Defect-mediated sputtering process of boron nitride during high incident angle low-energy ion bombardment

Abstract

Further development of hexagonal boron nitride (hBN) towards electronic devices requires the application of precise analytical techniques. High incident angle (¿ 65°) secondary ion mass spectrometry has been recently developed, and allows to reach atomic depth. However, the procedure has been optimized experimentally, and thus computer simulations are needed to validate and comprehend the experiment. It is revealed that a sample without any defects cannot be sputtered in such conditions — all ions are reflected from the surface. Only defects, particularly vacancies, can act as erosion centers. After prolong bombardment (dose in the range of 1017 ions cm-2), the number of defects and their sizes are sufficiently large that rapid removal of a top-most hBN layer can be observed. Computer simulations and additional experiments reveal that the sputtering process is defect-mediated and anisotropic — significantly more prominent along the incident direction.