  Boron (B)/phosphorus (P) doped single wall carbon nanotubes (B-PSWNTs) are
studied by using the First- Principle method based on density function theory
(DFT). Mayer bond order, band structure, electrons density and density of
states are calculated. It concludes that the B-PSWNTs have special band
structure which is quite different from BN nanotubes, and that metallic carbon
nanotubes will be converted to semiconductor due to boron/phosphorus co-doping
which breaks the symmetrical structure. The bonding forms in B-PSWNTs are
investigated in detail. Besides, Mulliken charge population and the quantum
conductance are also calculated to study the quantum transport characteristics
of B-PSWNT hetero-junction. It is found that the position of p-n junction in
this hetero-junction will be changed as the applied electric field increase and
it performs the characteristics of diode.
