Relationships for the drift and diffusion components of the drain current in an MOS transistor

It is shown that, by taking into account the current-continuity equation, analytical expressions for both the drift and the diffusion components of the drain current in an MOST can be derived. Also, these current components, which can be expressed as a function of the surface potential values at the source and at the drain ends of the channel, are reported against the voltages applied to the device.