Theoretical Computing of Nanocontact Resistance Between Atomic Force Microscope Tip and Gold Nanoparticles During Nanoindentation

Electrical characterization of nanostructures is useful in electronic applications as conducting wires, field-effect transistors, and single-electron tunneling transistors. The present work deals with the theoretical modeling of nanocontact resistance developed due to nanoindentation of the AFM tip on the gold nanoparticle. Validity of Maxwell and Sharvin model is discussed. Since the Fermi wavelength of the electrons in gold is smaller (0.5 nm) as compared with the contact radius of the tip (∼8–10 nm) hence Sharvin’s approach is used to predict the nanocontact resistance. The radius of contact between the tip and nanoparticle is given by Hertz formula which combines the elastic properties of the tip and the sample using effective elastic modulus. Two different types of tip — silicon tip and silicon tip coated with aluminium — are considered for the analysis. The variation of contact radius with the tip radius for two types of tips at specified contact forces during nanoindentation is shown. The dependence of the contact resistance on the contact radius is shown for two tips and interpreted in the physical domain.