Ballistic Conductance of a Swnt with a Positive Charge at Its Surface

The use of carbon nanotubes for nanoelectronics has been recently demonstrated The success in creating these eld e ect devices motivated further studies of electrochemical and chemical analogues In the present work we have simulat ed the modi cation of the conductance of a single wall carbon nanotube SWNT by applying a local electric eld of a charge placed near the surface of the nanotube The di erence between our calculations and what has been previously done is in perform ing a full selfconsistent electrostatics calculation for the SWNT electronic structure which allows to obtain a more precise band bending picture at the equilibrium in a continuum approximation This paper presents the calculations of a ballistic conductance for a zigzag SWNT whose valence band bends due to an external electrical potential created by a single charge near the SWNT surface We considered the p doped SWNT because this type of doping is widely observed experimentally The external potential creates a barrier for the holes to penetrate on their way from one end of the nanotube device to the other The hole transmission coe cient is calculated quantum mechanically taking into account the semiclassical tunneling It is not possible to treat the whole problem with the same level of accuracy at the same level of the theory complexity because a the system size is too large to implement a full quantum mechanics description b the system does not remain in the ground state and therefore it requires selfcon sistent modeling and c interactions between subsystems which are the charge and the SWNT are not necessarily weak which prohibits the use of continuum modeling at every step Thus the problem must be solved within a multiscale approach i