Observations of self-organized InAs nanoislands on GaAs (0 0 1) surface by electrostatic force microscopy

Ambient non-contact electrostatic force microscopy (EFM) experiments in the force and force gradient modes were carried out on InAs nanoislands, MBE-grown on a GaAs surface and passivated with nitrogen. Typical EFM and Kelvin voltage images for the InAs nanoislands were obtained. Electrical force images in air can resolved single InAs nanoislands with a height down to 1 nm and a diameter of 15 nm. The contrast of the EFM images was strongly influenced by the tip-individual nanoisland capacitive coupling. Local Kelvin voltage measurements revealed variations in surface contact potential, Vcp, between InAs nanoislands and the GaAs surface in the 40 mV range for the highest nanoisland. The Vcp variations are attributed to the different nature of InAs and GaAs materials.