The rapid progression of semiconductor device scaling toward the sub-nanometer regime has rendered particulate contamination a primary threat to manufacturing reliability. While conventional ex-situ inspection techniques offer high precision, they lack the real-time responsiveness required to trace dynamic sources of wafer defects within complex vacuum environments. This study introduces a monitoring framework that couples an in-situ real-time contaminant particle sensor (RTCPS) with artificial intelligence (AI) to forecast wafer-level defects during SiO2 plasma-enhanced chemical vapor deposition. By directly correlating real-time sensor signals with post-process wafer inspection data, we evaluated the linear relationship between in-situ monitoring and final contamination levels. This analysis revealed that particle generation during the cleaning process aligns much more closely with final wafer quality than during the deposition process. The cleaning process exhibited the coefficient of determination (R2) of 0.5149, which is over 2,500 times higher than the R2 of 0.0002 observed during deposition, providing a far more reliable indicator for wafer defect. Furthermore, a cross-validation-based AI model was developed to predict accumulated particle counts, achieving high precision with a mean deviation of approximately 73.3 particles. These results establish the RTCPS-AI integration as an essential diagnostic solution for linking in-situ process conditions directly to final wafer quality.
Precise control over defect structures in two-dimensional (2D) transition metal dichalcogenides (TMDCs) remains a critical challenge for high-performance gas sensors, as sensing characteristics are strongly governed by the density and distribution of adsorption-active sites. Among various defect types, grain boundary is of particular importance because they form interconnected networks of coordinatively unsaturated sites that enable both enhanced gas adsorption and efficient modulation of charge transport. However, practical strategies for controlling density of grain boundary in a simple and scalable manner remain limited, as it is primarily determined during nucleation and subsequent grain growth processes. Here, we report a pulsed laser-directed synthesis approach for controlling the density of grain boundary in MoS2 films. The laser pulse repetition frequency serves as a key parameter that dictates the energy distribution per pulse, thereby tuning the balance between nucleation and grain growth in a single processing step. As a result, the average grain size is reduced from about 27 to 8 nm with increasing pulse repetition frequency, accompanied by a significant increase in the density of grain boundary. Consistent with these structural changes, the NO2 gas sensing response is enhanced from about 10 to 48 %, demonstrating a clear correlation between the density of grain boundary and sensing performance. These results establish grain boundary as the dominant active sites governing gas adsorption and charge transfer in MoS2-based sensors and provide a scalable strategy for defect engineering in 2D TMDCs-based sensing platforms.
The development of techniques to sustain stable compact plasma discharge under low-pressure conditions is essential. Key design parameters for a coil-assisted compact plasma system were systematically swept, and variations in particle confinement characteristics were evaluated under an applied electric field environment. The investigated parameters included the number of coil turns, the inter-coil distance, and the thickness of the coil. An optimal design condition was identified, and the optimization results were interpreted through a physical analysis of electric field induced performance degradation. Practical design guidelines for efficient discharge systems are presented based on the results of three-dimensional electromagnetic simulations and particle simulation.
Second-order nonlinear optical (2NLO) materials are essential for practical photonic devices. Here, we demonstrate that external surface hydrophobic modification of silicalite-1 (SL1) films markedly enhances 2NLO activity by improving the degree of uniform orientation (DUO) of incorporated hemicyanine (HC-n) dyes. Attaching chlorodimethyloctadecylsilane to bare SL1 (bSL1) yielded strongly hydrophobic octadecylmodified SL1 (o-mSL1) (water contact angle: 75 degrees vs. 15 degrees), promoting unidirectional HC-n inclusion via hydrophobic-hydrophobic interactions. Although the number density in o-mSL1 is slightly reduced due to steric hindrance at channel entrances, the substantially higher DUO produces a significantly enhanced relative second harmonic generation intensity (rel-I2 omega). A maximum rel-I2 omega of 479.4% was achieved for HC-22@o-mSL1, surpassing 400.0 % for HC-15@bSL1, confirming that surface hydrophobicity directly governs DUO and 2NLO performance. This approach offers a practical route to high-performance inorganic-organic 2NLO materials.
The goal of this project is to determine the optimal process conditions for producing indium tin oxide (ITO) thin films with superior electrical and optical properties by controlling the oxygen (O2) flow rate during radio-frequency magnetron sputtering and the post-deposition annealing temperature. For this purpose, a systematic experimental plan was designed to quantitatively analyze the film properties as a function of two independent variables. We tried three O2 flow rates (0, 2.5, and 5.0 sccm) and three annealing temperatures (200, 250, and 300 degrees C) corresponding to nine different process combinations. The properties of these films were thoroughly evaluated using ultraviolet-visible spectrophotometry for optical transmittance, X-ray diffraction for crystal structure, atomic force microscopy for surface roughness, and the Van der Pauw method for sheet resistance. Importantly, the overall film performance is evaluated using Haacke's figure of merit, which provides a quantitative metric for both optical transmittance and electrical conductivity. Through this systematic evaluation, this study seeks to identify the optimal annealing temperature and O2 flow rate and to establish a comprehensive understanding in optimizing the ITO film as a transparent conducting material.
Deoxyribonucleic acid (DNA) data storage has attracted significant attention as an alternative to conventional digital storage media due to its high information density and long-term durability. However, biochemical processes involved in DNA synthesis, polymerase chain reaction (PCR) amplification, and sequencing inevitably introduce errors, which lead to an important challenge to reliable data recovery. In this study, an error-resilient DNA encoding scheme based on the classical Hamming coding system is described. Specifically, the 8-bit American standard code for information interchange data representing a single character is expanded into a 12-bit codeword by inserting four parity bits using a Hamming code, which enables the detection and correction of single-bit errors. Subsequently, the resulting 12-bit binary codeword is converted into a DNA sequence using a base-4 encoding scheme, in which the quaternary symbols 0, 1, 2, and 3 are mapped to the nucleotides adenine, cytosine, guanine, and thymine, respectively. During decoding, parity checks inherent to the Hamming code are employed to identify and correct erroneous bits, thereby allowing accurate reconstruction of the original data. Furthermore, PCR-induced DNA sequence errors were experimentally introduced and analyzed, demonstrating that the embedded Hamming code effectively detects and corrects errors under practical biochemical conditions. This work shows that fundamental digital error-correcting codes can be effectively integrated into DNA-based storage systems, providing a modular encoding framework that can be extended to other coding schemes for reliable DNA data storage.
All-polymer organic photodetectors (OPDs) offer mechanical flexibility and spectral tunability; however, their performance is highly sensitive to morphology and charge transport balance in photoactive layer. In this work, we systematically investigate the effects of film thickness, post-thermal annealing temperature, and donor-acceptor (D:A) ratio on the photodetection characteristics of poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))]:poly[[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)]-based all-polymer OPDs. Thickness optimization reveals a trade-off between optical absorption and carrier transport, leading to an optimal film formation condition that minimizes dark current while maintaining sufficient photocurrent generation. Post-thermal annealing enhances molecular ordering and responsivity at moderate temperatures, whereas excessive annealing induces aggregation and performance degradation. Furthermore, D:A ratio engineering demonstrates that responsivity and detectivity are maximized under different blend compositions, reflecting the interplay between interfacial exciton dissociation and charge percolation pathways. The optimized devices exhibit enhanced specific detectivity and wide linear dynamic range at both 650 and 808 nm. This study establishes a systematic parameter optimization framework for balancing signal and noise in all-polymer OPDs and provides practical design guidelines for high-performance near-infrared photodetection.
Quadrupole mass spectrometry (QMS) is widely used for diagnosing low-pressure plasma processes, and ionizer operation is often interpreted by assuming that the electron impact energy is determined by the electron acceleration voltage (Vacc) between the electron emitter and the anode grid. However, continuous electron emission can cause space-charge buildup inside the ionizer and form a space-charge-induced potential that distorts the intended potential profile. This work employs a three-dimensional electrostatic particle-in-cell simulation of a commercial QMS ionizer to quantify changes in the electrostatic potential as Vacc and the emission current are varied. The results show a potential depression inside the anode grid region, which reduces the effective accelerating potential.
Poly(3,4-ethylenedioxythiophene) (PEDOT) nanofilm was formed on an oxidized Si wafer surface via vapor phase polymerization (VPP) by using FeCl3 as the oxidant mixed with poly-urethane diol (DUDO) as a base inhibitor and poly(ethylene glycol)-block-poly(propylene glycol)block-poly(ethylene glycol) (PEG-PPG-PEG) as a film forming-mediator. Under optimal VPP deposition conditions (0.11 M of FeCl3 solution mixed with 8.5 mM of DUDO and 1.38 mM of PEG-PPG-PEG additives dissolved in n-butanol), the deposited nanofilm had outstanding smoothness and density combined with very high electrical conductivity of 6,345 S/cm. A slight increase in the concentration of FeCl3 to 0.26 M in the oxidant mixture had the effect of forming nanometer-sized holes in the surface of the nanofilm, and their size can be controlled by varying the annealing time at 333 K under vacuum immediately after VPP. This approach enabled a highly conductive PEDOT nanofilm with size-controllable nanoholes to be prepared simply and cost effectively. The method is particularly promising for applications that demand a vastly enlarged surface area and size-induced target-selectivity such as in electrodes for energy storage, flexible transparent conductors, and chemical/biosensors.
Two-dimensional Ruddlesden-Popper lead halide perovskites (2D-RPPs) are promising materials for solar cells and photovoltaic devices and their device stability is significantly improved compared to three-dimensional perovskites due to increased hydrophobicity and suppressed ion transport. However, 2D-RPPs are also known to be susceptible to moisture and light, which leads to rapid degradation and thus limits their direct applications. Recent research has focused on blocking degradation factors using insulating layers such as poly(methyl methacrylate) or hexagonal boron nitride (hBN). However, most studies have concentrated on blocking the effects of oxygen and moisture and examining their effects. In this study, we performed passivation with hBN flakes and placed silica gel in a vacuum desiccator to minimize the effects of oxygen and moisture. We then analyzed the differences in the effects on illumination depending on the hBN thickness.
Nanoparticle-based structural colors have emerged as a promising next-generation technology, offering environmental friendliness, durability, and tunability advantages over pigmentary colors. However, their self-assembly-induced long-range periodicity often results in strong angular dependence, limiting their practical applications. This review summarizes recent studies on achieving angle-independent structural colors to overcome these limitations. Various methods were introduced to reduce angular dependence, including control of solvent evaporation kinetics, particle-size polydispersity or binary mixtures, and disruptive agents. The principles, advantages, and disadvantages of each approach were compared. Overall, this review highlights a shift in nanoparticle-based structural colors from controlling order to harnessing disorder in nanoparticle aggregates. It also suggests future research to improve large-area uniformity, color purity, and reproducibility for broader use of nanoparticle-based angle-independent structural colors.
In this study, methane (CH4), a greenhouse gas (GHG), was converted into graphene through thermal plasma pyrolysis, and its electrochemical performance was evaluated when applied as a conductive additive in lithium-ion battery anodes. CH4 pyrolysis using a triple plasma torch system with 30 kW input power achieved a CH4 conversion of 99.48 % and a hydrogen selectivity of 84.65 %. The synthesized graphene exhibited superior crystallinity compared to the commercial conductive additive Super-P, as confirmed by X-ray diffraction and Raman analysis, with an ID/IG ratio of 0.46. Electrical conductivity was 3.15 & times; 103 S/m, higher than Super-P, and the specific surface area was 158 m2/g, more than twice that of Super-P. Battery performance evaluation showed that electrodes with a 1:1 mixing ratio of Super-P and graphene recorded the best performance with a discharge capacity of 286 mAh/g at the 50th cycle. When graphene content exceeded 75 %, capacity decreased sharply due to nanosheet aggregation, which was also confirmed through electrochemical impedance analysis. This study experimentally demonstrated that graphene synthesized via CH4 pyrolysis has practical applicability as a battery conductive additive and represents a process capable of simultaneously achieving GHG reduction and high-value-added material production.
Amorphous InGaZnO thin-film transistors (a-IGZO TFTs) are being explored as a low-cost path to complementary metal oxide semiconductor (CMOS)-class logic on transparent and flexible substrates for internet of things applications. This direction requires aggressive footprint reduction, bringing channel width (W) scaling to the foreground. Here, we investigate width-dependent behavior in self-aligned top-gate a-IGZO TFTs and observe a clear trend in subthreshold swing (SS) with W. As W increases from 19 to 103 mu m at a fixed channel length (L = 4.5 mu m), SS improves (decreases) from similar to 123 to similar to 103 mV/dec under ambient transfer measurements. To explain this, we adopt a simple two-path conduction model that separates side-edge transport from center-bulk transport in the IGZO channel. For narrow channels, the high perimeter-to-area ratio makes edge paths-more sensitive to sidewall damage and interface traps-dominant, yielding larger SS. As W grows, current shifts toward the center-bulk region with better interface quality, reducing SS. Fitting the measured minimum SS-W relationship yielded SSbulk = 87 mV/dec, SSedge = 140 mV/dec, and W-c = 75 mu m, quantitatively supporting that edge-dominated subthreshold conduction penalizes narrower channels. These results indicate that edge-related interface quality is a primary factor behind the observed width dependence and provide practical guidance for high-pixel-density display backplanes and emerging IGZO-based CMOS logic.
Hydrogenated nanocrystalline silicon (nc-Si:H) exhibits superior optical and electrical properties compared to hydrogenated amorphous silicon, making it highly attractive for electronic and optoelectronic devices. It is typically deposited using SiH4 gas via the plasma-enhanced chemical vapor deposition (PECVD) process. While PECVD generally operates at low temperatures, elevated temperatures are often employed to improve deposition rates or enhance film properties. To optimize the process and achieve the desired film characteristics, it is crucial to understand the deposition behavior and crystallographic properties of the film as a function of substrate temperature in the PECVD process. In this study, we investigated the deposition of nc-Si:H thin films at various substrate temperatures (300-800 degrees C) in the inductively coupled plasma PECVD process. We examined the effect of substrate temperature on the deposition rate, surface morphology, and crystallographic properties of the films. The results showed that as the temperature increased, the deposition rate also increased, and the films became denser. The crystallographic properties also changed, with a stronger preference for the (220) orientation. The results suggest that these changes in deposition characteristics are related to the thermal decomposition of SiH4, hydrogen effusion, and plasma-surface interactions.
We report the fabrication and characterization of solution-processed lead sulfide (PbS) quantum dot (QD) photodetectors with enhanced performance achieved by bandgap engineering the hole-transport layer (HTL). Favorable band alignment that effectively blocked electron leakage to the anode while facilitating hole extraction was created by incorporating small PbS QDs in the HTL, having a larger bandgap than the large QDs in the main absorption layer. This small-HTL structure significantly reduces dark current and improves responsivity, particularly in the short-wavelength infrared (SWIR) region, compared with a control structure with identical QDs in both layers. Systematic analysis of the energy levels, current-voltage characteristics, and responsivity spectra demonstrated the efficacy of size-tuned QDs for optimizing carrier dynamics. Our approach highlights the potential of bandgap-tuned QD layers in solution-processed optoelectronics and provides a pathway to highly sensitive SWIR photodetectors with superior stabilities and efficiencies.
