Simulation of tunneling field-effect transistors with extended source structures

Abstract

Articles you may be interested inResponse to "Comment on 'Assessment of field-induced quantum confinement in heterogate germanium electron-hole bilayer tunnel field-effect transistor'" [Appl.Physical operation and device design of short-channel tunnel field-effect transistors with graded silicongermanium heterojunctions J. Appl. Phys. 113, 134507 (2013); 10.1063/1.4795777Silicon-based tunneling field-effect transistor with elevated germanium source formed on (110) silicon substrate Appl. Phys. Lett. 98, 153502 (2011); 10.1063/1.3579242Device physics and design of germanium tunneling field-effect transistor with source and drain engineering for low power and high performance applicationsIn this paper, we perform a study of novel source structures in double-gate (DG) Tunneling Field-Effect Transistors (TFETs) by two-dimensional numerical simulation of source structures in double gate tunneling field effect. Extended source structures are employed in both pure Ge TFETs and Ge-source Si-body TFETs, and on-state current enhancement is observed in simulation results. Compared with conventional p þ -p À -n þ TFETs, the p þ region in extended source TFETs extends underneath the gates. When large gate bias is applied, high electric field n, which distributes along p þ -p À junction edge extends into the middle of the channel. More tunneling paths with short lengths are available in the on-state, effectively boosting the drive current of TFET. In addition, the extent of performance enhancement depends on the geometry of the extended source. By incorporating heterojunction, TFET drive current can be increased further, which is up to 0.8 mA/lm at V GS ¼ V DS ¼ 0.7 V. V C 2012 American Institute of Physics.

Radio-frequency modeling of square-shaped extended source tunneling field-effect transistors

“…The sub-threshold slope is also improved due to the better uniformity distribution of the high electric field along sourcechannel region [25,27]. In addition, for the TFET with short extended source length, effectively boosting the on-current with off-current being unchanged.…”

“…In addition, for the TFET with short extended source length, effectively boosting the on-current with off-current being unchanged. This explains the large improvement in the I ON /I OFF ratio (more than 11 orders of magnitude) that is the importance of the extended source TFET [25]. The benefit of extended source design is more obvious for TFET when it is combined with other structures, such as the small band-gap materials or high-j dielectric materials.…”

“…Due to low on-current of silicon-based TFETs, different techniques have been suggested to improve the on-current. On-current of TFETs can be enhanced by using band-gap engineering [10][11][12][13][14][15][16][17], small band-gap materials [18,19], high-j dielectric materials [20], pocket doping [21][22][23], vertical direction tunneling [24] and extended source [25]. Second challenge is not fully the understanding device physics that causes questionable the applicability of WKB approximation for phonon or impurity scattering and indirect bandgap semiconductors, such as Si and Ge [26].…”

A 3D analytical modeling of tri-gate tunneling field-effect transistors

“…However, planar silicon-based TFETs have very low on-state currents (I on ) compared to conventional MOSFETs (typically three to five decades) because of poor band-to-band tunneling efficiency, which is a serious drawback in circuit applications. In order to improve the TFET on-state currents, several techniques have been adopted including heterostructures [4,8], band-gap engineering [9,10], low band gap and high mobility materials [11], gate engineering [12,13], vertical direction tunneling [14], extended source [15][16][17], and source-pocket doping (p-np-n) [18,19].…”

High-k Gate Stacks on Low Bandgap Tensile Strained Ge and GeSn Alloys for Field-Effect Transistors

“…Low bandgap semiconductors with a direct gap are particularly desired for novel low power devices such as tunnel-field effect transistors (Tunnel-FET). 7,8 In this context, the electronic band structure of Ge can be tuned by applying biaxial tensile strain 9 or by Sn alloying 10 towards a fundamental direct bandgap which enhances the tunneling probability and thus the ON-current of Tunnel-FETs 8,11,12 . Vertical Tunnel-FET structures using strained Ge channels were recently proposed based on InGaAs 13 and GeSn 11 buffer substrates.…”