Silicon based technology has received its technical limitation because of its unstable structure at nano-level. Carbon nanotube as an alternative material has attracted significant scientific efforts. Fabrication of Schottky diode using carbon nanotube is an open area of research to overcome this limit. In this study, we model the current of CNT Schottky diode under applied voltage. Parabolic band approximation on CNT induces Fermi-Dirac integral of order zero on its current voltage which is similar to the conventional one dimensional material. This model shows that its current has a weak dependence on temperature corresponding to the small applied voltage. It is quite different in high bias voltages which are independent of temperature. Based on this model, incremental effect of the carbon nanotube diameter has been explained by increasing the current with the applied voltage. The model presented in this paper is in good agreement with the reported data from experiments. This device can be used in the integrated circuit miniaturization.