Abstract
Internet-of-Things (IoT) technologies require a new energy-efficient transistor which operates at ultralow voltage and ultralow power for sensor node devices employing energy-harvesting techniques as power supply. In this paper, a practical device design guideline for low voltage operation of steep-slope negative-capacitance field-effect-transistors (NCFETs) operating at sub-0.2V supply voltage is investigated regarding operation speed, material requirement and energy efficiency in the case of ferroelectric HfO2 gate insulator, which is the material fully compatible to Complementary Metal-Oxide-Semiconductor (CMOS) process technologies. A physics-based numerical simulator was built to design NCFETs with the use of experimental HfO2 material parameters by modeling the ferroelectric gate insulator and FET channel simultaneously. The simulator revealed that NCFETs with ferroelectric HfO2 gate insulator enable hysteresis-free operation by setting appropriate operation point with a few nm thick gate insulator. It also revealed that, if the finite response time of spontaneous polarization of the ferroelectric gate insulator is 10-100psec, 1-10MHz operation speed can be achieved with negligible hysteresis. Finally, by optimizing material parameters and tuning negative capacitance, 2.5 times higher energy efficiency can be achieved by NCFET than by conventional MOSFETs. Thus, NCFET is expected to be a new CMOS technology platform for ultralow power IoT.
Highlights
Modern mobile computing including wearables and emerging Internet-of-Things (IoT) technologies such as smart sensor network demand extremely low power Large-Scale-Integration (LSI) systems.[1]
To target sub-0.2V Vdd operation for ultralow voltage and ultralow power IoT application, we study practical device design for an energy-efficient negative-capacitance field-effecttransistors (NCFETs) with a ferroelectric HfO2 gate insulator by tuning its material parameters, based upon physics-based numerical simulations, with respect to operation speed, material requirement, and energy efficiency
This dynamic property of the ferroelectric can be another cause of the hysteretic behavior of NCFETs besides inappropriate static operation points, which was discussed in the previous section
Summary
Modern mobile computing including wearables and emerging Internet-of-Things (IoT) technologies such as smart sensor network demand extremely low power Large-Scale-Integration (LSI) systems.[1]. In order to promote research and development of NCFET with ferroelectric HfO2 for IoT application, it needs to be demonstrated that NCFET can be designed at ultralow supply voltage with ferroelectric HfO2 as well as with the previously reported ferroelectric material.[5,6] A practical device design guideline to achieve sufficiently fast operation speed and reliable operation should be provided so that material parameters are appropriately selected for process development It needs to be quantitatively estimated how much the energy per switching can be lowered by NCFET. To target sub-0.2V Vdd operation for ultralow voltage and ultralow power IoT application, we study practical device design for an energy-efficient NCFET with a ferroelectric HfO2 gate insulator by tuning its material parameters, based upon physics-based numerical simulations, with respect to operation speed, material requirement, and energy efficiency.
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