Traditional optical fiber communication encryption methods lack sufficient dynamic adaptability and hardware flexibility,while reconfigurable logic gates can overcome this limitation,thereby significantly improving th...Traditional optical fiber communication encryption methods lack sufficient dynamic adaptability and hardware flexibility,while reconfigurable logic gates can overcome this limitation,thereby significantly improving the flexibility of encryption systems.This study reports a reconfigurable optoelectronic logic gate(OELG)system based on hafnium-zirconium oxide(HZO)ferroelectric thin films.Through ultra-low temperature atomic layer deposition technique,the fabricated HZO thin films demonstrate an exceptional pyroelectric coefficient(1835.91μC m^(−2) K^(-1))and robust multi-level polarization stability,enabling efficient broadband photon-to-current conversion.By leveraging the pyroelectric effect and tunable polarization states,the OELG device achieves dynamic optical signal modulation and logic processing.The OELG device supports five fundamental logic operations(AND,OR,NAND,NOR,NOT)via electrical bias and polarization control,without requiring hardware modifications.The OELG device demonstrates stable performance over 109 cycles with no degradation,meeting practical application requirements.Furthermore,a convolutional neural network(CNN)-integrated image encryption-decryption framework was validated,achieving 95.01%recognition accuracy on decrypted data,while unauthorized decryption attempts resulted in significant feature loss.This study addresses security challenges in optical communication networks by proposing an innovative solution that integrates pyroelectric materials with reconfigurable logic gate technology,offering a new pathway to enhance physical-layer security.展开更多
Amorphous and non-stoichiometric hafnium oxide(a-HfO_(x))systems are essential for advanced electronic applications due to their superior electrical properties.Simulating their atomic behaviors under electric fields(E...Amorphous and non-stoichiometric hafnium oxide(a-HfO_(x))systems are essential for advanced electronic applications due to their superior electrical properties.Simulating their atomic behaviors under electric fields(Efield)is critical but challenging.Ab-initio molecular dynamics(AIMD)offer high accuracy but is computationally expensive,while classical MD lacks precision.To address this,we develop a charge equilibration integrated graph neural network(CIGNN)model that predicts atomic charge,energy,and force under Efield conditions.Using the CIGNN model and AIMD datasets,we develop a CIGNN-based machine learning potential(CNMP)optimized for a-HfO_(x)systems.The CNMP achieves quantum mechanical accuracy and effectively captures the atomic behaviors and dynamic properties of these systems across varying temperatures,densities,and E_(field)conditions.We expect the CNMP to serve as a valuable tool for studying field-induced phenomena in complex systems and to provide a foundation for advancing innovations in electronic applications.展开更多
In this work,a conventional HfO_(2) gate dielectric layer is replaced with a 3-nm ferroelectric(Fe) HZO layer in the gate stacks of advanced fin field-effect transistors(FinFETs).Fe-induced characteristics,e.g.,negati...In this work,a conventional HfO_(2) gate dielectric layer is replaced with a 3-nm ferroelectric(Fe) HZO layer in the gate stacks of advanced fin field-effect transistors(FinFETs).Fe-induced characteristics,e.g.,negative drain induced barrier lowering(N-DIBL) and negative differential resistance(NDR),are clearly observed for both p-and n-type HZO-based FinFETs.These characteristics are attributed to the enhanced ferroelectricity of the 3-nm hafnium zirconium oxide(HZO) film,caused by Al doping from the TiAlC capping layer.This mechanism is verified for capacitors with structures similar to the FinFETs.Owing to the enhanced ferroelectricity and N-DIBL phenomenon,the drain current(I_(DS))of the HZO-FinFETs is greater than that of HfO_(2)-FinFETs and obtained at a lower operating voltage.Accordingly,circuits based on HZO-FinFET achieve higher performance than those based on HfO_(2)-FinFET at a low voltage drain(V_(DD)),which indicates the application feasibility of the HZO-FinFETs in the ultralow power integrated circuits.展开更多
Sputtering deposition coatings offer significant advantages on electron beam (EB) deposition, including high packing density, environmental stability and extremely low losses. But the inherent high compressive stress ...Sputtering deposition coatings offer significant advantages on electron beam (EB) deposition, including high packing density, environmental stability and extremely low losses. But the inherent high compressive stress affects its application in high power laser system. This paper describes the technical feasibility of high damage threshold laser mirrors deposited by a novel remote plasma sputtering technique. This technique is based on generating intensive plasma remotely from the target and then magnetically steering the plasma to the target to realize the full uniform sputtering. The pseudo-independence between target voltage and target current provides us very flexible parameters tuning, especially for the films stress control. Deposition conditions are optimized to yield fully oxidized and low compressive stress single layer HfO2 and SiO2. The high damage threshold of 43.8 J/cm2 for HfO2/ SiO2 laser mirrors at 1064 nm is obtained. For the first time the remote plasma sputtering is successfully applied in depositing laser mirrors with high performance.展开更多
We report a method to produce a uniform mixture of uranium dioxide spherical particles in a tungsten matrix. This method involves mixing 0.5 weight percent of high density polyethylene binder with 60 volume percent ur...We report a method to produce a uniform mixture of uranium dioxide spherical particles in a tungsten matrix. This method involves mixing 0.5 weight percent of high density polyethylene binder with 60 volume percent uranium dioxide spheres and 40 volume percent tungsten powders. Initially, hafnium oxide spheres were used as a surrogate for uranium dioxide spheres. The HfO2/W/PE powders were thoroughly mixed in a Turbula, then mixed on a hot plate above the drop point of the binder. These powders were then densified using spark plasma sintering. Microstructure was evaluated using scanning electron microscopy, density was measured and hardness measurements were made. Initial carbon content of the powders were measured and carbon content of the sintered materials was measured. Subsequently, W/UO2/Binder powders were mixed using the same methodology to ensure the process could be used for this system. These powders were sintered using hot isostatic pressing and microstructures evaluated. The resultant microstructures contained uniform distribution of HfO2 and UO2 particles in the tungsten matrix with very low carbon content.展开更多
This paper describes a new method to design a laser mirror with high reflectivity, wide reflection bandwidth and high laser- induced damage threshold. The mirror is constructed by three materials of HfO/TiO2/SiO2 base...This paper describes a new method to design a laser mirror with high reflectivity, wide reflection bandwidth and high laser- induced damage threshold. The mirror is constructed by three materials of HfO/TiO2/SiO2 based on electric field and temperature field distribution characteristics of all-dielectric laser high reflector. TiO/SiO2 stacks act as the high reflector （HR） and broaden the reflection bandwidth, while HfO2/SiO2 stacks are used for increasing the laser resistance. The HfO/ TiO/SiO2 laser mirror with 34 layers is fabricated by a novel remote plasma sputtering deposition. The damage threshold of zero damage probability for the new mirror is up to 39.6 J/cm^2 （1064 nm, 12 ns）. The possible laser damage mechanism of the mirror is discussed.展开更多
Hafnium oxide thin films （HOTFs） were successfully deposited onto amorphous glasses using chemical bath deposition, successive ionic layer absorption and reaction （SILAR）, and sol-gel methods. The same reactive pr...Hafnium oxide thin films （HOTFs） were successfully deposited onto amorphous glasses using chemical bath deposition, successive ionic layer absorption and reaction （SILAR）, and sol-gel methods. The same reactive precursors were used for all of the methods, and all of the films were annealed at 300℃ in an oven （ambient conditions）. After this step, the optical and structural properties of the films produced by using the three different methods were compared. The structures of the films were analyzed by X-ray diffTaction （XRD）. The optical properties are investigated using the ultraviolet-visible （UV-VIS） spectroscopic technique. The film thickness was measured via atomic force microscopy （AFM） in the tapping mode. The surface properties and elemental ratios of the films were investigated and measured by scanning electron microscopy and energy-dispersive X-ray spectroscopy （EDX）. The lowest transmittance and the highest reflectance values were observed for the films produced using the SILAR method. In addition, the most intense characteristic XRD peak was observed in the diffraction pattern of the film produced using the SILAR method, and the greatest thickness and average grain size were calculated for the film produced using the SILAR method. The films produced using SILAR method contained fewer cracks than those produced using the other methods. In conclusion, the SILAR method was observed to be the best method for the production of HOTFs.展开更多
Amorphous HfO2 nano-helix arrays with different screw pitches were fabricated by the glancing angle deposition technique. Room temperature ferromagnetism was achieved in this undoped amorphous HfO2 nanostructure, whic...Amorphous HfO2 nano-helix arrays with different screw pitches were fabricated by the glancing angle deposition technique. Room temperature ferromagnetism was achieved in this undoped amorphous HfO2 nanostructure, which is attributed to singly charged oxygen vacancies. The different magnetic behavior and photoluminescence in flat film and nano-helix arrays originate from the distinction of defect components. This study could facilitate the understanding of ferromagnetism origin in undoped HfO2, it also suggests a possible way to alter the intrinsic defects in amorphous HfO2.展开更多
A highly efficient benzylation of arenes and heteroarenes catalyzed by HfCl4/HfO2 has been developed. Broad scope of benzylation reagents have been used in this process with high yields under mild condition. Additiona...A highly efficient benzylation of arenes and heteroarenes catalyzed by HfCl4/HfO2 has been developed. Broad scope of benzylation reagents have been used in this process with high yields under mild condition. Additionally, the HfO2 can be re-used after the reaction. ？2009 Xin Qin Gao. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
The Al-Hf alloy was prepared by open aluminothermic reduction of HfO_(2) using CaF_(2) and Na F as the flux. The influence of the slag composition, the amount of aluminum, and the heat energizer was studied detailly t...The Al-Hf alloy was prepared by open aluminothermic reduction of HfO_(2) using CaF_(2) and Na F as the flux. The influence of the slag composition, the amount of aluminum, and the heat energizer was studied detailly to establish optimum conditions for the sufficient recovery of the alloy and the complete slag-alloy separation. The Al-Hf alloy with 40 wt% Hf was obtained by this method, and the maximum recovery was 70.7%. The microstructure of the alloy was observed by scanning electron microscope(SEM). Moreover, X-ray diffraction(XRD) analysis and energy-disperse spectrometry(EDS) were applied to characterize the formation of the phases. The results show that the alloy consists of Al and Al_(3)Hf phases and the oxygen content is about 0.2 wt%.展开更多
Tunable modulations of terahertz waves in a graphene/ferroelectric-layer/silicon hybrid structure are demonstrated at low bias voltages. The modulation is due to the creation/elimination of an extra barrier in Si laye...Tunable modulations of terahertz waves in a graphene/ferroelectric-layer/silicon hybrid structure are demonstrated at low bias voltages. The modulation is due to the creation/elimination of an extra barrier in Si layer in response to the polarization in the ferroelectric Si:HfOlayer. Considering the good compatibility of HfOwith the Si-based semiconductor process, the highly tunable characteristics of the graphene metamaterial device under ferroelectric effect open up new avenues for graphene-based high performance integrated active photonic devices compatible with the silicon technology.展开更多
With advanced research for dielectrics including capacitors in DRAMs, decoupling filters in microcircuits and insulating gates in transistors, a lot of demand for the new challenging of high-k materials in semiconduct...With advanced research for dielectrics including capacitors in DRAMs, decoupling filters in microcircuits and insulating gates in transistors, a lot of demand for the new challenging of high-k materials in semiconductor industries has been emerged. This study explores and addresses the experimental approach for composite materials with one of the major concerns of high capacitance, and low leakage, as well as ease of integration technology. The characteristics of Al<sub>2</sub>O<sub>3</sub> supported HfO<sub>2</sub> (AHO) thin films for a series of different Hf ratios with Al<sub>2</sub>O<sub>3</sub> dielectrics by atomic layer deposition demonstrated as a candidate material. A composite AHO films with the homogeneous compositions of Al and Hf atoms into the Al-Hf-O mixed oxide system could stabilize the polycrystalline structure with increasing of dielectric constant (k) and decreasing of leakage current density, as well as a higher breakdown voltage than HfO<sub>2</sub> film on its own. 70 nm thick AHO thin films with different composition of Al and Hf contents were prepared by atomic layer deposition technique on titanium nitride (TiN) and silicon dioxide (SiO<sub>2</sub>) coated Si substrates. Photolithography and metal lift-off technique were used for the device fabrication of the metal-insulator-metal (MIM) capacitor structures. AHO films on TiN/SiO<sub>2</sub>/Si were measured by semiconductor analyzer and source/ measure system with probe station in the voltage range from -5 to 5 V with a frequency range from 10 kHz to 1 MHz were used to conduct capacitance-voltage (C-V) measurements with low/medium frequency range and current-voltage (I-V) measurements. It was found that Au/AHO/TiN/SiO<sub>2</sub>/Si MIM capacitors demonstrate a capacitance density of 1.5 - 4.5 fF/μm<sup>2</sup> at 10 kHz, a loss tangent of 0.02 - 0.04 at 10 kHz, dielectric constant of 11.7 - 35.5 depending on the composition and a low leakage current of 1.7 × 10<sup>-9</sup> A/cm<sup>2</sup> at 0.5 MV/cm at room temperature. The acquired experimental results could show the possibility of compositional alloy thin films that could potentially replace or open new market for high-k challenges in semiconductor technology.展开更多
Ferroelectric thin films based on HfO_(2) have garnered increasing attention worldwide,primarily due to their remarkable compatibility with silicon and scalability,in contrast to traditional perovskite-structured ferr...Ferroelectric thin films based on HfO_(2) have garnered increasing attention worldwide,primarily due to their remarkable compatibility with silicon and scalability,in contrast to traditional perovskite-structured ferroelectric materials.Nonetheless,significant challenges remain in their widespread commercial utilization,particularly concerning their notable wake-up effect and limited endurance.To address these challenges,we propose a novel strategy involving the inhomogeneous distribution of Hf/Zr elements within thin films and explore its effects on the ferroelectricity and endurance of Hf_(0.5)Zr_(0.5)O_(2) thin films.Through techniques such as grazing incidence X-ray diffraction,transmission electron microscopy,and piezoresponse force microscopy,we investigated the structural characteristics and domain switching behaviors of these materials.The experimental results indicate that the inhomogeneous distribution of Hf/Zr contributes to improving the frequency stability and endurance while maintaining a large remnant polarization in Hf_(0.5)Zr_(0.5)O_(2) ferroelectric thin films.By adjusting the distribution of Zr/Hf within the Hf_(0.5)Zr_(0.5)O_(2) thin films,significant enhancements in the remnant polarization(2P_(r)>35μC/cm2)and endurance(>109)along with a reduced coercive voltage can be achieved.Additionally,the fabricated ferroelectric thin films also exhibit high dielectric tunability(≥26%)under a low operating voltage of 2.5 V,whether in the wake-up state or not.This study offers a promising approach to optimize both the ferroelectricity and endurance of HfO_(2)-based thin films.展开更多
We have analyzed the effective oxide thickness （EOT） of the dielectric material for which we have optimum performance and the output characteristics of the silicon nanowire transistors by replacing the traditional S...We have analyzed the effective oxide thickness （EOT） of the dielectric material for which we have optimum performance and the output characteristics of the silicon nanowire transistors by replacing the traditional Si02 gate insulator with a material that has a much higher dielectric constant （high-k） gate, materials like Si3N4, Al2O3, Y2O3 and HfO2. We have also analyzed the channel conductance, the effect of a change in thickness, the average velocity of the charge carrier and the conductance efficiency in order to study the performance of silicon nanowire transistors in the nanometer region. The analysis was performed using the Fettoy, a numerical simulator for ballistic nanowire transistors using a simple top of the barrier （Natori） approach, which is composed of several matlab scripts. Our results show that hafnium oxide （HfO2） gate insulator material provides good thermal stability, a high recrystallization temperature and better interface qualities when compared with other gate insulator materials; also the effective oxide thickness of lifO2 is found to be 0.4 nm.展开更多
Analog reservoir computing(ARC)systems offer an energy-efficient platform for temporal information processing.However,their physical implementation typically requires disparate materials and device architectures for d...Analog reservoir computing(ARC)systems offer an energy-efficient platform for temporal information processing.However,their physical implementation typically requires disparate materials and device architectures for different system components,leading to complicated fabrication processes and increased system complexity.In this work,we present a coplanar floating-gate antiferroelectric field-effect transistor(FG AFeFET)that unifies multiple neural functionalities within a single device,enabling the physical implementation of a complete ARC system.By combining a coplanar layout design with an area ratio engineering strategy,we achieve tunable device behaviors,including volatile responses for artificial neuron emulation,nonvolatile states for synaptic functions,and fading memory dynamics for reservoir operations.The mechanisms underlying these functionalities and their operating mechanism are systematically elucidated using load line analysis and energy band diagrams.Leveraging these insights,we demonstrate an all-in-one ARC system based on the unified coplanar FG AFeFET architecture,which achieves recognition accuracies of 95.6%and 83.4%on the MNIST and Fashion-MNIST datasets,respectively.These findings highlight the potential of coplanar FG AFeFETs to deliver area-efficient,design-flexible neuromorphic hardware for next-generation computing systems.展开更多
This study proposes a novel approach to achieving highly reliable,low-voltage polarization switching of ferroelectric Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films using polymorph-and orientation-controlled W electrodes((111)-...This study proposes a novel approach to achieving highly reliable,low-voltage polarization switching of ferroelectric Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films using polymorph-and orientation-controlled W electrodes((111)-textured a-W and(200)-textured b-W)by adjusting the sputtering conditions.We demonstrated the formation of(111)and(002)/(020)-textured HZO films on the(111)-textured a-Wand(200)-textured b-W electrodes,respectively.Under a low-voltage pulse of 1.2 V(1.5 MV/cm),a-W/HZO/a-W and b-W/HZO/b-W capacitors exhibited double-remanent polarization(2Pr)values of 29.23 mC/cm^(2)and 25.16 mC/cm^(2),which were higher than that of the TiN/HZO/TiN capacitor by 33%and 14%,respectively,and a high endurance of 109 cycles without hard-breakdown.The differences in the ferroelectric properties and switching kinetics were understood based on the polymorphism and texture of the HZO films influenced by electrode materials.展开更多
The impact of oxygen content in the Ru electrode,grown using atomic layer deposition on ferroelectricity in Hf_(0.5)Zr_(0.5)O_(2)film is investigated.The oxygen content in Ru can be modulated by simply adjusting the d...The impact of oxygen content in the Ru electrode,grown using atomic layer deposition on ferroelectricity in Hf_(0.5)Zr_(0.5)O_(2)film is investigated.The oxygen content in Ru can be modulated by simply adjusting the deposition temperature from 210℃to 300◦C.Higher oxygen content in Ru reduces the oxygen vacancy concentration in subsequently grown Hf_(0.5)Zr_(0.5)O_(2)film,thereby mitigating the wake-up effect.However,the monoclinic phase fraction increased with decreasing Ru deposition temperature,resulting in a decrease in remanent polarization.The decreased oxygen vacancy concentration by oxygen diffusion from Ru electrode deposited at 210℃could decrease the leakage current density compared to that grown at higher temperatures.Nonetheless,the switching endurance of Hf_(0.5)Zr_(0.5)O_(2)film grown on Ru deposited at 210℃was shorter than those on Ru deposited at 300℃by 2 order of magnitude,being attributed to the oxygen diffusion caused interfacial damages.This observation suggests that the interfacial redox reactions between the electrode and Hf_(0.5)Zr_(0.5)O_(2)critically influence defect concentration,polymorphism,and the resulting ferroelectricity when using an atomic layer deposited Ru electrode to examine the impact of interfacial redox chemistry.展开更多
Hafnium oxide(HfO_(2))-based ferroelectric materials have been widely applied in logic and memory devices due to their favorable ferroelectric and dielectric properties.However,the weak ferroelectric polarization of p...Hafnium oxide(HfO_(2))-based ferroelectric materials have been widely applied in logic and memory devices due to their favorable ferroelectric and dielectric properties.However,the weak ferroelectric polarization of pure HfO_(2)limits its application potential in advanced ferroelectric devices.Here,an ultrahigh remanent polarization is successfully achieved in the Ce-doped HfO_(2)films through a chemical negative strain due to the biaxial strain engineering strategy.The Ce-doped HfO_(2)films with regulated ions concentrations are fabricated on crystallographic-oriented substrates,and the effects of substrate-induced strain on the film growth were systematically investigated.Notably,the Ce-doped HfO_(2)films grown on(011)oriented substrates exhibit an excellent remanent polarization(2P_(t)=102.1µC/cm^(2),representing the highest value reported for HfO_(2)-based ferroelectrics,along with the outstanding fatigue resistance(<10%degradation after 107 switching cycles).This work provides a novel strategy for developing high-performance HfO_(2)-based ferroelectric materials through strain engineering,laying a critical foundation for their applications in non-volatile memory technologies.展开更多
The physical mechanism of doping effects on switching uniformity and operation voltage in Al-doped HfO_2 resistive random access memory(RRAM) devices is proposed from another perspective:defects interactions, based on...The physical mechanism of doping effects on switching uniformity and operation voltage in Al-doped HfO_2 resistive random access memory(RRAM) devices is proposed from another perspective:defects interactions, based on first principle calculations.In doped HfO_2,dopant is proved to have a localized effect on the formation of defects and the interactions between them.In addition,both effects cause oxygen vacancies(V_O) to have a tendency to form clusters and these clusters are easy to form around the dopant.It is proved that this process can improve the performance of material through projected density of states(PDOS) analysis.For V_O filament-type RRAM devices, these clusters are concluded to be helpful for the controllability of the switching process in which oxygen vacancy filaments form and break.Therefore,improved uniformity and operation voltage of Al-doped HfjO_2 RRAM devices is achieved.展开更多
The emergence of data-centric applications such as artificial intelligence(AI),machine learning,and the Internet of Things(IoT),has promoted surges in demand for storage memories with high operating speed and nonvolat...The emergence of data-centric applications such as artificial intelligence(AI),machine learning,and the Internet of Things(IoT),has promoted surges in demand for storage memories with high operating speed and nonvolatile characteristics.HfO_(2)-based ferroelectric memory technologies,which emerge as a promising alternative,have attracted considerable attention due to their high performance,energy efficiency,and full compatibility with the standard complementary metal-oxide-semiconductors(CMOS)process.These nonvolatile storage elements,such as ferroelectric random access memory(FeRAM),ferroelectric field-effect transistors(FeFETs),and ferroelectric tunnel junctions(FTJs),possess different data access mechanisms,individual merits,and specific application boundaries in next-generation memories or even beyond von Neumann architecture.This paper provides an overview of ferroelectric HfO2 memory technologies,addresses the current challenges,and offers insights into future research directions and prospects.展开更多
基金financially supported by the National Key R&D Program of China(2021YFB4000800)the Provincial Natural Science Foundation of Hunan(2025JJ60351,2023JJ30599,2023JJ50009)the National Natural Science Foundation of China(U23A20322)。
文摘Traditional optical fiber communication encryption methods lack sufficient dynamic adaptability and hardware flexibility,while reconfigurable logic gates can overcome this limitation,thereby significantly improving the flexibility of encryption systems.This study reports a reconfigurable optoelectronic logic gate(OELG)system based on hafnium-zirconium oxide(HZO)ferroelectric thin films.Through ultra-low temperature atomic layer deposition technique,the fabricated HZO thin films demonstrate an exceptional pyroelectric coefficient(1835.91μC m^(−2) K^(-1))and robust multi-level polarization stability,enabling efficient broadband photon-to-current conversion.By leveraging the pyroelectric effect and tunable polarization states,the OELG device achieves dynamic optical signal modulation and logic processing.The OELG device supports five fundamental logic operations(AND,OR,NAND,NOR,NOT)via electrical bias and polarization control,without requiring hardware modifications.The OELG device demonstrates stable performance over 109 cycles with no degradation,meeting practical application requirements.Furthermore,a convolutional neural network(CNN)-integrated image encryption-decryption framework was validated,achieving 95.01%recognition accuracy on decrypted data,while unauthorized decryption attempts resulted in significant feature loss.This study addresses security challenges in optical communication networks by proposing an innovative solution that integrates pyroelectric materials with reconfigurable logic gate technology,offering a new pathway to enhance physical-layer security.
基金supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning No. NRF-2020R1A6C101A202 and NRF-2024M3A7C2045166 and NRF-2021M3I3A1084940 and RS-2023-00257666 and RS-2024-00446683 and RS-2024-00450836.
文摘Amorphous and non-stoichiometric hafnium oxide(a-HfO_(x))systems are essential for advanced electronic applications due to their superior electrical properties.Simulating their atomic behaviors under electric fields(Efield)is critical but challenging.Ab-initio molecular dynamics(AIMD)offer high accuracy but is computationally expensive,while classical MD lacks precision.To address this,we develop a charge equilibration integrated graph neural network(CIGNN)model that predicts atomic charge,energy,and force under Efield conditions.Using the CIGNN model and AIMD datasets,we develop a CIGNN-based machine learning potential(CNMP)optimized for a-HfO_(x)systems.The CNMP achieves quantum mechanical accuracy and effectively captures the atomic behaviors and dynamic properties of these systems across varying temperatures,densities,and E_(field)conditions.We expect the CNMP to serve as a valuable tool for studying field-induced phenomena in complex systems and to provide a foundation for advancing innovations in electronic applications.
基金financially supported by the Science and Technology Program of Beijing Municipal Science and Technology Commission (No.Z201100006820084)the National Natural Science Foundation of China (Nos.92064003,91964202 and 61904194)the Youth Innovation Promotion Association,Chinese Academy of Sciences under grant (Nos.2023130 and Y9YQ01R004)。
文摘In this work,a conventional HfO_(2) gate dielectric layer is replaced with a 3-nm ferroelectric(Fe) HZO layer in the gate stacks of advanced fin field-effect transistors(FinFETs).Fe-induced characteristics,e.g.,negative drain induced barrier lowering(N-DIBL) and negative differential resistance(NDR),are clearly observed for both p-and n-type HZO-based FinFETs.These characteristics are attributed to the enhanced ferroelectricity of the 3-nm hafnium zirconium oxide(HZO) film,caused by Al doping from the TiAlC capping layer.This mechanism is verified for capacitors with structures similar to the FinFETs.Owing to the enhanced ferroelectricity and N-DIBL phenomenon,the drain current(I_(DS))of the HZO-FinFETs is greater than that of HfO_(2)-FinFETs and obtained at a lower operating voltage.Accordingly,circuits based on HZO-FinFET achieve higher performance than those based on HfO_(2)-FinFET at a low voltage drain(V_(DD)),which indicates the application feasibility of the HZO-FinFETs in the ultralow power integrated circuits.
基金supported by the National Natural Science Foundation of China (No. 50802080)the Natural Science Foundation of Fujian Province of China (No.2010Jo1349)
文摘Sputtering deposition coatings offer significant advantages on electron beam (EB) deposition, including high packing density, environmental stability and extremely low losses. But the inherent high compressive stress affects its application in high power laser system. This paper describes the technical feasibility of high damage threshold laser mirrors deposited by a novel remote plasma sputtering technique. This technique is based on generating intensive plasma remotely from the target and then magnetically steering the plasma to the target to realize the full uniform sputtering. The pseudo-independence between target voltage and target current provides us very flexible parameters tuning, especially for the films stress control. Deposition conditions are optimized to yield fully oxidized and low compressive stress single layer HfO2 and SiO2. The high damage threshold of 43.8 J/cm2 for HfO2/ SiO2 laser mirrors at 1064 nm is obtained. For the first time the remote plasma sputtering is successfully applied in depositing laser mirrors with high performance.
文摘We report a method to produce a uniform mixture of uranium dioxide spherical particles in a tungsten matrix. This method involves mixing 0.5 weight percent of high density polyethylene binder with 60 volume percent uranium dioxide spheres and 40 volume percent tungsten powders. Initially, hafnium oxide spheres were used as a surrogate for uranium dioxide spheres. The HfO2/W/PE powders were thoroughly mixed in a Turbula, then mixed on a hot plate above the drop point of the binder. These powders were then densified using spark plasma sintering. Microstructure was evaluated using scanning electron microscopy, density was measured and hardness measurements were made. Initial carbon content of the powders were measured and carbon content of the sintered materials was measured. Subsequently, W/UO2/Binder powders were mixed using the same methodology to ensure the process could be used for this system. These powders were sintered using hot isostatic pressing and microstructures evaluated. The resultant microstructures contained uniform distribution of HfO2 and UO2 particles in the tungsten matrix with very low carbon content.
基金supported by the National Natural Science Foundation of China (No.50802080)the Natural Science Foundation of Fujian Province of China (No.2010J01349)
文摘This paper describes a new method to design a laser mirror with high reflectivity, wide reflection bandwidth and high laser- induced damage threshold. The mirror is constructed by three materials of HfO/TiO2/SiO2 based on electric field and temperature field distribution characteristics of all-dielectric laser high reflector. TiO/SiO2 stacks act as the high reflector （HR） and broaden the reflection bandwidth, while HfO2/SiO2 stacks are used for increasing the laser resistance. The HfO/ TiO/SiO2 laser mirror with 34 layers is fabricated by a novel remote plasma sputtering deposition. The damage threshold of zero damage probability for the new mirror is up to 39.6 J/cm^2 （1064 nm, 12 ns）. The possible laser damage mechanism of the mirror is discussed.
文摘Hafnium oxide thin films （HOTFs） were successfully deposited onto amorphous glasses using chemical bath deposition, successive ionic layer absorption and reaction （SILAR）, and sol-gel methods. The same reactive precursors were used for all of the methods, and all of the films were annealed at 300℃ in an oven （ambient conditions）. After this step, the optical and structural properties of the films produced by using the three different methods were compared. The structures of the films were analyzed by X-ray diffTaction （XRD）. The optical properties are investigated using the ultraviolet-visible （UV-VIS） spectroscopic technique. The film thickness was measured via atomic force microscopy （AFM） in the tapping mode. The surface properties and elemental ratios of the films were investigated and measured by scanning electron microscopy and energy-dispersive X-ray spectroscopy （EDX）. The lowest transmittance and the highest reflectance values were observed for the films produced using the SILAR method. In addition, the most intense characteristic XRD peak was observed in the diffraction pattern of the film produced using the SILAR method, and the greatest thickness and average grain size were calculated for the film produced using the SILAR method. The films produced using SILAR method contained fewer cracks than those produced using the other methods. In conclusion, the SILAR method was observed to be the best method for the production of HOTFs.
基金supported by the National Natural Science Foundation of China(Grant Nos.51372135 and 61176003)the Tsinghua University Initiative Scientific Research Program,China
文摘Amorphous HfO2 nano-helix arrays with different screw pitches were fabricated by the glancing angle deposition technique. Room temperature ferromagnetism was achieved in this undoped amorphous HfO2 nanostructure, which is attributed to singly charged oxygen vacancies. The different magnetic behavior and photoluminescence in flat film and nano-helix arrays originate from the distinction of defect components. This study could facilitate the understanding of ferromagnetism origin in undoped HfO2, it also suggests a possible way to alter the intrinsic defects in amorphous HfO2.
文摘A highly efficient benzylation of arenes and heteroarenes catalyzed by HfCl4/HfO2 has been developed. Broad scope of benzylation reagents have been used in this process with high yields under mild condition. Additionally, the HfO2 can be re-used after the reaction. ？2009 Xin Qin Gao. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
基金financially supported by the National Key Research and Development Program of China (No.2017YFB0305400)。
文摘The Al-Hf alloy was prepared by open aluminothermic reduction of HfO_(2) using CaF_(2) and Na F as the flux. The influence of the slag composition, the amount of aluminum, and the heat energizer was studied detailly to establish optimum conditions for the sufficient recovery of the alloy and the complete slag-alloy separation. The Al-Hf alloy with 40 wt% Hf was obtained by this method, and the maximum recovery was 70.7%. The microstructure of the alloy was observed by scanning electron microscope(SEM). Moreover, X-ray diffraction(XRD) analysis and energy-disperse spectrometry(EDS) were applied to characterize the formation of the phases. The results show that the alloy consists of Al and Al_(3)Hf phases and the oxygen content is about 0.2 wt%.
基金supported by the National Natural Science Foundation of China(Grant No.11374182)
文摘Tunable modulations of terahertz waves in a graphene/ferroelectric-layer/silicon hybrid structure are demonstrated at low bias voltages. The modulation is due to the creation/elimination of an extra barrier in Si layer in response to the polarization in the ferroelectric Si:HfOlayer. Considering the good compatibility of HfOwith the Si-based semiconductor process, the highly tunable characteristics of the graphene metamaterial device under ferroelectric effect open up new avenues for graphene-based high performance integrated active photonic devices compatible with the silicon technology.
文摘With advanced research for dielectrics including capacitors in DRAMs, decoupling filters in microcircuits and insulating gates in transistors, a lot of demand for the new challenging of high-k materials in semiconductor industries has been emerged. This study explores and addresses the experimental approach for composite materials with one of the major concerns of high capacitance, and low leakage, as well as ease of integration technology. The characteristics of Al<sub>2</sub>O<sub>3</sub> supported HfO<sub>2</sub> (AHO) thin films for a series of different Hf ratios with Al<sub>2</sub>O<sub>3</sub> dielectrics by atomic layer deposition demonstrated as a candidate material. A composite AHO films with the homogeneous compositions of Al and Hf atoms into the Al-Hf-O mixed oxide system could stabilize the polycrystalline structure with increasing of dielectric constant (k) and decreasing of leakage current density, as well as a higher breakdown voltage than HfO<sub>2</sub> film on its own. 70 nm thick AHO thin films with different composition of Al and Hf contents were prepared by atomic layer deposition technique on titanium nitride (TiN) and silicon dioxide (SiO<sub>2</sub>) coated Si substrates. Photolithography and metal lift-off technique were used for the device fabrication of the metal-insulator-metal (MIM) capacitor structures. AHO films on TiN/SiO<sub>2</sub>/Si were measured by semiconductor analyzer and source/ measure system with probe station in the voltage range from -5 to 5 V with a frequency range from 10 kHz to 1 MHz were used to conduct capacitance-voltage (C-V) measurements with low/medium frequency range and current-voltage (I-V) measurements. It was found that Au/AHO/TiN/SiO<sub>2</sub>/Si MIM capacitors demonstrate a capacitance density of 1.5 - 4.5 fF/μm<sup>2</sup> at 10 kHz, a loss tangent of 0.02 - 0.04 at 10 kHz, dielectric constant of 11.7 - 35.5 depending on the composition and a low leakage current of 1.7 × 10<sup>-9</sup> A/cm<sup>2</sup> at 0.5 MV/cm at room temperature. The acquired experimental results could show the possibility of compositional alloy thin films that could potentially replace or open new market for high-k challenges in semiconductor technology.
基金supported by the National Natural Science Foundation of China(Nos.52122205,52302151,11932016,12302429,and 12202330)the Qin Chuang Yuan Cited High-level Innovation and Entrepreneurship Talent Project(No.QCYRCXM-2023-075)+2 种基金the Fundamental Research Funds for the Central Universities(No.ZYTS24122)the Xidian University Specially Funded Project for Interdisciplinary Exploration(No.TZJH2024054)the Start-up Foundation of Xidian University(No.10251220008).
文摘Ferroelectric thin films based on HfO_(2) have garnered increasing attention worldwide,primarily due to their remarkable compatibility with silicon and scalability,in contrast to traditional perovskite-structured ferroelectric materials.Nonetheless,significant challenges remain in their widespread commercial utilization,particularly concerning their notable wake-up effect and limited endurance.To address these challenges,we propose a novel strategy involving the inhomogeneous distribution of Hf/Zr elements within thin films and explore its effects on the ferroelectricity and endurance of Hf_(0.5)Zr_(0.5)O_(2) thin films.Through techniques such as grazing incidence X-ray diffraction,transmission electron microscopy,and piezoresponse force microscopy,we investigated the structural characteristics and domain switching behaviors of these materials.The experimental results indicate that the inhomogeneous distribution of Hf/Zr contributes to improving the frequency stability and endurance while maintaining a large remnant polarization in Hf_(0.5)Zr_(0.5)O_(2) ferroelectric thin films.By adjusting the distribution of Zr/Hf within the Hf_(0.5)Zr_(0.5)O_(2) thin films,significant enhancements in the remnant polarization(2P_(r)>35μC/cm2)and endurance(>109)along with a reduced coercive voltage can be achieved.Additionally,the fabricated ferroelectric thin films also exhibit high dielectric tunability(≥26%)under a low operating voltage of 2.5 V,whether in the wake-up state or not.This study offers a promising approach to optimize both the ferroelectricity and endurance of HfO_(2)-based thin films.
基金supported by the Council of Scientific & Industrial Research(CSIR),India under the SRF scheme(No.08/237(0005)/2012-EMR-I)
文摘We have analyzed the effective oxide thickness （EOT） of the dielectric material for which we have optimum performance and the output characteristics of the silicon nanowire transistors by replacing the traditional Si02 gate insulator with a material that has a much higher dielectric constant （high-k） gate, materials like Si3N4, Al2O3, Y2O3 and HfO2. We have also analyzed the channel conductance, the effect of a change in thickness, the average velocity of the charge carrier and the conductance efficiency in order to study the performance of silicon nanowire transistors in the nanometer region. The analysis was performed using the Fettoy, a numerical simulator for ballistic nanowire transistors using a simple top of the barrier （Natori） approach, which is composed of several matlab scripts. Our results show that hafnium oxide （HfO2） gate insulator material provides good thermal stability, a high recrystallization temperature and better interface qualities when compared with other gate insulator materials; also the effective oxide thickness of lifO2 is found to be 0.4 nm.
基金supported by the National Research Foundation,Prime Minister's Office,Singapore,under its Competitive Research Program(NRF-CRP24-2020-0002)。
文摘Analog reservoir computing(ARC)systems offer an energy-efficient platform for temporal information processing.However,their physical implementation typically requires disparate materials and device architectures for different system components,leading to complicated fabrication processes and increased system complexity.In this work,we present a coplanar floating-gate antiferroelectric field-effect transistor(FG AFeFET)that unifies multiple neural functionalities within a single device,enabling the physical implementation of a complete ARC system.By combining a coplanar layout design with an area ratio engineering strategy,we achieve tunable device behaviors,including volatile responses for artificial neuron emulation,nonvolatile states for synaptic functions,and fading memory dynamics for reservoir operations.The mechanisms underlying these functionalities and their operating mechanism are systematically elucidated using load line analysis and energy band diagrams.Leveraging these insights,we demonstrate an all-in-one ARC system based on the unified coplanar FG AFeFET architecture,which achieves recognition accuracies of 95.6%and 83.4%on the MNIST and Fashion-MNIST datasets,respectively.These findings highlight the potential of coplanar FG AFeFETs to deliver area-efficient,design-flexible neuromorphic hardware for next-generation computing systems.
基金supported by the National Research Foundation of Korea,funded by the Ministry of Science and ICT(RS-2024-00445552)(50%)supported by the Nano&Material Technology Development Program through the National Research Foundation of Korea(NRF)funded by Ministry of Science and ICT(RS-2024-00444182)(50%).
文摘This study proposes a novel approach to achieving highly reliable,low-voltage polarization switching of ferroelectric Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films using polymorph-and orientation-controlled W electrodes((111)-textured a-W and(200)-textured b-W)by adjusting the sputtering conditions.We demonstrated the formation of(111)and(002)/(020)-textured HZO films on the(111)-textured a-Wand(200)-textured b-W electrodes,respectively.Under a low-voltage pulse of 1.2 V(1.5 MV/cm),a-W/HZO/a-W and b-W/HZO/b-W capacitors exhibited double-remanent polarization(2Pr)values of 29.23 mC/cm^(2)and 25.16 mC/cm^(2),which were higher than that of the TiN/HZO/TiN capacitor by 33%and 14%,respectively,and a high endurance of 109 cycles without hard-breakdown.The differences in the ferroelectric properties and switching kinetics were understood based on the polymorphism and texture of the HZO films influenced by electrode materials.
基金supported by the National Research Foundation of Korea,funded by the Ministry of Science and ICT(RS-2024-00445552)(50%)supported by the Technology Innovation Program(RS-2024-00509266,Development of Next-generation dielectric and electrode process equipment for logic 1 nm or less and memory x nm level)funded By the Ministry of Trade Industry&Energy(MOTIE,Korea).
文摘The impact of oxygen content in the Ru electrode,grown using atomic layer deposition on ferroelectricity in Hf_(0.5)Zr_(0.5)O_(2)film is investigated.The oxygen content in Ru can be modulated by simply adjusting the deposition temperature from 210℃to 300◦C.Higher oxygen content in Ru reduces the oxygen vacancy concentration in subsequently grown Hf_(0.5)Zr_(0.5)O_(2)film,thereby mitigating the wake-up effect.However,the monoclinic phase fraction increased with decreasing Ru deposition temperature,resulting in a decrease in remanent polarization.The decreased oxygen vacancy concentration by oxygen diffusion from Ru electrode deposited at 210℃could decrease the leakage current density compared to that grown at higher temperatures.Nonetheless,the switching endurance of Hf_(0.5)Zr_(0.5)O_(2)film grown on Ru deposited at 210℃was shorter than those on Ru deposited at 300℃by 2 order of magnitude,being attributed to the oxygen diffusion caused interfacial damages.This observation suggests that the interfacial redox reactions between the electrode and Hf_(0.5)Zr_(0.5)O_(2)critically influence defect concentration,polymorphism,and the resulting ferroelectricity when using an atomic layer deposited Ru electrode to examine the impact of interfacial redox chemistry.
基金the National Natural Science Foundation of China(22371013,92263205)the National Key Research and Development Program of China(2018YFA0703700)+3 种基金the Fundamental Research Funds for the Central Universities(FRF-IDRY-19-007 and FRF-TP-19-055A2Z)the National Program for Support of Top-notch Young Professionalsthe Young Elite Scientists Sponsorship Program by CAST(2019-2021QNRC)the"Xiaomi Young Scholar"Funding Project。
文摘Hafnium oxide(HfO_(2))-based ferroelectric materials have been widely applied in logic and memory devices due to their favorable ferroelectric and dielectric properties.However,the weak ferroelectric polarization of pure HfO_(2)limits its application potential in advanced ferroelectric devices.Here,an ultrahigh remanent polarization is successfully achieved in the Ce-doped HfO_(2)films through a chemical negative strain due to the biaxial strain engineering strategy.The Ce-doped HfO_(2)films with regulated ions concentrations are fabricated on crystallographic-oriented substrates,and the effects of substrate-induced strain on the film growth were systematically investigated.Notably,the Ce-doped HfO_(2)films grown on(011)oriented substrates exhibit an excellent remanent polarization(2P_(t)=102.1µC/cm^(2),representing the highest value reported for HfO_(2)-based ferroelectrics,along with the outstanding fatigue resistance(<10%degradation after 107 switching cycles).This work provides a novel strategy for developing high-performance HfO_(2)-based ferroelectric materials through strain engineering,laying a critical foundation for their applications in non-volatile memory technologies.
基金supported by the National Natural Science Youth Foundation of China(No.61006064)
文摘The physical mechanism of doping effects on switching uniformity and operation voltage in Al-doped HfO_2 resistive random access memory(RRAM) devices is proposed from another perspective:defects interactions, based on first principle calculations.In doped HfO_2,dopant is proved to have a localized effect on the formation of defects and the interactions between them.In addition,both effects cause oxygen vacancies(V_O) to have a tendency to form clusters and these clusters are easy to form around the dopant.It is proved that this process can improve the performance of material through projected density of states(PDOS) analysis.For V_O filament-type RRAM devices, these clusters are concluded to be helpful for the controllability of the switching process in which oxygen vacancy filaments form and break.Therefore,improved uniformity and operation voltage of Al-doped HfjO_2 RRAM devices is achieved.
基金supported in part by National Natural Science Foundation(62274101,U20A20168,61874065,51861145202)of Chinain part by the National Key R&D Program(2021YFC3002200,2020YFA0709800,2018YFC2001202,2022Y FB3204100)of China+2 种基金in part by JCCDFSIT(2022CDF003)QYJS-2022-1600-BBNR2024RC01002.
文摘The emergence of data-centric applications such as artificial intelligence(AI),machine learning,and the Internet of Things(IoT),has promoted surges in demand for storage memories with high operating speed and nonvolatile characteristics.HfO_(2)-based ferroelectric memory technologies,which emerge as a promising alternative,have attracted considerable attention due to their high performance,energy efficiency,and full compatibility with the standard complementary metal-oxide-semiconductors(CMOS)process.These nonvolatile storage elements,such as ferroelectric random access memory(FeRAM),ferroelectric field-effect transistors(FeFETs),and ferroelectric tunnel junctions(FTJs),possess different data access mechanisms,individual merits,and specific application boundaries in next-generation memories or even beyond von Neumann architecture.This paper provides an overview of ferroelectric HfO2 memory technologies,addresses the current challenges,and offers insights into future research directions and prospects.
