Molecular dynamics modeling of defect formation in many-layer hexagonal boron nitride

Abstract

Molecular dynamics simulations are conducted to examine lattice defect formation in a hexagonal boron nitride lattice by high-energy xenon ion impact. This work seeks to characterize the production of defects which occur under ion irradiation. Lattice defect formation is first examined in single-layer hexagonal boron nitride. Energetic xenon ions over a range of 10eV–10keV are used to randomly impact the central lattice at an angle of 90° (orthogonal to the lattice basal plane). The resulting defects are analyzed for 5000 ion impacts, and results are reported for average single and double vacancy formation per impact. A similar study is conducted for a many-layer hexagonal boron nitride lattice, to assess the influence of additional layers in the formation of point defects as a function of incident ion energy. Ion impacts at both 90° and 45° are examined. The defects formed in the top layer of the many-layer lattice are qualitatively similar to the single layer results, but the presence of the bulk lattice is found to reduce the single vacancy probability in the top-most layer. Point defects are prominent in the lattice sub-layers with increasing ion energy. Orthogonal ion impacts are found to cause the most damage, as measured by the number of vacancy defects produced; the number of vacancies increases linearly with energy, while the number of defects in the oblique impact configuration reaches an asymptotic limit with increasing energy.