Atomically Resolved Defect-Engineering Scattering Potential in 2D Semiconductors.

Engineering atomic-scale defects has become an important strategy for the future application of transition metal dichalcogenide (TMD) materials in next-generation electronic technologies. Thus, providing an atomic understanding of the electron-defect interactions and supporting defect engineering development to improve carrier transport is crucial to future TMDs technologies. In this work, we utilize low-temperature scanning tunneling microscopy/spectroscopy (LT-STM/S) to elicit how distinct types of defects bring forth scattering potential engineering based on intervalley quantum quasiparticle interference (QPI) in TMDs.

Hysteresis-Free Contact Doping for High-Performance Two-Dimensional Electronics.

Contact doping is considered crucial for reducing the contact resistance of two-dimensional (2D) transistors. However, a process for achieving robust contact doping for 2D electronics is lacking. Here, we developed a two-step doping method for effectively doping 2D materials through a defect-repairing process.

Low-defect-density WS by hydroxide vapor phase deposition.

Two-dimensional (2D) semiconducting monolayers such as transition metal dichalcogenides (TMDs) are promising channel materials to extend Moore's Law in advanced electronics. Synthetic TMD layers from chemical vapor deposition (CVD) are scalable for fabrication but notorious for their high defect densities. Therefore, innovative endeavors on growth reaction to enhance their quality are urgently needed.

Directly Visualizing Photoinduced Renormalized Momentum-Forbidden Electronic Quantum States in an Atomically Thin Semiconductor.

Resolving the momentum degree of freedom of photoexcited charge carriers and exploring the excited-state physics in the hexagonal Brillouin zone of atomically thin semiconductors have recently attracted great interest for optoelectronic technologies. We demonstrate a combination of light-modulated scanning tunneling microscopy and the quasiparticle interference (QPI) technique to offer a directly accessible approach to reveal and quantify the unexplored momentum-forbidden electronic quantum states in transition metal dichalcogenide (TMD) monolayers. Our QPI results affirm the large spin-splitting energy at the spin-valley-coupled Q valleys in the conduction band (CB) of a tungsten disulfide monolayer.

Internal Built-In Electric Fields at Organic-Inorganic Interfaces of Two-Dimensional Ruddlesden-Popper Perovskite Single Crystals.

Two-dimensional (2D) organic-inorganic hybrid Ruddlesden-Popper perovskites (OIRPPs), which consist of naturally formed "multiple quantum well (MQW)-like" structure, have received considerable interest in optoelectronic applications, owing to their outstanding optical properties and tailorable functionalities. While the quantum-confined electrons and holes at an MQW structure are under an applied electric field, the tilt of the energy bands may cause a significant influence on their optical properties. This work demonstrates the presence of internal built-in electric fields (BIEFs) at the as-synthesized 2D OIRPP single crystals.

Atomically Resolved Quantum-Confined Electronic Structures at Organic-Inorganic Interfaces of Two-Dimensional Ruddlesden-Popper Halide Perovskites.

This work demonstrates the direct visualization of atomically resolved quantum-confined electronic structures at organic-inorganic heterointerfaces of two-dimensional (2D) organic-inorganic hybrid Ruddlesden-Popper perovskites (RPPs); this is accomplished with scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) by using solvent engineering to prepare perpendicularly oriented 2D RPPs. Atomically resolved band mapping images across the organic-inorganic interfaces of 2D RPPs yield typical quantum-well-like type-I heterojunction band alignment with band gaps depending on the thicknesses or values of the inorganic perovskite slabs. The presence of edge states within the band gap due to organic cation vacancies is also observed.

Blood Glucose and Renal Function Evaluation in Patients with Viral Hepatitis.

Purpose: To evaluate the blood glucose and renal function, determine the prevalence of hyperglycemia/diabetes mellitus (DM) and renal disease (nephropathy), and investigate the association between hyperglycemia/DM and renal disease in patients with viral hepatitis (VH).

Patients And Methods: A total of 491 subjects were included in the study. Patients with VH were further divided into the hepatitis B virus (HBV) infection, hepatitis C virus (HCV) infection, and HBV-HCV co-infection subgroups.

Photodriven Dipole Reordering: Key to Carrier Separation in Metalorganic Halide Perovskites.

Photodriven dipole reordering of the intercalated organic molecules in halide perovskites has been suggested to be a critical degree of freedom, potentially affecting physical properties, device performance, and stability of hybrid perovskite-based optoelectronic devices. However, thus far a direct atomically resolved dipole mapping under device operation condition, that is, illumination, is lacking. Here, we map simultaneously the molecule dipole orientation pattern and the electrostatic potential with atomic resolution using photoexcited cross-sectional scanning tunneling microscopy and spectroscopy.

Thermoelectric Properties of Ag-Doped Bi2(Se,Te)3 Compounds: Dual Electronic Nature of Ag-Related Lattice Defects.

Effects of Ag doping and thermal annealing temperature on thermoelectric transport properties of Bi2(Se,Te)3 compounds are investigated. On the basis of the comprehensive analysis of carrier concentration, Hall mobility, and lattice parameter, we identified two Ag-related interstitial (Agi) and substitutional (AgBi) defects that modulate in different ways the thermoelectric properties of Ag-doped Bi2(Se,Te)3 compounds. When Ag content is less than 0.

Growth of high-density titanium silicide nanowires in a single direction on a silicon surface.

Understanding the growth mechanisms of nanowires is essential for their successful implementation in advanced devices applications. In situ ultrahigh-vacuum transmission electron microscopy has been applied to elucidate the interaction mechanisms of titanium disilicide nanowires (TiSi2 NWs) on Si(111) substrate. Two phenomena were observed: merging of the two NWs in the same direction, and collapse of one NW on a competing NW in a different direction when they meet at the ends.

Isolation effectively prevents the transmission of hepatitis C virus in the hemodialysis unit.

Background And Purpose: Many preventative strategies have been proposed to control hepatitis C virus (HCV) infection in the hemodialysis unit. The effectiveness of isolation as a preventive policy remains unclear. The aim of this study was to evaluate the effect of an isolation policy on the incidence of hepatitis C in our hemodialysis unit.