Tailoring Contacts for High-Performance 1D Ta2Pt3S8 Field-Effect Transistors.

Materials with van der Waals (vdW) unit structures rely on weak interunit vdW forces, facilitating physical separation and advancing nanomaterial research with remarkable electrical properties. Recently, there has been growing interest in one-dimensional (1D) vdW materials, celebrated for their advantageous properties, characterized by reduced dimensionality and the absence of dangling bonds. In this context, we synthesize Ta2Pt3S8, a 1D vdW material, and assess its suitability for field-effect transistor (FET) applications. Spectroscopic analysis and electrical characterization confirmed that the band gap and work function of Ta2Pt3S8 are 1.18 and 4.77 eV, respectively. Leveraging various electrode materials, we fabricated n-type FETs based on Ta2Pt3S8 and identified Cr as the optimal electrode, exhibiting a high mobility of 57 cm2 V-1 s-1. In addition, we analyzed the electron transport mechanism in n-type FETs by investigating Schottky barrier height, Schottky barrier tunneling width, and contact resistance. Furthermore, we successfully fabricated p-type operating Ta2Pt3S8 FETs using a molybdenum trioxide (MoO3) layer as a high work function contact electrode. Finally, we achieved Ta2Pt3S8 nanowire rectifying diodes by creating a p-n junction with asymmetric contact electrodes of Cr and MoO3, demonstrating an ideality factor of 1.06. These findings highlight the electronic properties of Ta2Pt3S8, positioning it as a promising 1D vdW material for future nanoelectronics and functional vdW-based device applications.

Gold Nanorod Density-Dependent Label-Free Bacteria Sensing on a Flake-like 3D Graphene-Based Device by SERS.

Surface-enhanced Raman spectroscopy (SERS) is an effective technique for biosensing, enabling label-free detection of biomolecules with enhanced sensitivity. There is a tremendous probability of signal failure in Raman frequencies because of the scattering of the Raman radiation in liquids, effective SERS improvement is required to reduce this issue when considering liquid specimens. We examined a liquid bacterial sample, investigating the electrostatic interactions of the bacterial samples with gold nanorods (AuNRs) and graphene. We established a voltage-gated 3D graphene functionalized with an AuNR-based device on the silicon substrate for SERS measurements when the applied voltage ranges from 0 to 3 V. Moreover, AuNRs density-susceptible bacterial sample analysis with varied concentrations of bacterial samples has also been described. Using bacterial SERS analysis, the bacterial components amide II (1555-1565 cm-1) and amide III (1250-1350 cm-1) have been discovered for both bacteria, Gram-positive, Listeria monocytogenes and Gram-negative, Salmonella typhi. Our fabricated device affords an interesting label-free, rapid, and reproducible bacterial sample analysis based on the density of the AuNRs when functionalizing flake-like 3D graphene, which can help facilitate label-free bacteria sensing platforms.

Moderate-intensity statin plus ezetimibe vs high-intensity statin according to baseline LDL-C in the treatment of atherosclerotic cardiovascular disease: A post-hoc analysis of the RACING randomized trial.

BACKGROUND AND AIMS: Whether the effect of a combination strategy rather than increasing doses of one drug to lower low-density lipoprotein cholesterol (LDL-C) levels is consistent across baseline LDL-C levels remains uncertain. METHODS: In the RACING trial, which showed a non-inferiority of moderate-intensity statin with ezetimibe (rosuvastatin 10 mg with ezetimibe 10 mg) to high-intensity statin (rosuvastatin 20 mg) for the primary outcome (3-year composite of cardiovascular death, major cardiovascular event, or stroke), the heterogeneity in treatment effect according to baseline LDL-C levels was assessed for the primary and secondary outcomes (clinical efficacy and safety). RESULTS: Of 3780 participants, 2817 participants (74.5%) had LDL-C <100 mg/dL, and 963 participants (25.5%) had LDL-C ≥100 mg/dL. The treatment effect of combination therapy versus high-intensity statin monotherapy was similar among the lower LDL-C subset (8.8% vs. 10.2%; hazard ratio [HR] 0.85, 95% confidence interval [CI] 0.67 to 1.08, p = 0.19) and the higher LDL-C subset (10.8% vs. 9.6 %; HR 1.14, 95% CI 0.76 to 1.7, p = 0.53) without a significant interaction (interaction p = 0.22). Of the secondary outcomes, the 1-, 2-, and 3-year achievement of LDL-C <70 mg/dL was greater in the combination therapy group regardless of baseline LDL-C levels. CONCLUSIONS: Among ASCVD patients, there was no heterogeneity in the effect of moderate-intensity statin plus ezetimibe combination therapy in the higher and lower baseline LDL-C levels for the 3-year composite of cardiovascular outcomes.

Fabrication of a Field-Effect Transistor Based on 2D Novel Ternary Chalcogenide PdPS.

Two-dimensional (2D) palladium phosphide sulfide (PdPS) has garnered significant attention, owing to its exotic physical properties originating from the distinct Cairo pentagonal tiling topology. Nevertheless, the properties of PdPS remain unexplored, especially for electronic devices. In this study, we introduce the thickness-dependent electrical characteristics of PdPS flakes into fabricated field-effect transistors (FETs). The broad thickness variation of the PdPS flakes, ranging from 0.7-306 nm, is prepared by mechanical exfoliation, utilizing large bulk crystals synthesized via chemical vapor transport. We evaluate this variation and confirm a high electron mobility of 14.4 cm2 V-1 s-1 and Ion/Ioff > 107. Furthermore, the 6.8 nm-thick PdPS FET demonstrates a negligible Schottky barrier height at the gold electrode contact, as evidenced by the measurement of the temperature-dependent transfer characteristics. Consequently, we adjusted the Fowler-Nordheim tunneling mechanism to elucidate the charge-transport mechanism, revealing a modulated mobility variation from 14.4 to 41.2 cm2 V-1 s-1 with an increase in the drain voltage from 1 to 5 V. The present findings can broaden the understanding of the unique properties of PdPS, highlighting its potential as a 2D ternary chalcogenide in future electronic device applications.

Phylogenetic and phylogeographic analyses of Anisakis simplex sensu stricto (Nematoda: Anisakidae) from the common minke whale in Korean waters.

The genus Anisakis is among the most significant parasites to public health, as it causes anisakiasis, a parasitic infection in humans resulting from consuming raw or undercooked seafood. Although the infection status of i>Anisakis in second intermediate hosts, such as marine fishes and cephalopods, and humans have been severally reported in Korea, no information about the definitive host in Korean waters is available. In 2014, 2 adult gastric nematodes were collected from a common minke whale (Balaenoptera acutorostrata) found in the East Sea, Korea. These worms were identified as A. simplex sensu stricto (s.s.) by comparing the mitochondrial COX2 marker with previously deposited sequences. Phylogenetic and phylogeographic analyses of A. simplex (s.s.) worldwide revealed 2 distinct populations: the Pacific population and the European waters population. This is the first report on adult i>Anisakis and its definitive host species in Korea. Further studies on Anisakis infection in other cetacean species and marine mammals in Korean seas are warrantedi>Anisakis.

Investigation into the Mechanism of Action of the Tuberculosis Drug Candidate SQ109 and Its Metabolites and Analogues in Mycobacteria.

We tested a series of SQ109 analogues against Mycobacterium tuberculosis and M. smegmatis, in addition to determining their uncoupling activity. We then investigated potential protein targets, involved in quinone and cell wall biosynthesis, using "rescue" experiments. There was little effect of menaquinone on growth inhibition by SQ109, but there were large increases in the IC50 of SQ109 and its analogues (up to 20×) on addition of undecaprenyl phosphate (Up), a homologue of the mycobacterial decaprenyl (C50) diphosphate. Inhibition of an undecaprenyl diphosphate phosphatase, an ortholog of the mycobacterial phosphatase, correlated with cell growth inhibition, and we found that M. smegmatis cell growth inhibition could be well predicted by using uncoupler and Up-rescue results. We also investigated whether SQ109 was metabolized inside Mycobacterium tuberculosis, finding only a single metabolite, previously shown to be inactive. The results are of general interest since they help explain the mechanism of SQ109 in mycobacteria.

Controlled Bipolar Doping of One-Dimensional van der Waals Nb2Pd3Se8.

Tailoring the electrical properties of one-dimensional (1D) van der Waals (vdW) materials is desirable for their applications toward electronic devices by exploiting their unique characteristics. However, 1D vdW materials have not been extensively investigated for modulation of their electrical properties. Here we control doping levels and types of 1D vdW Nb2Pd3Se8 over a wide energy range by immersion in AuCl3 or ß-nicotinamide adenine dinucleotide (NADH) solutions, respectively. Through spectroscopic analyses and electrical characterizations, we confirm that the charges were effectively transferred to Nb2Pd3Se8, and the dopant concentration was adjusted to the immersion time. Furthermore, we make the axial p-n junction of 1D Nb2Pd3Se8 by a selective area p-doping using the AuCl3 solution, which exhibits rectifying behavior with an Iforward/Ireverse of 81 and an ideality factor of 1.2. Our findings could pave the way to more practical and functional electronic devices based on 1D vdW materials.

Sex Differences in Outcomes of Ticagrelor Therapy With or Without Aspirin After Percutaneous Coronary Intervention in Patients With Acute Coronary Syndrome: A Post Hoc Secondary Analysis of the TICO Randomized Clinical Trial.

BACKGROUND: We sought to explore the sex differences in clinical outcomes among patients with acute coronary syndrome treated with ticagrelor monotherapy after ticagrelor-based 3-month versus 12-month dual-antiplatelet therapy. METHODS: This was a post hoc analysis of the TICO trial (Ticagrelor Monotherapy After 3 Months in the Patients Treated With New Generation Sirolimus-Eluting Stent for Acute Coronary Syndrome; n=3056)-a randomized controlled trial for patients with acute coronary syndrome treated with drug-eluting stent. The primary outcome was a net adverse clinical event (composite of major bleeding, death, myocardial infarction, stent thrombosis, stroke, or target-vessel revascularization) 1 year after drug-eluting stent implantation. Secondary outcomes included major bleeding and major adverse cardiac and cerebrovascular events. RESULTS: There were 27.3% (n=628) women in the TICO trial; they were older with lower body mass index and higher prevalence of hypertension, diabetes, or chronic kidney disease than men. Compared with men, women had higher risk of net adverse clinical events (hazard ratio [HR], 1.89 [95% CI, 1.34-2.67]), major adverse cardiac and cerebrovascular events (HR, 1.69 [95% CI, 1.07-2.68]), and major bleeding (HR, 2.04 [95% CI, 1.25-3.35]). Among the groups stratified by sex and dual-antiplatelet therapy strategy, the incidences of primary and secondary outcomes were significantly different and the highest in women with ticagrelor-based 12-month dual-antiplatelet therapy (P<0.001). There was no significant heterogeneity in the impact of treatment strategy on the risks of primary and secondary outcomes between both sexes. Ticagrelor monotherapy was associated with a lower risk of the primary outcome in women (HR, 0.47 [95% CI, 0.26-0.85]; P=0.02) and comparable in men (HR, 0.77 [95% CI, 0.52-1.14]; P=0.19) without significant interaction (P for interaction, 0.18). CONCLUSIONS: After percutaneous coronary intervention for acute coronary syndrome, women demonstrated worse clinical outcomes than men. Ticagrelor monotherapy after 3-month dual-antiplatelet therapy was associated with significantly lower risk of net adverse clinical events in women without sex interaction.

Stent expansion evaluated by optical coherence tomography and subsequent outcomes.

Regarding stent expansion indices, previous optical coherence tomography (OCT) studies have shown minimal stent area (MSA) to be most predictive of adverse events. We sought to evaluate the impact of various stent expansion and apposition indices by post-stent OCT on clinical outcomes and find OCT-defined optimal stent implantation criteria. A total of 1071 patients with 1123 native coronary artery lesions treated with new-generation drug-eluting stents with OCT guidance and final post-stent OCT analysis were included. Several stent expansion indices (MSA, MSA/average reference lumen area, MSA/distal reference lumen area, mean stent expansion, and stent expansion by linear model [stent volume/adaptive reference lumen volume]) were evaluated for their association with device-oriented clinical endpoints (DoCE) including cardiac death, target vessel-related myocardial infarction (MI) or stent thrombosis, and target lesion revascularization. MSA was negatively correlated with the risk of DoCE (hazard ratio [HR] 0.80 [0.68‒0.94]). However, stent expansion by linear model representing the overall volumetric stent expansion was associated with greater risk of DoCE (HR 1.02 [1.00‒1.04]). As categorical criteria, MSA < 5.0 mm2 (HR 3.90 [1.99‒7.65]), MSA/distal reference lumen area < 90% (HR 2.16 [1.12‒4.19]), and stent expansion by linear model ≥ 65.0% (HR 1.95 [1.03‒3.89]) were independently associated with DoCE. This OCT study highlights the importance of sufficient stent expansion to achieve adequate, absolute, and relative MSA criteria for improving clinical outcome. It also emphasises that overall volumetric excessive stent expansion may have detrimental effects.

Novel High Current-Carrying Quasi-1D Material: Nb2 PdS6.

A quasi-one-dimensional van der Waals metallic nanowire Nb2 PdS6 is synthesized, and its electrical characteristics are analyzed. The chemical vapor transport method is applied to produce centimeter-scale Nb2 PdS6 crystals with needle-like structures and X-ray diffraction (XRD) confirms their high crystallinity. Scanning transmission electron microscopy reveals the crystal orientation and atomic arrangement of the specific region with atomic resolution. The electrical properties are examined by delaminating bulk Nb2 PdS6 crystals into a few nanometer-scale wires onto 100 nm-SiO2 /Si substrates using a mechanical exfoliation process. Ohmic behavior is confirmed at the low-field measurements regardless of their thickness variation, and 4.64 nm-thick Nb2 PdS6 shows a breakdown current density (JBD ) of 52 MA cm-2 when the high electrical field is delivered. Moreover, with further exfoliation down to a single atomic chain, the JBD of Nb2 PdS6 is predicted to have a value of 527 MA cm-2 . The breakdown of Nb2 PdS6 proceeds due to the Joule heating mechanism, and the Nb2 PdS6 nanowires are well fitted to the 1D thermal dissipating model.

Enhancement of Storage Stability and Masking Effect of Curcumin by Turmeric Extract-Loaded Nanoemulsion and Water-Soluble Chitosan Coating.

This study focused on improving curcumin stability in various pHs and NaCl concentrations and reducing the strong scent of turmeric by the nanoemulsions system and further coating with water-soluble chitosan (WSC). Turmeric extract-loaded nanoemulsions (TE-NEs) were firstly prepared by mixing an oil phase containing turmeric extract, MCT oil, and lecithin, and an aqueous phase containing tween 80 using an ultrasonication method. TE-NEs were further coated with WSC in the ratio of TE-NEs and WSC (1:1 to 1:10). The optimum WSC-TE-NEs exhibited an average particle size of 182 nm, a PDI of 0.317, and a zeta potential of +30.42 mV when WSC-TE-NEs were prepared in the ratio of 1:1. The stability of the WSC-TE-NEs was also assessed by determining the remained curcumin content. The remained curcumin contents of the TE-NEs and the WSC-TE-NEs were higher than that of the turmeric extract (TE) at pH 2~7 and NaCl concentrations of 100~400 mM. Fourier transform infrared (FT-IR) spectra, transmission electron microscope (TEM), and confocal laser scanning microscope (CLSM) images confirmed that the TE-NEs were successfully encapsulated with a WSC coating. As a result of GC analysis, the content of aromatic-turmerone was significantly decreased in the TE-NEs and the WSC-TE-NEs compared to the pristine TE, but there was no significant difference between the TE-NEs and the WSC-TE-NEs. These results suggest that water-soluble chitosan-coated nanoemulsions may be suitable for improving the chemical stability and masking effect of curcumin to facilitate its application in food.

Sex Differences in Attitudes Toward Marriage and Childbearing Based on the Assumption of Being BRCA1/2 Mutation Carriers Among Young People.

PURPOSE: This study investigated changes in attitudes toward marriage and childbearing assuming a BRCA1/2 mutation carrier status among healthy, unmarried individuals in Korea. METHODS: A nationally representative sample of healthy, unmarried individuals aged 20-39 years was surveyed. A questionnaire on marriage and childbearing intentions was administered to the participants before and after providing them with information on BRCA1/2 mutation carriers' breast and ovarian cancer risks and their autosomal dominant inheritance pattern. The participants were asked about their attitudes toward childbearing through preimplantation genetic diagnosis (PGD). RESULTS: Of the participants who initially wanted to marry, the assumption that they or their partners had BRCA1/2 mutation caused 25.3% to no longer want to get married and 36.2% to change their attitude from wanting to bear children to no longer wanting them. Females were more likely than males to change their attitudes toward marriage and childbearing. The participants who had negative attitudes toward genetic testing were more likely to change their attitudes regarding marriage and childbearing than those who were favorable toward both disclosure and testing. More than 50% of the participants who did not want children were willing to bear children through PGD when it was assumed that they were BRCA mutation carriers. CONCLUSION: On the assumption of being carriers, general, young, and healthy females were more likely than males to negatively change their attitudes toward marriage and childbearing. Public education on the implications of living with mutation carriers and reproductive options may be required.

Liquid Precursor-Assisted Chemical Vapor Deposition of One-Dimensional van der Waals Material Nb2Se9: Tunable Growth for Room-Temperature Gas Sensors.

In this study, Nb2Se9, a one-dimensional (1D) material with van der Waals (vdWs) bonding, was synthesized by chemical vapor deposition (CVD). A liquid precursor was used to overcome the difficulty of controlling the length and density of Nb2Se9 by CVD due to the high melting point of Nb. Growth proceeded horizontally in a nano-ribbon shape on the substrate in the [100] direction, which had the most stable bonding distance, resulting in a preferred orientation of the (010) plane on the out-of-plane axis. Unlike that grown by conventional mechanical or chemical exfoliation, the nanoscale Nb2Se9 grown by CVD was uniform and did not have contaminants, such as dispersants, on its surface, meaning it could effectively induce reactions such as gas adsorption and desorption. It exhibited high sensitivity to NO2 gas adsorption at room temperature (27 °C), and its behavior was confirmed in a high-humidity environment. For the first time, this study demonstrated the possibility of synthesizing a vdWs bonding-based 1D material by CVD, which is expected to be widely used in a variety of low-dimensional materials and devices.

Attitudes toward Risk-Reducing Mastectomy and Risk-Reducing Salpingo-oophorectomy among Young, Unmarried, Healthy Women in Korea.

PURPOSE: This study investigated the attitudes toward risk-reducing mastectomy (RRM) and risk-reducing salpingo-oophorectomy (RRSO) as cancer prevention options for BRCA1/2 carriers in healthy, young, unmarried Korean women. MATERIALS AND METHODS: A nationally representative sample of 600 women, aged 20-39 years, completed a questionnaire on sociodemographic variables, preference for genetic testing, and intention to undergo risk-reducing surgeries after receiving information on the cancer risk of BRCA1/2 mutations and benefits of risk-reducing surgeries. RESULTS: A total of 54.7% and 57.7% had the intention to undergo RRM and RRSO, respectively, on the assumption that they were BRCA1/2 carriers. Older age and no intention to undergo genetic testing were associated with a reduced likelihood of undergoing RRM (odds ratio [OR], 0.30; 95% confidence interval [CI], 0.14 to 0.61 for age 35-39 years and OR, 0.35; 95% CI, 0.20 to 0.62 for no intention for genetic testing) and RRSO (OR, 0.39; 95% CI, 0.19 to 0.79 for age 35-39 years and OR, 0.30; 95% CI, 0.17 to 0.53 for no intention for genetic testing). Women who chose to be single were likely to undergo risk-reducing surgeries (OR, 1.67; 95% CI, 1.07 to 2.60 for RRM and OR, 1.56; 95% CI, 1.00 to 2.44 for RRSO). CONCLUSION: More than 50% of healthy, unmarried, young Korean women were inclined to undergo prophylactic surgeries if they were BRCA1/2 mutation carriers. Further studies on decision-making process for cancer prevention in individuals at high risk for cancer need to be conducted.

High Breakdown Current Density in Quasi-1D van der Waals Layered Material Ta2NiSe7.

We synthesized ternary composition chalcogenide Ta2NiSe7, a quasi-one-dimensional (Q1D) material with excellent crystallinity. To utilize the excellent electrical conductivity property of Ta2NiSe7, the breakdown current density (JBD) according to thickness change through mechanical exfoliation was measured. It was confirmed that as the thickness decreased, the maximum breakdown voltage (VBD) increased, and at 18 nm thickness, 35 MA cm-2 of JBD was measured, which was 35 times higher than that of copper, which is commonly used as an interconnect material. By optimization of the exfoliation process, it is expected that through a theoretical model fitting, the JBD can be increased to about 356 MA cm-2. It is expected that the low-dimensional materials with ternary compositions proposed through this experiment can be used as candidates for current-carrying materials that are required for the miniaturization of various electronic devices.

Luminescence Properties of InGaN/GaN Green Light-Emitting Diodes with Si-Doped Graded Short-Period Superlattice.

The optical properties of InGaN/GaN green light-emitting diodes (LEDs) with an undoped graded short-period superlattice (GSL) and a Si-doped GSL (SiGSL) were investigated using photoluminescence (PL) and time-resolved PL spectroscopies. For comparison, an InGaN/GaN conventional LED (CLED) without the GSL structure was also grown. The SiGSL sample showed the strongest PL intensity and the largest PL peak energy because of band-filling effect and weakened quantum- confined stark effect (QCSE). PL decay time of SiGSL sample at 10 K was shorter than those of the CLED and GSL samples. This finding was attributed to the oscillator strength enhancement by the reduced QCSE due to the Coulomb screening by Si donors. In addition, the SiGSL sample exhibited the longest decay time at 300 K, which was ascribed to the reduced defect and dislocation density. These results indicate that insertion of the Si-doped GSL structure is an effective strategy for improving the optical properties in InGaN/GaN green LEDs.

Escalation of liPid-lOwering therapy in patientS wiTh vascular disease receiving HIGH-intensity statins: the retrospective POST-HIGH study.

In this retrospective study, we investigated whether lipid-lowering therapy (LLT) escalation has clinical benefits in patients with atherosclerotic cardiovascular disease (ASCVD) and low-density lipoprotein cholesterol (LDL-C) levels of 55-99 mg/dL (1.4-2.6 mmol/L), post high-intensity. Out of 6317 Korean patients screened in 2005-2018, 1159 individuals with ASCVD and LDL-C levels of 55-99 mg/dL after statin use equivalent to 40 mg atorvastatin were included. After 1:2 propensity score matching, 492 patients (164 with LLT escalation, 328 controls without LLT escalation) were finally analysed. Primary outcome variables were major adverse cardiovascular and cerebrovascular events (MACCE) and all-cause death. At median follow-up (1.93 years), the escalation group had a lower MACCE rate (1.72 vs. 3.38 events/100 person-years; hazard ratio [HR] 0.34, 95% confidence interval [CI] 0.14-0.83; p = 0.018) than the control group. The incidence of all-cause death (0.86 vs. 1.02 events/100 person-years; HR 0.58, 95% CI 0.15-2.19; p = 0.42) and each MACCE component did not differ between groups. Kaplan-Meier curves exhibited lower risk of MACCE in the escalation group (HR 0.36, 95% CI 0.12-0.97; p = 0.040) but a difference not statistically significant in all-cause death (HR 0.30, 95% CI 0.04-2.48; p = 0.26). LLT escalation was associated with reduced cardiovascular risk, supporting more aggressive LLT in this population.

High Performance Field-Effect Transistors Based on Partially Suspended 2D Materials via Block Copolymer Lithography.

Although various two-dimensional (2D) materials hold great promise in next generation electronic devices, there are many challenges to overcome to be used in practical applications. One of them is the substrate effect, which directly affects the device performance. The large interfacial area and interaction between 2D materials and substrate significantly deteriorate the device performance. Several top-down approaches have been suggested to solve the problem. Unfortunately, however, they have some drawbacks such as a complicated fabrication process, a high production cost, or a poor mechanical property. Here, we suggest the partially suspended 2D materials-based field-effect transistors (FETs) by introducing block copolymer (BCP) lithography to fabricate the substrate effect-free 2D electronic devices. A wide range of nanometer size holes (diameter = 31~43 nm) is successfully realized with a BCP self-assembly nanopatterning process. With this approach, the interaction mechanism between active 2D materials and substrate is elucidated by precisely measuring the device performance at varied feature size. Our strategy can be widely applied to fabricate 2D materials-based high performance electronic, optoelectronic, and energy devices using a versatile self-assembly nanopatterning process.

Hierarchical Self-Assembly of Thickness-Modulated Block Copolymer Thin Films for Controlling Nanodomain Orientations inside Bare Silicon Trenches.

We study the orientation and ordering of nanodomains of a thickness-modulated lamellar block copolymer (BCP) thin film at each thickness region inside a topological nano/micropattern of bare silicon wafers without chemical pretreatments. With precise control of the thickness gradient of a BCP thin film and the width of a bare silicon trench, we successfully demonstrate (i) perfectly oriented lamellar nanodomains, (ii) pseudocylindrical nanopatterns as periodically aligned defects from the lamellar BCP thin film, and (iii) half-cylindrical nanostructure arrays leveraged by a trench sidewall with the strong preferential wetting of the PMMA block of the BCP. Our strategy is simple, efficient, and has an advantage in fabricating diverse nanopatterns simultaneously compared to conventional BCP lithography utilizing chemical pretreatments, such as a polymer brush or a self-assembled monolayer (SAM). The proposed self-assembly nanopatterning process can be used in energy devices and biodevices requiring various nanopatterns on the same device and as next-generation nanofabrication processes with minimized fabrication steps for low-cost manufacturing techniques.

Neutral-layer-free directed self-assembly of block copolymer in trench using capillary force-induced meniscus.

We propose trench-directed self-assembly (TDSA) of a block copolymer (BCP) driven by a capillary force-induced meniscus as a facile scalable nanolithography method. Unlike conventional directed self-assembly methods, TDSA enables the achievement of neutral surface-free vertical orientations of the BCP nanopatterns irrespective of the polarizability of the substrate, which may be, for example, a ceramic (SiO2) on Semiconductor (Si). In our demonstration of the proposed method, we generated various morphologies of the BCP nanopatterns by varying the trench width, and molecular weight of the BCP. The proposed TDSA method is potentially advantageous for the design of a process/device layout required for the development of an effective manufacturing process.