期刊
JOURNAL OF PHYSICS-MATERIALS
卷 4, 期 2, 页码 -出版社
IOP Publishing Ltd
DOI: 10.1088/2515-7639/abdc6e
关键词
2D semiconductor; alloy; angle resolved photoemission spectroscopy; linear scaling density functional theory
资金
- Engineering and Physical Sciences Research Council [EP/M508184/1, EP/R513374/1, EP/P01139X/1]
- University of Warwick Chancellor's Scholarships
- EU [730872]
- EPSRC [EP/P022561/1, EP/P01139X/1] Funding Source: UKRI
The study investigates the atomic and electronic structure of Mo(1-x)WxS2 alloys, showing that alloying is an important tool for controlling the electronic structure of MX2 for spintronic and valleytronic applications. The results also demonstrate the retention of spin-valley locking in monolayer Mo0.5W0.5S2 despite the predicted reduction of spin-orbit splitting at intermediate compositions.
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)WxS2 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.
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