Laser‐induced oxidation of silicon under 355 nm ultraviolet (UV) pulsed laser irradiation is investigated through a combined experimental and molecular dynamics (MD) simulation approach. FT‐IR analysis confirms the formation of Si–O–Si networks on the silicon surface, with oxidation enhanced at lower scanning speeds due to increased pulse overlap and local thermal accumulation. To elucidate the underlying atomistic mechanisms, ReaxFF‐based MD simulations are performed over a temperature range of 700–1900 K, revealing two key findings. First, temperature governs a transition in the dominant oxidation mechanism: oxidation proceeds via surface‐limited lateral diffusion at low temperatures and gradually shifts toward depth‐wise oxygen penetration as temperature increases. Second, despite enhanced oxygen mobility at elevated temperatures, the effective oxide thickness evolves nonmonotonically, indicating that oxide growth is governed not simply by oxygen diffusivity but by the competition between lateral and penetrative oxidation pathways. These findings provide atomistic insight into silicon oxidation under highly transient thermal conditions and offer guidance for controlling localized, low‐thermal‐budget oxidation processes in advanced semiconductor fabrication.
This report presents a comprehensive ensemble machine learning study for predicting the Bandgap × Thickness product (eV·nm), a key opto‐electronic figure of merit for perovskite solar cell absorber layers. A dataset of device records is featurized using physics‐informed descriptors encoding device architecture‐related composition fractions with layer‐stack interactions, RDKit molecular descriptors for perovskite organic A‐site cations (methylammonium, formamidinium) with halide anions as fraction‐weighted averages, and Mordred extended descriptor vectors for the same chemical components. Six ensemble regressors are trained and benchmarked as Random Forest, Extra Trees, XGBoost, LightGBM, a Voting Ensemble, and a Stacking Ensemble with a Ridge meta‐learner. Among them, XGBoost achieves the highest test R 2 of 0.98 (RMSE = 14.28 eV·nm and MAE = 5.98 eV·nm), while the Stacking Ensemble delivers the lowest MAE of 4.79 eV·nm. Feature attribution via SHAP, MDI, and permutation importance (PI) consistently identifies perovskite thickness, the engineered effective absorbance term (BG × Thickness × PCE), and the Br/I halide mixing ratio as the dominant predictors. Mordred descriptors contributed ~20.5% of the total MDI importance to demonstrate molecular fingerprinting at device‐level datasets.
In this work, we explore the potential of tungsten oxide (WO x ) as a bifunctional material in inverted perovskite solar cells (IPSCs), simultaneously serving as both hole and electron transport layers (HTL and ETL) within the same device. By integrating WO x as HTL and ETL, we demonstrate a simplified device architecture [ITO/WO x /PTAA/MAPbI 3 /WO x /Al] and compare it to a conventional control structure employing PTAA as HTL and PC 61 BM as ETL. The WO x ‐based device achieved a power conversion efficiency (PCE) of 16.3%. Our findings demonstrated the viability of WO x as a multifunctional material, offering a path toward streamlined fabrication and reduced material complexity in PSCs. Notably, the WO x ‐based devices displayed superior long‐term stability under continuous 1‐sun illumination, maintaining over 95% of their initial efficiency after 1000 h of operation, in stark contrast to the control devices, which degraded significantly within the first 100 h. This enhanced operational stability is attributed to the robust physical and chemical properties of WO x , which act to suppress interfacial degradation and ion migration. This study paves the way for future exploration of multifunctional oxide materials in the development of high‐performance perovskite photovoltaics.
To alleviate electron leakage, the effect of electron blocking layer (EBL) structures on the optical performance of AlGaN‐based ultraviolet light‐emitting diodes is simulated and compared. The results indicate that the optimized composition‐graded EBL structure can effectively improve the energy band structure and enhance the radiative recombination rate within the active region. Compared with Device A using a reference EBL structure, Device D using a multi‐layer composition‐graded EBL structure shows a 41.62% increase in peak internal quantum efficiency (IQE) and a 343.40% increase in light output power (LOP) at 200 mA. The improved light properties are mainly due to the fact that the multi‐layer composition‐graded EBL structure can effectively alleviate polarization effects, reduce electron leakage, increase hole injection, and thus achieve an increase in luminous efficiency.
Biomass‐derived carbon nanomaterials have emerged as sustainable alternatives to platinum‐based counter electrodes for dye‐sensitized solar cells (DSSCs). In the present study, interconnected carbon nanosheets (ICNS) were synthesized from hemp bast fibers through hydrothermal carbonization followed by KOH activation and investigated as counter‐electrode materials for DSSCs. Morphological and structural characterization revealed a highly porous interconnected nanosheet architecture containing partially graphitized carbon domains and abundant defect sites. Raman and X‐ray diffraction analyses confirmed the coexistence of graphitic and disordered carbon structures, providing a favorable combination of electrical conductivity and electrocatalytic activity. Electrochemical studies demonstrated that the ICNS electrodes were catalytically active toward the I 3 − /I − redox couple, although their charge‐transfer resistance remained high. To improve interfacial charge‐transfer kinetics, Pt–ICNS hybrid electrodes containing different platinum loadings were fabricated. Electrochemical impedance spectroscopy revealed a progressive decrease in charge‐transfer resistance from 7.704 Ω cm 2 for pure ICNS to 2.75 Ω cm 2 for the 18 wt.% Pt–ICNS electrode. Consequently, the power conversion efficiency increased from 4.01% to 6.56%, approaching the performance of the reference Pt/FTO electrode (7.18%). The enhanced performance is attributed to the synergistic interaction between the conductive porous carbon framework and catalytically active platinum sites.
This work employs optical pulses spanning microsecond to nanosecond durations, demonstrating pulse‐length‐dependent photocurrent plasticity in a self‐adaptive manner. Learn‐forget cycles are realized through two distinct synaptic behaviors: depression and potentiation. Both are exploited for in‐sensor denoising of digital images, enhancing recognition accuracy from 92% to 96% and from 93% to 96%, respectively. This research provides an optoelectronic device scheme for high‐speed, low‐power neuromorphic vision systems.
Near‐infrared (NIR) light sources based on colloidal two‐dimensional (2D) semiconductor heterostructures hold significant promise for biomedical imaging and optical communications, yet their practical deployment is constrained by surface trap‐mediated nonradiative decay and poor solid‐state stability. Herein, we report a solution‐processable interfacial passivation strategy for PbSe/PbS core/shell and core/wings nanoplatelets using a mixed‐halide CsPb(Br/I) 3 perovskite matrix. Comprehensive structural and spectroscopic analyses demonstrate that the perovskite overlayer effectively suppresses surface defects, yielding a 2.3–2.7× enhancement in relative photoluminescence intensity and extending emission lifetimes to 3.8 ns while preserving the intrinsic NIR/short‐wave infrared (SWIR) emission profiles. When integrated into solution‐processed devices, the passivated films enable down‐conversion light‐emitting diodes (LEDs) with radiance of up to 0.026 W/sr/m 2 under 450 nm excitation, as well as charge‐injection LEDs exhibiting a low turn‐on voltage of ~4.1 V and electroluminescence at 1310 and 1610 nm. This work establishes a robust surface‐engineering framework that bridges colloidal 2D lead chalcogenide heterostructures with practical solid‐state optoelectronics, paving the way for novel NIR/SWIR emitters.
Associative learning, a key higher‐order function of biological synapses, remains challenging to implement in hardware due to limitations in existing memristor architectures. Here we develop a four‐terminal TiO 2 −x memristor enabling two‐dimensional control of oxygen vacancy distributions, exhibiting stable non‐filamentary resistive switching accompanied by visible electrocoloring with applied voltages. Using a single four‐terminal device, we demonstrate bidirectional Pavlovian conditioning encompassing both learning and forgetting processes. Furthermore, by arranging multiple memristors based on this architecture, multidimensional associative learning of two‐dimensional image data is realized without involving any external circuits or computing units. These findings indicate that the proposed memristor architecture functions as a self‐contained physical learning element capable of acquiring and updating associations between stimuli. This work thus provides a conceptual framework for neuromorphic hardware that implements higher‐order associative functions, advancing beyond conventional software‐based artificial neural networks.
This study presents a broadband photodetector operating from the near‐infrared (NIR) to the ultraviolet (UV) region, based on a 0D/2D unipolar heterojunction. The heterostructure, composed of nitrogen‐doped graphene quantum dots (N‐GQDs) and molybdenum disulfide (MoS 2 ), was fabricated via a simple one‐pot hydrothermal method. Broadband detection is enabled by combining the UV‐absorbing N‐GQDs with MoS 2 , which absorbs visible and NIR light. The Fermi level alignment between the two materials creates a unipolar junction, generating a localized electric field that promotes efficient separation of photogenerated carriers. The fabricated device exhibits responsivities of 189, 95, and 845 mA W −1 in the NIR, visible, and UV regions, demonstrating its highest sensitivity within the UV spectrum. The underlying photodetection mechanism is explained through band alignment theory and the role of trap states. This cost‐effective and scalable 0D/2D heterojunction design shows significant potential for applications in optoelectronics, security systems, and wearable devices.
Tin monosulfide (SnS) is an excellent candidate for thin‐film solar cell absorbers due to its earth abundance, environmental friendliness, and suitable optoelectronic properties for efficient solar energy conversion. In this study, SnO 2 /SnS/CuSCN device structure, where SnO 2 serves as an electron transport and window layer simultaneously, while CuSCN acts as a hole transport layer, has been simulated using SCAPS‐1D. It is found that increasing the shallow acceptor density up to 10 17 cm −3 improves collection, while lowering the bulk and interface defect density in SnS is crucial for reducing the recombination. Losses are further reduced by managing resistance levels judiciously. The simulated structure after multiparameter optimization produces a theoretical highest conversion efficiency of 29.06%, with associated photovoltaic parameters of open‐circuit voltage () = 1.01 V, short‐circuit current density () = 33.62 mA/cm 2 , and fill factor = 85.89%. The observed parameters are typical of limits reported in literature on SnS absorbers. The main performance boost is due to favourable band alignment offered by SnO 2 and CuSCN that results in the reduced interface‐associated recombination losses. Overall, this study shows that the SnO 2 /SnS/CuSCN design has the potential for being an efficient and stable thin‐film solar cell architecture.
Gadolinium‐substituted cobalt–zinc spinel ferrite nanoparticles, Co 0.5 Zn 0.5 Gd x Fe 2− x O 4 ( x = 0.00–0.10), were synthesized by the sol–gel autocombustion method and calcined at 700 °C for 5 h. Rietveld refinement of X‐ray diffraction data confirmed a single‐phase cubic spinel structure (space group Fd 3¯m ) up to x = 0.08. A secondary GdFeO 3 phase appeared at x = 0.10, indicating a Gd 3+ solubility limit between x = 0.08 and 0.10. The lattice parameter increased overall from 8.3954(6) to 8.4159(7) Å, with a minor nonmonotonic deviation at low Gd content, due to substitution of larger Gd 3+ ions at octahedral B‐sites. Bertaut cation‐distribution analysis revealed progressive migration of Co 2+ ions from B‐sites to A‐sites with increasing Gd substitution. FTIR and SAED confirmed the formation of the spinel phase, while TEM showed agglomerated polycrystalline nanoparticles (13.5–25.5 nm), consistent with XRD results. Magnetic measurements indicated a decrease in saturation magnetization (45.73–33.01 emu g −1 ) and coercivity (392.9–199.1 Oe) with increasing Gd content due to B‐sublattice dilution, cation redistribution, and enhanced Yafet–Kittel spin canting. The ferrites exhibit promising soft magnetic characteristics and provide valuable insights into rare‐earth‐substituted spinel ferrites for future electromagnetic and functional material applications.
This work presents a biosensor based on T‐shaped source tunneling field‐effect transistor biosensor with N + pocket layer and insulated pocket layer (IP‐P‐T‐TFET). The insulated pocket layer is used to increase the drain current sensitivity of the IP‐P‐T‐TFET biosensor through decreasing the drain current of the biosensor when it is filled with air. In addition, the subthreshold swing (SS) of the IP‐P‐T‐TFET is also improved owing to the fact that the insulated pocket layer mitigates the source‐corner effect which exists in extended‐source TFET and deteriorates the SS of the device. What is more, using the N + pocket layer leads to decreased tunneling distance and increased sensitivity in comparison with a conventional T‐shaped source TFET (T‐TFET) biosensor. For K = 10, S I on = 8.72 × 10 9 , S I on/ I off = 1.8 × 10 9 , and S G m = 2.37 × 10 9 . The effect of charged biomolecules on the sensitivity performance is examined. Finally, the effect of various fill factors on the sensitivity characteristic is discussed. The results show the IP‐P‐T‐TFET biosensor can still achieve a relatively higher I on sensitivity at lower fill factors.
Gate dielectric engineering is investigated in a p‐type WSe 2 junctionless gate‐all‐around (JL‐GAA) MOSFET (3 nm diameter, 2 nm oxide) using the FETtoy 2.0 simulator. Three high‐ κ dielectrics—Al 2 O 3 ( κ = 9), HfO 2 ( κ = 22), and ZrO 2 ( κ = 25)—are compared at 300 K under identical geometry, with hole effective mass 0.45 m 0 and threshold voltage −0.18 V. All three dielectrics yield near‐ideal subthreshold swing (62.72 mV/dec) and ultralow DIBL (7.28 mV/V), showing that JL‐GAA electrostatic integrity is governed by nanowire geometry rather than dielectric permittivity. Saturation ON‐current rises 25.4% with dielectric constant, from 34.7 μ A (Al 2 O 3 ) to 43.5 μ A (ZrO 2 ), driven by increased gate capacitance. The I ON / I OFF ratio exceeds 10 10 for all dielectrics, reaching 1.95 × 10 10 for ZrO 2 , while peak transconductance rises from 51 to 63 μ S. Band diagram and capacitance analyses confirm the hole accumulation mechanism and origin of the drive current enhancement. Comparison with published n‐type WSe 2 JL‐GAA devices confirms comparable subthreshold performance, supporting a WSe 2 complementary MOS pair. ZrO 2 emerges as optimal, offering the best drive current, I ON / I OFF ratio, and transconductance without subthreshold penalty.
The present work discusses the optimization of the sulfate bath utilizing a novel sodium vinyl sulfonate (SVS) as a chemical additive for bright and uniform Ni–Co alloy deposits on mild steel (MS). The coating parameters, such as pH, rate of stirring, temperature, role of current density (CD) on hardness, thickness, surface feature, phase behavior, and elemental composition, are systematically determined using various characterizations. The results confirm the anomalous codeposition behavior with Co depositing preferentially over Ni. The increased CD resulted in progressive enhancement in coating thickness, while the hardness improves up to the optimal CD and subsequently decreases. The corrosion behavior of the deposited Ni–Co alloy coating indicates that at a CD of 4 A dm −2 , it exhibits the decreased corrosion rate, which occurs with a composition of 16.7 wt% Ni and 80.1 wt% Co. Based on the experimental findings, a bright, dense Ni–Co coating on MS specimens showed enhanced corrosion resistance and has a potential application in defense, aerospace, and automobiles.
Dual‐surface bandgap grading has emerged as an effective strategy for suppressing recombination losses in Sb 2 Se 3 thin‐film solar cells, yet the mechanisms by which front‐ and back‐surface grading influence device performance remain insufficiently understood. In this work, an HTL‐free Sb 2 Se 3 solar cell incorporating independently tunable front‐surface grading (FSG) and back‐surface grading (BSG) Sb 2 (S, Se) 3 layers was systematically investigated using SCAPS‐1D simulation. An asymmetric sulfur‐rich‐front reverse‐hook bandgap profile was identified as the optimal design, achieving a simulated power conversion efficiency (PCE) of 20.42%—an idealized upper‐limit prediction—compared with 16.17% for the ungraded baseline. Compared with conventional forward‐hook and symmetric V‐shaped grading structures, the reverse‐hook design provides superior carrier transport and recombination suppression. Mechanism analysis reveals that the FSG layer primarily improves front‐interface carrier collection and enhances V oc and J sc , whereas the BSG layer mainly suppresses back‐interface recombination and governs FF. The reverse‐hook band profile establishes favorable quasi‐electric fields that drive electrons toward the front contact and holes toward the back contact, thereby improving carrier separation and reducing recombination losses. These findings clarify the performance enhancement mechanisms of asymmetric dual grading and provide practical design guidelines for high‐efficiency Sb 2 Se 3 solar cells.
Thermal annealing critically affects ferroelectric phase formation in HfO 2 ‐based films and governs stabilization of the polar orthorhombic phase. Here, we demonstrate that the annealing ramp‐up rate strongly influences the polarization and endurance of ferroelectric Hf 0.5 Zr 0.5 O 2 (HZO) capacitors. When the ramp‐up rate to 400 °C is controlled, capacitors annealed at rates of ≥200 °C/h exhibit saturated hysteresis loops with remanent polarization (2 P r ) above 40 μC/cm 2 and robust endurance up to 5 × 10 8 switching cycles, whereas those annealed at a rate of 100 °C/h show suppressed 2 P r and early endurance failure. Structural and electrical analyses indicate that a slow ramp‐up rate promotes the formation of the nonferroelectric monoclinic phase, whereas a rapid ramp‐up kinetically favors the stabilization of the ferroelectric orthorhombic phase. These findings establish the ramp‐up rate as a critical thermal processing parameter for optimizing phase formation and reliability in HZO. Importantly, the improved ferroelectric performance is achieved without additional process complexity while remaining fully compatible with a back‐end‐of‐line thermal budget.
Electrical properties of H‐diamond field effect transistor with ZrO 2 /HfO 2 stacked gate deposited by electron beam have been investigated in this letter. Due to the fixed positive charge in ZrO 2 contact layer, both devices exhibit normally‐off operation. Compared with ZrO 2 monolayer gate sample, the ZrO 2 /HfO 2 stacked‐gate device showed an order of magnitude improvement in gate leakage current (~3.5 × 10 −6 A/cm 2 at V GS = −5 V), on/off ratio (10 9 ), SS (138 mV/dec @ V GS = −0.2 V) and a relatively higher I Dmax of −50 mA/mm at V GS = −6 V. Therefore, the ZrO 2 /HfO 2 stacked‐gate is a promising gate dielectric to improve the performance of H‐diamond FETs.
The increasing demand for low‐cost and efficient optoelectronic materials has intensified research on I–III–VI 2 chalcogenides, particularly silver indium diselenide (AgInSe 2 ), due to its suitable direct band gap and strong optical absorption. However, issues such as defect‐induced recombination, low carrier mobility, and limited photoelectrochemical (PEC) efficiency restrict its practical applications. In this work, AgInSe 2 thin films were synthesized using a simple and cost‐effective chemical bath deposition method. Structural analysis confirmed the formation of phase‐pure chalcopyrite structure with preferential orientation, while SEM revealed a uniform and compact morphology. Optical studies showed a direct band gap of 1.20 eV with a high absorption coefficient. Electrical measurements indicated semiconducting behavior with carrier concentration decreasing from 8.7 × 10 17 to 1.1 × 10 17 cm −3 and mobility increasing from 9.9 × 10 −3 to 13.5 cm 2 /V·s as temperature increased. The positive Seebeck coefficient (437–549 µV/K) confirmed p‐type conductivity. PEC studies exhibited enhanced performance with photocurrent density up to 1.2 mA/cm 2 , a photovoltaic of 0.62 V, and an efficiency of 1.35%. The results demonstrate improved transport and photoresponse properties due to controlled growth. Further enhancement is recommended through doping and interface engineering for photovoltaic applications.
A bulk (cm 3 ‐large) and homogeneous Ba 4 Si 6 O 16 :Eu 2+ , Ho 3+ ‐containing glass‐ceramic was previously obtained from the congruent crystallization of an oxynitride glass. We show in the present work that the europium oxidation state can be controlled by the incorporation of silicon nitride (<6 mol. %). The elastico‐mechanoluminescence (EML) is investigated by means of experiments involving different mechanical loading modes, including pure hydrostatic loading, uniaxial compression, torsion, three‐point bending and dynamic loading (ball drop). The effect of the loading parameters on the EML response is examined, both during the loading and the unloading stages. A model is proposed, which is based on thermoluminescence investigations and on the physics of persistent luminescence. An optimal fitting of the EML intensity is obtained under the assumption of a linear dependence of the depth of the energy level on the applied stress. A value of 1.37·10 –3 eV·MPa –1 is determined from uniaxial compression experiments. The EML phenomenon is found to chiefly stem from the hydrostatic part of the stress. Unlike the SrAl 2 O 4 :Eu 2+ , Dy 3+ crystal, (i) there is no EML signal under pure shear (torsion experiments) for the studied active phase and (ii) the EML intensity weakens upon unloading in uniaxial compression.
