Electrical Contact Resistance - Electron Microscopes
Electrical Contact Resistance – Electron Microscopes
Conductive nanoindentation involves passing a current through the indenter probe and sample interface. This technique has commonly been used to study stress-induced phase transformations, oxide fracture, MEMS contact switch resistance fatigue, nanoscale breakdown voltage, and piezoelectric material response. When performed in-situ, the combined electromechanical response can be characterized, while the current resulting from the electron beam of the microscope represents a constant offset which can be easily subtracted, leaving only the desired material response. Site-specific testing can be performed by confirming proper tip placement with electron microscope imaging. Through-tip electrical measurements can also be used to gain insight into electromechanical properties of micro- or nano-structures such as pillars and particles. Humidity or water adsorption effects are minimized by the vacuum environment of the electron microscope.
For 1D and 2D materials, a MEMS Electrical Push-to-Pull (E-PTP) device enables tensile testing while simultaneously measuring sample resistivity using a standard four-point measurement. The separation of current sourcing and voltage sensing electrodes allow accurate measurements of the electrical properties by elimination of contact and lead resistance on the measurement. Voltage sweeps can also be performed to measure IV curves, while true stress and strain are determined by monitoring and measuring specimen dimensions in the electron microscopes