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

This paper investigates the impact of backgate biasing (V_BS) on the drain current (I_D) 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_OFF (I_D at VGS = 0 V and V_DS = 0.5 V) modulation efficiency and the influence of V_BS rapidly decreases with increasing V_GS. In addition, it is observed that the change of source available states with V_BS determines the I_D modulation efficiency of p-type HTFET (pHTFET). Depending on the source doping concentration and operating VGS, the I_D of HTFET under forward V_BS can be anomalously smaller than that at V_BS = 0 V. Furthermore, the impacts of source/drain doping concentrations and junction properties are discussed and shown to be critical in determining the I_D modulation efficiency of HTFET. We find that, under controlled ambipolar current, reverse backgate biasing can be utilized to suppress the I_OFF 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.