Sample Preparation and Resistivity Measurements for Operando Transmission Electron Microscopy During Heating and...

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Material microstructure characterization is crucial for understanding properties.
• Thermoelectric devices operate under high temperatures and electrical bias, altering microstructures.
• In situ characterization requires specialized sample preparation techniques.

Purpose of the Study:

• To develop a method for preparing transmission electron microscope (TEM) samples on in situ microelectromechanical systems (MEMS) chips.
• To enable operando characterization of thermoelectric materials under heating and electrical biasing.
• To accurately measure electrical resistivity and contact resistance of thermoelectric materials.

Main Methods:

• Focused ion beam (FIB) lift-out technique for sample preparation on MEMS chips.
• Ion beam deposition of platinum-carbon (Pt-C) for electrical contact formation.
• In situ electrical measurements and focused ion beam (FIB) thinning for resistance analysis.

Main Results:

• Successful preparation of TEM samples on heating and biasing MEMS chips.
• Demonstrated reduction in contact resistance upon heating to 200 °C.
• Reliable measurement of electrical resistivity from high temperatures down to room temperature, independent of contact resistance.

Conclusions:

• The developed FIB-based sample preparation method is effective for in situ TEM studies of thermoelectric materials.
• The technique allows for accurate electrical resistivity measurements by mitigating contact resistance issues.
• This approach facilitates the understanding of microstructural evolution and its impact on thermoelectric device performance.