Abstract Structural and morphological investigations validated the successful incorporation of both fillers. Dielectric spectroscopy over an extensive frequency and temperature spectrum revealed that the real permittivity (ε′) markedly increased at low frequencies and high temperatures, attaining approximately 163 at 100 Hz and 353 K for the PVDF/GO composite, a substantial improvement from around 53 for pure PVDF at 303 K. The addition of 0.25 wt% MoS₂ diminished the dielectric loss (ε″) by almost 70% in comparison to the binary PVDF/GO composite at 1 kHz and 353 K. The PVDF/GO/0.25 wt% MoS₂ sample attained the maximum energy density of 18.8 J/cm³ at 353 K and low frequency. The AC conductivity adhered to Jonscher’s power law, and impedance analysis demonstrated that GO diminished bulk resistance (from 82×10⁶ Ω to 38×10⁶ Ω), whereas MoS₂ elevated interfacial resistivity. The findings underscore the synergistic function of GO in augmenting interfacial polarization and MoS₂ in mitigating dielectric loss, resulting in a composite that achieves an ideal equilibrium of elevated permittivity and minimal loss. This customized performance establishes PVDF/GO/MoS₂ hybrid films as viable dielectrics for high-temperature flexible energy storage applications, such as capacitors for wearable electronics, and low-loss parts in next-generation flexible electronics

Abstract Upconversion nanoparticles (UCNPs) typically suffer from low emission intensity and aggregation during conventional annealing. Herein, we demonstrate molten salt annealing (MSA) as an effective strategy to enhance the luminescence of hydrothermally synthesized YPO4:15%Yb3+,2%Er3+ nanocrystals. Optimized MSA at 900°C for 2 hours yielded a ~700-fold emission enhancement over the hydrothermally synthesized nanocrystals and ~2.5-fold improvement relative to conventional annealing while preserving the rod-like morphology. These results identify MSA as a promising approach for producing brighter UCNPs while overcoming particle growth during thermal processing.

Abstract A scalable electrochemical synthesis strategy utilizing a three-compartment cell is reported for the controlled production of nickel carbonate hydroxide. By employing selective ion transport through cation and anion exchange membranes, this approach enables the precise regulation of potential and exposure to generate a poorly crystalline, monoclinic phase. To validate the electrochemical quality of the synthesized material, it was evaluated as a positive electrode in an asymmetric supercapacitor using a TEATFB/acetonitrile electrolyte. The device exhibited distinct pseudocapacitive behaviour and exceptional durability, retaining over 80% of its initial capacity after 10,000 cycles at 5 A/g. These results highlight the efficacy of this compartmentalized electrochemical method in producing robust transition metal carbonates that deliver high energy density and competitive power for advanced energy storage applications.

Gallium nitride (GaN) high-electron-mobility transistors (HEMTs) have high electron mobility, a high breakdown voltage, and low on-resistance. In addition, normally-off operation is highly desirable for their safe, reliable operation as power devices. In this work, we fabricated a GaN HEMT with a floating gate (FG) and an injection gate (IG), where the threshold voltage (V TH ) can be changed via electron injection. In this structure, V TH depends on the FG potential, which is determined by the number of injected electrons. Therefore, V TH can be controlled to any value by changing the number of injected electrons. The number of injected electrons necessary for normally-off operation is calculated from the relationship between V TH and the number of injected electrons. The tunneling current was measured using a Metal-Insulator-Metal (MIM) capacitor corresponding to the IG-FG MIM structure, and the injection conditions to adjust V TH to 3.0 V were determined. The FG GaN HEMT showed a V TH of 3.2 V after the injection, which was close to V TH of 3.0 V calculated based on the MIM capacitor measurement. Precise control of V TH for normally-off operation was thus demonstrated for the FG GaN HEMT with the IG.

Abstract Gallium oxide (β-Ga2O3), as a representative fourth-generation semiconductor material, exhibits exceptional physical properties. However, it’s challenging to achieve high-quality wafer surfaces of β-Ga2O3 crystal due to its inherent cleavability. To provide theoretical guidance for the surface machining of such cleavable materials, this study systematically investigated the micro/nano-mechanical properties of β-Ga2O3 crystal by integrating first-principles calculations with nanoindentation/micro-scratch testing. First-principles calculations were employed to analyze the atomic structure and cleavage behavior of β-Ga2O3, revealing that the [GaO6] octahedron is more prone to disruption than the [GaO4] tetrahedron, which explains why cleavage delamination occurs on the (100)A and (100)B planes. Combining the elastic parameters obtained from first-principles calculations with nanoindentation experimental results, the following values were obtained: shear modulus (G) of GPa, bulk modulus (B) of GPa, elastic modulus (E) of GPa, hardness (H) of GPa, and a Poisson’s ratio (v) of . Based on nanoindentation energy analysis, linear elastic fracture mechanics (LEFM) theory, and three distinct equivalent strain energy density (ESEL) theories, the fracture toughness (Kc) of β-Ga2O3 crystal was calculated to be approximately 1.87 MPa·m1/2. The Kc calculation method derived from LEFM theory is particularly well-suited for exfoliation-prone brittle crystalline materials.

Abstract Traditional Fenton reaction has been widely investigated for enhancing oxidation efficiency in the chemical mechanical polishing (CMP) of silicon carbide (SiC). However, their applications in CMP are limited by the generation of insoluble iron precipitates and the instability of the Fe2+/Fe3+ redox cycle, which results in low oxidation capacity. Herein, a sustainable CMP strategy based on the piezoelectric-Fenton-like reaction of bismuth ferrite (BiFeO3) is reported. In this strategy, the piezoelectric effect activates and stabilizes the Fe2+/Fe3+ redox cycle by enabling polarization-induced electrons to participate in the reduction of Fe3+, thereby sustaining continuous and efficient generation of reactive radicals. BiFeO3 abrasives with a rhombohedral perovskite structure are both piezoelectric and catalytically active as Fe-based Fenton-like agents. This combination thus significantly enhances the oxidation of single-crystal SiC wafers by the slurry, while the abrasives themselves also act as mechanical carriers to remove the oxide products. Consequently, an ultra-smooth surface with a roughness of 0.287 nm and a high material removal rate of 223.6 nm h-1 is achieved with significantly reduced secondary pollution from dissolved iron ions. This study demonstrates the potential of the piezoelectric-Fenton synergistic strategy for ultra-precision machining and advanced polishing applications.

Abstract Rubidium-lead-halide perovskites have attracted much interest because of their promising structural, electronic, and optical properties. In this work, RbPbBr3-based hybrid perovskite solar cells with different kesterite-type HTLs like CBTS, CFTS, CNTS, and CZTSe, were simulated using the SCAPS-1D simulations. The impact of the main parameters, such as band alignment, layer thickness, doping concentration, defect density, and operating temperature, on the device performance has been systematically studied. Among the electron transport layers, phenyl C61 butyric acid methyl ester (PCBM) showed the best performance. Optimized device structure ITO/PCBM/RbPbBr3/HTLs/Au yielded a maximum PCE of 31.78% for CNTS as HTL. Comparison of results illustrates the better charge transport by PCBM and points out CNTS and CBTS as potential HTL candidates for efficient RbPbBr3-based perovskite solar cells.

Abstract The increasing usage of solid-state temperature and biosensors in embedded and real-time monitoring systems has intensified the demand for low-power arithmetic units capable of continuous signal processing. The rapid growth of data processing and storage demands requires advanced arithmetic architectures beyond traditional binary systems. Higher radix representations, such as radix-4, are suitable for low-power real-time sensor processing due to reduced switching activity and carry propagation. Multipliers impact the speed and energy efficiency of VLSI processors. This work proposes an energy-aware Radix-4 QSD multiplier with parallel 2-bit grouping and local carry generation, enabling efficient processing of temperature and biosensor signals. The recoded QSD digits are then applied to an optimized Radix-4 QSD adder–multiplier data path implemented and evaluated using the T-SPICE simulator in 90-nm CMOS technology. The experimental results show that the Radix-4 QSD approach achieves notable improvements in the average power and the static power, consuming only about 6% of the average power and 33% of the static power required by the existing QSD CLA-based design. Across the wide range of operating temperatures, the proposed architecture maintains stable performance making it suitable for real-time sensor-driven signal-processing tasks.

Abstract A Si1-xGex pocket is reported to enhanced device performance, providing a boost in the proposed device on-current by 24.19%. The effects of adding a dual-k spacer (low-k + High-k) on the design viability of a pocket hybrid double gate junctionless transistor (PHDG-JnLT) were also examined. Compared to a traditional DG-JnLT, fringing field effects and off-current are reduced, enhancing energy band profiles. The suggested gadget is hence ideal for high-performance complimentary metal oxide semiconductor circuits. To enhance device performance, we also investigated optimisation of a suggested PHDG-JnLT structure. Near the source-channel interface, integrating a pocket close to the interface induces a local minimum in the conduction band edge. Both tunnelling speeds and current handling capacity are enhanced. To improve important device characterisation metrics such as on-state current (Ion), on-to-off-state current ratio (Ion/Ioff), subthreshold swing (SS), etc., the simulation study focused on optimising the position of the pocket. The resulting optimised design has a pocket length of 10 nm and a shift in pocket of 1nm (5%) to 10nm(50%) for a 20 nm channel length. A notable 20% to 59% boost in on current is achieved by this arrangement in the range of 0.7 mA/µm to 0.85 mA/µm compared to a standard HDG-JnLT.

HighlightsA humidity sensor employing nanowire arrays with temperature control is developed.The nanowire arrays structure with a larger specific surface area can enhance water molecule adsorption.Thermoelectric cooling enhances sensitivity by 139% within the low RH range of 10%–40%.Thermoelectric heating reduces recovery time by 67.6% at high humidity levels.