Luminescent Nanocrystal Probes for Monitoring Temperature and Thermal Energy Dissipation of Electrical Microcircuit.

In this work, we present an experimental approach for monitoring the temperature of submicrometric, real-time operating electrical circuits using luminescence thermometry. For this purpose, we utilized lanthanide-doped up-converting nanocrystals as nanoscale temperature probes, which, combined with a highly sensitive confocal photoluminescence microscope, enabled temperature monitoring with spatial resolution limited only by the diffraction of light. To validate our concept, we constructed a simple model of an electrical microcircuit based on a single silver nanowire with a diameter of approximately 100 nm and a length of about 50 µm, whose temperature increase was induced by electric current flow. By driving electric current only along one half of the nanowire, we created a dual-function microstructure, where one section is a resistive heater, while the other operates as a radiator. Such a combination realistically reflects the electronic circuit and its thermal behavior. We demonstrated that nanocrystals distributed around this circuit allow for remote temperature readout and enable precise monitoring of the thermal energy propagation and heat dissipation processes, which are crucial for designing and developing highly integrated electronic on-chip devices.