Tunnel Field-Effect Transistors: Prospects and Challenges

Avci, Uygar E.; Morris, Daniel; Young, Ian A.

doi:10.1109/jeds.2015.2390591

Cited by 415 publications

(180 citation statements)

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“…As the TFET current is dependent on the barrier shrinking in the sourcechannel interface, the resulting CGS is shown much lower than CGD when the transistor is active [13,14] The lower gate-capacitance of TFETs in comparison with Si MOSFETs can reduce the dynamic power consumption and delays of digital circuits as shown in [15]. In digital logic, the uni-directional conduction of TFET devices and the enhanced Miller capacitance can result in bootstrapped nodes within the circuit, causing potential failures and reliability risks [15,16]. In conventional MOSFETs , charges can be transferred under both positive and negative VDS bias due to a similar doping structure in the source and drain junctions.…”

Section: Tunnel Fet Intrinsic Capacitancementioning

confidence: 99%

“…19, it is shown that despite the lower efficiency values at RF VAC values above 0.3 V, the FinFET-based GCCR presents the highest output voltage values. This characteristic is explained due to the higher current conducted by FinFETs at voltage values above 0.25 V when compared to heterojunction Tunnel FETs [15]. V. CONCLUSIONS In this work, the TFET device is explored as an alternative technology for front-end energy harvesting circuits as chargepumps and rectifiers.…”

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confidence: 99%

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Insights Into Tunnel FET-Based Charge Pumps and Rectifiers for Energy Harvesting Applications

Cavalheiro

Moll

Valtchev

2017

IEEE Trans. VLSI Syst.

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Abstract-In this work the electrical characteristics of Tunnel FET (TFET) devices are explored for energy harvesting frontend circuits with ultra-low power consumption. Compared to conventional thermionic technologies the improved electrical characteristics of TFET devices are expected to increase the power conversion efficiency (PCE) of front-end charge-pumps and rectifiers powered at sub-μW power levels. Under reverse bias conditions the TFET device presents particular electrical characteristics due to the different carrier injection mechanism. A negative differential resistance (NDR) is observed at low reverse bias and high drift diffusion (DD) current is observed at high reverse bias, thus degrading the efficiency of low-power front-end circuits and limiting their operation range. Therefore, in order to take full advantage of the TFET electrical characteristics in front-end energy harvesting circuits, different circuit approaches are required. In this work we propose and discuss different topologies for TFET-based charge-pumps and rectifiers for energy harvesting applications.Index Terms-Charge-Pump, Energy Harvesting, Passive Rectifier, Thermogenerator, Tunnel FET, Ultra-Low Power. I. INTRODUCTIONHE emerging Tunnel Field-Effect Transistor (TFET) has been considered an attractive alternative to replace conventional CMOS technologies in ultra-low power and energy efficient computing applications [1][2][3][4][5][6][7]. In contrast to thermionic devices, the high energy filtering of the band -toband tunneling (BTBT) carrier injection mechanism characterizes the TFET device with a sub-threshold slope (SS) below 60 mV/dec (at room temperature) and lower leakage current.Simulation results show that TFET devices present better electrical characteristics than conventional technologies at sub-0.25 V operation [8]. On the other hand, TFETs conduct less current at voltages around 1 V, and thereby their use is envisioned for low voltage, low performance applications.T his paragraph of the first footnote will contain the date on which you submitted your paper for review. This work was supported by the Portuguese funding institution FCT (Fundação para a Ciência e a T ecnologia) and Spanish Ministry of Economy (MINECO) and ERDF funds through project T EC2013-45638-C3-2-R (Maragda).D. Cavalheiro and F. Moll are with the Department of Electronic Engineering, Polytechnic University of Catalonia, Jordi Girona, 31, 08034, Barcelona, francesc.moll@upc.edu).S. Valtchev is with the Department of Electrical Engineering, New University of Lisbon FCT , Quinta da T orre, 2829-516 Caparica, Portugal (e-mail: ssv@fct.unl.pt).As energy harvesting transducers produce low output voltage values from typical ambient conditions with small temperature gradients (case of thermogenerators) and low RF power (antennas powered by electromagnetic radiation), energy conversion circuits are required to increase these values for use by the electronic systems . Under extreme low voltage scenarios, TFETs appear as an interesting device to implement the...

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Section: Tunnel Fet Intrinsic Capacitancementioning

confidence: 99%

mentioning

confidence: 99%

Insights Into Tunnel FET-Based Charge Pumps and Rectifiers for Energy Harvesting Applications

Cavalheiro

Moll

Valtchev

2017

IEEE Trans. VLSI Syst.

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“…5,6) Therefore, narrower-bandgap materials have been intensively studied as TFET channel materials. [7][8][9][10][11][12][13] Among them, Ge is a unique and attractive material, [10][11][12][13] since it can be used as both n-and p-type MOS structure channels.…”

Section: Introductionmentioning

confidence: 99%

Ge p-channel tunneling FETs with steep phosphorus profile source junctions

Takaguchi

Matsumura

Katoh

et al. 2018

Jpn. J. Appl. Phys.

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The solid-phase diffusion processes of three n-type dopants, i.e., phosphorus (P), arsenic (As), and antimony (Sb), from spin-on-glass (SOG) into Ge are compared. We show that P diffusion can realize both the highest impurity concentration (>7 ' 10 19 cm %3 ) and the steepest impurity profile (>10 nm/dec) among the cases of the three n-type dopants because the diffusion coefficient is strongly dependent on the dopant concentration. As a result, we can conclude that P is the most suitable dopant for the source formation of Ge p-channel TFETs. Using this P diffusion, we fabricate Ge p-channel TFETs with high-P-concentration and steep-P-profile source junctions and demonstrate their operation. A high ON current of >1.7 µA/µm is obtained at room temperature. However, the subthreshold swing and ON current/OFF current ratio are degraded by any generation-recombination-related current component. At 150 K, SS min of >108 mV/dec and ON/OFF ratio of >3.5 ' 10 5 are obtained.

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“…The use of different materials, device physics, and system architectures have been proposed to ensure continued performance improvement and energy efficiency. [1][2][3][4][5][6][7] Among these options, spintronic devices take advantage of the low switching energy of nanosized magnets, which theoretically can be switched with only a few tens of k B T per magnet. 8 Furthermore, since the information is processed in the form of magnetization, spin logic devices also possess memory storage capability that is nonvolatile, which could further reduce the power overhead.…”

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confidence: 99%

Independent gate control of injected and detected spin currents in CVD graphene nonlocal spin valves

Anugrah

Stecklein

et al. 2018

AIP Advances

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Graphene is an ideal material for spintronic devices due to its low spin-orbit coupling and high mobility. One of the most important potential applications of graphene spintronics is for use in neuromorphic computing systems, where the tunable spin resistance of graphene can be used to apply analog weighting factors. A key capability needed to achieve spin-based neuromorphic computing systems is to achieve distinct regions of control, where injected and detected spin currents can be tuned independently. Here, we demonstrate the ability to achieve such independent control using a graphene spin valve geometry where the injector and detector regions are modulated by two separate bottom gate electrodes. The spin transport parameters and their dependence on each gate voltage are extracted from Hanle precession measurements. From this analysis, local spin transport parameters and their dependence on the local gate voltage are found, which provide a basis for a spatially-resolved spin resistance network that simulates the device. The data and model are used to calculate the spin currents flowing into, through, and out of the graphene channel. We show that the spin current flowing through the graphene channel can be modulated by 30% using one gate and that the spin current absorbed by the detector can be modulated by 50% using the other gate. This result demonstrates that spin currents can be controlled by locally tuning the spin resistance of graphene. The integration of chemical vapor deposition (CVD) grown graphene with local gates allows for the implementation of large-scale integrated spin-based circuits.

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Tunnel Field-Effect Transistors: Prospects and Challenges

Cited by 415 publications

References 20 publications

Insights Into Tunnel FET-Based Charge Pumps and Rectifiers for Energy Harvesting Applications

Insights Into Tunnel FET-Based Charge Pumps and Rectifiers for Energy Harvesting Applications

Ge p-channel tunneling FETs with steep phosphorus profile source junctions

Independent gate control of injected and detected spin currents in CVD graphene nonlocal spin valves

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