Design and Investigation of a Dual Material Gate Arsenic Alloy Heterostructure Junctionless TFET with a Lightly Doped Source

Abstract

This paper designs and investigates a novel structure of dual material gate-engineered heterostructure junctionless tunnel field-effect transistor (DMGE-HJLTFET) with a lightly doped source. Similar to the conventional HJLTFET, the proposed structure still adopts an InAs/GaAs0.1Sb0.9 heterojunction at source and channel interface and employs a polarization electric field at the arsenic heterojunction induced by the lattice mismatch in the InAs and GaAs0.1Sb0.9 zinc blende crystal to improve band to band tunneling (BTBT) current. However, the gate electrode is divided into three parts in DMGE-HJLTFET namely the auxiliary gate (M1), control gate (M2) and tunnel gate (M3) with workfunctions ΦM1, ΦM2 and ΦM3, where ΦM1 = ΦM3 < ΦM2, which not only improves ON-state current but also decreases the OFF-state current. In addition, a lightly doped source is used to further decrease the OFF-state current of this device. Simulation results indicate that DMGE-HJLTFET provides superior metrics in terms of logic and analog/radio frequency (RF) performance as compared with conventional HJLTFET, the maximum ON-state current and transconductance of the DMGE-HJLTFET increases up to 5.46 × 10−4 A/μm and 1.51 × 10−3 S/μm at 1.0 V drain-to-source voltage (Vds). Moreover, average subthreshold swing (SSave) of DMGE-HJLTFET is as low as 15.4 mV/Dec at low drain voltages. Also, DMGE-HJLTFET could achieve a maximum cut-off frequency (fT) of 423 GHz at 0.92 V gate-to-source voltage (Vgs) and a maximum gain bandwidth (GBW) of 82 GHz at Vgs = 0.88 V, respectively. Therefore, it has great potential in future ultra-low power integrated circuit applications.

Study of a Gate-Engineered Vertical TFET with GaSb/GaAs0.5Sb0.5 Heterojunction

“…Another important parameter to measure the analog performance of devices is output transconductance (g ds ), which can be calculated by the first derivative of the drain current (I ds ) with respect to V DS , as shown in Equation (3) [ 35 ]: …”

“…In this paper, a novel structure of dual material gate heterogeneous dielectric vertical TFET (DMG-HD-VTFET) with a lightly doped source-pocket is designed and investigated. Compared with our previous work, the technological realization of this structure is greatly improved due to the use of top–down nanofabrication technology, while its performance is similar to other structures [ 35 , 36 , 37 ]. DMG-HD-VTFET adopts a GaSb/GaAs 0.5 Sb 0.5 heterostructure at the source/source-pocket interface to improve the band-to-band tunneling (BTBT) current, and it uses intrinsic GaSb as channel material and GaAs as drain material.…”

“…As illustrated in Figure 6a, the maximum drain saturation current of DMG-HD-VTFET under Vgs = 0.5 V is 3.47 × 10 −5 A/μm, whereas the maximum drain saturation currents of VTFET and HD-VTFET in this condition are only 3.70 × 10 −6 A/μm and 4.15 × 10 −6 A/μm. Another important parameter to measure the analog performance of devices is output transconductance (g ds ), which can be calculated by the first derivative of the drain current (I ds ) with respect to V DS , as shown in Equation (3) [35]:…”

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

“…The reason is that the forbidden band width is so large that it reduces the electron tunneling probability in tunneling junction [6,11]. With the recent progress, the low ION problem in JLTFET has been resolved by various strategies, such as using small band gape materials [15,16] gate engineering [17,18]. and hetero-gate dielectric [11,19].…”

“…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].…”