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Composition-Gradient-Mediated Semiconductor-Metal Transition in Ternary Transition-Metal-Dichalcogenide Bilayers
Qifan Chen1, Mingwei Chen1, Linggang Zhu1
1School of Materials Science and Engineering, Beihang University, Beijing 100191, China.
ACS Applied Materials & Interfaces
|September 11, 2020
Summary
We discovered a new way to control semiconductor-metal transitions (SMT) in layered materials like MoS2-Ox bilayers. A chalcogen atom concentration gradient across the van der Waals gap drives this SMT, enabling tunable electronic properties.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Solid State Chemistry
Background:
- Semiconductor-metal transitions (SMT) are crucial for advanced electronic devices, but controlling them in two-dimensional layered materials remains challenging.
- Understanding the mechanisms behind SMT is key to designing novel materials with tunable electronic properties.
Purpose of the Study:
- To investigate and realize SMT in molybdenum disulfide (MoS2) bilayers with oxygen incorporation.
- To identify the key factors driving SMT in these disordered bilayers.
- To explore the potential of this phenomenon for designing next-generation electronic devices.
Main Methods:
- Utilized the cluster expansion method to determine stable and metastable states of MoS2-Ox bilayers.
- Employed machine learning analysis to identify the primary drivers of SMT.
- Analyzed the electronic band structure changes associated with the transition.
Main Results:
- Achieved SMT in MoS2-Ox bilayers driven by a chalcogen atom concentration gradient across the van der Waals gap.
- Identified the concentration gradient as the leading factor for SMT, with structural distortion as a secondary factor.
- Observed broadening of Mo d and O p bands and d-electron redistribution as the electronic origin of SMT.
- Demonstrated that this phenomenon is applicable to MoSe2-Ox and MoTe2-Ox bilayers.
Conclusions:
- Introduced a novel, intrinsic mechanism for SMT in van der Waals bilayers based on in-gap composition gradients.
- Showcased the composition gradient as a new degree of freedom for band gap tuning without extrinsic doping.
- Highlighted the potential of this approach for developing small-scale, energy-efficient electronic devices.
Keywords:
MoS2−xOx bilayercomposition gradientdensity functional theorymachine learningsemiconductor−metal transitionMore Related Videos
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