling strength was characterized by tensile strength, shear strength and shock acceleration testing, and the samples were exposed to high and low temperatures for evaluation of their environmental adaptability. The curing mechanism was analyzed by surface morphology of the adhesive layer after decoupling and an energy-dispersive X-ray spectroscopy elemental analysis of interface layer. The results show that when the interval time is extended from 5 min to 60 min, the shock acceleration of the coupling device decreases by 26.1%, while the tensile and shear strengths also decrease by 49.4% and 60.7%, respectively. The decline in coupling strength is attributed to oxygen inhibition during interval time. The exposure of the adhesive surface to the air allows oxygen to diffuse into and react with active the free radicals that remain from the initial curing, which inhibits further polymerization and generates a thin, incompletely cured weak boundary layer. These findings provide insights for optimizing stage-wise curing processes and improving the reliability of coupled imaging devices. Full article