Supported Two-Dimensional Materials under Ion Irradiation: The Substrate Governs Defect Production

Area of Science:

• Materials Science
• Nanotechnology
• Computational Physics

Background:

• Focused ion beams (FIB) are vital for patterning two-dimensional (2D) materials.
• Defect production mechanisms in supported 2D materials remain poorly understood, hindering parameter optimization.
• Existing research often overlooks substrate interactions during ion irradiation.

Purpose of the Study:

• To develop a computationally efficient model for simulating ion irradiation of supported 2D materials.
• To investigate defect production mechanisms, distinguishing contributions from direct impacts, backscattered ions, and substrate sputtering.
• To analyze damage in graphene and MoS2 on SiO2 substrates for various ion types and energies.

Main Methods:

• A hybrid simulation scheme combining analytical potential molecular dynamics and Monte Carlo simulations.
• Modeling irradiation of graphene and MoS2 on SiO2 substrates.
• Simulation of helium and neon ion impacts across a range of energies, including those relevant to Helium Ion Microscopy (HIM).

Main Results:

• Defect production is significantly influenced by backscattered ions and substrate-sputtered atoms, not just direct ion impacts.
• The presence of a substrate dramatically alters the extent of damage in 2D materials compared to freestanding systems.
• Damage contributions vary with ion energy and mass, impacting patterning resolution and material integrity.

Conclusions:

• The developed model provides crucial insights into defect formation in supported 2D materials under ion irradiation.
• Results highlight the importance of substrate effects in FIB applications, impacting imaging and patterning.
• Quantitative data aids in minimizing damage during HIM imaging and optimizing FIB patterning processes for 2D materials.