Roles of chalcogen sublayers of 1H transition metal dichalcogenides in metal-semiconductor van der Waals heterostructures

In this paper, the crystal and electronic structures are investigated using first-principles theory for metal-semiconductor van der Waals heterostructures <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mn>1</a:mn><a:mi>H</a:mi></a:mrow></a:math>-transition-metal dichalcogenides (<b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msub><b:mi>NbS</b:mi><b:mn>2</b:mn></b:msub><b:mo>,</b:mo><b:mo> </b:mo><b:msub><b:mi>NbSe</b:mi><b:mn>2</b:mn></b:msub><b:mo>,</b:mo><b:mo> </b:mo><b:msub><b:mi>TaS</b:mi><b:mn>2</b:mn></b:msub><b:mo>,</b:mo><b:mo> </b:mo><b:msub><b:mi>TaSe</b:mi><b:mn>2</b:mn></b:msub><b:mo>,</b:mo><b:mo> </b:mo><b:msub><b:mi>MoS</b:mi><b:mn>2</b:mn></b:msub><b:mo>,</b:mo><b:mo> </b:mo><b:msub><b:mi>MoSe</b:mi><b:mn>2</b:mn></b:msub><b:mo>,</b:mo><b:mo> </b:mo><b:msub><b:mi>WS</b:mi><b:mn>2</b:mn></b:msub></b:math>, and <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:msub><c:mi>WSe</c:mi><c:mn>2</c:mn></c:msub></c:math>). The theoretical investigations reveal that chalcogen sublayers play crucial roles in the crystal and electronic structures though these sublayers are minor parts in the pristine crystals. Actually, selenide sublayers energetically stabilize the commensurate heterobilayers, whereas moiré structure gives a much lower electronic energy with sulfide sublayers. Moreover, the chalcogen sublayers dominate the charge distribution via the difference of work functions in the component layers, i.e., the charge transfer between the metallic and semiconducting layers in the heterobilayers. The theoretical results suggest that the chalcogen sublayers can be the key to control the crystal and electronic structures in the metal-semiconductor vdW heterostructure of TMDC monolayers. Published by the American Physical Society 2024