The effects of the impurity concentration and electric field strength on the electronic and thermal properties of carbon doped boron nitride nanotubes are investigated by the tight binding model, Kubo-Greenwood formula and Green function approach. The position, intensity and number of the density of sate peaks are affected by electric field strength F and dopant concentration which leads to band gap reduction in the doped boron nitride nanotubes compared to the pure boron nitride nanotubes. The thermal functions of the doped boron nitride nanotubes are zero first in very low temperature due to existing the large band gap and become zero by increasing the temperature until reach their maximum values at TM and finally decrease significantly in higher temperature above the TM. The increasing (decreasing) pattern in low (high) temperature region occurs due to the band gap modifications (scattering and collision between charge carriers) and for all selected structures, they are related to the electric field strength and doping concentration. The Lorenz number of the doped boron nitride nanotubes with and without the electric field has a peak with LMax intensity at TM which in the presence of the external electric field, it moves to lower temperature with decreasing intensity. By increasing the nanotube radius, the thermal properties of the doped boron nitride nanotubes increase in terms of the temperature and this behavior becomes valid in the presence of the electric field.
