Thermoelectric voltage at a nanometer-scale heated tip point contact

We report thermoelectric voltage measurements between the platinum-coated tip of a heated atomic force microscope (AFM) cantilever and a gold-coated substrate. The cantilevers have an integrated heaterthermometer element made from doped single crystal silicon, and a platinum tip. The voltage can be measured at the tip, independent from the cantilever heating. We used the thermocouple junction between the platinum tip and the gold substrate to measure thermoelectric voltage during heating. Experiments used either sample-side or tip-side heating, over the temperature range 25275°C. The tipsubstrate contact is 4nm in diameter and its average measured Seebeck coefficient is 3.4VK ¹. The thermoelectric voltage is used to determine tipsubstrate interface temperature when the substrate is either glass or quartz. When the non-dimensional cantilever heater temperature is 1, the tipsubstrate interface temperature is 0.593 on glass and 0.125 on quartz. Thermal contact resistance between the tip and the substrate heavily influences the tipsubstrate interface temperature. Measurements agree well with modeling when the tipsubstrate interface contact resistance is 10 ⁸KW ¹.