Elimination of S Vacancy as the Cause for the n-Type Behavior of MoS₂ from the First-Principles Perspective

Abstract

Molybdenum disulfide (2H-MoS) based low-dimensional nanostructure materials have great potential for applications in electronic and optoelectronic devices. However, some of the properties such as the origin of the native n-type electrical conductivity (EC) observed in these materials still remain elusive. Here, the defect properties in the 2H-MoS bulk system are systematically investigated by first-principles calculation to address these issues. We find that the S vacancy V with low formation energy cannot be the origin of n-type EC owing to its deep defect levels within the valence band region. All other donor defects such as antisite Mo or Mo interstitial Mo also have deep levels that can trap electrons leading to depressed EC. S and S could be the origin of the p-type EC in 2H-MoS, but the concentrations are expected to be rather low due to their high formation energies and can only be enhanced under S-rich/Mo-poor conditions. These results provide the underlying insights on the defect properties 2H-MoS and explain well the experimental observations.

Gate Stack Engineering in MoS2 Field‐Effect Transistor for Reduced Channel Doping and Hysteresis Effect

“…[ 16,17 ] However, it is rather difficult to form a uniform and high‐quality dielectric layer on most 2DLMs as they lack dangling bonds on the surface for a homogeneous reaction during the atomic layer deposition (ALD) process. In addition, most of the reported MoS 2 ‐based TG FETs with an ALD high‐ k dielectric layer suffer from a serious n‐doping effect in the channel due to the sulfur vacancies, [ 18 ] which limits its practical application in large scale circuits. To overcome this problem, various methods have been studied.…”

Breast cancer biomarker detection through the photoluminescence of epitaxial monolayer MoS2 flakes

“…It is important to note that the homogeneity is high in the central region, where most of the sulfur vacancies (V s ) are found. At the borders of the MoS 2 flakes the vacancies are predominantly Mo-based, as it has been demonstrated in different works 19,21,29 . Indeed, the borders exhibit p-type doping, typically ascribed to molybdenum vacancies (V Mo ), which results in a blueshift of the PL main peak, an effect confirmed in our maps.…”

“…1 d). The intensity in the central part of the flake is essentially constant, and it increases considerably in the borders due to structural defects, typically Mo vacancies 21 , 29 .…”

p-/n-Type modulation of 2D transition metal dichalcogenides for electronic and optoelectronic devices

“…2(h)). Even some defect-related doping results have been demonstrated experimentally according to the aforementioned studies, some defect energy level variations (such as S vacancy defects) have not reached a consensus, and their inherent mechanisms are not that explicit yet [38,69,[76][77][78]. These aforementioned limitations might originate from additional damages (other vacancies, chemical clusters, local curling, and deformations) caused by ion/electron etching, light illumination, etc., that are not comprehensively analyzed.…”