Manipulation of defects on oxide surfaces via barrier reduction induced by atomic force microscope tips

We used theoretical modeling to propose possible mechanisms of defect manipulation using a noncontact atomic force microscope (NC-AFM) on a generic oxide, MgO. First, we simulated NC-AFM images of a Ca substitutional defect on the MgO surface aiming to help identify a site where tip polarity could be reliably identified, and as a possible target for manipulation. We conclude that controlled manipulation of substitutional ions on the MgO surface is not feasible due to the strength of the interaction within the surface. Secondly, we demonstrate that controlled manipulation of a charged surface O vacancy can be easily achieved via the reduction of a vacancy diffusion barrier by the tip electrostatic potential, which facilitates thermal vacancy diffusion.