1f:T416,Three different carbon nanotube (CN) field-effect transistor (CNFET) designs are compared by simulation and experiment. While a C-CNFET with a doping profile similar to a "conventional" (referred to as C-CNFET in the following) p-or n-MOSFET in principle exhibits superior device characteristics when compared with a Schottky barrier CNFET, we find that aggressively scaled C-CNFET devices suffer from "charge pile-up" in the channel. This effect which is also known to occur in floating body silicon transistors deteriorates the C-CNFET off-state substantially and ultimately limits the achievable on/off-current ratio. In order to overcome this obstacle we explore the possibility of using CNs as gate-controlled tunneling devices (T-CNFETs). The T-CNFET benefits from a steep inverse subthreshold slope and a well controlled off-state while at the same time delivering high performance on-state characteristics. According to our simulation, the T-CNFET is the ideal transistor design for an ultrathin body three-terminal device like the CNFET.20:T4e4,Experimental data from undoped-body gate-all-around (GAA) silicon nanowire (NW) MOSFETs with different sizes demonstrate the universality of short-channel effects as a function of L _EFF /λ, where L _EFF is the effective channel length and λ is the electrostatic scaling length. Data from undoped-body single-gate extremely thin SOI (ETSOI) devices additionally show that the universality of short-channel effects is valid for any undoped-body fully depleted SOI MOSFET. Our data indicate that L _EFF of undoped GAA NW MOSFETs can be scaled down by ~2.5 times compared with undoped single-gate ETSOI MOSFETs while maintaining equivalent short-channel control.21:T43f,In this brief, a novel U-shape-channel tunneling field-effect transistor (UTFET) with a SiGe source region is investigated by 2-D technology computer aided design simulation. The enlarged tunneling area and enhanced tunneling rate dramatically increase the tunneling current when the device is turned on. Meanwhile, the off-leakage current of UTFET is suppressed because of the extended physical channel length. The on-state tunneling current of UTFET can be further improved by introducing an n ⁺ -doped Si delta layer under the source region. The inserted delta layer significantly shortens the band-to-band tunneling path, enlarges tunneling area, and thus enhances the tunneling rate of this device. The average value of the subthreshold swing (SS) of the optimized UTFET is 58 mV/dec when VGS is varied from 0 to 0.46 V. Using the SiGe-source UTFET structure with a delta layer, the merits of low leakage current, high drive current, and ultralow SS can be realized simultaneously.22:T70f,

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