Switching Mechanism and the Scalability of Vertical-TFETs

In this brief, vertical tunnel field-effect transistors (v-TFETs) based on vertically stacked heretojunctions from 2-D transition metal dichalcogenide materials are studied by atomistic quantum transport simulations. The switching mechanism of a v-TFET is found to be different from previous predictions. As a consequence of this switching mechanism, the extension region where the materials are not stacked over is found to be critical for turning off the v-TFET. This extension region makes the scaling of v-TFETs challenging. In addition, due to the presence of both positive and negative charges inside the channel, v-TFETs also exhibit negative top gate capacitance. As a result, v-TFETs have good energy-delay products and are one of the promising candidates for low-power applications.