研究目的
Exploring the band structure modification via electric field of as many stable, layered, predominately semiconducting TMDCs as possible.
研究成果
Band gaps generally decrease down the chalcogen group from oxides to tellurides, increase across the transition metals from left to right, are larger for T-phase materials than corresponding H-phase ones, and decrease with more layers. The responses to the electric field decrease down the chalcogens and across transition metals in the same period, are larger for T-phase materials than H-phase ones, and increase with increasing number of layers.
研究不足
The influence of field-based geometric disturbances on the band structures is negligible. Spin–orbit coupling was not incorporated in the computations, which may open a tiny gap in the metallic systems resulting in a small error of order of meV in the zero-field band gap and critical field strength values.
1：Experimental Design and Method Selection:
Density-functional theory (DFT) in the crystal09 code was used for all calculations. The PBEsol functional was employed for structure relaxation and electronic response to potentials.
2：Sample Selection and Data Sources:
39 stable, layered, transition-metal dichalcogenides (TMDCs) were studied.
3：List of Experimental Equipment and Materials:
Gaussian basis sets; triple-zeta for valence electrons plus a polarization function (TZVP) for lighter elements and pseudopotential basis sets for heavy elements.
4：Experimental Procedures and Operational Workflow:
Geometries were optimized to default crystal09 convergence criteria. Band structures were calculated along the high-symmetry path Γ-M-K-Γ for uniformly varying electric fields applied perpendicular to the TMDC slabs.
5：Data Analysis Methods:
The change in the band gap with the electric field was analyzed, and the giant-Stark-effect (GSE) coefficient was calculated from the slope of the linear fits to the data.
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