Controlled defect creation and removal in graphene and MoS₂ monolayers

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Defects significantly impact the properties of two-dimensional (2D) materials.
• Controlled defect engineering is crucial for tailoring optical and electronic responses in 2D materials for optoelectronic and nanoelectronic devices.

Purpose of the Study:

• To develop an efficient and reversible method for controlling defect states in graphene and molybdenum disulfide (MoS2) monolayers.
• To demonstrate the application of this method for functional design of 2D material-based devices.

Main Methods:

• Utilized aluminum oxide (Al2O3) plasmas to introduce defects into mechanically exfoliated graphene and MoS2 monolayers.
• Employed moderate thermal annealing (up to 300 °C) to remove and control defect levels.
• Monitored defect variations using Raman spectroscopy, photoluminescence (PL), and electrical characterization.

Main Results:

• Al2O3 plasma successfully induced controllable sp3-type defects in graphene, which were substantially removed by thermal annealing.
• Similar defect control was observed in monolayer MoS2, evidenced by changes in the defect-related emission peak (Xb) in PL spectra.
• Demonstrated that plasma-induced defects in both materials can be restored to desired levels through controlled annealing.

Conclusions:

• Presented an efficient approach for reversible defect control in graphene and MoS2.
• Showcased defect engineering as a viable strategy for tailoring optical and electronic properties of 2D materials.
• Opened new avenues for designing functional graphene and MoS2-based optoelectronic and nanoelectronic devices.