Atomic-scale structures and electronic states of defects on Ar+-ion irradiated MoS2

Inoue, Akihiro; Komori, Takahiro; Shudo, K.

doi:10.1016/j.elspec.2012.12.005

Cited by 41 publications

(55 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The dark regions bordering the bright defects were previously explained by local band-bending generated by Coulomb repulsion. 31,41 In addition, these STM images indicate a different defect behavior as outlined by the black square in Figure 3a,b, where a bright defect at negative bias disappears at positive bias. Moreover, the STM image measured at positive biases (inset to Figure 3a) shows a very flat surface with an average roughness of <0.35 nm without any indication of structural defects or imperfections.…”

Section: ■ Results and Discussionmentioning

confidence: 93%

Surface Defects on Natural MoS₂

Addou

Colombo

Wallace

2015

ACS Appl. Mater. Interfaces

340

349

View full text Add to dashboard Cite

Transition metal dichalcogenides (TMDs) are being considered for a variety of electronic and optoelectronic devices such as beyond complementary metal-oxide-semiconductor (CMOS) switches, light-emitting diodes, solar cells, as well as sensors, among others. Molybdenum disulfide (MoS2) is the most studied of the TMDs in part because of its availability in the natural or geological form. The performance of most devices is strongly affected by the intrinsic defects in geological MoS2. Indeed, most sources of current transition metal dichalcogenides have defects, including many impurities. The variability in the electrical properties of MoS2 across the surface of the same crystal has been shown to be correlated with local variations in stoichiometry as well as metallic-like and structural defects. The presence of impurities has also been suggested to play a role in determining the Fermi level in MoS2. The main focus of this work is to highlight a number of intrinsic defects detected on natural, exfoliated MoS2 crystals from two different sources that have been often used in previous reports for device fabrication. We employed room temperature scanning tunneling microscopy (STM) and spectroscopy (STS), inductively coupled plasma mass spectrometry (ICPMS), as well as X-ray photoelectron spectroscopy (XPS) to study the pristine surface of MoS2(0001) immediately after exfoliation. ICPMS used to measure the concentration of impurity elements can in part explain the local contrast behavior observed in STM images. This work highlights that the high concentration of surface defects and impurity atoms may explain the variability observed in the electrical and physical characteristics of MoS2.

show abstract

Section: ■ Results and Discussionmentioning

confidence: 93%

Surface Defects on Natural MoS₂

Addou

Colombo

Wallace

2015

ACS Appl. Mater. Interfaces

340

349

View full text Add to dashboard Cite

show abstract

“…Since the α particle irradiation1218 and thermal annealing may result in various types of sulfur vacancies in MoS 2 , the monolayer MoS 2 was modelled in the presence of sulfur vacancies in different arrangements (Supplementary Information Fig. S1).…”

Section: Discussionmentioning

confidence: 99%

Defects activated photoluminescence in two-dimensional semiconductors: interplay between bound, charged and free excitons

Tongay

Suh

Ataca

et al. 2013

Sci Rep

982

990

View full text Add to dashboard Cite

Point defects in semiconductors can trap free charge carriers and localize excitons. The interaction between these defects and charge carriers becomes stronger at reduced dimensionalities, and is expected to greatly influence physical properties of the hosting material. We investigated effects of anion vacancies in monolayer transition metal dichalcogenides as two-dimensional (2D) semiconductors where the vacancies density is controlled by α-particle irradiation or thermal-annealing. We found a new, sub-bandgap emission peak as well as increase in overall photoluminescence intensity as a result of the vacancy generation. Interestingly, these effects are absent when measured in vacuum. We conclude that in opposite to conventional wisdom, optical quality at room temperature cannot be used as criteria to assess crystal quality of the 2D semiconductors. Our results not only shed light on defect and exciton physics of 2D semiconductors, but also offer a new route toward tailoring optical properties of 2D semiconductors by defect engineering.

show abstract

“…Such finding is nevertheless very reasonable since oxygen and sulfur are valence isoelectronic atoms, and oxygen‐containing molecules can also contribute to defect healing via strong chemical interaction with unsaturated molybdenum atoms . Moreover, the presence of multiple sulfur vacancies, which are likely to be generated during Ar‐ion bombardment, could increase significantly the reactivity of the MoS 2 basal plane with such molecular species. Therefore, we implemented a vapor‐phase treatment to exclude secondary healing mechanisms (see the Experimental Section).…”

mentioning

confidence: 95%

Engineering Chemically Active Defects in Monolayer MoS₂ Transistors via Ion‐Beam Irradiation and Their Healing via Vapor Deposition of Alkanethiols

et al. 2017

View full text Add to dashboard Cite

Irradiation of 2D sheets of transition metal dichalcogenides with ion beams has emerged as an effective approach to engineer chemically active defects in 2D materials. In this context, argon-ion bombardment has been utilized to introduce sulfur vacancies in monolayer molybdenum disulfide (MoS ). However, a detailed understanding of the effects of generated defects on the functional properties of 2D MoS is still lacking. In this work, the correlation between critical electronic device parameters and the density of sulfur vacancies is systematically investigated through the fabrication and characterization of back-gated monolayer MoS field-effect transistors (FETs) exposed to a variable fluence of low-energy argon ions. The electrical properties of pristine and ion-irradiated FETs can be largely improved/recovered by exposing the devices to vapors of short linear thiolated molecules. Such a solvent-free chemical treatment-carried out strictly under inert atmosphere-rules out secondary healing effects induced by oxygen or oxygen-containing molecules. The results provide a guideline to design monolayer MoS optoelectronic devices with a controlled density of sulfur vacancies, which can be further exploited to introduce ad hoc molecular functionalities by means of thiol chemistry approaches.

show abstract

Atomic-scale structures and electronic states of defects on Ar+-ion irradiated MoS2

Cited by 41 publications

References 33 publications

Surface Defects on Natural MoS₂

Surface Defects on Natural MoS₂

Defects activated photoluminescence in two-dimensional semiconductors: interplay between bound, charged and free excitons

Engineering Chemically Active Defects in Monolayer MoS₂ Transistors via Ion‐Beam Irradiation and Their Healing via Vapor Deposition of Alkanethiols

Contact Info

Product

Resources

About

Atomic-scale structures and electronic states of defects on Ar+-ion irradiated MoS2

Cited by 41 publications

References 33 publications

Surface Defects on Natural MoS2

Surface Defects on Natural MoS2

Defects activated photoluminescence in two-dimensional semiconductors: interplay between bound, charged and free excitons

Engineering Chemically Active Defects in Monolayer MoS2 Transistors via Ion‐Beam Irradiation and Their Healing via Vapor Deposition of Alkanethiols

Contact Info

Product

Resources

About

Surface Defects on Natural MoS₂

Surface Defects on Natural MoS₂

Engineering Chemically Active Defects in Monolayer MoS₂ Transistors via Ion‐Beam Irradiation and Their Healing via Vapor Deposition of Alkanethiols