Controlling the Drain Side Tunneling Width to Reduce Ambipolar Current in Tunnel FETs Using Heterodielectric BOX

In this brief, we demonstrate using 2-D simulations that the use of a heterodielectric BOX (HDB) above a highly doped ground plane can control the tunneling width at the channel-drain interface and lead to a significant reduction in the ambipolar current in tunnel FETs (TFETs). The HDB consists of SiO2under the source and the channel regions, and HfO2under the drain region. When the thickness of the HDB is 25 nm and the ground plane is heavily doped, we show that the drain region at the channel-drain interface is effectively depleted. As a result, the tunneling width at the channel-drain interface increases leading to a complete suppression of ambipolar conduction in a TFET even when the gate voltage VGS= -0.8 V.