In this paper, we have developed a rigorous model for the quantum mechanical source to drain electron/hole tunneling in sub 10nm nanometer scale metal-oxide-semiconductor field effect transistor (MOSFETs). Inversion layer quantization, band-gap narrowing, drain induced barrier lowering (DIBL) and variable doping at source and channel have been included in the developed model. Results predict that the source to drain tunneling results in an increase of leakage currents in sub 10nm MOSFETs and hence cannot ignored. The results match closely with the numerical results already reported in literature proving the accuracy of the model
