FURI | Fall 2020

Radiative Heat Transfer Measurement at Nanoscale Vacuum Gaps

Near-field thermal radiation across nanoscale vacuum gaps is predicted to achieve heat flux that exceeds blackbody limit. The objective of this project is to experimentally demonstrate the super-Planckian radiative heat transfer with a home-built thermal metrology that uses a laser-heated AFM bi-material probe. The temperature change of the silica microsphere attached to the probe tip can be measured from the deflected laser signal due to cantilever bending at different vacuum gaps away from the flat substrate, controlled by a piezo-stage with single nanometer resolution. As the substrate gets closer, the cantilever will increasingly bend due to the temperature drop as it radiates more heat to the substrate. The novel near-field thermal metrology will be calibrated, and different probes such as a Pyrex-based one will be tested for possibly higher measurement sensitivity due to smaller thermal conductance than the silicon-based ones.