Spectroscopic studies of atomic defects and bandgap renormalization in semiconducting monolayer transition metal dichalcogenides

Abstract

Assessing atomic defect states and their ramifications on the electronic properties of two dimensional van der Waals semiconducting transition metal dichalcogenides (SC TMDs) is the primary task to expedite multi disciplinary efforts in the promotion of next generation electrical and optical device applications utilizing these low dimensional materials. Here, with electron tunneling and optical spectroscopy measurements with density functional theory, we spectroscopically locate the midgap states from chalcogen atom vacancies in four representative monolayer SC TMDs (MoS2, WS2, MoSe2, WSe2), and carefully analyze the similarities and dissimilarities of the atomic defects in four distinctive materials regarding the physical origins of the missing chalcogen atoms and the implications to SC mTMD properties. In addition, we address both quasiparticle and optical energy gaps of the SC mTMD films and find out many body interactions significantly enlarge the quasiparticle energy gaps and excitonic binding energies, when the semiconducting monolayers are encapsulated by non interacting hexagonal boron nitride layers.

References in corpus (6)

• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Determination of band alignment in the single layer MoS2/WSe2 heterojunction
• Twist-controlled resonant tunnelling in graphene-boron nitride-graphene heterostructures
• First-principles theory of field-effect doping in transition-metal dichalcogenides: Structural properties, electronic structure, Hall coefficient, and electrical conductivity
• Probing the spin-polarized electronic band structure in monolayer transition metal dichalcogenides by optical spectroscopy
• Tuning the valley and chiral quantum state of Dirac electrons in van der Waals heterostructures

Cited by in corpus (4)

• Stability of charged sulfur vacancies in 2D and bulk MoS${}_2$ from plane-wave density functional theory with electrostatic corrections
• Direct probing of phonon mode specific electron-phonon scatterings in two-dimensional semiconductor transition metal dichalcogenides: Symmetry and Berry phase
• Low temperature carrier transport mechanism and photoconductivity of WSe2
• Methods for coherent optical Doppler orbitography