Gate Tunnelling Current Model for Nanoscale MOSFETs with Varying Surface Potential

摘要

At nanoscale, the channel of metal oxide semiconductor field effect transistors (MOSFETs) acts like a potential well within which electron energy levels are quantized and a nonzero wavefunction is obtained at the oxide-semiconductor interface. As a result the gate tunnelling current has emerged a significant constraint in respect of scaling of ultrathin gate oxides. We have developed an analytical model considering varying surface potential with applied voltage for evaluating gate tunnelling current through thin dielectrics in nanoscale MOSFETs. The electron wavefunction has been calculated by treating the band profile in the channel as a triangular potential well. The tunnelling probability through the gate oxide has been evaluated using Jeffreys-Wentzel-Kramers-Brillouin approximation method. The tunnelling current density is estimated from the evaluated interface wavefunction along with the tunnelling probability. The results from the present model compare well with the published Mondal-Dutta model and the experimental data. The novelty of the present model lies in its simplicity and its analyticity requiring much less computational efforts for its implementation.