One-Step Passivation of Both Sulfur Vacancies and SiO2 Interface Traps of MoS2 Device.

Transition metal dichalcogenides (TMDs) benefit electrical devices with spin-orbit coupling and valley- and topology-related properties. However, TMD-based devices suffer from traps arising from defect sites inside the channel and the gate oxide interface. Deactivating them requires independent treatments, because the origins are dissimilar. This study introduces a single treatment to passivate defects in a multilayer MoS2 FET. By applying back-gate bias, protons from an H-TFSI droplet are injected into the MoS2, penetrating deeply enough to reach the SiO2 gate oxide. The characterizations employing low-temperature transport and deep-level transient spectroscopy (DLTS) studies reveal that the trap density of S vacancies in MoS2 drops to the lowest detection level. The temperature-dependent mobility plot on the SiO2 substrate resembles that of the h-BN substrate, implying that dangling bonds in SiO2 are passivated. The carrier mobility on the SiO2 substrate is enhanced by approximately 2200% after the injection.

Investigation of Cation Exchange Behaviors of FAxMA1-xPbI3 Films Using Dynamic Spin-Coating.

In this study, we fabricated and characterized uniform multi-cation perovskite FAxMA1-xPbI3 films. We used the dynamic spin-coating method to control the cation ratio of the film by gradually increasing the FA+, which replaced the MA+ in the films. When the FA+ concentration was lower than xFA ~0.415 in the films, the stability of the multi-cation perovskite improved. Above this concentration, the film exhibited δ-phase FAPbI3 in the FAxMA1-xPbI3 films. The formation of δ-phase FAPbI3 disturbed the homogeneity of the photoluminescence spatial distribution and suppressed the absorption spectral bandwidth with the increasing bandgap. The precise control of the cation ratio of multi-cation perovskite films is necessary to optimize the energy-harvesting performance.

Nano-Thermal Analysis of Defect-Induced Surface Pre-Melting in 2D Tellurium.

Thermal properties, such as thermal conductivity, heat capacity, and melting temperature, influence the efficiency and stability of two-dimensional (2D) material applications. However, existing studies on thermal characteristics-except for thermal conductivity-are insufficient for 2D materials. Here, we investigated the melting temperature of 2D Tellurium (2D Te) using the nano-thermal analysis technique and found anomalous behavior that occurs before the melting temperature is reached. The theoretical calculations present surface pre-melting in 2D Te and Raman scattering measurements suggest that defects in 2D Te accelerate surface pre-melting. Understanding the pre-melting surface characteristics of 2D Te will provide valuable information for practical applications.