Kelvin probe force microscopy on III-V semiconductors: the effect of surface defects on the local work function

The application of Kelvin probe force microscopy (KPFM) in ultra high vacuum (UHV) allows to determine the absolute work function of surfaces with a very high energy (<5 meV) and lateral (<20 nm) resolution. We present measurements on different UHV cleaved III-V compound semiconductors. The (110)-surface shows work function variations due to defect states at step edges. We observed band bending on the (110)-surface of GaAs from surface photovoltage measurements. Finally, we discuss the influence of the previous effects on KPFM measurement of a UHV cleaved GaP pn-homojunction. Due to the long range nature of the electrostatic forces the geometry of the tip, cantilever and sample plays an important role in KPFM