Performance investigation of a semi‐junctionless type II heterojunction tunnel field effect transistor in nanoscale regime

Abstract

In this work, the electrical characteristics and impact of physical and structural parameters on the performance of a novel heterojunction GaAs 0.1 Sb 0.9-InAs semi-junctionless tunnel field effect transistor (SJTFET) is demonstrated. Unlike the conventional p-in tunnel field effect transistor, the n-channel SJTFET is a p +-p +-n structure having similar doping profile for the source and channel regions. First, all the structural and physical parameters are set to their initial values, and then, one parameter is varied to investigate its variation effect on the performance of SJTFET. Standard deviation and mean value of subthreshold swing, off-state and on-state current manifests that the performance of SJTFET is more sensitive to the gate workfunction, source-channel doping density and gate oxide thickness, respectively, in comparison with other structural parameters. The two-dimensional variation matrix of off-state current, on-state current and threshold voltage is calculated as a function of gate workfunction and source-channel p + doping density for determining an optimum value for the source-channel doping concentration and gate workfunction. Due to the n-p + drain-channel junction, the tunnel barrier in the off-state mode can be increased into the drain region, providing low off-state current in the ultra-scaled device and makes this device become less sensitive to short channel effects.

Investigation of the impact of mole-fraction on the digital benchmarking parameters as well as sensitivity in GaXIn1−XAs/GaYIn1−YSb vertical heterojunctionless tunneling field effect transistor

“…Equation 1 shows the probability of tunneling in a TFET device, in which Wentzel-Kramers-Brillouin approximation is used [12,16].…”

“…Nonlocal BTBT model considers spatial variations of energy bands and quasi-fermi levels in tunneling path [22,29]. The Hansch model is used to consider the quantum confinement effect as well as interface defects of oxide/semiconductor [12,29]. The dependence of the mobility on the vertical electric field, doping concentration, and temperature is considered using Lombardi model [22,29].…”

“…However, the ultra-sharp doping concentration gradient in the source/channel and the drain/channel junctions complicates the fabrication process of TFET device in nanometer regime [6,7]. Recently, a junctionless TFET (JLTFET) has been proposed, in which issues caused by ultra-sharp doping concentration gradient in the source/channel and the drain/channel junctions are eliminated [6][7][8][9][10][11][12]. JLTFET is a heavy doped thin film semiconductor, in which the type and level of doping are unchanged throughout the device.…”

“…Our simulation results show that selecting a material with larger band gap in the drain-channel region as well as a material with smaller band gap in the source region in VHJL-TFET device drastically reduce the ambipolarity behavior. Based on the simulation results, the improvement of the SS and ON-state current to OFFstate current (ION/IOFF) ratio of VHJL-TFET structure with Y=0.85 and X=0.8 is noticeable compared to the recently proposed structures [11,12,18,21,22,26]. With changes in X and Y, in addition to energy band gap and electron affinity, the electron tunneling effective mass and hole tunneling effective mass are also changed [27].…”