Density functional theory calculations of the carbon nanotube based P–N junction by substitution of carbon atoms with B, N, Ge and Sn

Ab initio density functional theory calculations have been used to investigate the carbon nanotube-based P–N, N–P–N and P–N–P junctions. For this purpose, we have used a zigzag (5, 0) carbon nanotube and some of it’s derivatives, obtained by manually replacing carbon atoms with doping elements like B, N, Ge and Sn. To characterize the stability and electrical functionality of these structures, different quantum mechanical parameters such as Gibbs free energy, energy gap, dipole moment and density of states have been investigated. The obtained results indicate that the doping mechanism implemented for these structure designs, are highly promising for high speed diodes applications.