Thickness and strain effects on electronic structures of transition metal dichalcogenides: 2H-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>M</mml:mi><mml:msub><mml:mi>X</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>semiconductors (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>M</mml:mi></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mo>=</mml:mo></mml:math>Mo, W;<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>X</mml:mi></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mo>=</mml:mo></mml:math>S, Se, Te)
Won Seok YunDepartment of Physics and Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 680-749, Republic of KoreaSang Wook HanDepartment of Physics and Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 680-749, Republic of KoreaSoon Cheol HongDepartment of Physics and Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 680-749, Republic of KoreaIn Gee KimGraduate Institute of Ferrous Technology, Pohang University of Science and Technology, Pohang 790-784, Republic of KoreaJ. D. LeeSchool of Materials Science & Research Center for Integrated Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
2012lv
ABI
Аннотация
Using the first-principles calculations, we explore the electronic structures of 2H-$M{X}_{2}$ ($M$ $=$ Mo, W; $X$ $=$ S, Se, Te). When the number of layers reduces to a single layer, the indirect gap of bulk becomes a direct gap with larger gap and the band curvatures are found to lead to the drastic changes of effective masses. On the other hand, when the strain is applied on the single layer, the direct gap becomes an indirect gap and the effective masses vary. Especially, the tensile strain reduces the gap energy and effective masses while the compressive strain enhances them. Furthermore, the much larger tensile stress leads to become metallic.
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