The team has shown that the tip loading force can affect electrical measurements of gold nanoparticle-strontium titanate (STO) interfaces. The conductive tip contacts the nanoparticles and closes the electrical circuit thanks to a built-in module. In this study, the voltage was applied through the particle/oxide interface, and current simultaneously measured.

The current response is very sensitive to the contact quality between the tip and the nanoparticle and can be improved by increasing the loading force. Interestingly, the researchers found negligible nanoparticle deformation for loading forces in the nN–µN range because the induced stress in this range is still lower than the yield stress of gold nanoparticles.

As mentioned in a recent publication by the same group, improving the current-voltage response requires a sufficiently high loading force for good contact in nanoscale electrical measurements. A larger loading force is believed to effectively "tear off" any contaminated layers of the commercial conductive tips, and thus improves intimate contact between the two surfaces. On the other hand, the applied stress should be lower than the yield stress of the metal particles to protect the nanoparticle and the tip. Therefore, tip loads on the order of tens to hundreds of nN are high enough to investigate local electrical properties.

In conclusion, this work could help improve electrical measurements on the nanoscale in the future.

More detailed information can be found in the journal Nanotechnology 24 395703.

Further reading

Phenomenological model uses CAFM to characterize tunnel-junction-like devices (Nov 2012)