A novel gate engineered L-shaped dopingless tunnel field-effect transistor
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A novel gate engineered L‑shaped dopingless tunnel field‑effect transistor Cong Li1 · Jiamin Guo1 · Haofeng Jiang1 · Hailong You1 · Weifeng Liu1 · Yiqi Zhuang1 Received: 5 March 2020 / Accepted: 15 April 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Recently, dopingless tunnel FET (DL-TFET) has emerged and gathered much attention, for it avoids the physical doping process and provides superior immunity against random dopant fluctuation. Nevertheless, it also suffers from low drive current and severe ambipolar effect. In order to overcome these problems, an L-shaped DL-TFET (LDL-TFET) with the gate engineering technique is proposed in this paper. In this device, the space between the source and the gate electrodes can be further optimized to reduce the tunneling distance, and hence boost the drive current. Also, without much fabrication difficulties, hetero-gate-dielectric (HGD) and tunneling gate (TG) structures can be utilized in the LDL-TFET. Benefiting from the modification of the band energy by HGD and TG, the source-channel tunneling distance is further reduced, while the drain-channel tunneling distance is enlarged. TCAD simulation results show that in comparison with planar DL-TFET (PDL-TFET), LDL-TFET offers better performance in terms of on-current, switch ratio, subthreshold slope, ambipolar current and RF parameters. It indicates that the LDL-TFET is a promising device for low-power RF and digital logic applications. Keywords TFET · L-shaped structure · Dopingless · Hetero-gate-dielectric · Tunneling gate
1 Introduction In order to overcome the fundamental limit of MOSFET on the subthreshold slope (SS), tunnel FET (TFET) has emerged as a potential replacement and attracted much attention [1–3]. It can be selected as a full or partial unit in convention CMOS inverter, 6T SRAM and DRAM to obtain lower power dissipation. The ideal TFET is based on the assumption that the abrupt tunneling junction has been created, for it is essential to provide efficient tunneling and achieve higher on-current ( Ion ) [4–6]. However, the diffusion of the dopant atoms makes it harder to create an abrupt junction with state-of-the-art technology [7, 8]. Besides, the random dopant fluctuation (RDF) becomes another severe problem in the heavily doped devices, resulting in larger off-current ( Ioff ), threshold voltage ( Vt ) variability, and highamplitude random telegraph noise (RTN) [9–11]. In order to solve the problems mentioned above, Kumar et al. proposed * Cong Li [email protected] 1
Wide Bandgap Semiconductor Technology Disciplines State Key Laboratory, School of Microelectronics, Xidian University, Xi’an 710071, China
a dopingless TFET (DL-TFET) using charge plasma concept [12]. In DL-TFET, the “ p+ ” source and “ n+ ” drain regions are induced with appropriate metal work functions. As a result, this device avoids the physical doping process and provides superior immunity against RDF [13–15]. For DL-TFET, it is worth noting that since the source and the drain regions are induce
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