Investigation of contact-force dependent effects in conductive atomic force microscopy on Si and GaAs

Abstract

In this work, we systematically investigated the force dependence of conductive atomic force microscopy on n-type Si and n-type GaAs. IV curves were recorded under different tip sample forces and the corresponding Schottky barrier heights were extracted. The force dependent barrier heights of the Si and GaAs samples showed distinct reproducible differences. At low forces, the Schottky barriers decrease with increasing force because the native oxide layer on both the Si and the GaAs sample surface has to be penetrated. At intermediate forces on the GaAs sample, the Schottky barrier showed a large forced dependent increase due to the pressure coefficient of the GaAs band gap. Furthermore, a sudden change in the Schottky barrier increase with tip force was interpreted as the Γ-X band crossover in GaAs.