Abstract
Abstract
Alloying enables engineering of the electronic structure of semiconductors for optoelectronic applications. Due to their similar lattice parameters, the two-dimensional semiconducting transition metal dichalcogenides of the MoWSeS group (MX2 where M = Mo or W and X = S or Se) can be grown as high-quality materials with low defect concentrations. Here we investigate the atomic and electronic structure of Mo(1−x)W
x
S2 alloys using a combination of high-resolution experimental techniques and simulations. Analysis of the Mo and W atomic positions in these alloys, grown by chemical vapour transport, shows that they are randomly distributed, consistent with Monte Carlo simulations that use interaction energies determined from first-principles calculations. Electronic structure parameters are directly determined from angle resolved photoemission spectroscopy measurements. These show that the spin–orbit splitting at the valence band edge increases linearly with W content from MoS2 to WS2, in agreement with linear-scaling density functional theory predictions. The spin–orbit splitting at the conduction band edge is predicted to reduce to zero at intermediate compositions. Despite this, polarisation-resolved photoluminescence spectra on monolayer Mo0.5W0.5S2 show significant circular dichroism, indicating that spin-valley locking is retained. These results demonstrate that alloying is an important tool for controlling the electronic structure of MX2 for spintronic and valleytronic applications.
Funder
Engineering and Physical Sciences Research Council
H2020 Science with and for Society
Subject
Condensed Matter Physics,General Materials Science,Atomic and Molecular Physics, and Optics
Cited by
8 articles.
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