Thermoelectric voltage at a nanometer-scale heated tip point contact

Area of Science:

• Materials Science
• Nanotechnology
• Physics

Background:

• Atomic Force Microscopy (AFM) is a powerful tool for nanoscale imaging and manipulation.
• Thermoelectric effects, such as the Seebeck effect, can be harnessed for temperature sensing.
• Accurate measurement of tip-substrate interface temperature is crucial in many AFM applications.

Purpose of the Study:

• To investigate thermoelectric voltage generation between a heated AFM tip and a gold substrate.
• To determine the Seebeck coefficient of the platinum tip-gold substrate junction.
• To utilize thermoelectric voltage for measuring tip-substrate interface temperature on different materials.

Main Methods:

• Utilized a heated AFM cantilever with a platinum-coated tip and a gold-coated substrate.
• Measured thermoelectric voltage generated at the tip-substrate junction during heating (25-275°C).
• Employed both sample-side and tip-side heating configurations.

Main Results:

• Measured an average Seebeck coefficient of 3.4 μV K⁻¹ for the tip-substrate contact (∼4 nm diameter).
• Successfully determined tip-substrate interface temperatures on glass and quartz substrates using thermoelectric voltage.
• Observed significant influence of thermal contact resistance on interface temperature, with good agreement with modeling at 10⁸ K W⁻¹.

Conclusions:

• Thermoelectric voltage measurements provide a viable method for determining tip-substrate interface temperature in AFM.
• Thermal contact resistance is a critical parameter affecting nanoscale temperature measurements.
• The developed technique offers potential for advanced thermal characterization at the nanoscale.