Total ionization dose effects of N-type tunnel field effect transistor (TFET) with ultra-shallow pocket junction
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Total ionization dose effects of N‑type tunnel field effect transistor (TFET) with ultra‑shallow pocket junction Kai Xi1 · Jinshun Bi1,2 · Jiamin Chu3 · Gaobo Xu1 · Bo Li1 · Haibin Wang3 · Ming Liu1 · Majumdar Sandip4 Received: 25 November 2019 / Accepted: 11 May 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract N-type tunnel field effect transistors (TFETs) with Si1−xGex/Si hetero-junction in the ultra-shallow N+ pocket region have been fabricated. This paper investigates the total ionization dose (TID) effects on the electrical characteristics of these N-type TFET devices, including transfer and output characteristics, via a 60Co γ-ray irradiation source. TID has little impact on the on-state current for TFETs with and without P well. With the increase in total dose, however, a shift in the transfer characteristics, such as the off-state current and subthreshold slope is observed. Under the same TID condition, TFETs with P well exhibit more robustness as compared to TFETs without P well. The characteristics under room temperature and high temperature annealing conditions after irradiation are also investigated. The underlying mechanisms, such as the interplay among bulk trapped charge in gate oxide-induced inversion and interface trap-induced trap-assisted-tunneling, are identified by TCAD simulation and are discussed in detail. Keywords Tunnel field effect transistor · Logic device · Total ionization dose · γ-ray · Rad-hard
1 Introduction In the quest for achieving higher performance and functionality, even at lower power, the tunnel field effect transistor (TFET) has been explored as an alternative to the conventional transistor, MOSFET (metal–oxide–semiconductorfield-effect-transistor) [1–5]. With scaling down, the power supply voltage (VDD) and the off-state current (Ioff) need to be decreased. In addition, a steep subthreshold slope (SS) characteristic is required to achieve sufficient on-state current (Ion) to power the devices and circuits. However, in conventional MOSFET, the operation principle of thermionic * Jinshun Bi [email protected] * Gaobo Xu [email protected] 1
Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China
2
University of Chinese Academy of Sciences, Beijing 100029, China
3
School of Internet of Things Engineering, Hohai University, Changzhou 213022, China
4
Electrical and Computer Engineering Department, Sri Sri University, Godi Sahi, Cuttack, Orissa 754006, India
carrier injection requires the SS of the device to be greater than 60 mV/dec at room temperature. In principle, the TFET device is a gated PiN diode. In contrast to conventional MOSFETs, in which charge carriers are thermally injected over a barrier, the primary injection mechanism in a TFET is band-to-band tunneling (BTBT). TFET is recognized as a candidate for energy-efficient technologies due to its outstanding performance, such as its low SS, low IOFF, and high switching ratio (ION/IOFF), among others [6–8]. Hu et al. [8] reported carefully desig
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