Tunnel junctions (TJs) provide an alternative electrode architecture for GaN-based micro-light-emitting diodes (μ-LEDs) by replacing conventional p-type contacts with highly conductive n-type GaN layers. However, their performance is often limited by incomplete activation of Mg acceptors in buried p-type GaN after the thermal annealing process, which increases resistivity and degrades tunneling efficiency. In this work, we investigate a V-pitted n-type GaN structure grown on a TJ and its impact on the activation of buried p-type GaN and TJ. Compared with a flat n-type GaN reference (Flat μ-LED), the V-pitted structure (VP μ-LED) exhibits enhanced optical performance. For 20 × 20 μm2 VP μ-LEDs, the integrated EL intensity increases by approximately 1.35 times at 5 A/cm2, while the optical output power increases by 1.3 times at 30 mA/cm2 compared with the Flat μ-LED. Electrical characterization shows that the forward operating voltage improves from 5.46 V to 3.48 V at 200 μA. At -15 V, the reverse leakage current is significantly reduced, shifting from the 10-10-10-7 A range in the Flat μ-LED to the 10-12-10-10 A range in the VP μ-LED, along with a much narrower statistical distribution. The effective series resistance is also reduced from 2.77 kΩ to 1.66 kΩ. Structural analysis shows that V-pits form nanoscale vertical channels penetrating the overgrown n-type GaN layer toward the buried p-type GaN region. These channels, with a characteristic width of ∼12 nm, are significantly larger than the kinetic diameter (∼0.289 nm) of H2, providing an effective out-diffusion pathway for H2 gas during activation annealing. This promotes more effective and spatially uniform activation of the buried p-type GaN and TJ, resulting in reduced leakage, improved carrier transport, and enhanced device performance.

Nanoporous semiconductor structures provide a large interfacial area and tunable surface properties, enabling effective control of material/interface interactions. In this study, nanoporous GaN (NP GaN) was employed as an electron transport layer (ETL) to incorporate CsPbBr3, and the resulting interfacial and optical characteristics were systematically investigated. NP GaN with a controlled pore fraction (rho(pore) = 3.7 similar to 36.8 %) was fabricated via electrochemical (EC) etching. Cross-sectional SEM analysis revealed that the pore morphology evolves significantly with etching time, forming vertically aligned porous networks with increased pore density, connectivity, and diameter, which enables efficient infiltration of the CsPbBr3 precursor into the NP framework. Consequently, CsPbBr3 on NP GaN exhibits higher photoluminescence (PL) intensity, reduced full width at half maximum (FWHM), and improved internal quantum efficiency (IQE) from 4.9 % to 15.6 %. Temperature-dependent PL (TDPL) analysis revealed suppressed thermal quenching, accompanied by increased activation energy and reduced non-radiative recombination. These results demonstrate that NP GaN effectively modulates interfacial structure and carrier recombination behavior, providing a viable strategy for enhancing the optical performance of perovskite materials.

Lead halide perovskite semiconductors have attracted significant attention because of their defect tolerance, tunable bandgap, and excellent optoelectronic properties. In this work, symmetric and asymmetric multiple quantum wells (MQWs) based on CsPbBr3 were fabricated using a thermal evaporation process, and their photoluminescence (PL) properties were systematically investigated. TPBi (2,2 ',2 ''-(1,3,5-benzenetriyl)-tris(1-phenyl-1H-benzimidazole)) and BCP (bathocuproine) were employed as barrier materials to form Type I and Type II band alignments, respectively, resulting in distinct optical characteristics and carrier recombination behaviors in the MQW structures. Despite using the same CsPbBr3 material, the MQWs exhibited significantly different PL characteristics depending on the band alignment and structural configuration. In particular, asymmetric MQWs with Type I and Type II band alignments exhibited completely different carrier dynamics in temperature-dependent PL measurements. The Type I structures exhibited thermally activated carrier redistribution, whereas the Type II structures showed dominant energy funneling toward the lowest energy states. These results demonstrate that carrier dynamics and optical properties in perovskite MQWs can be effectively controlled by band alignment and structural asymmetry, providing a direct physical basis for designing quantum well-based optoelectronic devices.

The anisotropic properties of materials profoundly influence their electronic, magnetic, optical, and mechanical behaviors and are critical for a wide range of applications. In this study, the anisotropic characteristics of Ni-based van der Waals materials, specifically NiTe2 and its alloy NiTeSe, utilizing a combination of comprehensive scanning tunneling microscopy (STM), angle-resolved photoemission spectroscopy (ARPES), and density functional theory (DFT) calculations, are explored. Unlike 1T-NiTe2, which exhibits trigonal in-plane symmetry, the substitution of Te with Se in NiTe2 (resulting in the NiTeSe alloy) induces a pronounced in-plane anisotropy. This anisotropy is clear in the STM topographs, which reveal a distinct linear order of charge distribution. Corroborating these observations, ARPES measurements and DFT calculations reveal an anisotropic Fermi surface centered at the Γ ¯ $\bar \Gamma $ point, which is notably elongated along the ky direction, leading to directional variations in in-plane carrier velocities. Consequently, the Fermi velocity is highest along the kx direction where the linear charge distribution aligns in real space and is lowest along the ky direction. These findings offer valuable insights into the tunability of anisotropic properties in ternary transition metal dichalcogenide systems, highlighting their potential applications in the development of anisotropic electronic and optoelectronic devices.

Background/Aims: Clinical data on the efficacy and safety of the dual delayed-release formulation of 10-mg esomeprazole (HIP2101) are currently limited. Therefore, this study compared the efficacy and safety of HIP2101 and 20-mg famotidine (RLD2101) in patients with gastric erosions. Methods: In this multicenter, randomized, double-blind, active-control, phase III study, 326 patients with endoscopically proven gastric mucosal erosion were randomly assigned to receive either HIP2101 or RLD2101 once daily for 2 weeks. The primary endpoint was the rate of improvement of erosion. Secondary endpoints (rate of cure of erosion and edema, and rate of improvement of hematin and gastrointestinal symptoms) and treatment-emergent adverse events were compared between the groups. Results: Based on the per-protocol set (PPS) analysis, the improvement rates for erosion were 64.9% (98/151) and 63.7% (100/157) in the HIP2101 and RLD2101 groups, respectively (95% confidence interval, -9.5 to 11.9). The lower bound of the 95% confidence interval was greater than the noninferiority margin of-14%. These results were similar to those of the full analysis set (FAS) (HIP2101 group, 64.6%; RLD2101 group, 62.7%). Based on the PPS and FAS analyses, the cure rates for erosion and edema and the improvement rates for hematin and gastrointestinal symptoms were comparable between the groups. The number of adverse events did not differ significantly between the groups. Conclusions: The efficacy and safety of HIP2101 were comparable to those of RLD2101 in the treatmentof gastric erosions and symptomatic improvement. These findings suggestthat HIP2101 may be a novel treatment option for gastritis (ClinicalTrials.gov identifier: NCT05024721).

The advancement of ultra-large-scale integration (ULSI) technology has significantly improved semiconductor performance through the miniaturization of chip feature sizes. However, this scaling has led to increased resistance-capacitance (RC) delays in back end of line (BEOL) processes. To mitigate these issues, the semiconductor industry has transitioned from silicon dioxide (SiO2) to low-k dielectric materials such as organosilicate glass (SiCOH). This study investigates the deposition of SiCOH films using plasma-enhanced chemical vapor deposition (PECVD) with a novel precursor, C6H16OSi, focusing on the impact of the oxygen/carbon (O/C) ratio on film properties. Fourier-transform infrared (FT-IR) spectroscopy confirms the presence of various hydrocarbon and organosilicon bonds including C-Hx (3100-2800 cm-1), Si-CH3 (1260 cm- 1), and Si(CH3)x (775, 805, 845 cm- 1) as well as the Si-O-Si asymmetric stretching band at 1250-950 cm- 1. Systematic deconvolution of these peaks reveals how increasing O/C shifts the balance between siloxane suboxide, network, and cage structures, alongside changes in Si-(CH3)x and C-Hx contributions. X-ray photoelectron spectroscopy (XPS) analysis corroborates these trends, showing that increased O2 flow enhances the deposition rate and lowers the refractive index. Mechanical tests further indicate that hardness and elastic modulus follow similar tendencies. Computational simulations further demonstrate that higher carbon content leads to the formation of CH3 bonds, which increase free volume, reduce density, and lower the dielectric constant. These findings highlight the potential of this novel precursor to produce SiCOH films with enhanced electrical, mechanical, and thermal properties for next-generation BEOL applications.

The interplay between surface reconstruction and depolarization of ferroelectric oxide surfaces is strongly influenced by oxygen vacancies (VO). Using in-situ atomic-resolution electron microscopy imaging and spectroscopy techniques, it is directly observed that a clean BaTiO3 (001) surface stabilizes into (2 × 1) BaO-terminated reconstruction during vacuum annealing. This surface reconstruction is achieved with accommodating BaO deficiency and incorporates TiOx adunits. The cooperative atomic rumpling in both the surface and subsurface layers, arranged in a tail-to-tail configuration, is stabilized by planar accumulation of VO in the subsurface TiO2 layer. This reduces the net polarization of surface unit cells, contributing to overall depolarization. Under this atomic rumpling, the polarization-down (P↓) state is energetically favored over the polarization-up (P↑) state, as the P↓ state requires less atomic relaxation in the bulk layers to achieve dipole inversion at the subsurface. The energetic preference for VO in the subsurface TiO2 layer of the P↓ state is confirmed through calculations of VO formation energy and the energy barrier for surface-to-subsurface migration. These findings reveal that the presence of VO in the subsurface layer lifts the degeneracy in the double-well potential between the P↓ and P↑ states in BaTiO3 (001).

Understanding the ultra-fast dynamics of ferroelectric materials is essential for advancing the development of next-generation high speed electronic and photonic devices. Here, the ultrafast piezoelectric response of cobalt-substituted BiFeO3 (BiFe1-xCoxO3) with x = 0.15, consisting of morphotropic phase boundary of monoclinic M-C and M-A -type phases is investigated. The real-time piezoelectric response in (001)-oriented BiFe0.85Co0.15O3 (BFCO) epitaxial thin film was monitored using the time-resolved X-ray microdiffraction technique under an applied electric field with pulse widths 70 ns and 100 ns. The BFCO thin film yielded a high piezoelectric strain of approximately 0.53 % along [001] direction, with a giant c/a ratio (similar to 1.26) at an electric field of 1.3 MV/cm and a pulse width of 100 ns, with a piezoelectric coefficient (d(33)) of 40 pm/V. This finding is an important step towards the development of a high performance lead-free piezoelectric material for ultrafast operations in advanced technological applications.

Engineered defect chemistry in ultrathin (≈5 nm) hafnia through substitutional cobalt (HCO) is investigated for selective glucose sensing. Thin films of HCO, grown using chemical solution deposition (CSD)-traditionally used to grow thick films-on silicon, show significant glucose sensing activity and undergo monoclinic to orthorhombic phase transformation. The presence of multivalent cobalt in hafnia, with oxygen vacancies in proximity, selectively oxidizes glucose with minimal interference from ascorbic acid, dopamine, and uric acid. Theoretical investigations reveal that these oxygen vacancies create a shallow donor level that significantly enhances electrocatalytic activity by promoting charge transfer to the conduction band. This results in considerable selectivity, repeatability, and reproducibility in sensing characteristics. These findings highlight the technological importance of using CSD for thin films, paving the way for ultrathin CSD-processed HCOs as potential candidates for selective glucose sensing applications.

Background/Aims:Serum gastrin levels may be elevated following proton pump inhibitor (PPI) therapy. We aim to elucidate the predictors for the development of hypergastrinemia in maintenance treatment for mild gastroesophageal reflux disease (GERD) using a half-dose PPI. Methods:This study analyzed data from a prospective randomized trial to compare continuous versus on-demand maintenance treatment modalities in patients with mild GERD. Age, sex, body mass index, Helicobacter pylori infection, serum gastrin levels, pepsinogen (PG) I/II ratios, total days of PPI intake, and weight-based PPI dosage (mg/kg) were evaluated. Results:Data from 293 patients who completed a randomized trial were analyzed (continuous group, n = 147 vs on-demand group, n = 146). In univariate analysis, age (P < 0.001), H. pylori infection (P = 0.012), baseline gastrin levels (P < 0.001), and baseline PG ratios (P = 0.016) significantly correlated with post-treatment gastrin levels. In multivariate analysis, age, baseline gastrin levels, and baseline PG ratios were independently associated with final serum gastrin levels. In univariate analysis, age (P = 0.018), H. pylori infection (P = 0.028), baseline gastrin levels (P = 0.011), and baseline PG ratios (P = 0.031) significantly correlated with the development of hypergastrinemia. In multivariate analysis, age, baseline gastrin levels, and baseline PG ratios were independently associated with the development of hypergastrinemia. Conclusion:Old age, high baseline serum gastrin levels, and low baseline PG ratios are significant predictors of the development of hypergastrinemia in maintenance treatment for mild GERD using a half-dose PPI.

Prolonging hot carrier cooling, a crucial factor in optoelectronic applications, including hot carrier photovoltaics, presents a significant challenge. High-energy band-nesting excitons within parallel bands offer a promising and underexplored avenue for addressing this issue. Here, we exploit an exceptional D exciton cooling prolongation of 2 to 3 orders of magnitude compared to sub-picosecond in typical transition metal dichalcogenides (TMDs) owing to the complex Coulomb environment and the sequential and mismatch-valley relaxation. Simultaneously, the intervalley scattering upconversion of band-edge excitons with the slow D exciton formation in the metastable Γ valley/hill also reduces the cooling rate. We successfully extract D and C excitons as hot carriers through integrating with various thicknesses of TiOx, achieving the highest efficiency of 98% and 85% at a Ti thickness of 2 nm. Our findings highlight the potential of band-nesting excitons for extending hot carrier cooling time, paving the way for advancements in hot carrier-based optoelectronic devices.

Gastroesophageal reflux disease (GERD) significantly affects the health-related quality of life and healthcare costs. The prevalence of this disease is increasing in Asia, leading to a rapid increase in the demand of proton pump inhibitors (PPIs). Despite effective symptom management during initial treatment, relapse rates after PPI cessation remain high in patients with GERD, warranting longterm maintenance therapy. Concerns regarding potential side effects related to the long-term use of PPIs are escalating with increased usage. Studies have reported diverse side effects of PPIs, such as increased fracture risk, cardiovascular concerns, enteric infections, neurological diseases, and potential associations with gastric cancer. However, definitive causal relationships remain unclear. This review comprehensively summarizes the latest knowledge on the potential risks associated with long-term use of PPIs. Continuous or noncontinuous therapy can be used as a maintenance treatment modality for GERD. For patients with mild GERD, including those with nonerosive and mildly erosive reflux disease, on-demand therapy following a sufficient period of continuous maintenance therapy is recommended as a long-term maintenance treatment option. (J Neurogastroenterol Motil 2024;30:407-420)

Since the discovery of two-dimensional electron gas at the LaAlO3/SrTiO3 interface, its intriguing physical properties have garnered significant interests for device applications. Yet, understanding its response to electrical stimuli remains incomplete. Our in-situ transmission electron microscopy analysis of a LaAlO3/SrTiO3 two-dimensional electron gas device under electrical bias reveals key insights. Inline electron holography visualized the field-induced modulation of two-dimensional electron gas at the interface, while electron energy loss spectroscopy showed negligible electromigration of oxygen vacancies. Instead, atom-resolved imaging indicated that electric fields trigger polar distortion in the LaAlO3 layer, affecting two-dimensional electron gas modulation. This study refutes the previously hypothesized role of oxygen vacancies, underscoring the lattice flexibility of LaAlO3 and its varied polar distortions under electric fields as central to two-dimensional electron gas dynamics. These findings open pathways for advanced oxide nanoelectronics, exploiting the interplay of polar and nonpolar distortions in LaAlO3.

Defects in perovskite oxide solid electrolytes (SEs) impact Li-ion conductivity. However, the role of oxygen vacancies (Vo) in transport behavior has been less explored. Herein, our study elucidates the microscopic origin of the role of Vo in enhancing the total ionic conductivity of a prototype lithium lanthanum titanate while maintaining its insulating properties. Scanning transmission electron microscopy and theoretical calculations reveal that the presence of Vo significantly lowers the activation energy of Li-ion migration. The Vo is revealed to be preferentially aligned parallel to c-planes and causes modulated lattice expansion in an alternating manner, resulting in easy directional Li-ion transport. The effect of Vo-assisted Li-ion transport is optimized through the hierarchical rearrangement of structural features at multiple length scales close to the direction of the Vo arrays. Our results offer novel insights into the microscopic origins of superior ion conductivity facilitated by Vo, contributing to the design of high-performance SEs.

Achieving precise electron or spin confinement is essential for the progress of oxide electronics and emerging quantum information processing. While 2D electron confinement is commonly achieved with bare surfaces, heteroepitaxial interfaces, and charged domain walls, its practical application poses challenges, notably by diverse confinement widths, limited material selection, and the lack of freedom of positioning to a desired location within a given material system. Here, with scrutinizing a novel defect structure, the study suggests a new strategy with compelling evidence to trigger electron confinement down to single unit-cell-thickness, through geometrically constrained antipolar ordering facilitated by superlattice-like periodic planar faults in metallic SrFeO3. Employing atomic resolution electron microscopy and density functional theory, the results demonstrate that electrons are confined two-dimensionally to screen the positive bound charges on head-to-head antipolar state boundary, meanwhile oxygen vacancies segregated in the planar faults compensate the negative bound charges on the tail-to-tail one, leading to the stabilization of the antipolar ordering. Additionally, distinguished from traditional methods, this approach offers a potential programing capability for achieving precise charge and spin control by regulating planar fault structure at atomic scale. Unit-cell-thickness 2D electron confinement is realized through geometrically constrained antipolar ordering in metallic SrFeO3. Revealed by atomic resolution electron microscopy and density functional theory, electrons are confined two-dimensionally to screen the positive bound charges on head-to-head antipolar phase boundaries. Meanwhile, oxygen vacancies segregated into planar faults compensate the negative bound charges on the tail-to-tail ones, stabilizing the antipolar ordering state. image

Ferrimagnetic SrFe12O19 (SrM) is a mother phase for ferrite permanent magnets, which are commonly used due to its low cost compared to that of Nd-based permanent magnets and broader uses in permanent magnet markets. Recently, its electronic ground state has been debated. It has been proposed that the SrM is in a quantum paraelectric state in its single -crystal form, while polycrystalline SrM is a ferroelectric state. In this work, strain can stabilize ferroelectricity at room temperature, while keeping its ferrimagnetism. The strained SrM shows not only clear magnetic hysteresis but also -4.4 mu C/cm2 as remnant polarization. From high -temperature thermal annealing, its crystallinity and ferroelectricity are even strengthened. Those are visualized by significant reduction in full width at half maximum of the rocking curve and -7.9 mu C/cm2 in remnant polarization The results indicate this functionality can be discovered from old and well-known materials.

The investigation focused on examining the impact of incorporating Fe-carbon nanotubes (CNTs) on the valence state and oxygen vacancies, and the physicochemical parameters of the catalytic system. For the CeO2/TiO2 catalyst with Fe-CNTs, no distinct X-ray diffraction (XRD) peaks corresponding to Fe-CNTs were observed. This indicated their uniform dispersion, supported by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) imaging. X-ray photoelectron spectroscopy (XPS) analysis was conducted to observe the changes in the valence state due to the addition of Fe-CNTs. The concentration of Ce3+ on catalyst surface increased from 19.90% to 29.48% with an increased concentration of the chemisorbed oxygen species (O-alpha). This suggests that the addition of Fe-CNTs into CeO2/TiO2 catalyst reduced Ce4+ on the catalyst surface, resulting in the formation of oxygen vacancies. Oxygen temperature-programmed desorption (O-2-TPD) and hydrogen temperature-programmed reduction (H-2-TPR) analyses showed both the adsorbed oxygen species and H-2 consumption increased with adding Fe-CNTs. Furthermore, the onset temperatures for O-2 desorption and H-2 consumption became lower, confirming the enhancement of catalytic redox properties.