Forming
bilayer or multilayer heterostructures via interlayer van der Waals
interactions is a superior preparation strategy for two-dimensional
heterojunctions. In this work, by employing density functional theory
computations, we investigated heterostructured bilayers of transition-metal
dichalcogenides (TMDs) (including MoS2, WS2,
MoSe2, and WSe2) and MXene (exemplified by Sc2CF2) monolayer. All TMD and Sc2CF2 materials are hexagonal with little mismatch. Compared with
separate TMD and Sc2CF2 monolayers, TMD–Sc2CF2 bilayers can be tuned to indirect semiconductors
with the band gaps of 0.13–1.18 eV; more importantly, they
are type-II heterostructures with the valence band maximum and conduction
band minimum located at Sc2CF2 and TMDs, respectively.
Stretching or compressing would reduce or enlarge the band gaps of
the heterostructures, respectively. The tunable band structures make
TMD–Sc2CF2 bilayers pomising candidates
for electronic device applications.
Using a first-principles method, we investigate the structural and electronic properties of grain boundaries (GBs) in polycrystalline CdTe and the effects of copassivation of elements with far distinct electronegativities. Of the two types of GBs studied in this Letter, we find that the Cd core is less harmful to the carrier transport, but is difficult to passivate with impurities such as Cl and Cu, whereas the Te core creates a high defect density below the conduction band minimum, but all these levels can be removed by copassivation of Cl and Cu. Our analysis indicates that for most polycrystalline systems copassivation or multipassivation is required to passivate the GBs.
Recently a superconducting transition was found in silane in high-pressure experiments. However, the experimental x-ray diffraction (XRD) patterns do not match any one of proposed silane structures, and it has been suggested to be originated from a platinum hydride. Neither the structure nor superconductivity of any platinum hydride is known. Here the underlying physics behind the anomalous superconducting transition in experiment is revealed by first-principles calculations. We predict a stable hexagonal P63/mmc phase of platinum hydride at high pressure. Its lattice constants and simulated XRD pattern are in excellent agreement with the experimental results. The superconducting transition temperatures in this phase are found to coincide with the measured values, too. This discovery provides new insights into the unusual superconducting behavior reported for silane.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.