Using the tight-binding method based on density functional theory (DFT) calculations, the thermoelectric properties of pure and B/N doped carbon nanotubes (CNTs) are investigated in terms of temperature (T) and in the presence of external electric and magnetic fields. All thermoelectric properties for pure and doped structures increase with temperature and the increasing rate is stronger in the presence of the external fields. The electrical conductivity and heat capacity of pure CNTs is larger than doped structures. For pure and doped structures, the heat capacity increases linearly with T independent to the dopant atoms. In the presence of electric (magnetic) field, the electrical conductivity and heat capacity of pure CNT are smaller (larger) than that other. The thermoelectric functions are strongly dependent on the strength of applied electric field rather than electric field.
