Thermal management is an increasing area of demand for the performance of electronic devices as their dimensions continue to decrease. As a consequence, there is great interest in understanding the thermal properties of the devices and the mechanisms of heat dissipation. In addition, nanoscale studies of heat transport is of fundamental scientific interest, especially at dimensions smaller than the mean free path of the dominant heat carriers. The main challenge at these small dimensions is the interaction between the measurement tools and the samples. This can be overcome by the development of advance noncontact thermometry techniques.
We have developed a Transmission Electron Microscope (TEM) based thermal imaging technique to specifically enable the studies of heat dissipation phenomena in Joule heated devices. In-situ biasing experiments are conducted inside the TEM using metal heater wires fabricated on SiN TEM membranes. Monitoring the temperature of the SiN in real-time allows the understanding of the dissipation mechanisms. A similar thermometry setup, relying on the solid to liquid phase transition of indium islands , has been used to study heat dissipation in carbon nanotube and metal nanowires . Modifications of the previously used technique allow us to measure temperatures between 30-160 °C in a field of view that is larger than 50 um2 with sub 50nm spatial resolution. This gives us the ability to not only measure local temperature but also the temperature gradient across the membrane which acts as the cooling pathway for the heater wire, allowing the quantification of the heat dissipation and understanding the dominant transport mechanism.
1. Brintlinger, T., et al., Electron thermal microscopy. Nano Letters, 2008. 8(2): p. 582-585.
2. Baloch, K.H., et al., Remote Joule heating by a carbon nanotube. Nature Nanotechnology, 2012. 7(5): p. 315-318.