Quantitative probing of tip-induced local cooling with a resistive nanoheater/thermometer

Abstract

This article reports the investigation of tip-induced local cooling when an atomic force microscope (AFM) cantilever tip scans over a joule-heated Pt nanowire. We fabricated four-pointprobe Pt resistive nanothermometers having a sensing area of 250 nm x 350 nm by combining electron-beam lithography and photolithography. The electrical resistance of a fabricated nanothermometer is similar to 27.8 Omega at room temperature and is linearly proportional to the temperature increase up to 350 K. The equivalent temperature coefficient of resistance is estimated to be (7.0 +/- 0.1) x 10(-4) K-1. We also joule-heated a nanothermometer to increase its sensing area temperature up to 338.5 +/- 0.2 K, demonstrating that the same device can be used as a nanoheater. An AFM probe tip scanning over a heated nanoheater/thermometer's sensing area induces local cooling due to heat conduction through solid-solid contact, water meniscus, and surrounding air. The effective contact thermal conductance is 32.5 +/- 0.8 nW/K. These results contribute to the better understanding of tip-substrate thermal interactions, which is the fundamental subject in tip-based thermal engineering applications. Published by AIP Publishing.