Bombarding Graphene with Oxygen Ions: Combining Effects of Incident Angle and Ion Energy To Control Defect Generation
ZT Bai and L Zhang and L Liu, JOURNAL OF PHYSICAL CHEMISTRY C, 119, 26793-26802 (2015).
Ion bombardment is a key physical process in the ion implantation and irradiation of graphene, with important implications for tuning graphenes electronic properties and for understanding the materials behavior in irradiative environment. Using molecular dynamics with a reactive force field, this work systematically investigates the influence of the incident angle on the generation of defects and vacancies during the bombardment process. It is found that larger incident angles (between the incident line and the surface of graphene) ranging from 70 degrees to 90 degrees are desired for substitution and single vacancy, whereas smaller incident angles ranging from 30 degrees to 50 degrees are favored for forming double vacancies, multiple vacancies, and in-plane disorder. Oxygen ions with the incident angle of 70 degrees produce the highest probability of ion substitution, and the ions at 40-60 eV and 70 degrees yield the highest quality of doping with minimum other defects. These results demonstrate that bombarding graphene along oblique directions may be a promising approach to effectively and efficiently modify graphene for wide applications in nanoelectronics. The angle/energy-damage relationships developed by this study are expected to guide future efforts in ion implantation and to improve the understanding of various irradiation processes.
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