Origin of layer-dependent electrical conductivity of transition metal dichalcogenides

Singh, Akash and Dey, Akash and Singh, Abhishek Kumar (2022) Origin of layer-dependent electrical conductivity of transition metal dichalcogenides. In: Physical Review B, 105 (16). ISSN 2469-9950

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Abstract

Transition metal dichalcogenide (TMD) shows layer-dependent electrical conductivity. However, there are conflicting experimental reports on the trend of conductivity, which is attributed to originating from point defects as a function of the number of layers (NLs). Using density functional theory, we analyze the layer-dependent defect thermodynamics of n- and p-type defects in MoS2 and WS2. The shallow donor levels of hydrogen defects systematically become deep with the increasing NLs to six or seven-layers and hence reduces the n-type conductivity. Moreover, the deep acceptor VS in a one-layer turns into a weak shallow acceptor for six-layers. Interestingly, from eight-layers onwards, the thermodynamic defect transition levels shift towards the conduction band due to the interplay between the bonding characteristic of the localized defect state and Coulombic repulsion of the added charge in the changing dielectric environment. The study uncovers the plausible cause of the layer-dependent electrical conductivity of TMDs.

Item Type:	Journal Article
Publication:	Physical Review B
Additional Information:	The copyright of this article belongs to American Physical Society.
Keywords:	Engineering controlled terms Chemical bonds; Density functional theory; Layered semiconductors; Molybdenum compounds; Point defects; Thermodynamics; Transition metals; Tungsten compounds Engineering uncontrolled terms Density-functional-theory; Dichalcogenides; Donor levels; Electrical conductivity; Hydrogen defects; N-type conductivity; Number of layers; P-type; Shallow donors; Transition metal dichalcogenides (TMD) Engineering main heading Electric conductivity
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	25 May 2022 04:31
Last Modified:	25 May 2022 04:31
URI:	https://eprints.iisc.ac.in/id/eprint/72359

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