Tunable Colossal Anomalous Hall Conductivity in Half-Metallic Material Induced by d-Wave-Like Spin-Orbit Gap.

The anomalous Hall conductivity (AHC) in magnetic materials, resulting from inverted band topology, has emerged as a key adjustable function in spin-torque devices and advanced magnetic sensors. Among systems with near-half-metallicity and broken time-reversal symmetry, cobalt disulfide (CoS2) has proven to be a material capable of significantly enhancing its AHC. In this study, the AHC of CoS2 is empirically assessed by manipulating the chemical potential through Fe- (hole) and Ni- (electron) doping. The primary mechanism underlying the colossal AHC is identified through the application of density functional theory and tight-binding analyses. The main source of this substantial AHC is traced to four spin-polarized massive Dirac dispersions in the kz = 0 plane of the Brillouin zone, located slightly below the Fermi level. In Co0.95Fe0.05S2, the AHC, which is directly proportional to the momentum-space integral of the Berry curvature (BC), reached a record-breaking value of 2507 Ω-1cm-1. This is because the BCs of the four Dirac dispersions all exhibit the same sign, a consequence of the d-wave-like spin-orbit coupling among spin-polarized eg orbitals.

Ultraclean Interface of Metal Chalcogenides with Metal through Confined Interfacial Chalcogenization.

Acquisition of defect-free transition metal dichalcogenides (TMDs) channels with clean heterojunctions is a critical issue in the production of TMD-based functional electronic devices. Conventional approaches have transferred TMD onto a target substrate, and then apply the typical device fabrication processes. Unfortunately, those processes cause physical and chemical defects in the TMD channels. Here, a novel synthetic process of TMD thin films, named confined interfacial chalcogenization (CIC) is proposed. In the proposed synthesis, a uniform TMDlayer is created at the Au/transition metal (TM) interface by diffusion of chalcogen through the upper Au layer and the reaction of chalcogen with the underlying TM. CIC allows for ultraclean heterojunctions with the metals, synthesis of various homo- and hetero-structured TMDs, and in situ TMD channel formation in the last stage of device fabrication. The mechanism of TMD growth is revealed by the TM-accelerated chalcogen diffusion, epitaxial growth of TMD on Au(111). We demonstrated a wafer-scale TMD-based vertical memristors which exhibit excellent statistical concordance in device performance enabled by the ultraclean heterojunctions and superior uniformity in thickness. CIC proposed in this study represents a breakthrough in in TMD-based electronic device fabrication and marking a substantial step toward practical next-generation integrated electronics.

The future of two-dimensional semiconductors beyond Moore's law.

The primary challenge facing silicon-based electronics, crucial for modern technological progress, is difficulty in dimensional scaling. This stems from a severe deterioration of transistor performance due to carrier scattering when silicon thickness is reduced below a few nanometres. Atomically thin two-dimensional (2D) semiconductors still maintain their electrical characteristics even at sub-nanometre scales and offer the potential for monolithic three-dimensional (3D) integration. Here we explore a strategic shift aimed at addressing the scaling bottleneck of silicon by adopting 2D semiconductors as new channel materials. Examining both academic and industrial viewpoints, we delve into the latest trends in channel materials, the integration of metal contacts and gate dielectrics, and offer insights into the emerging landscape of industrializing 2D semiconductor-based transistors for monolithic 3D integration.

Electrically Confined Electroluminescence of Neutral Excitons in WSe2 Light-Emitting Transistors.

Monolayer transition metal dichalcogenides (TMDs) have drawn significant attention for their potential in optoelectronic applications due to their direct band gap and exceptional quantum yield. However, TMD-based light-emitting devices have shown low external quantum efficiencies as imbalanced free carrier injection often leads to the formation of non-radiative charged excitons, limiting practical applications. Here, electrically confined electroluminescence (EL) of neutral excitons in tungsten diselenide (WSe2) light-emitting transistors (LETs) based on the van der Waals heterostructure is demonstrated. The WSe2 channel is locally doped to simultaneously inject electrons and holes to the 1D region by a local graphene gate. At balanced concentrations of injected electrons and holes, the WSe2 LETs exhibit strong EL with a high external quantum efficiency (EQE) of ≈8.2 % at room temperature. These experimental and theoretical results consistently show that the enhanced EQE could be attributed to dominant exciton emission confined at the 1D region while expelling charged excitons from the active area by precise control of external electric fields. This work shows a promising approach to enhancing the EQE of 2D light-emitting transistors and modulating the recombination of exciton complexes for excitonic devices.