Experimental Investigation of Thermal Transport Mechanisms Through a Nanoscale Point Contact

Using a silicon nitride cantilever with an integral Si tip and a micro-fabricated Pt-C resistance thermometer placed close to the tip, we have measured the thermal contact resistance of a nanoscale Si point contact in an ultrahigh vacuum atomic force microscope at near room temperature. The temperature of the cantilever tip was observed to remain constant during approach to, while in contact with, and during retraction from the Si substrate, while a large temperature drop was observed at the points of contact and separation, suggesting negligible near-field radiation transport in the experiment reported here. Detailed contact mechanics calculations of the contact diameter and modeling of the nanocontact show that solid-solid conduction with phonon transmission coefficient of at least 0.12 is the dominant mode of heat transfer through the nanoscale contact.