Scanned electrical probe characterization of carrier transport behavior in InAs nanowires

Conductive atomic force microscopy combined with detailed calculations of electronic subband structure has been used to analyze electron transport behavior across the transition between ballistic and drift/diffusive motion in InAs nanowires grown by metal organic chemical vapor deposition. Using a conducting tip in an atomic force microscope as a local, positionable electrical probe, InAs nanowire resistance as a function of electron transport distance within the nanowire has been measured. For distance of ∼200nm or less, this resistance is observed to be nearly independent of distance, while for larger distances the resistance increases linearly with distance. Analytical calculations indicate that a resistance only weakly dependent on distance should be observed for distances up to a few times the electron mean free path, and calculations of the mean free path using a variety of approaches yield values in the range of ∼50nm, very consistent with the observation of distance-independent resistance for transport distances up to ∼200nm.