On-device synthesis of customized carbon nanotube structures

Carbon nanotubes are known for their excellent mechanical and electrical properties, that have fostered a vast number of applications during the last two decades. Direct integration of CNTs into devices is not straightforward, as high growth temperatures (over 600 centigrade) challenge the stability of the applied substrate. However, by decreasing growth temperature and working out protocols that take into account the thermal stability of the materials involved, it is possible to create several new types of architectures and devices with functionalities not shown before. In this work, we show that, with selection of the appropriate substrate, diffusion barrier and catalyst materials, direct growth of functional CNT films and their micropatterns may be achieved, not only on Si chips, but also on other atypical surfaces, using chemical vapor deposition.

This thesis explores low-temperature Carbon nanotube growth over bi- and trimetallic catalysts and investigates the effect of barrier layers on the electrical properties of substrate-to-nanotube contacts. On one hand, the lowest achieved carbon nanotube growth temperature (400 centigrade) is compatible with most silicon technologies, thus enabling direct integration of CNTs with materials that are not compatible with high temperatures. On the other hand, the results of barrier layer studies enabled growth of carbon nanotubes on metals for supercapacitors applications. In addition, we also show a method where laser-treatment of steel and superalloy surfaces enabled micropatterned carbon nanotube growth. Furthermore, we present CNT growth on carbon materials and demonstrate entirely carbon-based hierarchical composites for electromagnetic interference shielding applications, exhibiting outstanding shielding performance.