As a typical in-memory computing hardware design, nonvolatile ternary content-addressable memories(TCAMs) enable the logic operation and data storage for high throughout in parallel big data processing. However,TCAM c...As a typical in-memory computing hardware design, nonvolatile ternary content-addressable memories(TCAMs) enable the logic operation and data storage for high throughout in parallel big data processing. However,TCAM cells based on conventional silicon-based devices suffer from structural complexity and large footprintlimitations. Here, we demonstrate an ultrafast nonvolatile TCAM cell based on the MoTe2/hBN/multilayergraphene (MLG) van der Waals heterostructure using a top-gated partial floating-gate field-effect transistor(PFGFET) architecture. Based on its ambipolar transport properties, the carrier type in the source/drain andcentral channel regions of the MoTe2 channel can be efficiently tuned by the control gate and top gate, respectively,enabling the reconfigurable operation of the device in either memory or FET mode. When working inthe memory mode, it achieves an ultrafast 60 ns programming/erase speed with a current on-off ratio of ∼105,excellent retention capability, and robust endurance. When serving as a reconfigurable transistor, unipolar p-typeand n-type FETs are obtained by adopting ultrafast 60 ns control-gate voltage pulses with different polarities.The monolithic integration of memory and logic within a single device enables the content-addressable memory(CAM) functionality. Finally, by integrating two PFGFETs in parallel, a TCAM cell with a high current ratioof ∼10^(5) between the match and mismatch states is achieved without requiring additional peripheral circuitry.These results provide a promising route for the design of high-performance TCAM devices for future in-memorycomputing applications.展开更多
With the explosive exploration of two-dimensional(2D)semiconductors for device applications,ensuring effective electrical contacts has become critical for optimizing device performance.Here,we demonstrate a universal ...With the explosive exploration of two-dimensional(2D)semiconductors for device applications,ensuring effective electrical contacts has become critical for optimizing device performance.Here,we demonstrate a universal resist-assisted metal transfer method for creating nearly free-standing metal electrodes on the SiO_(2)/Si substrate,which can be easily transferred onto 2D semiconductors to form van der Waals(vdW)contacts.In this method,polymethyl methacrylate(PMMA)serves both as an electron resist for electrode patterning and as a sacrificial layer.Contacted with our transferred electrodes,MoS2exhibits tunable Schottky barrier heights and a transition from n-type dominated to ambipolar conduction with increasing metal work functions,while In Se shows pronounced ambipolarity.Additionally,usingα-In2Se3as an example,we demonstrate that our transferred electrodes enhance resistance switching in ferroelectric memristors.Finally,the universality of our method is evidenced by the successful transfer of various metals with different adhesion forces and complex patterns.展开更多
Charge trapping devices incorporating 2D materials and high-κdielectrics have emerged as promising candidates for compact,multifunctional memory devices compatible with silicon-based manufacturing processes.However,t...Charge trapping devices incorporating 2D materials and high-κdielectrics have emerged as promising candidates for compact,multifunctional memory devices compatible with silicon-based manufacturing processes.However,traditional charge trapping devices encounter bottlenecks including complex device structure and low operation speed.Here,we demonstrate an ultrafast reconfigurable direct charge trapping device utilizing only a 30 nm-thick Al_(2)O_(3)trapping layer with a MoS_(2)channel,where charge traps reside within the Al_(2)O_(3)bulk confirmed by transfer curves with different gatevoltage sweeping rates and photoluminescence(PL)spectra.The direct charging tapping device shows exceptional memory performance in both three-terminal and two-terminal operation modes characterized by ultrafast three-terminal operation speed(~300 ns),an extremely low OFF current of 10^(-14)A,a high ON/OFF current ratio of up to 10^(7),and stable retention and endurance properties.Furthermore,the device with a simple symmetrical structure exhibits VDpolarity-dependent reverse rectification behavior in the high resistance state(HRS),with a rectification ratio of 10^(5).Additionally,utilizing the synergistic modulation of the conductance of the MoS_(2)channel by V_(D)and V_(G),it achieves gate-tunable reverse rectifier and ternary logic capabilities.展开更多
Metal contacts to two-dimensional(2D)semiconductors are crucial for determining the electrical performance of electronic devices.However,traditional three-dimensional metal deposition processes cause damage to 2D semi...Metal contacts to two-dimensional(2D)semiconductors are crucial for determining the electrical performance of electronic devices.However,traditional three-dimensional metal deposition processes cause damage to 2D semiconductors and considerable Fermi-level-pinning effects.In this study,a hexagonal boron nitride(h-BN)-assisted transfer method was proposed for transferring metal contacts to few-layered InSe for fabricating 2D functional electronic devices.Using the transferred Pt electrodes as the contact,p-type dominated ambipolar conduction behavior with the hole Schottky barrier height(SBH)approaching 0meV was observed in field-effect transistors(FETs)comprising multilayered InSe.Based on this phenomenon,several InSe homojunctions were fabricated using a dual-gate modulating method such as p-p,n-n,p-n,and n-p.For InSe p-n homojunctions,a current rectification ratio of over 104 and optoelectronic detection capabilities were achieved.Furthermore,a complementary metal-oxide-semiconductor(CMOS)inverter with an ultra-high voltage gain exceeding 60 at VDD=−1V was fabricated.The proposed h-BN-assisted metal contact transfer method can be easily extended to other 2D semiconductors for fabricating complementary electronic and optoelectronic devices.展开更多
With the explosive expansion of information,there is a growing need for non-volatile memories with high storage density and reconfigurability.Emerging two-dimensional(2D)ferroelectric materials enable the design of va...With the explosive expansion of information,there is a growing need for non-volatile memories with high storage density and reconfigurability.Emerging two-dimensional(2D)ferroelectric materials enable the design of various high-performance functional devices that can potentially address these challenges.Here,we report a ferroelectric semiconductor floating-gate transistor based on an α-In_(2)Se_(3)/hexagonal boron nitride(h-BN)/multi-layered graphene(MLG)van der Waals heterostructure on a SiO_(2)/Si substrate.Thanks to the coexistence of both out-of-plane and in-plane polarizations in an α-In_(2)Se_(3) channel,pairs of polarization-modulated channel resistance states can be successfully generated between the floating-gate-modulated on and off states,which can be programmed by either vertical gate pulses or planar drain pulses.These features enable a 2-bit multi-level memory in both three-terminal or two-terminal operational modes,significantly increasing the storage density and reconfigurability.The present results introduce a new design degree of freedom for floating-gate memories and provide fresh insights into future non-volatile memory technologies.展开更多
基金supported by the National Key Research&Development Projects of China(Grant No.2022YFA1204100)National Natural Science Foundation of China(Grant No.62488201)+1 种基金CAS Project for Young Scientists in Basic Research(YSBR-003)the Innovation Program of Quantum Science and Technology(2021ZD0302700)。
文摘As a typical in-memory computing hardware design, nonvolatile ternary content-addressable memories(TCAMs) enable the logic operation and data storage for high throughout in parallel big data processing. However,TCAM cells based on conventional silicon-based devices suffer from structural complexity and large footprintlimitations. Here, we demonstrate an ultrafast nonvolatile TCAM cell based on the MoTe2/hBN/multilayergraphene (MLG) van der Waals heterostructure using a top-gated partial floating-gate field-effect transistor(PFGFET) architecture. Based on its ambipolar transport properties, the carrier type in the source/drain andcentral channel regions of the MoTe2 channel can be efficiently tuned by the control gate and top gate, respectively,enabling the reconfigurable operation of the device in either memory or FET mode. When working inthe memory mode, it achieves an ultrafast 60 ns programming/erase speed with a current on-off ratio of ∼105,excellent retention capability, and robust endurance. When serving as a reconfigurable transistor, unipolar p-typeand n-type FETs are obtained by adopting ultrafast 60 ns control-gate voltage pulses with different polarities.The monolithic integration of memory and logic within a single device enables the content-addressable memory(CAM) functionality. Finally, by integrating two PFGFETs in parallel, a TCAM cell with a high current ratioof ∼10^(5) between the match and mismatch states is achieved without requiring additional peripheral circuitry.These results provide a promising route for the design of high-performance TCAM devices for future in-memorycomputing applications.
基金supported by the National Key Research&Development Project of China(Grant No.2022YFA1204100)the National Natural Science Foundation of China(Grant No.62488201)+4 种基金Strategic Priority Research Program of Chinese Academy of Sciences(CAS,Grant Nos.XDB30000000 and XDB28000000)CAS Project for Young Scientists in Basic Research(Grant No.YSBR-003)the Innovation Program of Quantum Science and Technology(Grant No.2021ZD0302700)Beijing Outstanding Young Scientist Program(Grant No.BJJWZYJH01201914430039)support from the Electron Microscopy Center at the University of Chinese Academy of Sciences。
文摘With the explosive exploration of two-dimensional(2D)semiconductors for device applications,ensuring effective electrical contacts has become critical for optimizing device performance.Here,we demonstrate a universal resist-assisted metal transfer method for creating nearly free-standing metal electrodes on the SiO_(2)/Si substrate,which can be easily transferred onto 2D semiconductors to form van der Waals(vdW)contacts.In this method,polymethyl methacrylate(PMMA)serves both as an electron resist for electrode patterning and as a sacrificial layer.Contacted with our transferred electrodes,MoS2exhibits tunable Schottky barrier heights and a transition from n-type dominated to ambipolar conduction with increasing metal work functions,while In Se shows pronounced ambipolarity.Additionally,usingα-In2Se3as an example,we demonstrate that our transferred electrodes enhance resistance switching in ferroelectric memristors.Finally,the universality of our method is evidenced by the successful transfer of various metals with different adhesion forces and complex patterns.
基金supported by the National Key Research&Development Project of China(Grant No.2022YFA1204100)the National Natural Science Foundation of China(Grant No.62488201)+1 种基金CAS Project for Young Scientists in Basic Research(Grant No.YSBR-003)the Innovation Program of Quantum Science and Technology(Grant No.2021ZD0302700)。
文摘Charge trapping devices incorporating 2D materials and high-κdielectrics have emerged as promising candidates for compact,multifunctional memory devices compatible with silicon-based manufacturing processes.However,traditional charge trapping devices encounter bottlenecks including complex device structure and low operation speed.Here,we demonstrate an ultrafast reconfigurable direct charge trapping device utilizing only a 30 nm-thick Al_(2)O_(3)trapping layer with a MoS_(2)channel,where charge traps reside within the Al_(2)O_(3)bulk confirmed by transfer curves with different gatevoltage sweeping rates and photoluminescence(PL)spectra.The direct charging tapping device shows exceptional memory performance in both three-terminal and two-terminal operation modes characterized by ultrafast three-terminal operation speed(~300 ns),an extremely low OFF current of 10^(-14)A,a high ON/OFF current ratio of up to 10^(7),and stable retention and endurance properties.Furthermore,the device with a simple symmetrical structure exhibits VDpolarity-dependent reverse rectification behavior in the high resistance state(HRS),with a rectification ratio of 10^(5).Additionally,utilizing the synergistic modulation of the conductance of the MoS_(2)channel by V_(D)and V_(G),it achieves gate-tunable reverse rectifier and ternary logic capabilities.
文摘Metal contacts to two-dimensional(2D)semiconductors are crucial for determining the electrical performance of electronic devices.However,traditional three-dimensional metal deposition processes cause damage to 2D semiconductors and considerable Fermi-level-pinning effects.In this study,a hexagonal boron nitride(h-BN)-assisted transfer method was proposed for transferring metal contacts to few-layered InSe for fabricating 2D functional electronic devices.Using the transferred Pt electrodes as the contact,p-type dominated ambipolar conduction behavior with the hole Schottky barrier height(SBH)approaching 0meV was observed in field-effect transistors(FETs)comprising multilayered InSe.Based on this phenomenon,several InSe homojunctions were fabricated using a dual-gate modulating method such as p-p,n-n,p-n,and n-p.For InSe p-n homojunctions,a current rectification ratio of over 104 and optoelectronic detection capabilities were achieved.Furthermore,a complementary metal-oxide-semiconductor(CMOS)inverter with an ultra-high voltage gain exceeding 60 at VDD=−1V was fabricated.The proposed h-BN-assisted metal contact transfer method can be easily extended to other 2D semiconductors for fabricating complementary electronic and optoelectronic devices.
基金supported by the National Key Research and Development Program of China(No.2022YFA1204100)the National Natural Science Foundation of China(No.62488201)+1 种基金CAS Project for Young Scientists in Basic Research(No.YSBR-003)the Innovation Program of Quantum Science and Technology(No.2021ZD0302700).
文摘With the explosive expansion of information,there is a growing need for non-volatile memories with high storage density and reconfigurability.Emerging two-dimensional(2D)ferroelectric materials enable the design of various high-performance functional devices that can potentially address these challenges.Here,we report a ferroelectric semiconductor floating-gate transistor based on an α-In_(2)Se_(3)/hexagonal boron nitride(h-BN)/multi-layered graphene(MLG)van der Waals heterostructure on a SiO_(2)/Si substrate.Thanks to the coexistence of both out-of-plane and in-plane polarizations in an α-In_(2)Se_(3) channel,pairs of polarization-modulated channel resistance states can be successfully generated between the floating-gate-modulated on and off states,which can be programmed by either vertical gate pulses or planar drain pulses.These features enable a 2-bit multi-level memory in both three-terminal or two-terminal operational modes,significantly increasing the storage density and reconfigurability.The present results introduce a new design degree of freedom for floating-gate memories and provide fresh insights into future non-volatile memory technologies.
