In this paper, we have demonstrated that overlapping the gate on the drain can suppress the ambipolar conduction, which is an inherent property of a tunnel field effect transistor (TFET). Unlike in the conventional TFET where the gate controls the tunneling barrier width at both source-channel and channel-drain interfaces for different polarity of gate voltage, overlapping the gate on the drain limits the gate to control only the tunneling barrier width at the source-channel interface irrespective of the polarity of the gate voltage. As a result, the proposed overlapping gate-on-drain TFET exhibits suppressed ambipolar conduction even when the drain doping is as high as 1 × 10 19 cm −3 .INDEX TERMS Ambipolarity, overlapping gate-on-drain, TFET, tunneling barrier width, overlap length.

The source-pocket (p-n-p-n) tunnel field effect transistor (TFET) has a narrow and highly doped N + pocket layer between the source and channel to enhance the overall performance of the conventional p-i-n TFET. However, realizing this, N + pocket increases the fabrication complexity since either an epitaxial growth in vertical TFETs or an implantation in planar TFETs is required to create the N + pocket. In this letter, using the charge plasma concept, we propose a technique to realize an in-built N + pocket without the need for a separate implantation. We demonstrate using 2-D simulations that the proposed in-built N + pocket p-n-p-n TFET exhibits a higher I ON (∼20 times) and a steeper subthreshold swing (25 mV/decade) as compared with the conventional p-i-n TFET. Our approach overcomes the difficulty of creating a narrow N + pocket doping and thus makes the p-n-p-n TFET more attractive in carrying on with the scaling trend.Index Terms-Source-pocket (PNPN) TFET, tunneling, pocket implantation, steep subthreshold slope, 2D TCAD simulation.

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