Influence of Fermi level pinning on contact potential difference measurements using Kelvin probe force microscopy

We theoretically investigated the influence of Fermi level pinning on contact potential difference (CPD) measurements conducted via Kelvin probe force microscopy (KPFM) on semiconductor surfaces. To systematically modulate the strength of the surface pinning, virtual surface states were introduced within the semiconductor band gap, and the density of states (DOS) was varied. The numerically simulated CPD values varied depending on the DOS of the surface states, reflecting the magnitude of the surface band bending (surface potential). However, we found that under certain conditions, the CPD values obtained by KPFM deviated from the physical quantities directly associated with the surface potential. Our results provide valuable insights for enhancing the accuracy of KPFM data analysis and interpretation.