Patterned growth of CNT pillars for thermal applications

The approach of minimizing structures in electronic devices has led to greater heat densities within the systems, which demands high performance heat sinks with even smaller dimensions. The low thermal conductivity of fluids such as air and liquids has been always a problem for heat transfer systems. To overcome this limitation heat transfer can be improved by introducing vertically aligned Carbon Nanotubes cylinders in the fluids because they have a unique cooling capability due to their anisotropic thermal conductivity and they increase the contact area for heat exchange. In addition, the capability of patterning surfaces is crucial to certain applications. For this reason we developed a procedure that allows us to grow patterned CNT systems. In the first part we will describe in details the steps leading to substrate patterning. In the second we will focus on the Carbon Nanotubes pillars, grown using a Chemical vapour deposition technique at 850 °C with Camphor and Ferrocene as precursors. Field emission electron scanning microscopy (FESEM) was used to study the surface morphology of CNT cylinders. The diameter of CNT pillars is as low as 275 micrometers. The diameter of single CNTs was in the range of 30-80nm. This system is suitable to use for heat transfer leading to significantly higher laminar heat exchange coefficients compared to flat surfaces.