I2DM: A Monte Carlo framework for ion irradiation on two-dimensional materials

Abstract

Recent years have witnessed a surge of research on the structure, property and performance engineering of two-dimensional (2D) materials by ion irradiation. Compared to the 3D counterparts, 2D systems exhibit drastically different and even counter-intuitive irradiation response, and an atomic insight into the ion bombardment and defect formation is essential. In this work, we develop a theoretical framework I2DM for simulating ion irradiation on two-dimensional (2D) materials using Monte Carlo (MC) algorithm. I2DM can generate incident ions with adjustable ion species, incident energy, ion fluence and incident angle. Based on binary collision approximation (BCA), the primary collisions, cascade collisions and defect recombination during irradiation process are explicitly described. As output, details on the defect type/yield and morphology of irradiated material are provided. We have performed systematic simulations on three typical 2D structures, including graphene, h-BN, and MoS₂ under different ion irradiation conditions, and reveal that the obtained results are in excellent agreement with the available experimental measurements and molecular dynamics data. The developed framework is generally applicable and computationally efficient, highly valuable for understanding the fundamental mechanism of ion irradiation on 2D systems and designing/optimizing low-dimensional structures for nanoelectronics, spintronics, optics, energy storage and environmental protection.

Program summary: Program Title: I2DM. CPC Library link to program files: https://doi.org/10.17632/pf2pz4fxj3.1. Licensing provisions: GPLv2. Programming language: Python. Supplementary material: Supplementary material is available. Nature of problem: A general MC framework for simulating ion irradiation on 2D materials; calculate the energy loss by nuclear stopping and electronic stopping; simulate primary/cascade collisions and defect recombination; predict defect type/yield and morphology of 2D target. Solution method: This framework uses BCA to describe nuclear stopping for the irradiation process; the energy loss by electronic stopping is computed by a semiempirical model combining Oen-Robinson model and Lindhard-Scharff model; simultaneous collision is included for describing many-body interaction; capture radius is introduced to simulate defect recombination.