Search Results (743)

The V/G criterion is a critical indicator for monitoring dynamic changes during Czochralski silicon single crystal (Cz-SSC) growth. However, the inability to measure it in real time forces reliance on offline feedback for process regulation, leading to imprecise control and compromised crystal quality. To overcome this limitation, this paper proposes a novel soft sensor modeling framework that integrates both mechanism-based knowledge and data-driven learning for the real-time prediction of the crystal quality parameter, specifically the V/G value (the ratio of growth rate to axial temperature gradient). The proposed approach constructs a hybrid prediction model by combining a data-driven sub-model with a physics-informed mechanism sub-model. The data-driven component is developed using an attention-based dynamic stacked enhanced autoencoder (AD-SEAE) network, where the SEAE structure introduces layer-wise reconstruction operations to mitigate information loss during hierarchical feature extraction. Furthermore, an attention mechanism is incorporated to dynamically weigh historical and current samples, thereby enhancing the temporal representation of process dynamics. In addition, a robust ensemble approach is achieved by fusing the outputs of two subsidiary models using an adaptive weighting strategy based on prediction accuracy, thereby enabling more reliable V/G predictions under varying operational conditions. Experimental validation using actual industrial Cz-SSC production data demonstrates that the proposed method achieves high-prediction accuracy and effectively supports real-time process optimization and quality monitoring. Full article

This review explores the variety of diamond-based sensing applications, emphasizing their material properties, such as high Young’s modulus, thermal conductivity, wide bandgap, chemical stability, and radiation hardness. These diamond properties give excellent performance in mechanical, pressure, thermal, magnetic, optoelectronic, radiation, biosensing, quantum, and other applications. In vibration sensing, nano/poly/single-crystal diamond resonators operate from MHz to GHz frequencies, with high quality factor via CVD growth, diamond-on-insulator techniques, and ICP etching. Pressure sensing uses boron-doped piezoresistive, as well as capacitive and Fabry–Pérot readouts. Thermal sensing merges NV nanothermometry, single-crystal resonant thermometers, and resistive/diode sensors. Magnetic detection offers FeGa/Ti/diamond heterostructures, complementing NV. Optoelectronic applications utilize DUV photodiodes and color centers. Radiation detectors benefit from diamond’s neutron conversion capability. Biosensing leverages boron-doped diamond and hydrogen-terminated SGFETs, as well as gas targets such as NO₂/NH₃/H₂ via surface transfer doping and Pd Schottky/MIS. Imaging uses AFM/NV probes and boron-doped diamond tips. Persistent challenges, such as grain boundary losses in nanocrystalline diamond, limited diamond-on-insulator bonding yield, high temperature interface degradation, humidity-dependent gas transduction, stabilization of hydrogen termination, near-surface nitrogen-vacancy noise, and the cost of high-quality single-crystal diamond, are being addressed through interface and surface chemistry control, catalytic/dielectric stack engineering, photonic integration, and scalable chemical vapor deposition routes. These advances are enabling integrated, high-reliability diamond sensors for extreme and quantum-enhanced applications. Full article

High-precision prediction of the crystal diameter during the growth of electronic-grade silicon single crystals is a critical step for the fabrication of high-quality single crystals. However, the process features high-temperature operation, strong nonlinearities, significant time-delay dynamics, and external disturbances, which limit the accuracy of conventional mechanism-based models. In this study, mechanism-based models denote physics-informed heat-transfer and geometric models that relate heater power and pulling rate to diameter evolution. To address this challenge, this paper proposes a hybrid deep learning model combining a convolutional neural network (CNN), a bidirectional long short-term memory network (BiLSTM), and self-attention to improve diameter prediction during the shoulder-formation and constant-diameter stages. The proposed model leverages the CNN to extract localized spatial features from multi-source sensor data, employs the BiLSTM to capture temporal dependencies inherent to the crystal growth process, and utilizes the self-attention mechanism to dynamically highlight critical feature information, thereby substantially enhancing the model’s capacity to represent complex industrial operating conditions. Experiments on operational production data collected from an industrial Czochralski (Cz) furnace, model TDR-180, demonstrate improved prediction accuracy and robustness over mechanism-based and single data-driven baselines, supporting practical process control and production optimization. Full article

The inevitable introduction of oxygen into Czochralski-method-grown single crystal silicon, facilitated by the use of quartz crucibles, can result in the failure of chips and devices. Both the size and position of the heater exert a significant influence on the oxygen concentration within the Czochralski-method-grown silicon. In this study, a novel short-type heater was designed and evaluated for its effect on melt temperature and oxygen diffusion during crystal growth. The silicon melt temperatures and oxygen diffusion coefficients in an MCZ furnace for several heater settings were simulated, and the results were implemented in experiments. From the examination of the growth process through computation, the heater and its positional adjustments were determined to be effective modulators of oxygen concentration during crystal growth, which was consequently reduced to below 4 ppma (ASTM F121-83). Finally, the simulations were validated experimentally, limitations in production were discussed, and possible improvements were outlined. Full article

As the core abrasive in chemical mechanical polishing (CMP) processes, the morphology, size uniformity, and chemical reactivity of CeO₂ nanoparticles (NPs) are crucial factors determining the surface precision and yield of devices. In this work, a KNO₃–LiNO₃ eutectic molten salt was used as the reaction medium. By systematically adjusting key processing parameters (such as the type of cerium source, the species and dosage of surfactants, and calcination conditions), the regulatory effects of these factors on particle growth mechanisms were clarified. This adjustment enabled the controlled synthesis of spherical CeO₂ NPs with customized morphology, particle size, and surface defect states. The multi-stage reaction process of the precursor during calcination was identified by applying thermal analysis techniques, including TG-DSC and TG-FTIR. This process includes dehydration, ion exchange, and thermal decomposition. Microstructural analysis shows that the type and dosage of the cerium source and template agent significantly affect the uniformity of particle size and spherical morphology. Moreover, by using an optimized process with a heating rate of 6 °C/min and maintaining at 400 °C for 3 h, spherical CeO₂ NPs with an average particle size of 60 nm, uniform size distribution, and high sphericity were successfully synthesized via a single-step calcination process. Based on these findings, a further proposal was put forward regarding a crystal growth mechanism mediated by micelle-directed assembly and oriented attachment. This method only requires a single calcination step, has mild reaction conditions, and involves a simple process without the need for specialized equipment—features that show great potential for scalable production. It provides both a theoretical basis and experimental support for the controlled preparation of high-performance CeO₂ abrasives. Full article

Tin selenide (SnSe) is a sustainable, lead-free IV–VI semiconductor whose layered orthorhombic crystal structure induces pronounced electronic and phononic anisotropy, enabling diverse energy-related functionalities. This review systematically summarizes recent progress in understanding the structure–property–processing relationships that govern SnSe performance in thermoelectric and optoelectronic applications. Key crystallographic characteristics are first discussed, including the temperature-driven Pnma–Cmcm phase transition, anisotropic band and valley structures, and phonon transport mechanisms that lead to intrinsically low lattice thermal conductivity below 0.5 W m⁻¹ K⁻¹ and tunable carrier transport. Subsequently, major synthesis strategies are critically compared, spanning Bridgman and vertical-gradient single-crystal growth, spark plasma sintering and hot pressing of polycrystals, as well as vapor- and solution-based thin-film fabrication, with emphasis on process windows, stoichiometry control, defect chemistry, and microstructure engineering. For thermoelectric applications, directional and temperature-dependent transport behaviors are analyzed, highlighting record thermoelectric performance in single-crystal SnSe at hi. We analyze directional and temperature-dependent transport, highlighting record thermoelectric figure of merit values exceeding 2.6 along the b-axis in single-crystal SnSe at ~900 K, as well as recent progress in polycrystalline and thin-film systems through alkali/coinage-metal doping (Ag, Na, Cu), isovalent and heterovalent substitution (Zn, S), and hierarchical microstructural design. For optoelectronic applications, optical properties, carrier dynamics, and photoresponse characteristics are summarized, underscoring high absorption coefficients exceeding 10⁴ cm⁻¹ and bandgap tunability across the visible to near-infrared range, together with interface engineering strategies for thin-film photovoltaics and broadband photodetectors. Emerging applications beyond energy conversion, including phase-change memory and electrochemical energy storage, are also reviewed. Finally, key challenges related to selenium volatility, performance reproducibility, long-term stability, and scalable manufacturing are identified. Overall, this review provides a process-oriented and application-driven framework to guide the rational design, synthesis optimization, and device integration of SnSe-based materials. Full article

Calcium carbonate (CaCO₃) whiskers are promising materials for the high-value utilization of calcium-based resources. Here, aragonite whiskers were synthesized at a carbonation temperature of 90 °C using carbide slag ammonium leachate as the calcium source and CO₂ as the precipitant. The effects of control agents, carbonation temperature, Ca²⁺ solution feeding rate, CO₂ flow rate, and stirring speed on whisker morphology and aspect ratio were systematically investigated. Characterization via SEM and XRD revealed that the optimal conditions—carbonation temperature of 90 °C, Ca²⁺ feeding rate of 1.2 mL∙min⁻¹, ethanol addition of 2 mL, CO₂ flow rate of 150 mL∙min⁻¹, and stirring speed of 300 rpm—yielded uniform CaCO₃ whiskers with an average length of ~10 μm, an aspect ratio of ~24, and an aragonite purity of 99.42%. TEM confirmed that the whiskers are single crystals growing preferentially along the [001] direction. Hydroxyl groups were found to suppress lateral growth on the (200) facet, favoring elongation along the c-axis and enabling high-aspect-ratio whisker formation. These findings provide useful guidance for the scalable synthesis and industrial application of aragonite whiskers. Full article

The general procedure for measurement of impurities in hot zones of high-temperature growth setups is proposed and developed. In the first step, we prepared extra-pure 15 × 15 × 8 mm collecting cubes from composite graphite by high-temperature annealing in dry dynamic vacuum. The collecting cubes were placed in different parts of the hot zones of growth setups. We tested two types of crystal growth setups: single- and multi-crucible growth setups of a VGF configuration for A^IIIB^V semiconductors’ crystal growth. The hot zones of the setups were built from different types of graphite materials and high-temperature dielectric ceramics (BN and Al₂O₃) as insulators. The growth setups with collecting cubes without raw crystal materials were heated to operating temperatures, exposed for certain operating periods, and cooled to room temperature. The cubes were taken off and analyzed by extraction of condensed impurities into an analytic super-pure acid. The extracted impurities in the acid were determined by ICP-MS analysis. We showed that the hot zone of a single-crucible growth setup was nearly twice as pure (averaged 2.45 mg/g) compared with the hot zone of a multi-crucible setup (averaging 4.06 mg/g) because of the different graphite materials of the constructions. Full article

Directional heat treatment reduces the number of transverse grain boundaries in pure copper wires at suitable temperatures, thereby promoting the formation of columnar or even single-crystal structures. This process significantly enhances the electrical conductivity of the wires and has become a research focus. Fundamentally, directional heat treatment is a secondary recrystallization process, involving key microstructural evolutions such as grain growth and grain boundary migration. Investigating its mechanism in pure copper wires is essential for optimizing their conductive performance. In this study, pure copper wires were subjected to directional heat treatment and systematically characterized using electron backscatter diffraction (EBSD). The effects of treatment on grain growth and boundary migration were analyzed, clarifying the evolution of grain boundary structures and crystallographic textures during columnar grain development. It was revealed that grains with a <112> orientation preferentially develop into columnar structures, with most inter-columnar grain boundaries being low-energy ∑ 3 and ∑ 9 types. The novelty of this work lies in revealing the mechanism of directional grain boundary migration in pure copper wires and elucidating the formation mechanism of island grains after directional heat treatment. Full article

During the growth of lead halide perovskite single crystals (SCs) with the conventional inverse temperature crystallization (ITC) method, the blast nucleation of the precursor under supersaturation conditions is always unavoidable. In the current study, three kinds of additives namely methanol (MOE), ethyl alcohol (EtOH), and polyethylene glycol (PEG) are introduced to regulate the growth of CsPbBr₃ SCs. Benefiting from the strong anchoring hydroxy groups (-OH) with the Pb²⁺ species, large-sized CsPbBr₃ crystals with reduced defect densities were prepared (PEG-regulated). In addition, the viscosity of the precursor solution increases after adding PEG additive, which provides a more stabilized environment for crystal growth. Finally, the photodetectors prepared from our PEG-tuned CsPbBr₃ SCs show a responsivity of 2.25 A/W and a detectivity of 6.06 × 10¹¹ Jones, demonstrating the potential of CsPbBr₃ SCs for photo-detecting applications. Full article

Metal-free aminobenzoic acid-derived Schiff bases are attractive antimicrobial leads because their azomethine (–C=N–) functionality enables tunable electronic properties and target engagement. We investigated whether halogenation on the phenolic ring would modulate the redox behavior and enhance antibacterial potency, and hypothesized that heavier halogens would favorably tune physicochemical and electronic descriptors. We synthesized three derivatives (SB-3/Cl, SB-4/Br, and SB-5/I) and confirmed their structures using FTIR, ¹H- and ¹³C-NMR, UV-Vis, and HRMS. For SB-5, single-crystal X-ray diffraction and Hirshfeld analysis verified the intramolecular O–H⋯N hydrogen bond and key packing contacts. Cyclic voltammetry revealed an irreversible oxidation (aminobenzoic ring) and, for the halogenated series, a reversible reduction associated with the imine; peak positions and reversibility trends are consistent with halogen electronic effects and DFT-based MEP/LHS descriptors. Antimicrobial testing showed that SB-5 was selectively potent against Gram-positive aerobes, with low-to-mid micromolar MICs across the panel. Among anaerobes, activity was more substantial: Clostridioides difficile was inhibited at 0.1 µM, and SB-3/SB-5 reduced its sporulation at sub-MICs, while Blautia coccoides was highly susceptible (MIC 0.01 µM). No activity was detected against Gram-negative bacteria at the tested concentrations. In the fungal assay, Botrytis cinerea displayed only a transient fungistatic response without complete growth inhibition. In mammalian cells (HeLa), the compounds displayed clear concentration-dependent behavior. Overall, halogenation, particularly iodination, emerges as a powerful tool to couple redox tuning with selective Gram-positive activity and a favorable cellular tolerance window, nominating SB-5 as a promising scaffold for further antimicrobial optimization. Full article

Epitaxial thick films of yttrium iron garnet (YIG) are ideal for use in microwave devices due to their low losses at high frequencies. This report is on the growth of strain-engineered YIG films by liquid-phase epitaxy (LPE) on yttrium aluminum garnet (YAG) substrates with −3% lattice mismatch with YIG. Since the use of a lattice-matched substrate is preferred for LPE growths, a seed layer of YIG, 370–400 nm in thickness, was deposited by pulsed laser deposition (PLD) on (100), (110), and (111) YAG substrates. The seed layers were stoichiometric with magnetic parameters in agreement with the parameters for bulk single-crystal YIG and with strain-induced perpendicular magnetic anisotropy field H_a = 0.19–0.43 kOe. YIG films, 4 to 8.4 μm in thickness, were grown by LPE at 870 °C on YAG substrates with the seed layers using the PbO+B₂O₃ flux and annealed in air at 1000 °C. The films were Y-rich and Fe-deficient and confirmed to be epitaxial single crystals by X-ray diffraction. The saturation magnetization 4πM_s at room temperature was rather high and ranged from 1.9 kG to 2.3 kG. Ferromagnetic resonance at 5–15 GHz showed the absence of significant magneto-crystalline anisotropy in the LPE films with the line-width ΔH in the range 85–160 Oe, and H_a = 0.27–0.80 kOe which is much higher than for the seed layers. The high magnetization and H_a-values for the LPE films could be partially attributed to the off-stoichiometry. Although the strain due to the film–substrate lattice mismatch contributes to H_a, the mismatch in the thermal expansion coefficients for YIG and YAG is also a likely cause of H_a due to the high growth and annealing temperatures. The LPE-grown YIG films with high strain-induced anisotropy fields have the potential for use in self-biased microwave devices. Full article

Diamond, as an exceptional material with many superior properties, requires a single crystal in a reasonably large size for practical industrial applications. However, achieving large-area single-crystal diamond (SCD) growth without the formation of polycrystalline rims remains challenging. Microwave plasma chemical vapor deposition (MPCVD) using a gas mixture of 10% CH₄-H₂ was used for the homoepitaxial growth of (001) SCD. The effect of nitrogen gas addition in the range of 0–2000 ppm on lateral growth was investigated. Deposition with 180 ppm N₂ over a growth duration of 20 h to reach a thickness of 0.95 mm resulted in significantly enhanced lateral growth without the appearance of a polycrystalline diamond (PCD) rim for the grown diamond, and the total top surface area of SCD increased by an area gain of 1.6 relative to the substrate. The corresponding vertical and lateral growth rates were 47.3 µm/h and 52.5 µm/h, respectively. Characterization by Raman spectroscopy and atomic force microscopy (AFM) revealed uniform structural integrity across the whole surface from the laterally grown regions to the center, including the entire expanded area, in terms of surface morphology and crystalline quality. Moreover, measurements of the etch pit densities (EPDs) showed a substantial reduction in the laterally grown regions, approximately an order of magnitude lower than those in the central region. The high quality of the homoepitaxial diamond layer was further verified with (004) X-ray rocking curve analysis, showing a narrow full width at half maximum (FWHM) of 11 arcsec. Full article

During the preparation of gallium nitride (GaN) single crystals by Hydride Vapor Phase Epitaxy (HVPE), variations in growth pressure within the reaction chamber can easily lead to a mismatch between vapor transport dynamics and surface reaction processes, thereby affecting crystal growth rate and uniformity. To address this issue, this study established a multi-physics coupled simulation model based on the HVPE equipment structure. By integrating reaction gas flow, heat transfer, chemical reactions, and mass transport mechanisms, systematic finite element analysis was employed to simulate the flow field distribution, thermal field stability, and precursor concentration field evolution within the reaction chamber under different growth pressures (91–141 kPa). The simulation results indicate that, on one hand, the growth rate exhibits a nearly linear increase trend with rising pressure. At lower pressures (<100 kPa), vapor transport is limited, leading to a significant decrease in growth rate, while at higher pressures (>110 kPa), growth uniformity deteriorates. Optimizing the pressure parameter can enhance both the growth rate and thickness uniformity of GaN single crystals, providing a basis for process control in the preparation of high-performance GaN devices. Full article

A multi-strip detector made of synthetic single crystal diamond (SCD), based on a p-type/intrinsic diamond/Schottky metal transverse configuration and operating at zero bias voltage, was developed for imaging from extreme UV (EUV) to soft X-rays. The photodetector was patterned with 32 strips made of boron-doped diamond directly deposited, by means of the CVD technique and the standard lithographic technique, on top of the HPHT diamond growth substrate. The width of each strip and the gap between two adjacent strips were 100 μm and 20 μm, respectively. The strips were embedded in intrinsic SCD of an active area of 3.2 × 2.5 mm², also deposited using the CVD technique in a separate growing machine. In the present structure, the prototype photodetector is suitable for 1D imaging. However, all the dimensions above can be varied depending on the applications. The use of p-type diamond strips represents an attempt to mitigate the photoelectron emission from metal contacts, a non-negligible problem under EUV irradiation. The detector was tested with UV radiation and soft X-rays. To test the photodetector as an imaging device, a headboard (XDAS-DH) and a signal processing board (XDAS-SP) were used as front-end electronics. A standard XDAS software was used to acquire the experimental data. The results of the tests and the detector’s construction process are presented and discussed in the paper. Full article