Tabletop Fabrication of High-Performance MoS2 Field-Effect Transistors

Disorder impacts on transport and magnetoresistance properties in a gapless ferromagnetic/normal/ferromagnetic phosphorene junction

The ballistic electronic transport and tunneling magnetoresistance (TMR) in a ferromagnetic/normal/ferromagnetic (F/N/F) gapless phosphorene junction have been investigated. This study focuses on the effects of structural disorder-specifically, variations in the width and height of the electrostatic potential barrier and magnetic field-on transport and TMR properties. A low-energy two-band Hamiltonian, derived from the tight-binding model along the armchair direction of phosphorene, is used. Transmission, conductance, and magnetoresistance are calculated using the transfer matrix technique, the Landauer-Büttiker formalism, and the TMR relation, respectively. The findings reveal that structural disorder related to barrier width reduces transmission oscillations and moderately suppresses conductance. A key result is that even slight combined structural disorder significantly degrades TMR properties in a gapless phosphorene F/N/F junction. Furthermore, maintaining transport properties, particularly TMR, in this device requires precise control over fluctuations in externally applied fields, especially the magnetic field.

Proton-electron coupling and mixed conductivity in a hydrogen-bonded coordination polymer

The fundamental understanding of coupled proton-electron transport in mixed protonic-electronic conductors (MPECs) remains unexplored in materials science, despite its potential significance within the broader context of mixed ionic-electronic conductors (MIECs) and the possibility of controlled diffusion of protons using hydrogen-bond networks. To address these limitations, we present a hydrogen-bonded coordination polymer Ni-BAND ({[Ni(bpy)(H2O)2(DMF)2](NO3)2·2DMF}n), which demonstrates high mixed protonic-electronic conductivity at room temperature. Through detailed analysis, we unravel the coupled transport mechanism, offering insights for the rational design of high-performance MPECs. We demonstrate the practical implications of this mechanism by examining the humidity-dependent synaptic plasticity of Ni-BAND, showcasing how MPECs can expand into traditional MIEC applications while leveraging their unique proton-mediated advantages.

Interface analysis of oxide free MoS2 films fabricated by solution process

We report a solution-based approach for the synthesis of oxidation-free MoS2 films, focusing on interface analysis. Through a sulfurization-free solution process and single-step annealing, the oxidation-free MoS2 film is successfully prepared on Si3N4 surfaces, showing improved uniformity with a surface roughness below 0.5 nm and a thickness of 4 nm at a precursor solution concentration of 30 mM, annealed between 700 and 800ºC. The MoS2 films exhibit a hexagonal lattice structure with crystallographic orientations of (1 1 0 0) and (1 2 1 0) with lattice spacings of 0.27 nm and 0.16 nm respectively. Interfacial analysis by X-ray photoelectron spectroscopy (XPS) on SiO2 reveals migration of oxygen species as evidenced by a shift in the Si 2p spectrum at binding energies between 102.6 eV and 102.8 eV. MoS2 films on Si3N4 show a complex Si 2p peak evolution at binding energies between 100.9 and 101.8 eV, providing valuable insights into the synthesis of oxide-free MoS2 films for potential applications in advanced electronic devices.

NaCl-Assisted Temperature-Dependent Controllable Growth of Large-Area MoS2 Crystals Using Confined-Space CVD

Due to its semiconducting nature, controlled growth of large-area chemical vapor deposition (CVD)-grown two-dimensional (2D) molybdenum disulfide (MoS2) has a lot of potential applications in photodetectors, sensors, and optoelectronics. Yet the controllable, large-area, and cost-effective growth of highly crystalline MoS2 remains a challenge. Confined-space CVD is a very promising method for the growth of highly crystalline MoS2 in a controlled manner. Herein, we report the large-scale growth of MoS2 with different morphologies using NaCl as a seeding promoter for confined-space CVD. Changes in the morphologies of MoS2 are reported by variation in the amount of seeding promoter, precursor ratio, and the growth temperature. Furthermore, the properties of the grown MoS2 are analyzed using optical microscopy, scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM). The electrical properties of the CVD-grown MoS2 show promising performance from fabricated field-effect transistors. This work provides new insight into the growth of large-area MoS2 and opens the way for its various optoelectronic and electronic applications.