RT), precluding the use of these materials to practical implementations. [2][3][4][5]14] The ferromagnetic state in magnetic metaldoped oxides and nitrides is available at RT but is localized to aggregated metal oxide/nitride nanoparticles without a longrange magnetic order. [4] The ferromagnetic state in van der Waals 2D materials has been observed recently in the monolayer limit. [15][16][17][18][19][20][21] Intrinsic CrI 3 and CrGeTe 3 semiconductors reveal ferromagnetism but the T c is still low below 60 K. [20,21] In contrast, monolayer VSe 2 and MnSe 2 are ferromagnetic metals with T c above RT but incapable of controlling its carrier density. [22,23] Moreover, the long-range ferromagnetic order in doped diluted chalcogenide semiconductors has not been demonstrated at RT. [24][25][26][27][28] The key research target is to realize the long-range order ferromagnetism, T c over RT, and semiconductor with gate tunability. Here, we unambiguously observe tunable magnetic domains by a gate bias above RT in diluted V-doped WSe 2 , while maintaining the semiconducting characteristic of WSe 2 with a high on/off current ratio of five orders of magnitude. Figure 1a illustrates the schematic for the synthesis of V-doped monolayer WSe 2 via chemical vapor deposition (CVD). A metal precursor solution prepared by mixing V and W liquid sources at a given atomic ratio was spin-coated on SiO 2 substrate and the substrate was introduced into the CVD chamber with selenium. The metal precursors get decomposed into metal oxides at growth temperature, resulting in monolayer V x W 1−x Se 2 , followed by selenization. The atomic ratio of V to W sources in precursor solution can be precisely controlled from 0.1% to 40%, while the hexagonal flakes are retained in a monolayer form (the optical image in Figure 1a; Figure S1, Supporting Information). Meanwhile, the dendritic and multilayer flakes are partially generated at higher V-concentration. The V atoms are incorporated into monolayer WSe 2 with V/W contents similar to nominal values, as confirmed by X-ray photoelectron spectroscopy ( Figure S2, Supporting Information). With low V-doping concentration, the hexagonal V-doped WSe 2 flake is a single crystal confirmed by previous TEM study. [29] To study the doping effect of vanadium to the electronic properties of WSe 2 , field effect transistors (FETs) of V-doped mono layer WSe 2 were fabricated (Figure 1b). The CVD-grown pristine WSe 2 manifests a p-type semiconductor with a threshold voltage at −50 V. The threshold voltage is shifted to −10 V for Diluted magnetic semiconductors including Mn-doped GaAs are attractive for gate-controlled spintronics but Curie transition at room temperature with longrange ferromagnetic order is still debatable to date. Here, the room-temperature ferromagnetic domains with long-range order in semiconducting V-doped WSe 2 monolayer synthesized by chemical vapor deposition are reported. Ferromagnetic order is manifested using magnetic force microscopy up to 360 K, while retaining high on/off current rati...
Chemical treatment using bis(trifluoromethane) sulfonimide (TFSI) was shown to be particularly effective for increasing the photoluminescence (PL) of monolayer (1L) MoS, suggesting a convenient method for overcoming the intrinsically low quantum yield of this material. However, the underlying atomic mechanism of the PL enhancement has remained elusive. Here, we report the microscopic origin of the defect healing observed in TFSI-treated 1L-MoS through a correlative combination of optical characterization and atomic-scale scanning transmission electron microscopy, which showed that most of the sulfur vacancies were directly repaired by the extrinsic sulfur atoms produced from the dissociation of TFSI, concurrently resulting in a significant PL enhancement. Density functional theory calculations confirmed that the reactive sulfur dioxide molecules that dissociated from TFSI can be reduced to sulfur and oxygen gas at the vacancy site to form strongly bound S-Mo. Our results reveal how defect-mediated nonradiative recombination can be effectively eliminated by a simple chemical treatment method, thereby advancing the practical applications of monolayer semiconductors.
Inflammatory cytokines mediate inflammatory bowel diseases (IBDs) and cytokine blocking therapies often ameliorate the disease severity. IL-32 affects inflammation by increasing the production of IL-1, TNFα, and several chemokines. Here, we investigated the role of IL-32 in intestinal inflammation by generating a transgenic (TG) mouse expressing human IL-32γ (IL-32γ TG). Although IL-32γ TG mice are healthy, constitutive serum and colonic tissue levels of TNFα are elevated. Compared with wild-type (WT) mice, IL-32γ TG mice exhibited a modestly exacerbated acute inflammation early following the initiation of dextran sodium sulfate (DSS)-induced colitis. However, after 6 d, there was less colonic inflammation, reduced tissue loss, and improved survival rate compared with WT mice. Associated with attenuated tissue damage, colonic levels of TNFα and IL-6 were significantly reduced in the IL-32γ TG mice whereas IL-10 was elevated. Cultured colon explants from IL-32γ TG mice secreted higher levels of IL-10 compared with WT mice and lower levels of TNFα and IL-6. Constitutive levels of IL-32γ itself in colonic tissues were significantly lower following DSS colitis. Although the highest level of serum IL-32γ occurred on day 3 of colitis, IL-32 was below constitutive levels on day 9. The ability of IL-32γ to increase constitutive IL-10 likely reduces TNFα, IL-6, and IL-32 itself accounting for less inflammation. In humans with ulcerative colitis (UC), serum IL-32 is elevated and colonic biopsies contain IL-32 in inflamed tissues but not in uninvolved tissues. Thus IL-32γ emerges as an example of how innate inflammation worsens as well as protects intestinal integrity.
A dielectric superstrate layer above a microstrip patch antenna has remarkable effects on its gain and resonant characteristics. This paper experimentally investigates the effect of a superstrate layer for high gain on microstrip patch antennas. We measured the gain of antennas with and without a superstrate and found that the gain of a single patch with a superstrate was enhanced by about 4 dBi over the one without a superstrate at 12 GHz. The impedance bandwidths of a single patch with and without a superstrate for VSWR < 2 were above 11%. The designed 2×8 array antenna using a superstrate had a high gain of over 22.5 dB and a wide impedance bandwidth of over 17%.
Atomic dopants and defects play a crucial role in creating new functionalities in 2D transition metal dichalcogenides (2D TMDs). Therefore, atomic‐scale identification and their quantification warrant precise engineering that widens their application to many fields, ranging from development of optoelectronic devices to magnetic semiconductors. Scanning transmission electron microscopy with a sub‐Å probe has provided a facile way to observe local dopants and defects in 2D TMDs. However, manual data analytics of experimental images is a time‐consuming task, and often requires subjective decisions to interpret observed signals. Therefore, an approach is required to automate the detection and classification of dopants and defects. In this study, based on a deep learning algorithm, fully convolutional neural network that shows a superior ability of image segmentation, an efficient and automated method for reliable quantification of dopants and defects in TMDs is proposed with single‐atom precision. The approach demonstrates that atomic dopants and defects are precisely mapped with a detection limit of ≈1 × 1012 cm−2, and with a measurement accuracy of ≈98% for most atomic sites. Furthermore, this methodology is applicable to large volume of image data to extract atomic site‐specific information, thus providing insights into the formation mechanisms of various defects under stimuli.
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