Generating large out-of-plane piezoelectric properties of atomically thin MoS₂via defect engineering

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional materials like molybdenum disulfide (MoS2) are promising for electronic applications.
• Conventional piezoelectric materials often face integration challenges in nanoscale devices.
• Achieving piezoelectricity in 2D materials requires breaking centrosymmetry.

Purpose of the Study:

• To investigate the induction of piezoelectric properties in MoS2 through asymmetric defect engineering.
• To quantify the piezoelectric response based on defect density and distribution.
• To explore the potential of defect-engineered MoS2 as a piezoelectric material for 2D devices.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• Asymmetric defect creation on MoS2 layers was simulated.
• Piezoelectric properties, including the d33 coefficient, were calculated.
• Metal-insulator transition critical defect density was determined.

Main Results:

• Asymmetric defecting breaks out-of-plane centrosymmetry, inducing piezoelectricity.
• The largest piezoelectric response correlates with the highest defect ratio for semiconducting MoS2.
• A critical defect density of 9.90 × 10^14 cm^-2 (MoS1.22) was calculated for the metal-insulator transition.
• The d33 coefficient of defected MoS2 surpasses AlN and ZnO, comparable to lead zirconate titanate.

Conclusions:

• Asymmetric defect engineering is a viable method to create piezoelectricity in 2D transition metal dichalcogenides.
• Tunable piezoelectric properties can be achieved by controlling defect density via ion irradiation or plasma treatment.
• Defect-engineered MoS2 offers superior integration potential for 2D electronic devices compared to conventional piezoelectric films.