Investigation of Backgate-Biasing Effect for Ultrathin-Body III-V Heterojunction Tunnel FET

Abstract

This paper investigates the impact of backgate biasing (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BS</sub> ) on the drain current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> ) of ultrathin-body III-V heterojunction tunnel FET (HTFET). Compared with homojunction TFET and III-V/Ge MOSFET, this paper indicates that HTFET exhibits significantly higher I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> at VGS = 0 V and V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> = 0.5 V) modulation efficiency and the influence of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BS</sub> rapidly decreases with increasing V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</sub> . In addition, it is observed that the change of source available states with V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BS</sub> determines the I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> modulation efficiency of p-type HTFET (pHTFET). Depending on the source doping concentration and operating VGS, the I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> of HTFET under forward V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BS</sub> can be anomalously smaller than that at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BS</sub> = 0 V. Furthermore, the impacts of source/drain doping concentrations and junction properties are discussed and shown to be critical in determining the I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> modulation efficiency of HTFET. We find that, under controlled ambipolar current, reverse backgate biasing can be utilized to suppress the I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> of HTFET, and the modulation efficiency increases with decreasing source doping concentration. Our study may provide insights for device/circuit designs with advanced TFET technologies.