With ultrafast laser systems reaching presently 10 PW peak power or operating at high repetition rates,research towards ensuring the long-term,trouble-free performance of all laser-exposed optical components is critic...With ultrafast laser systems reaching presently 10 PW peak power or operating at high repetition rates,research towards ensuring the long-term,trouble-free performance of all laser-exposed optical components is critical.Our work is focused on providing insight into the optical material behavior at fluences below the standardized laser-induced damage threshold(LIDT)value by implementing a simultaneous dual analysis of surface emitted particles using a Langmuir probe(LP)and the target current(TC).HfO_(2) and ZrO_(2) thin films deposited on fused silica substrates by pulsed laser deposition at various O_(2) pressures for defect and stoichiometry control were irradiated by Gaussian,ultrashort laser pulses(800 nm,10 Hz,70 fs)in a wide range of fluences.Both TC and LP collected signals were in good agreement with the existing theoretical description of laser–matter interaction at an ultrashort time scale.Our approach for an in situ LIDT monitoring system provides measurable signals for below-threshold irradiation conditions that indicate the endurance limit of the optical surfaces in the single-shot energy scanning mode.The LIDT value extracted from the LP-TC system is in line with the multipulse statistical analysis done with ISO 21254-2:2011(E).The implementation of the LP and TC as on-shot diagnostic tools for optical components will have a significant impact on the reliability of next-generation ultrafast and high-power laser systems.展开更多
Field-free spin-orbit torque(SOT)switching of perpendicular magnetization is essential for future spintronic devices.This study demonstrates the field-free switching of perpendicular magnetization in an HfO_(2)/Pt/Co/...Field-free spin-orbit torque(SOT)switching of perpendicular magnetization is essential for future spintronic devices.This study demonstrates the field-free switching of perpendicular magnetization in an HfO_(2)/Pt/Co/TaO_(x) structure,which is facilitated by a wedge-shaped HfO_(2)buffer layer.The field-free switching ratio varies with HfO_(2)thickness,reaching optimal performance at 25 nm.This phenomenon is attributed to the lateral anisotropy gradient of the Co layer,which is induced by the wedge-shaped HfO_(2)buffer layer.The thickness gradient of HfO_(2)along the wedge creates a corresponding lateral anisotropy gradient in the Co layer,correlating with the switching ratio.These findings indicate that field-free SOT switching can be achieved through designing buffer layer,offering a novel approach to innovating spin-orbit device.展开更多
Ferroelectric random access memory(FeRAM)based on conventional ferroelectric perovskites,such as Pb(Zr,Ti)O_(3)and SrBi_(2)T_(2)O_(9),has encountered bottlenecks on memory density and cost,because those conventional p...Ferroelectric random access memory(FeRAM)based on conventional ferroelectric perovskites,such as Pb(Zr,Ti)O_(3)and SrBi_(2)T_(2)O_(9),has encountered bottlenecks on memory density and cost,because those conventional perovskites suffer from various issues mainly including poor complementary metal-oxide-semiconductor(CMOS)-compatibility and limited scalability.Next-generation cost-efficient,high-density FeRAM shall therefore rely on a material revolution.Since the discovery of ferroelectricity in Si:HfO_(2)thin films in 2011,HfO_(2)-based materials have aroused widespread interest in the field of FeRAM,because they are CMOS-compatible and can exhibit robust ferroelectricity even when the film thickness is scaled down to below 10 nm.A review on this new class of ferroelectric materials is therefore of great interest.In this paper,the most appealing topics about ferroelectric HfO_(2)-based materials including origins of ferroelectricity,advantageous material properties,and current and potential applications in FeRAM,are briefly reviewed.展开更多
The discovery of ferroelectricity in HfO_(2) based materials reactivated the research on ferroelectric memory.However,the complete mechanism underlying its ferroelectricity remains to be fully elucidated.In this study...The discovery of ferroelectricity in HfO_(2) based materials reactivated the research on ferroelectric memory.However,the complete mechanism underlying its ferroelectricity remains to be fully elucidated.In this study,we conducted a systematic study on the microstructures and ferroelectric properties of Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films with various annealing rates in the rapid thermal annealing.It was observed that the HZO thin films with higher annealing rates demonstrate smaller grain size,reduced surface roughness and a higher portion of orthorhombic phase.Moreover,these films exhibited enhanced polarization values and better fatigue cycles compared to those treated with lower annealing rates.The grazing incidence x-ray diffraction measurements revealed the existence of tension stress in the HZO thin films,which was weakened with decreasing annealing rate.Our findings revealed that this internal stress,along with the stress originating from the top/bottom electrode,plays a crucial role in modulating the microstructure and ferroelectric properties of the HZO thin films.By carefully controlling the annealing rate,we could effectively regulate the tension stress within HZO thin films,thus achieving precise control over their ferroelectric properties.This work established a valuable pathway for tailoring the performance of HZO thin films for various applications.展开更多
In this letter,an enhancement-mode(E-mode)GaN p-channel field-effect transistor(p-FET)with a high current den-sity of−4.9 mA/mm based on a O_(3)-Al_(2)O_(3)/HfO_(2)(5/15 nm)stacked gate dielectric was demonstrated on ...In this letter,an enhancement-mode(E-mode)GaN p-channel field-effect transistor(p-FET)with a high current den-sity of−4.9 mA/mm based on a O_(3)-Al_(2)O_(3)/HfO_(2)(5/15 nm)stacked gate dielectric was demonstrated on a p++-GaN/p-GaN/AlN/AlGaN/AlN/GaN/Si heterostructure.Attributed to the p++-GaN capping layer,a good linear ohmic I−V characteristic fea-turing a low-contact resistivity(ρc)of 1.34×10^(−4)Ω·cm^(2) was obtained.High gate leakage associated with the HfO_(2)high-k gate dielectric was effectively blocked by the 5-nm O_(3)-Al_(2)O_(3)insertion layer grown by atomic layer deposition,contributing to a high ION/IOFF ratio of 6×10^(6)and a remarkably reduced subthreshold swing(SS)in the fabricated p-FETs.The proposed structure is compelling for energy-efficient GaN complementary logic(CL)circuits.展开更多
DNA origami-assisted nanolithography(DOANL)for fabricating custom-designed nanomaterials through pattern transfer from DNA origami to different substrates materials are presented.However,the pattern's integrity an...DNA origami-assisted nanolithography(DOANL)for fabricating custom-designed nanomaterials through pattern transfer from DNA origami to different substrates materials are presented.However,the pattern's integrity and resolution face considerable challenges due to the uncontrollable growth of the nanomaterials during transformation and the unclear mechanism of DOANL.Herein,we report a DOANL combined with area-selective atomic layer deposition(ALD)strategy for fabricating custom shapes hafnium oxide(HfO2)with the high-fidelity and high-throughput.We find that the HfO_(2)selectively grows on DNA origami substrates in a hydroxyl-rich area instead of a methyl-rich protective layer.Combined with the merit of the area-selective ALD method,theHfO_(2)atom selectively coated on the DNA origami surface,thus,precisely modeling the shapes with high-precision in our study based on the surface groups difference of DNA origami and the naked hexamethyldisilane(HMDS)-treated substrates,which reveal the mechanical of high-fidelity pattern transfer based on DOANL.As a result,DNA origami structures can program the shape ofHfO_(2)nanostructures.The DOANL that is based on the principle of"bottom-up"precision assembly breaks through the shape complexity and high-throughput fabrication limitation of theHfO_(2)nanostructures,including two-and three-dimensional structures,plane and curved structures,monolithic and hollow structures.Based on the"top-down"accurate fabrication principle,the area-selective ALD on methyl-rich protective layer substrates improves the integrity and resolution of the pattern transfer process.Overall,this work provides a general technology for nanofabrication strategy.展开更多
The pulsed laser deposition(PLD)technology was used to effectively create conductive nano and micro hafnium oxide with great purity and transparency for(HfO_(2))nanofilms.In many optoelectronics devices and their appl...The pulsed laser deposition(PLD)technology was used to effectively create conductive nano and micro hafnium oxide with great purity and transparency for(HfO_(2))nanofilms.In many optoelectronics devices and their applications,the presence of a high dielectric substance like a nano HfO2,between the metal contacts and the substrates was critical.We used the Pulsed Laser Deposition method to fabricate an Al/HfO_(2)/p-Si Schottky barrier diode where the nanostructured HfO2 films as an intermediate layer and varied substrate temperatures.The optical result reveals a high degree of transparency(93%).The optical bandgap of deposited HfO2 films was observed to vary between 4.9 and 5.3 eV,with a value of roughly 5.3 eV at the optimal preparation condition.The morphology of the surface shows a high homogeneous nano structure with the average values of the roughness about(0.3 nm).With regard to substrate temperature,the produced factor ideality for fabricated diode was determined to be lowering and the associated values of the barrier height rose based on I-Vcharacterization.With regard to substrate temperature,the produced factor ideality for fabricated diode was determined to be lowering and the associated values of the barrier height rose based on I-V characterization.The diode manufactured at 600℃,in particular,had a higher ideality factor value(n=3.2).展开更多
Neodymium and manganese doped BiFeO_(3)-(Bi_(0.95)Nd_(0.05))(Fe_(0.95)Mn_(0.05))O_(3)(BNFMO)ferro-electric film and HfO_(2)layer with different thickness were fabricated using metal-organic decomposition and atomic la...Neodymium and manganese doped BiFeO_(3)-(Bi_(0.95)Nd_(0.05))(Fe_(0.95)Mn_(0.05))O_(3)(BNFMO)ferro-electric film and HfO_(2)layer with different thickness were fabricated using metal-organic decomposition and atomic layer deposition(ALD)method,respectively.Metal ferroelectric-insulator-semiconductor(MFIS)capacitors with 200 nm thick BNFMO and 5 nm thick HfO_(2)layer on silicon substrate have been prepared and characterized.It is found that there is no distinct interdifusion and reaction occurring at the interface between BNFMO/HfO_(2)and HfO_(2)/Si.The capacitance-voltage(C-V)and leakage current properties of Pt/HfO_(2)/Si capacitors with different HfO_(2)thickness were studied.The MFIS structure showed clockwise C-V hysteresis loops due to the ferroelectric polarization of BNFMO.The maximum memory window is 5 V.The.leakage current of the Pt/BNFMO/HfO_(2)/Si capacitor was about 2.1×10^(-6)A/cm^(2)at an applied voltage of 4V.展开更多
基金This work was supported by the Romanian Ministry of Education and Research,under Nucleus Project LAPLAS VII contract No.30N/2023,ELI RO 2020-12,PCE 104/2022,PED 580/2022We would also like to acknowledge the support from project code PN 2321 sponsored by the Romanian Ministry of Research,Innovation,and Digitalisation by the Nucleus program.Financial support of the ASUR platform was provided by the European Community and LaserLab Europe programs EU-H2020654148 and 871124(projects Nos.CNRS-LP3002460 and CNRS-LP3002589).
文摘With ultrafast laser systems reaching presently 10 PW peak power or operating at high repetition rates,research towards ensuring the long-term,trouble-free performance of all laser-exposed optical components is critical.Our work is focused on providing insight into the optical material behavior at fluences below the standardized laser-induced damage threshold(LIDT)value by implementing a simultaneous dual analysis of surface emitted particles using a Langmuir probe(LP)and the target current(TC).HfO_(2) and ZrO_(2) thin films deposited on fused silica substrates by pulsed laser deposition at various O_(2) pressures for defect and stoichiometry control were irradiated by Gaussian,ultrashort laser pulses(800 nm,10 Hz,70 fs)in a wide range of fluences.Both TC and LP collected signals were in good agreement with the existing theoretical description of laser–matter interaction at an ultrashort time scale.Our approach for an in situ LIDT monitoring system provides measurable signals for below-threshold irradiation conditions that indicate the endurance limit of the optical surfaces in the single-shot energy scanning mode.The LIDT value extracted from the LP-TC system is in line with the multipulse statistical analysis done with ISO 21254-2:2011(E).The implementation of the LP and TC as on-shot diagnostic tools for optical components will have a significant impact on the reliability of next-generation ultrafast and high-power laser systems.
基金Project supported by the National Natural Science Foundation of China (Grant No.12274108)the Natural Science Foundation of Zhejiang Province,China (Grant Nos.LY23A040008 and LY23A040008)the Basic Scientific Research Project of Wenzhou,China (Grant No.G20220025)。
文摘Field-free spin-orbit torque(SOT)switching of perpendicular magnetization is essential for future spintronic devices.This study demonstrates the field-free switching of perpendicular magnetization in an HfO_(2)/Pt/Co/TaO_(x) structure,which is facilitated by a wedge-shaped HfO_(2)buffer layer.The field-free switching ratio varies with HfO_(2)thickness,reaching optimal performance at 25 nm.This phenomenon is attributed to the lateral anisotropy gradient of the Co layer,which is induced by the wedge-shaped HfO_(2)buffer layer.The thickness gradient of HfO_(2)along the wedge creates a corresponding lateral anisotropy gradient in the Co layer,correlating with the switching ratio.These findings indicate that field-free SOT switching can be achieved through designing buffer layer,offering a novel approach to innovating spin-orbit device.
基金the Singapore National Research Foundation under CRP Award No.NRF-CRP10-2012-02.
文摘Ferroelectric random access memory(FeRAM)based on conventional ferroelectric perovskites,such as Pb(Zr,Ti)O_(3)and SrBi_(2)T_(2)O_(9),has encountered bottlenecks on memory density and cost,because those conventional perovskites suffer from various issues mainly including poor complementary metal-oxide-semiconductor(CMOS)-compatibility and limited scalability.Next-generation cost-efficient,high-density FeRAM shall therefore rely on a material revolution.Since the discovery of ferroelectricity in Si:HfO_(2)thin films in 2011,HfO_(2)-based materials have aroused widespread interest in the field of FeRAM,because they are CMOS-compatible and can exhibit robust ferroelectricity even when the film thickness is scaled down to below 10 nm.A review on this new class of ferroelectric materials is therefore of great interest.In this paper,the most appealing topics about ferroelectric HfO_(2)-based materials including origins of ferroelectricity,advantageous material properties,and current and potential applications in FeRAM,are briefly reviewed.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.62174059 and 52250281)the Science and Technology Projects of Guangzhou Province of China (Grant No.202201000008)+1 种基金the Guangdong Science and Technology Project-International Cooperation (Grant No.2021A0505030064)the Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials (Grant No.2020B1212060066)。
文摘The discovery of ferroelectricity in HfO_(2) based materials reactivated the research on ferroelectric memory.However,the complete mechanism underlying its ferroelectricity remains to be fully elucidated.In this study,we conducted a systematic study on the microstructures and ferroelectric properties of Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films with various annealing rates in the rapid thermal annealing.It was observed that the HZO thin films with higher annealing rates demonstrate smaller grain size,reduced surface roughness and a higher portion of orthorhombic phase.Moreover,these films exhibited enhanced polarization values and better fatigue cycles compared to those treated with lower annealing rates.The grazing incidence x-ray diffraction measurements revealed the existence of tension stress in the HZO thin films,which was weakened with decreasing annealing rate.Our findings revealed that this internal stress,along with the stress originating from the top/bottom electrode,plays a crucial role in modulating the microstructure and ferroelectric properties of the HZO thin films.By carefully controlling the annealing rate,we could effectively regulate the tension stress within HZO thin films,thus achieving precise control over their ferroelectric properties.This work established a valuable pathway for tailoring the performance of HZO thin films for various applications.
基金This work was supported in part by the National Key Research and Development Program of China under Grant 2022YFB3604400in part by the Youth Innovation Promotion Association of Chinese Academy Sciences(CAS)+4 种基金in part by CAS-Croucher Funding Scheme under Grant CAS22801in part by National Natural Science Foundation of China under Grant 62074161,Grant 62004213,and Grant U20A20208in part by the Beijing Municipal Science and Technology Commission project under Grant Z201100008420009 and Grant Z211100007921018in part by the University of CASin part by IMECAS-HKUST-Joint Laboratory of Microelectronics.
文摘In this letter,an enhancement-mode(E-mode)GaN p-channel field-effect transistor(p-FET)with a high current den-sity of−4.9 mA/mm based on a O_(3)-Al_(2)O_(3)/HfO_(2)(5/15 nm)stacked gate dielectric was demonstrated on a p++-GaN/p-GaN/AlN/AlGaN/AlN/GaN/Si heterostructure.Attributed to the p++-GaN capping layer,a good linear ohmic I−V characteristic fea-turing a low-contact resistivity(ρc)of 1.34×10^(−4)Ω·cm^(2) was obtained.High gate leakage associated with the HfO_(2)high-k gate dielectric was effectively blocked by the 5-nm O_(3)-Al_(2)O_(3)insertion layer grown by atomic layer deposition,contributing to a high ION/IOFF ratio of 6×10^(6)and a remarkably reduced subthreshold swing(SS)in the fabricated p-FETs.The proposed structure is compelling for energy-efficient GaN complementary logic(CL)circuits.
基金supported by the National Key R&D Program of China(No.2019YFA0905800)the National Natural Science Foundation of China(No.21705048)+5 种基金Guangdong Basic and Applied Basic Research Foundation(No.2021A1515012333)Natural Science Foundation of Jiangxi Province(No.20192ACBL20046)the Fundamental Research Funds for the Central Universities(No.20720200004)the Key Project of College Youth Natural Fund of Fujian Province(No.JZ160404)the Key Laboratory of Sensing Technology and Biomedical Instruments of Guangdong Province(No.2020B1212060077)support from Qingdao XINO Tech company.Thanks to Yange Wang for his help in AFM scanning。
文摘DNA origami-assisted nanolithography(DOANL)for fabricating custom-designed nanomaterials through pattern transfer from DNA origami to different substrates materials are presented.However,the pattern's integrity and resolution face considerable challenges due to the uncontrollable growth of the nanomaterials during transformation and the unclear mechanism of DOANL.Herein,we report a DOANL combined with area-selective atomic layer deposition(ALD)strategy for fabricating custom shapes hafnium oxide(HfO2)with the high-fidelity and high-throughput.We find that the HfO_(2)selectively grows on DNA origami substrates in a hydroxyl-rich area instead of a methyl-rich protective layer.Combined with the merit of the area-selective ALD method,theHfO_(2)atom selectively coated on the DNA origami surface,thus,precisely modeling the shapes with high-precision in our study based on the surface groups difference of DNA origami and the naked hexamethyldisilane(HMDS)-treated substrates,which reveal the mechanical of high-fidelity pattern transfer based on DOANL.As a result,DNA origami structures can program the shape ofHfO_(2)nanostructures.The DOANL that is based on the principle of"bottom-up"precision assembly breaks through the shape complexity and high-throughput fabrication limitation of theHfO_(2)nanostructures,including two-and three-dimensional structures,plane and curved structures,monolithic and hollow structures.Based on the"top-down"accurate fabrication principle,the area-selective ALD on methyl-rich protective layer substrates improves the integrity and resolution of the pattern transfer process.Overall,this work provides a general technology for nanofabrication strategy.
文摘The pulsed laser deposition(PLD)technology was used to effectively create conductive nano and micro hafnium oxide with great purity and transparency for(HfO_(2))nanofilms.In many optoelectronics devices and their applications,the presence of a high dielectric substance like a nano HfO2,between the metal contacts and the substrates was critical.We used the Pulsed Laser Deposition method to fabricate an Al/HfO_(2)/p-Si Schottky barrier diode where the nanostructured HfO2 films as an intermediate layer and varied substrate temperatures.The optical result reveals a high degree of transparency(93%).The optical bandgap of deposited HfO2 films was observed to vary between 4.9 and 5.3 eV,with a value of roughly 5.3 eV at the optimal preparation condition.The morphology of the surface shows a high homogeneous nano structure with the average values of the roughness about(0.3 nm).With regard to substrate temperature,the produced factor ideality for fabricated diode was determined to be lowering and the associated values of the barrier height rose based on I-Vcharacterization.With regard to substrate temperature,the produced factor ideality for fabricated diode was determined to be lowering and the associated values of the barrier height rose based on I-V characterization.The diode manufactured at 600℃,in particular,had a higher ideality factor value(n=3.2).
基金support from International cooperation project from Ministry of Science and Technology of China(2008DFA12000)NSF of China(60936002,51072089)+1 种基金NSF of Beijing(3111002)Foundation of State Key Laboratory of Electronic Thin Films and Integrated Devices,University of Electronic Science and Technology of China,Chengdu(KFJJ200904).
文摘Neodymium and manganese doped BiFeO_(3)-(Bi_(0.95)Nd_(0.05))(Fe_(0.95)Mn_(0.05))O_(3)(BNFMO)ferro-electric film and HfO_(2)layer with different thickness were fabricated using metal-organic decomposition and atomic layer deposition(ALD)method,respectively.Metal ferroelectric-insulator-semiconductor(MFIS)capacitors with 200 nm thick BNFMO and 5 nm thick HfO_(2)layer on silicon substrate have been prepared and characterized.It is found that there is no distinct interdifusion and reaction occurring at the interface between BNFMO/HfO_(2)and HfO_(2)/Si.The capacitance-voltage(C-V)and leakage current properties of Pt/HfO_(2)/Si capacitors with different HfO_(2)thickness were studied.The MFIS structure showed clockwise C-V hysteresis loops due to the ferroelectric polarization of BNFMO.The maximum memory window is 5 V.The.leakage current of the Pt/BNFMO/HfO_(2)/Si capacitor was about 2.1×10^(-6)A/cm^(2)at an applied voltage of 4V.
