Controlled electrical contact of a scanned probe to nanostructures

An optically guided scanned probe has been used to establish electrical contact with and obtain electrical characteristics of individual, identifiable nanostructures. Previous reports of measurements of the electrical characteristics of nanostructures have been obtained in vacuum and without knowledge or control of the amount of electrical contact. We describe new techniques for establishing controlled, nondestructive electrical contact to nanostructures in air that improve the reproducibility and interpretation of the electrical measurements. Repeated measurements of current (I)-voltage (V) relations during controlled approach of the probe tip to the sample surface permitted nondestructive establishment of electrical contact. The efficacy of the technique was determined by measuring the I-V characteristics of Schottky barriers as a function of temperature. An identifiable quantum dot resonant tunneling diode was then successfully characterized.