Interacting Trimagnetic Ensembles for Enhanced Magnetic Resonance Transverse Relaxivity.

An ensemble of nanosystems can be considered to improve magnetic resonance imaging (MRI) transverse relaxivity. Herein, an interacting superparamagnetic competing structure of an isotropic-anisotropic trimagnetic hybrid nanosystem, γ-FeO@δ-MnO@NiFeO, is considered for MRI relaxivity exploration. The interacting superparamagnetic system reveals fascinating dynamic magnetic behavior, where flower-shaped two-dimensional flakes are decorated over nanoparticles.

Electrically Controlled High Sensitivity Strain Modulation in MoS Field-Effect Transistors via a Piezoelectric Thin Film on Silicon Substrates.

Strain can modulate bandgap and carrier mobilities in two-dimensional (2D) materials. Conventional strain-application methodologies relying on flexible/patterned/nanoindented substrates are limited by low thermal tolerance, poor tunability, and/or scalability. Here, we leverage the converse piezoelectric effect to electrically generate and control strain transfer from a piezoelectric thin film to electromechanically coupled 2D MoS.

Integrative Modulation of Magnetic Resonance Transverse and Longitudinal Relaxivity in a Cell-Viable Bimagnetic Ensemble, γ-FeO@ZnFeO.

The potential application of magnetic nanosystems as magnetic resonance imaging (MRI) contrast agents has been thoroughly investigated. This work seeks to attain robust MRI-contrast efficiency by designing an interacting landscape of a bimagnetic ensemble of zinc ferrite nanorods and maghemite nanoparticles, γ-FeO@ZnFeO. Because of competing spin clusters and structural anisotropy triggered by isotropic γ-FeO and anisotropic ZnFeO, γ-FeO@ZnFeO undergoes the evolution of cluster spin-glass state as evident from the critical slowing down law.

Novel Nano-Electroplating-Based Plasmonic Platform for Giant Emission Enhancement in Monolayer Semiconductors.

Two-dimensional semiconductors such as monolayer MoS have attracted considerable attention owing to their exceptional electronic and optical characteristics. However, their practical application has been hindered by the limited light absorption resulting from atomically thin thickness and low quantum yield. A highly effective approach to address these limitations is by integrating subwavelength plasmonic nanostructures with monolayer semiconductors.

Polarity-Tunable Photocurrent through Band Alignment Engineering in a High-Speed WSe/SnSe Diode with Large Negative Responsivity.

Excellent light-matter interaction and a wide range of thickness-tunable bandgaps in layered vdW materials coupled by the facile fabrication of heterostructures have enabled several avenues for optoelectronic applications. Realization of high photoresponsivity at fast switching speeds is a critical challenge for 2D optoelectronics to enable high-performance photodetection for optical communication. Moving away from conventional type-II heterostructure pn junctions towards a WSe/SnSe type-III configuration, we leverage the steep change in tunneling current along with a light-induced heterointerface band shift to achieve high negative photoresponsivity, while the fast carrier transport under tunneling results in high speed.

Multi-Bit Analog Transmission Enabled by Electrostatically Reconfigurable Ambipolar and Anti-Ambipolar Transport.

Various analog applications, such as phase switching, have been demonstrated using either ambipolar or anti-ambipolar transport in two-dimensional materials. However, the availability of only one transport mode severely limits the application scope and range. This work demonstrates electrostatically reconfigurable and tunable ambipolar and anti-ambipolar transport in the same field-effect transistor using a photoactive ambipolar WSe channel with gate-controlled channel and Schottky barriers.

First-principles based simulations of electronic transmission in ReS/WSe and ReS/MoSe type-II vdW heterointerfaces.

Electronic transmission in monolayer ReS[Formula: see text] and ReS[Formula: see text] based van der Waals (vdW) heterointerfaces are studied here. Since ReS[Formula: see text]/WSe[Formula: see text] and ReS[Formula: see text]/MoSe[Formula: see text] type-II vdW heterostructures are suitable for near infrared (NIR)/short-wave infrared (SWIR) photodetection, the role of interlayer coupling at the heterointerfaces is examined in this work. Besides, a detailed theoretical study is presented employing density functional theory (DFT) and nonequilibrium Green's function (NEGF) combination to analyse the transmission spectra of the two-port devices with ReS[Formula: see text]/WSe[Formula: see text] and ReS[Formula: see text]/MoSe[Formula: see text] channels and compare the near-equilibrium conductance values.

All-Electrical High-Sensitivity, Low-Power Dual-Mode Gas Sensing and Recovery with a WSe/MoS pn Heterodiode.

Two-dimensional MoS gas sensors have conventionally relied on a change in field-effect-transistor (FET) channel resistance or in the Schottky contact/pn homojunction barrier. We demonstrate an enhancement in sensitivity (6×) and dynamic response along with a reduction in detection limit (8×) and power (10×) in a gate-tunable type-II WSe(p)/MoS(n) heterodiode gas sensor over an MoS FET on the same flake. Measurements for varying NO concentration, gate bias, and MoS flake thickness, reinforced with first-principles calculations, indicate dual-mode operation due to (i) a series resistance-based exponential change in the high-bias thermionic current (high sensitivity), and (ii) a heterointerface carrier concentration-based linear change in near-zero-bias interlayer recombination current (low power) resulting in sub-100 μW/cm power consumption.

Enhanced responsivity and detectivity of fast WSe phototransistor using electrostatically tunable in-plane lateral p-n homojunction.

Layered transition metal dichalcogenides have shown tremendous potential for photodetection due to their non-zero direct bandgaps, high light absorption coefficients and carrier mobilities, and ability to form atomically sharp and defect-free heterointerfaces. A critical and fundamental bottleneck in the realization of high performance detectors is their trap-dependent photoresponse that trades off responsivity with speed. This work demonstrates a facile method of attenuating this trade-off by nearly 2x through integration of a lateral, in-plane, electrostatically tunable p-n homojunction with a conventional WSe phototransistor.

Electrically Tunable Room Temperature Hysteresis Crossover in Underlap MoS Field-Effect Transistors.

Clockwise to anticlockwise hysteresis crossover in current-voltage transfer characteristics of field-effect transistors (FETs) with graphene and MoS channels holds significant promise for nonvolatile memory applications. However, such crossovers have been shown to manifest only at high temperature. In this work, for the first time, we demonstrate room temperature hysteresis crossover in few-layer MoS FETs using a gate-drain underlap design to induce a differential response from traps near the MoS-HfO channel-gate dielectric interface, also referred to as border traps, to applied gate bias.

Near-Direct Bandgap WSe/ReS Type-II pn Heterojunction for Enhanced Ultrafast Photodetection and High-Performance Photovoltaics.

Pn heterojunctions comprising layered van der Waals (vdW) semiconductors have been used to demonstrate current-rectifiers, photodetectors, and photovoltaic devices. However, a direct or near-direct heterointerface bandgap for enhanced photogeneration in high light-absorbing few-layer vdW materials remains unexplored. In this work, for the first time, density functional theory calculations show that the heterointerface of few-layer group-6 transition metal dichalcogenide (TMD) WSe with group-7 ReS results in a sizable (0.

Accurate Threshold Voltage Reliability Evaluation of Thin AlO Top-Gated Dielectric Black Phosphorous FETs Using Ultrafast Measurement Pulses.

Few-layer black phosphorus (BP) has attracted significant interest in recent years due to electrical and photonic properties that are far superior to those of other two-dimensional layered semiconductors. The study of long term electrical stability and reliability of black phosphorus field effect transistors (BP-FETs) with technologically relevant thin, and device-selective, gate dielectrics, stressed under realistic (closer to operation) bias and measured using state-of-the-art ultrafast reliability characterization techniques, is essential for their qualification and use in different applications. In this work, air-stable BP-FETs with a thin top-gated dielectric (15 nm AlO, SiO equivalent thickness of 5 nm) were fabricated and comprehensively characterized for threshold voltage ( V) instability under negative gate bias stress at various measurement delays ( t), stress biases ( V), temperatures ( T), and stress times ( t) for the first time.

Janus nanoparticles for contrast enhancement of T-T dual mode magnetic resonance imaging.

The accuracy of magnetic resonance imaging (MRI) scanning can be improved using a multifunctional nanosystem having T1-T2 dual contrast enhancement. Specifically, the combination of both T1 and T2 effects in a single system helps in acquiring cross validated information during dual mode MRI and reduces the required dose. In this study, polyethylene glycol (PEG) stabilized MnFe2O4@MnO Janus nanoparticles were developed as novel dual-mode MR imaging agents.

Multilayer ReS Photodetectors with Gate Tunability for High Responsivity and High-Speed Applications.

Rhenium disulfide (ReS) is an attractive candidate for photodetection applications owing to its thickness-independent direct band gap. Despite various photodetection studies using two-dimensional semiconductors, the trade-off between responsivity and response time under varying measurement conditions has not been studied in detail. This report presents a comprehensive study of the architectural, laser power and gate bias dependence of responsivity and speed in supported and suspended ReS phototransistors.

Enhanced stability and performance of few-layer black phosphorus transistors by electron beam irradiation.

Few layer black phosphorus (BP) has recently emerged as a potential graphene analogue due to its high mobility and direct, appreciable, band gap. The fabrication and characterization of field effect transistors (FETs) involves exposure of the channel material to an electron beam (e-beam) in imaging techniques such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and fabrication techniques like electron beam lithography (EBL). Despite this, the effect of e-beam irradiation on BP-FET performance has not been studied experimentally.

Phase engineering of seamless heterophase homojunctions with co-existing 3R and 2H phases in WS monolayers.

Self-organized semiconductor-semiconductor heterostructures (3R-2H) that coexist in atomically thin 2D monolayers forming homojunctions are of great importance for next-generation nanoelectronics and optoelectronics applications. Herein, we investigated the defect controlled growth of heterogeneous electronic structure within a single domain of monolayer WS to enable in-plane homojunctions consisting of alternate 2H semiconducting and 3R semiconducting phases of WS. X-ray photoelectron, Raman, and photoluminescence spectroscopy along with fluorescence and Kelvin probe force microscopy imaging confirm the formation of homojunctions, enabling a direct correlation between chemical heterogeneity and electronic heterostructure in the atomically thin WS monolayer.

Few-Layer MoS₂ p-Type Devices Enabled by Selective Doping Using Low Energy Phosphorus Implantation.

P-type doping of MoS2 has proved to be a significant bottleneck in the realization of fundamental devices such as p-n junction diodes and p-type transistors due to its intrinsic n-type behavior. We report a CMOS compatible, controllable and area selective phosphorus plasma immersion ion implantation (PIII) process for p-type doping of MoS2. Physical characterization using SIMS, AFM, XRD and Raman techniques was used to identify process conditions with reduced lattice defects as well as low surface damage and etching, 4X lower than previous plasma based doping reports for MoS2.

Interfacial n-Doping Using an Ultrathin TiO2 Layer for Contact Resistance Reduction in MoS2.

We demonstrate a low and constant effective Schottky barrier height (ΦB ∼ 40 meV) irrespective of the metal work function by introducing an ultrathin TiO2 ALD interfacial layer between various metals (Ti, Ni, Au, and Pd) and MoS2. Transmission line method devices with and without the contact TiO2 interfacial layer on the same MoS2 flake demonstrate reduced (24×) contact resistance (RC) in the presence of TiO2. The insertion of TiO2 at the source-drain contact interface results in significant improvement in the on-current and field effect mobility (up to 10×).

Solution-processed poly(3,4-ethylenedioxythiophene) thin films as transparent conductors: effect of p-toluenesulfonic acid in dimethyl sulfoxide.

Conductivity enhancement of thin transparent films based on poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) by a solution-processed route involving mixture of an organic acid and organic solvent is reported. The combined effect of p-toluenesulfonic acid and dimethyl sulfoxide on spin-coated films of PEDOT-PSS on glass substrates, prepared from its commercially available aqueous dispersion, was found to increase the conductivity of the PEDOT-PSS film to ∼3500 S·cm(-1) with a high transparency of at least 94%. Apart from conductivity and transparency measurements, the films were characterized by Raman, infrared, and X-ray photoelectron spectroscopy along with atomic force microscopy and secondary ion mass spectrometry.

Sarcoidosis of the skin: a review for the pulmonologist.

With vastly heterogeneous morphologic manifestations, sarcoidosis is one of the "great imitators" of medicine. Because there is no specific confirmatory test, the diagnosis rests on clinical acumen coupled with supportive information from tissue or blood evaluation and the exclusion of other diseases. The characteristic histologic pattern of noncaseating, epithelioid cell granulomas is not always present in skin lesions, which may be visually distinctive or diverse in appearance.

Discordance in the histopathologic diagnosis of difficult melanocytic neoplasms in the clinical setting.

Background: The gold standard for diagnosing melanocytic neoplasms is by histopathologic examination. However, lack of agreement among expert dermatopathologists in evaluating these tumors has been well established in experimental settings.

Objective: This study examines the discordance among dermatopathologists in evaluating difficult melanocytic neoplasms in a clinical setting where the diagnosis impacts patient management.

Angiotensin II-induced mesangial cell apoptosis: role of oxidative stress.

Background: Angiotensin II (ANG II) has been shown to play a role in the induction of glomerular injury. In the present study, we evaluated the effects of ANG II on mesangial cell apoptosis and the involved molecular mechanism.

Materials And Methods: The effect of ANG II on apoptosis of mouse mesangial cells (MC) was evaluated by morphologic, DNA fragmentation and TUNEL assays.