Periodic Reporting for period 4 - Milli-Tech (Milli-Volt Switch Technologies for Energy Efficient Computation and Sensing)
Okres sprawozdawczy: 2020-12-01 do 2022-05-31
The Milli-Tech proposal aim has been a novel technology platform serving both computation and sensing: electronic switch architectures, called steep slope switches, exploiting new device physics and concepts in emerging 2D materials to achieve steep switching and operation at voltages near 100 millivolts. Such characteristics will dramatically improve both the energy efficiency of logic circuits and the transduction sensitivity for many classes of sensors.
The project has contributed to the development of ‘millivolt technology’ focusing on low power digital and sensing/ analog electronic functions with the goal of lowering the energy per useful function. Such ultra-low operation voltage will contribute to solving major challenges of nanoelectronics such as leakage power issues and it will enable energy efficient super-sensitive sensors for Internet-of-Everything (IoE). Milli-Tech includes fundamental research on new solid-state steep slope device concepts: heterostructure tunnel FETs in 2D Transition-Metal-Dichalcogenides (TMD) and hybrid architectures combining two switching principles. Such high-risk ‘millivolt technology’ enables energy efficient technological solutions for the Internet of Things, making it more sustainable.
Milli-Tech objectives were focused on advanced electronic functions: (i) achieve energy efficient computation blocks for Von-Neumann ICs near 100mV; (ii) achieve advanced 2D-/2D tunnel FETs with and without ferroelectric negative capacitance booster; (iii) realize steep-slope hybrid 2D/VO2 switches offering with subthermionic switching and novel functionality; (iv) propose active optical sensors based on VO2 and hybrid 2D/VO2 technology; (v) demonstrate Terahertz spiking detectors based on VO2 or hybrid 2D VO2/TMD switches, and, (vi) develop ultra-sensitive charge detectors using steep slope devices for biosensing.
The project has contributed to the development of ‘millivolt technology’ focusing on low power digital and sensing/ analog electronic functions with the goal of lowering the energy per useful function. Such ultra-low operation voltage will contribute to solving major challenges of nanoelectronics such as leakage power issues and it will enable energy efficient super-sensitive sensors for Internet-of-Everything (IoE). Milli-Tech includes fundamental research on new solid-state steep slope device concepts: heterostructure tunnel FETs in 2D Transition-Metal-Dichalcogenides (TMD) and hybrid architectures combining two switching principles. Such high-risk ‘millivolt technology’ enables energy efficient technological solutions for the Internet of Things, making it more sustainable.
Milli-Tech objectives were focused on advanced electronic functions: (i) achieve energy efficient computation blocks for Von-Neumann ICs near 100mV; (ii) achieve advanced 2D-/2D tunnel FETs with and without ferroelectric negative capacitance booster; (iii) realize steep-slope hybrid 2D/VO2 switches offering with subthermionic switching and novel functionality; (iv) propose active optical sensors based on VO2 and hybrid 2D/VO2 technology; (v) demonstrate Terahertz spiking detectors based on VO2 or hybrid 2D VO2/TMD switches, and, (vi) develop ultra-sensitive charge detectors using steep slope devices for biosensing.
In MilliTech prohject we achieved a number of excellent results in terms of advanced technological and functional proof of concepts for steep slope 2D devices and hybridization with phase change technologies for low power digital, analog and sensing applications.
We have developed novel Band-to-Band-Tunneling devices based on 2D/2D semiconducting structures, such as WSe2/SnSe2 Vertical Tunnel FETs and have integrated on the same technology platform WSe2 MOSFETs, with capability of steep-slope swing below 60mV/decade and voltage operation below 0.3V. By using negative capacitance (NC) as technology boosters we have created novel functionalities and improved the performance of devices, creating NC 2/2D Tunnel FETs and NC 2D MOSFETs with excellent low power capabilities. We have integrated and optimized Si-doped HfO2 as ferroelectric in the gate stacks of our 2D device platform to create opportunities for both negative capacitance devices and memristive functions.
We have developed the integration of 2D semiconductors with Metal-Insulator-Transition (MIT) materials such as VO2 to realize a hybrid heterostructure technological platform with hysteric abrupt switches with low power applications ranging from low power steep slope to neuromorphic circuits.
The MIT devices served to design and demonstrate new classes of low power optical and Terahertz sensing functions, having the capability to generated spiking signals with the frequency modulated by power/intensity of input waves/signals. We have developed the analytical modeling with physical parameters of these new classes of MIT devices enabling both optimizations and co-design with advanced CMOS platform. In the biosensing domain, we have achieved experimental prof of concepts for negative capacitance sensors and we have explored the sensing of other biomarkers, beyond PH and ions, like hormones. The work has been very experimental and technological in its nature but we devised the necessary understanding of device physics for 2D semiconducting and MIT device underneath physics, enabling optimization path for various types of applications.
The MilliTech team members participated and disseminated their results to many international events such as in IEEE International Electron Devices Meeting editions, from 2017 to 2020, the leading conference in nanoelectronics, where we presented the first hybrid VO2/MOS2 junction transistor, novel ferro-functionalization of gate stacks for biosensing (work included in the very selective conference press kit), and where we presented a keynote talk showing the important role of the technology develop in the project for Edge Artificial Intelligence applications. Other conferences have been attended such as ESSDERC/ESSCIRC, Transducers, MRS, IRMMW-THz and SPIE Sensors. Collaborations with other EU projects have been established. We have also update our Master and Doctoral Courses at Ecole Polytechnique Fédérale de Lausanne based on the results of the Milli-Tech project.
Overall, the project produced more that 40 journals and conference papers and supported the career of 7 PhDs and 2 Post-doctoral fellows in academic research and industry.
We have developed novel Band-to-Band-Tunneling devices based on 2D/2D semiconducting structures, such as WSe2/SnSe2 Vertical Tunnel FETs and have integrated on the same technology platform WSe2 MOSFETs, with capability of steep-slope swing below 60mV/decade and voltage operation below 0.3V. By using negative capacitance (NC) as technology boosters we have created novel functionalities and improved the performance of devices, creating NC 2/2D Tunnel FETs and NC 2D MOSFETs with excellent low power capabilities. We have integrated and optimized Si-doped HfO2 as ferroelectric in the gate stacks of our 2D device platform to create opportunities for both negative capacitance devices and memristive functions.
We have developed the integration of 2D semiconductors with Metal-Insulator-Transition (MIT) materials such as VO2 to realize a hybrid heterostructure technological platform with hysteric abrupt switches with low power applications ranging from low power steep slope to neuromorphic circuits.
The MIT devices served to design and demonstrate new classes of low power optical and Terahertz sensing functions, having the capability to generated spiking signals with the frequency modulated by power/intensity of input waves/signals. We have developed the analytical modeling with physical parameters of these new classes of MIT devices enabling both optimizations and co-design with advanced CMOS platform. In the biosensing domain, we have achieved experimental prof of concepts for negative capacitance sensors and we have explored the sensing of other biomarkers, beyond PH and ions, like hormones. The work has been very experimental and technological in its nature but we devised the necessary understanding of device physics for 2D semiconducting and MIT device underneath physics, enabling optimization path for various types of applications.
The MilliTech team members participated and disseminated their results to many international events such as in IEEE International Electron Devices Meeting editions, from 2017 to 2020, the leading conference in nanoelectronics, where we presented the first hybrid VO2/MOS2 junction transistor, novel ferro-functionalization of gate stacks for biosensing (work included in the very selective conference press kit), and where we presented a keynote talk showing the important role of the technology develop in the project for Edge Artificial Intelligence applications. Other conferences have been attended such as ESSDERC/ESSCIRC, Transducers, MRS, IRMMW-THz and SPIE Sensors. Collaborations with other EU projects have been established. We have also update our Master and Doctoral Courses at Ecole Polytechnique Fédérale de Lausanne based on the results of the Milli-Tech project.
Overall, the project produced more that 40 journals and conference papers and supported the career of 7 PhDs and 2 Post-doctoral fellows in academic research and industry.
The major achievements, beyond the state of the art for the overall Millitech project, are summarized below:
(i) the realization of first ever van der Waals devices based on VO2/MOS2 junctions and their use for abrupt electronic switching and for light detection. This type of devices and technology has also a great potential for future neuromorphic applications.
(ii) the achievement of the first hybrid Phase-Change – Tunnel FET (PC-TFET) switch with subthreshold swing smaller than 10mV/decade and sub-0.1 body factor at room temperature.
(iii) the functionalization of undoped and Si-doped HfO2 gate stacks to selectively detect electrolytes in biofluids. Here, we have proposed one of the first experimental proof of concept of biosensors, a pH sensor using negative capacitance FETs.
(iii) the optimization of a technological process for the transfer of 2D material flakes with improved control that enabled the fabrication of various classes of 2D and 2D/2D devices. This can be extended to multiple stacking of 2D flakes for more complex vdW devices.
(iv) the realization of complementary 2D FETs (n- and p-type) based on 2D BP material, by engineering the workfunctions of the metal contacts.
(v) the very first co-integration of a subthermionic 2D/2D WSe2/SnSe2 Vertical Tunnel FET and WSe2 MOSFET on same flake, which in it self was a world first result of this kind and enabled the demonstration of dual-mechanism (BTBT and thermionic field-effect conductions) switches for improving the performance of low power 2D steep slope electronic switches.
(vi) the demonstration of GHz to THz power detection with stochastic sensors using VO2 thin film devices and oscillators.
(vii) original compact modeling of spiking VO2 oscillators and their use for optical sensing.
All these achievements have contributed to advance the state of the art in the field of low power devices and technologies, achieving energy/power savings of the order of 10x to 100x, therefore enabling more energy efficient technologies for Internet-of-Things and Edge Artificial Intelligence applications.
(i) the realization of first ever van der Waals devices based on VO2/MOS2 junctions and their use for abrupt electronic switching and for light detection. This type of devices and technology has also a great potential for future neuromorphic applications.
(ii) the achievement of the first hybrid Phase-Change – Tunnel FET (PC-TFET) switch with subthreshold swing smaller than 10mV/decade and sub-0.1 body factor at room temperature.
(iii) the functionalization of undoped and Si-doped HfO2 gate stacks to selectively detect electrolytes in biofluids. Here, we have proposed one of the first experimental proof of concept of biosensors, a pH sensor using negative capacitance FETs.
(iii) the optimization of a technological process for the transfer of 2D material flakes with improved control that enabled the fabrication of various classes of 2D and 2D/2D devices. This can be extended to multiple stacking of 2D flakes for more complex vdW devices.
(iv) the realization of complementary 2D FETs (n- and p-type) based on 2D BP material, by engineering the workfunctions of the metal contacts.
(v) the very first co-integration of a subthermionic 2D/2D WSe2/SnSe2 Vertical Tunnel FET and WSe2 MOSFET on same flake, which in it self was a world first result of this kind and enabled the demonstration of dual-mechanism (BTBT and thermionic field-effect conductions) switches for improving the performance of low power 2D steep slope electronic switches.
(vi) the demonstration of GHz to THz power detection with stochastic sensors using VO2 thin film devices and oscillators.
(vii) original compact modeling of spiking VO2 oscillators and their use for optical sensing.
All these achievements have contributed to advance the state of the art in the field of low power devices and technologies, achieving energy/power savings of the order of 10x to 100x, therefore enabling more energy efficient technologies for Internet-of-Things and Edge Artificial Intelligence applications.