Controlling the kink angle of intramolecular carbon nanotube junctions: A combined experimental and theoretical study

Intramolecular carbon nanotube (CNT) junctions are nanotubes with kinks generated by heptagon-pentagon defect pairs. They are very attractive functional building blocks for future electronics, as they can be used as diodes and transistors. Usually CNT junctions are synthesized incidentally [1]. Using chemical vapor deposition techniques we are trying to grow CNT junctions in a more controlled way. In particular, we want to control the kink angle in order to produce junctions with well defined electronic properties. Our approach raises the question: Are there special kink angles that induce a certain change in electronic properties? In order to answer this question we developed a scheme that allows generating the atomic structure of CNT junctions with an arbitrary number of heptagon-pentagon defects. To break down the large number of different geometrical possibilities to achieve a CNT junction with a specific angle we study the energetics of different defect combinations and discuss the implication of these results for the experimental realization of well defined CNT junctions. [1] Wei et al., Adv. Mater. 20, 2815 (2008).