Pocket engineered electrostatically doped tunnel field effect transistor

Abstract

In this paper, we propose the use of pockets to improve the performance of an electrostatically doped double-gate tunnel field effect transistor. The required n-i-p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> structure for tunneling is formed on a thin intrinsic silicon film by electrostatic doping based on charge plasma concept. The source, drain and gate electrodes of different workfunctions are employed to form the p-type, n-type and intrinsic regions. Analysis using 2D TCAD simulations suggest that the proposed structure can significantly overcome the low I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> and ambipolarity problem in conventional dopingless tunnel field effect transistor (DLTFET). The n-type pocket in channel and p-type pocket in source provides noteworthy improvement in the transfer characteristics of pocket engineered (PE) DLTFET. The proposed PE-DLTFET offers higher I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> (2.4x10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> A), high ION/IOFF ratio ~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> and lower subthreshold slope (SS) of 42 mV/dec. We also propose an n-type pocket in the channel adjacent to the drain region to reduce the inherent ambipolarity in DLTFET. The results show that PE-DLTFET effectively suppresses ambipolarity and offers 25x higher I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> as compared to DLTFET, making it a viable candidate for switching applications.