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In this paper the electrical properties of InAs/InP nanostructures (wires and dots) were investigated using Kelvin probe electrostatic force microscopy and conductive atomic force microscopy techniques. Surface potential measurements were strongly affected by the presence of the thin InAs film at the top surface of the undoped InP buffer layer. These results and the electrical images suggest the suppression of the surface depletion region due to electron accumulation in InAs wires and dots. I–V spectroscopy shows the formation of a Schottky-type junction between the metal-coated Si tip and the semiconductor surface exposed to air. Larger conductances and different threshold voltages for current onset for the two types of nanostructure analysed here can be related to the particular electronic structure of InAs wires and dots.

We have studied the equilibrium electrostatic profile of III-V semiconductor nanowires using Kelvin probe force microscopy. Qualitative agreement of the measured surface potential levels and expected Fermi level variation for pure InP and InAs nanowires is obtained from electrical images with spatial resolution as low as 10 nm. Surface potential mapping for pure and heterostructured nanowires suggests the existence of charge transfer mechanisms and the formation of a metal-semiconductor electrical contact at the nanowire apex.

We investigate electrical properties of InAs/InP semiconductor nanostructures by conductive atomic force microscopy (C-AFM) and current measurements at low temperatures in processed devices. Different conductances and threshold voltages for current onset were observed for each type of nanostructure. In particular, the extremity of the wire could be compared to a dot with similar dimensions. The processed devices were used in order to access the in-plane conductance of an assembly of a reduced number of nanostructures. Here, fluctuations on I -V curves at low temperatures (<40 K) were observed. At these low temperatures and for a suitable range of applied voltages, random telegraph noise (RTN) in the current was observed for devices with dots. These fluctuations can be associated to electrons trapped in dots, as suggested by numerical simulations. A crossover from a semiconductor-like to a metallic transport behavior is also observed for similar parameters.

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