Fig. 5. Finite element modeling of hole transport across an individual step edge. (a) Experimental and simulated CG-TC SECCM responses, utilizing diffusion lengths determined from basal plane measurements as inputs. An effective surface charge at the step edge surface was varied between 0 and −8 mC m⁻² in 1 mC m⁻² increments. Simulations were carried out for the sheet geometry depicted in Fig. 4, assuming diffusion lengths of L_xy = 2.8 µm and L_z = 5.8 nm. (b) Simulated potential (φ) and hole concentration (C) profiles in the vicinity of the step edge defect in the absence or presence of a −5 mC m⁻² surface charge.