Work Function Modulation of Molybdenum Disulfide Nanosheets by Introducing Systematic Lattice Strain

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional transition metal dichalcogenides (TMDs) like molybdenum disulfide (MoS2) are promising for flexible electronics.
• Tuning surface electronic properties is crucial for optimizing device performance, especially in strain-sensitive applications.

Purpose of the Study:

• To investigate the correlation between swift heavy ion irradiation-induced tensile strain and surface electronic property modifications in MoS2 nanosheets.
• To explore the potential of controlled defect engineering via ion irradiation for tuning MoS2 electronic properties.

Main Methods:

• Chemically exfoliated MoS2 nanosheets were subjected to 100 MeV Ag ion irradiation at varying fluences.
• Structural characterization using transmission electron microscopy (TEM).
• Strain analysis via Raman spectroscopy and X-ray Diffraction (XRD).
• Surface electronic property assessment through work function measurements using scanning Kelvin probe microscopy (SKPM).

Main Results:

• Defect creation through ion irradiation resulted in systematic tensile strain in MoS2 nanosheets, verified by Raman and XRD.
• The in-plane vibrational mode of MoS2 was more significantly affected by irradiation than the out-of-plane mode.
• Work function was found to be linearly proportional to the in-plane tensile strain, indicating Fermi level shifts towards the valence band with increasing ion fluence.

Conclusions:

• Swift heavy ion irradiation is an effective method for inducing controlled tensile strain and modifying the electronic properties of MoS2 nanosheets.
• The observed linear relationship between strain and work function highlights the potential for precise tuning of MoS2 for strain-engineered flexible electronic applications.