Analysis of the Influence of Carrier Scattering in the Channel of a Metal/Insulator Tunneling Field Effect Transistor

A tunneling field effect transistor using CoSi2/Si/CdF2/CaF2 heterostructures on a Si substrate is theoretically studied. It is controlled by the electric field from the gate bias and saturation characteristics are expected even with a 5-nm-long channel. In the tunneling field effect transistor, carrier density in the channel increases when electrons tunneling from source to channel are scattered in the channel. Therefore, the transconductance and the transit velocity of electrons in the channel decrease. As a result, the cut-off frequency of the device decreases. A theoretical analysis shows that the cut-off frequency of a tunneling field effect transistor with a 5-nm-long channel is reduced by a factor of two compared to the value without scattering, when all the tunneling electrons are scattered in the channel.