Modelling the drain current

Summary

The problem of modelling the drain current in a tunnel field‐effect transistors (TFET) can be divided into two major parts, finding the surface potential and finding the tunnelling rate. This chapter outlines the common methods used to find the tunnelling rate in a TFET for obtaining the drain current in the device. It discusses the local and non‐local methods used to find the tunnelling probability in TFETs. In non‐local models, the most widely used method to calculate the tunnelling probability is the WKB approximation. The chapter considers the WKB approximation to find the probability of an electron in the valence band of the source tunnelling to the conduction band of the channel. The local methods to calculate the current in a TFET provide a suitable alternative they are able to predict the sub‐threshold current and can incorporate the effects of the varying electric field throughout the device.