Resistivity of Thin Films
Developing a Four Point Probe
Macklin Johnson
Dixie State University
Introduction
Method
Four point probes eliminate contact
resistance, allowing for more accurate
measurements of thin film resistance.
Needle spacing = 1 cm
Results
Probe Components
• Four sewing needles composed of
chrome-plated steel
Current (I) is passed through outer probes
• Copper conducting wire
Voltage (V) is measured across inner
probes
Resistivity is calculated by applying
𝑉
geometry factors to 𝑅 =
• Hot glue secures needles and allows
springiness
Springiness of glue allows all needles to contact sample simultaneously
𝐼
Conclusion
Results
Aim
Results
To create a four point probe that will
consistently and accurately measure
resistivity of thin films
Measuring the resistivity of thin films is done
using a four point probe. Voltage is
measured when a known current is sent
through the probes. Resistivity is then
calculated using a modified version of
𝑉
𝑅 = , where factors have been applied to
𝐼
account for geometry of sample.
Acknowledgements
Dr. Samuel Tobler, mentor
Dixie State University
Using the four point probe to measure the
resistivity of a gold film sample
A four point probe used to test resistivity of thin films
Collinear probes are evenly spaced to allow for
consistent measurements
Utah NASA Space Grant Consortium,
funding