Structural and electronic properties of zigzag carbon nanotubes filled with small fullerenes

In this work we investigated the encapsulation of C 20 and C 30 fullerenes into semiconducting carbon nanotubes to study the possibility of bandgap engineering in such systems. Classical molecular dynamics simulations coupled to tight-binding calculations were used to determine the conformational and electronic properties of carbon nanotubes with an increasing fullerene concentration. We have observed that C 20 fullerenes behave similarly to a n-type dopant while C 30 can provide p-type doping in some cases. The combined incorporation of both types of fullerenes (hybrid encapsulation) into the same nanotube leads to a behaviour similar to that found in electronic pn-junctions. These aspects can be exploited in the design of nanoelectronic devices using semiconducting carbon nanotubes.