Ferroelectric materials are widely applied in the ferroelectronic devices,photovoltaics,and so on.Ultrathin ferroelectric thin films are highly desired for their applications,which still remain a challenge.In this wor...Ferroelectric materials are widely applied in the ferroelectronic devices,photovoltaics,and so on.Ultrathin ferroelectric thin films are highly desired for their applications,which still remain a challenge.In this work,the ultrathin barium titanate(BaTiO_(3),BTO)films are deposited directly on the fluorine-doped tin oxide glass(SnO_(2):F,FTO)substrates by radio frequency magnetron sputtering method at different temperatures.All BTO ultrathin films exhibit strong ferroelectric properties.Interestingly,BTO thin films deposited at room temperature(RT)also exhibit robust ferroelectricity.The polar domains are switched reversibly with a phase degree of~180°by piezoelectric force microscopy for the BTO thin films deposited at room temperature,attributing to the strain and ion migration.展开更多
Thin film capacitors with excellent energy storage performances,thermal stability and fatigue endurance are strongly desired in modern electrical and electronic industry.Herein,we design and prepare lead-free0.7Sr_(0....Thin film capacitors with excellent energy storage performances,thermal stability and fatigue endurance are strongly desired in modern electrical and electronic industry.Herein,we design and prepare lead-free0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3BiFeO_(3)-x%Mn(x=0,0.5,1.5,2,3)thin films via sol-gel method.Mn ions of divalent valence combine with oxygen vacancies,forming defect complex,which results in marked decline in leakage current and obvious enhancement in breakdown strength.A high energy storage density~47.6 J cm^(-3)and good efficiency~65.68%are simultaneously achieved in 2%Mn doped 0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3 BiFeO_(3)thin film capacitor.Moreover,the 2%Mn-doped thin film exhibits excellent thermal stability in wide operating temperature range(35–115℃)and strong fatigue endurance behaviors after 108 cycles.The above results demonstrate that 2%Mn-doped 0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3 BiFeO_(3)thin film capacitor with superior energy storage performances is a potential candidate for electrostatic energy storage.展开更多
The effects of the modification of electrode/ceramic interfaces through a chemical solution deposition-derived PbO buffer layer on the fatigue endurance of lead zirconate titanate（PZT） thin films were investigated.T...The effects of the modification of electrode/ceramic interfaces through a chemical solution deposition-derived PbO buffer layer on the fatigue endurance of lead zirconate titanate（PZT） thin films were investigated.The grain size and the surface roughness of the PZT films increased through PbO interfacial modification.Moreover,the PZT films with PbO interfacial modification had a better crystallographic structure and no evident secondary phases were observed.While the remanent polarization and dielectric constant were reduced,the fatigue endurance was improved.Based on the results,the mechanism for the fatigue endurance improvement was discussed.展开更多
This paper discusses the possibility of synthesis of SBTL sol-gel films for use as active layers for non-volatile memory （FRAM）. La-doped SrBi2Ta209 thin films were synthesized by sol-gel method on Pt/TiO2/BPSG/SiO2...This paper discusses the possibility of synthesis of SBTL sol-gel films for use as active layers for non-volatile memory （FRAM）. La-doped SrBi2Ta209 thin films were synthesized by sol-gel method on Pt/TiO2/BPSG/SiO2/Si substrates. The structural features of the surface （AFM）, crystallization behavior （XRD） during the heating and ferroelectric properties of synthesized films were discussed. It was shown that an optimum surface structure and a high share of perovskite phase of SBTL-films were compared to SBT-films （Theating=800 ℃）. Achieved ferroelectric parameters suggested the possibility of using synthesized SBTL sol-gel films in non-volatile memory devices.展开更多
The 0.9Pb（Sc0.5Ta0.5）O3-0.1PbTiO3/0.55Pb（Sc0.5Ta0.5）O3-0.45 PbTiO3 multilayer thin films（（PSTT10/45）n, n = 1-6, 10） are deposited on SiO2/Si（100） substrates by radio frequency magnetron sputtering technique ...The 0.9Pb（Sc0.5Ta0.5）O3-0.1PbTiO3/0.55Pb（Sc0.5Ta0.5）O3-0.45 PbTiO3 multilayer thin films（（PSTT10/45）n, n = 1-6, 10） are deposited on SiO2/Si（100） substrates by radio frequency magnetron sputtering technique with La Ni O3 buffer and electrode layer, and the films are subsequently annealed by a two-step rapid thermal approach. It is found that the interfacial density of the film has an important influence on the electric property of the film. The electric property of the film increases and reaches its critical point with the increase of interface density, and then decreases with the further increase of the interface density. With an interfacial density of 16 μm-1, the film shows an optimized dielectric property（high dielectric constant, εr = 765, lowest dielectric loss, tan δ = 0.041, at 1 k Hz） and ferroelectric property（highest remnant polarization,2Pr = 36.9 μC/cm2, low coercive field, 2Ec = 71.9 k V/cm）. The possible reason for the electric behavior of the film is the competition of the interface stress with the interface defect.展开更多
Bismuth ferrite（Bi_2Fe_4O_9） thin films were grown on p-type Si（100） substrate by radio-frequency magnetron sputtering at 873 K. X-ray diffraction, field emission scanning electron microscopy and Raman spectroscop...Bismuth ferrite（Bi_2Fe_4O_9） thin films were grown on p-type Si（100） substrate by radio-frequency magnetron sputtering at 873 K. X-ray diffraction, field emission scanning electron microscopy and Raman spectroscopy studies revealed that the grown films have single-phase polycrystalline nature and are crystallized in orthorhombic structure. The grain size of the grown thin films was found to increase（56–130 nm） with sputtering power. Atomic force microscopy images clearly illustrated that the grown thin films have smooth surface. Energy-dispersive X-ray analysis revealed the presence of Bi, Fe and O elements with desired ratio and also the absence of impurities in the grown films. Analysis of ferroelectric hysteresis loops revealed that the remanent polarization and coercive field increase with the increase in sputtering power. Vicker＇s hardness analysis showed that the hardness of films strongly depends on the grain size and film thickness, which are mainly determined by the sputtering power. The above observations revealed that Bi_2Fe_4O_9 thin film deposited at higher sputtering power has good crystallinity and shows better electrical properties.展开更多
Properties of ferroelectric xBiInO3-（1-x）PbTiO3（xBI-（1-x）PT） thin films deposited on（101） SrRuO3/（200）Pt/（200） MgO substrates by rf magnetron sputtering method and effects of deposition conditions are inve...Properties of ferroelectric xBiInO3-（1-x）PbTiO3（xBI-（1-x）PT） thin films deposited on（101） SrRuO3/（200）Pt/（200） MgO substrates by rf magnetron sputtering method and effects of deposition conditions are investigated.The structures of the xBI-（1-x）PT films are characterized by x-ray diffraction and scanning electron microscopy.The results indicate that the thin films are grown with mainly（001） orientation. The chemical compositions of the films are analyzed by scanning electron probe and the results indicate that the loss phenomena of Pb and Bi elements depend on the pressure and temperature during the sputtering process.The sputtering parameters including target composition, substrate temperature, and gas pressure are adjusted to obtain optimum sputtering conditions. To decrease leakage currents,2 mol% La2 O3 is doped in the targets. The P-E hysteresis loops show that the optimized xBI-（1-x）PT（x = 0.24） film has high ferroelectricities with remnant polarization2 Pr = 80μC/cm2 and coercive electric field 2 EC = 300 kV/cm. The Curie temperature is about 640℃. The results show that the films have optimum performance and will have wide applications.展开更多
PbZr0.53Ti0.47O3 (PZT) ferroelectric thin films were deposited on LaNiO3 (LNO) by sol-gel method. The PbTiO3 (PT) seed layer was depos-ited between the LNO buffer layer and stainless steel (SS) substrate, which effect...PbZr0.53Ti0.47O3 (PZT) ferroelectric thin films were deposited on LaNiO3 (LNO) by sol-gel method. The PbTiO3 (PT) seed layer was depos-ited between the LNO buffer layer and stainless steel (SS) substrate, which effectively decreased the annealing temperature of LNO layer from 750 C to 650 C. X-ray diffraction (XRD) reveals that LNO layers with PT layer crystallize into a perovskite phase on annealing at 650 C for 10 min. PZT deposited on LNO buffer layer with PT seed layer exhibits good ferroelectric property.展开更多
BiMeO_(3)–PbTiO_(3)(where Me represents transition metals)perovskite-type thin films have been widely studied due to their superior ferroelectric properties,including robust ferroelectric polarization and high Curie ...BiMeO_(3)–PbTiO_(3)(where Me represents transition metals)perovskite-type thin films have been widely studied due to their superior ferroelectric properties,including robust ferroelectric polarization and high Curie temperatures.In this study,PbTiO_(3)-based perovskite thin films of xBi(Cu_(1/2)Zr_(1/2))O_(3)–(1-x)PbTiO_(3)(xBCZ–(1-x)PT)were designed and prepared on Pt(111)/Ti/SiO_(2)/Si substrates using the conventional sol–gel method.The x BCZ–(1-x)PT thin films demonstrate remarkable crystallinity,characterized by a perovskite structure and a dense microstructure,which contribute to their highperformance ferroelectric and fatigue properties.Notably,the thin films exhibit large remnant polarization(2P_(r0))values,reaching 98μC·cm^(-2)and 74μC·cm^(-2)for the 0.05BCZ–0.95PT and 0.1BCZ–0.9PT compositions,respectively.Furthermore,the thin films also demonstrate a high Curie temperature(T_(C)=510℃),as well as favorable fatigue properties and low leakage current,suggesting their potential applicability in ferroelectric devices.展开更多
As the core component of ferroelectric memories,HfO_(2)-based ferroelectric thin films play a crucial role in achieving their excellent storage performance.Here,we improved the ferroelectric properties and domain swit...As the core component of ferroelectric memories,HfO_(2)-based ferroelectric thin films play a crucial role in achieving their excellent storage performance.Here,we improved the ferroelectric properties and domain switching properties through in situ stress loading during annealing.The thin films are annealed under different bending states by applying different stress actions,and it is observed that,within a certain range of stress bending,the optimization of the ferroelectric properties of the annealed thin films can reach an extreme value.Specifically,under the influence of a small electric field,the 2Pr values of thin films annealed at+10 and-10 mm increased by 87.1%and 71.1%,respectively,compared with the unbent films.Additionally,these thin films exhibit extremely high domain wall mobility and excellent domain switching capabilities.Once the ferroelectric phase is formed through in situ stress modulation,it remains stable even under multiple service environments.展开更多
High-scalability HfO_(2)-based ferroelectric thin films are promising for application in fast,energy-efficient,and high-density non-volatile memories.This ferroelectricity is believed to originate from the metastable ...High-scalability HfO_(2)-based ferroelectric thin films are promising for application in fast,energy-efficient,and high-density non-volatile memories.This ferroelectricity is believed to originate from the metastable orthorhombic phase,which is difficult to obtain.Post-metallization annealing with a top electrode capping layer is a useful method for stabilizing the ferroelectric orthorhombic phase.However,direct physical evidence of the top electrode role is lacking.In this study,we visualized the dynamic process of the phase transition in Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films with TiN and Pt top electrodes during the heating and cooling processes through in-situ scanning transmission electron microscopy(STEM).The TiN top electrode stabilized the orthorhombic phase,whereas the Pt top electrode induced a phase transition to the monoclinic phase.Subsequently,we elucidated the phase transition mechanism in HZO thin films using the kinetic effect and revealed that it was related to the concentration of oxygen vacancies induced by the top electrode.This study provides valuable insights into the stabilization of the orthorhombic phase in HfO_(2)-based ferroelectric thin films and contributes to the elucidation of the phase transition mechanism of HfO_(2)-based ferroelectric thin films.展开更多
Chip-based soliton frequency microcombs combine compact size,broad bandwidth,and high coherence,presenting a promising solution for integrated optical telecommunications,precision sensing,and spectroscopy.Recent progr...Chip-based soliton frequency microcombs combine compact size,broad bandwidth,and high coherence,presenting a promising solution for integrated optical telecommunications,precision sensing,and spectroscopy.Recent progress in ferroelectric thin films,particularly thin-film lithium niobate(LiNbO_(3))and thin-film lithium tantalate(LiTaO_(3)),has significantly advanced electro-optic(EO)modulation and soliton microcombs generation,leveraging their strong third-order nonlinearity and high Pockels coefficients.However,achieving soliton frequency combs in X-cut ferroelectric materials remains challenging due to the competing effects of thermo-optic and photorefractive phenomena.These issues hinder the simultaneous realization of soliton generation and high-speed EO modulation.Here,following the thermal-regulated carrier behavior and auxiliary-laser-assisted approach,we propose a convenient mechanism to suppress both photorefractive and thermal dragging effects at once,and implement a facile method for soliton formation and its longterm stabilization in integrated X-cut LiTaO_(3) microresonators for the first time,to the best of our knowledge.The resulting mode-locked states exhibit robust stability against perturbations,enabling new pathways for fully integrated photonic circuits that combine Kerr nonlinearity with high-speed EO functionality.展开更多
Ferroelectric materials are highly promising for next-generation electro-optic(EO)modulators because of their ultrafast and efficient light modulation.However,efforts to maximize polarization freedom for large refract...Ferroelectric materials are highly promising for next-generation electro-optic(EO)modulators because of their ultrafast and efficient light modulation.However,efforts to maximize polarization freedom for large refractive index modulation—through domain engineering,epitaxial strain,and defect engineering—have hit limitations,leaving intrinsic polarization mechanisms largely unexplored.Here,we report a giant effective EO coefficient(~233.5 pm/V)in PbZr_(0.52)Ti_(0.48)O_(3)(PZT)films,which surpasses all reported values measured under an in-plane electric field and significantly exceeds the theoretical limit(~13 pm/V)as well as the value of LiNbO_(3)(~31 pm/V).Beyond conventional domain switching,phase transitions and domain wall variations critically enhance the EO effect.The highly relaxed structure of the PZT film,with mixed[001]and[100]orientations and disordered nanoscale phases,enables unprecedented polarization control.This unique configuration breaks the theoretical EO coefficient limit,bridging the gap between predictions and experimental results.Owing to its high Curie temperature and compatibility with wafer-scale fabrication,PZT has emerged as a promising candidate for next-generation high-performance EO modulators.Our findings not only advance the frontiers of ferroelectric EO materials but also pave the way for exploring other ferroelectric thin-film devices,such as those for energy storage and electrocaloric cooling,by leveraging enhanced polarization modulation mechanisms.展开更多
基金financially supported by the National Key Research and Development Program of China(No.2019YFB1503500)
文摘Ferroelectric materials are widely applied in the ferroelectronic devices,photovoltaics,and so on.Ultrathin ferroelectric thin films are highly desired for their applications,which still remain a challenge.In this work,the ultrathin barium titanate(BaTiO_(3),BTO)films are deposited directly on the fluorine-doped tin oxide glass(SnO_(2):F,FTO)substrates by radio frequency magnetron sputtering method at different temperatures.All BTO ultrathin films exhibit strong ferroelectric properties.Interestingly,BTO thin films deposited at room temperature(RT)also exhibit robust ferroelectricity.The polar domains are switched reversibly with a phase degree of~180°by piezoelectric force microscopy for the BTO thin films deposited at room temperature,attributing to the strain and ion migration.
基金the National Natural Science Foundation of China under Grant No.51332003 and 51372171。
文摘Thin film capacitors with excellent energy storage performances,thermal stability and fatigue endurance are strongly desired in modern electrical and electronic industry.Herein,we design and prepare lead-free0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3BiFeO_(3)-x%Mn(x=0,0.5,1.5,2,3)thin films via sol-gel method.Mn ions of divalent valence combine with oxygen vacancies,forming defect complex,which results in marked decline in leakage current and obvious enhancement in breakdown strength.A high energy storage density~47.6 J cm^(-3)and good efficiency~65.68%are simultaneously achieved in 2%Mn doped 0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3 BiFeO_(3)thin film capacitor.Moreover,the 2%Mn-doped thin film exhibits excellent thermal stability in wide operating temperature range(35–115℃)and strong fatigue endurance behaviors after 108 cycles.The above results demonstrate that 2%Mn-doped 0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3 BiFeO_(3)thin film capacitor with superior energy storage performances is a potential candidate for electrostatic energy storage.
基金support of Beijing Nova Program of China (2007B025)the National Natural Science Foundation of China (10979013)+1 种基金the Innovative Research Team in Universities (IRT 0509)the Major State Basic Research Development Program of China (No.2009CB623306)
文摘The effects of the modification of electrode/ceramic interfaces through a chemical solution deposition-derived PbO buffer layer on the fatigue endurance of lead zirconate titanate（PZT） thin films were investigated.The grain size and the surface roughness of the PZT films increased through PbO interfacial modification.Moreover,the PZT films with PbO interfacial modification had a better crystallographic structure and no evident secondary phases were observed.While the remanent polarization and dielectric constant were reduced,the fatigue endurance was improved.Based on the results,the mechanism for the fatigue endurance improvement was discussed.
文摘This paper discusses the possibility of synthesis of SBTL sol-gel films for use as active layers for non-volatile memory （FRAM）. La-doped SrBi2Ta209 thin films were synthesized by sol-gel method on Pt/TiO2/BPSG/SiO2/Si substrates. The structural features of the surface （AFM）, crystallization behavior （XRD） during the heating and ferroelectric properties of synthesized films were discussed. It was shown that an optimum surface structure and a high share of perovskite phase of SBTL-films were compared to SBT-films （Theating=800 ℃）. Achieved ferroelectric parameters suggested the possibility of using synthesized SBTL sol-gel films in non-volatile memory devices.
基金Project supported by the National Natural Science Foundation of China(Grant No.60771016)the Scientific Research Foundation of Mianyang Normal University,China(Grant No.QD2013A07)
文摘The 0.9Pb（Sc0.5Ta0.5）O3-0.1PbTiO3/0.55Pb（Sc0.5Ta0.5）O3-0.45 PbTiO3 multilayer thin films（（PSTT10/45）n, n = 1-6, 10） are deposited on SiO2/Si（100） substrates by radio frequency magnetron sputtering technique with La Ni O3 buffer and electrode layer, and the films are subsequently annealed by a two-step rapid thermal approach. It is found that the interfacial density of the film has an important influence on the electric property of the film. The electric property of the film increases and reaches its critical point with the increase of interface density, and then decreases with the further increase of the interface density. With an interfacial density of 16 μm-1, the film shows an optimized dielectric property（high dielectric constant, εr = 765, lowest dielectric loss, tan δ = 0.041, at 1 k Hz） and ferroelectric property（highest remnant polarization,2Pr = 36.9 μC/cm2, low coercive field, 2Ec = 71.9 k V/cm）. The possible reason for the electric behavior of the film is the competition of the interface stress with the interface defect.
文摘Bismuth ferrite（Bi_2Fe_4O_9） thin films were grown on p-type Si（100） substrate by radio-frequency magnetron sputtering at 873 K. X-ray diffraction, field emission scanning electron microscopy and Raman spectroscopy studies revealed that the grown films have single-phase polycrystalline nature and are crystallized in orthorhombic structure. The grain size of the grown thin films was found to increase（56–130 nm） with sputtering power. Atomic force microscopy images clearly illustrated that the grown thin films have smooth surface. Energy-dispersive X-ray analysis revealed the presence of Bi, Fe and O elements with desired ratio and also the absence of impurities in the grown films. Analysis of ferroelectric hysteresis loops revealed that the remanent polarization and coercive field increase with the increase in sputtering power. Vicker＇s hardness analysis showed that the hardness of films strongly depends on the grain size and film thickness, which are mainly determined by the sputtering power. The above observations revealed that Bi_2Fe_4O_9 thin film deposited at higher sputtering power has good crystallinity and shows better electrical properties.
基金Supported by the National Natural Science Foundation of China under Grant No 11304160the Special Fund for Public Interest of China under Grant No 201510068,and the NUPTFC under Grant No NY215111
文摘Properties of ferroelectric xBiInO3-（1-x）PbTiO3（xBI-（1-x）PT） thin films deposited on（101） SrRuO3/（200）Pt/（200） MgO substrates by rf magnetron sputtering method and effects of deposition conditions are investigated.The structures of the xBI-（1-x）PT films are characterized by x-ray diffraction and scanning electron microscopy.The results indicate that the thin films are grown with mainly（001） orientation. The chemical compositions of the films are analyzed by scanning electron probe and the results indicate that the loss phenomena of Pb and Bi elements depend on the pressure and temperature during the sputtering process.The sputtering parameters including target composition, substrate temperature, and gas pressure are adjusted to obtain optimum sputtering conditions. To decrease leakage currents,2 mol% La2 O3 is doped in the targets. The P-E hysteresis loops show that the optimized xBI-（1-x）PT（x = 0.24） film has high ferroelectricities with remnant polarization2 Pr = 80μC/cm2 and coercive electric field 2 EC = 300 kV/cm. The Curie temperature is about 640℃. The results show that the films have optimum performance and will have wide applications.
基金supported by the National Natural Science Foundation of China (No. 50872080)Shanghai Special Foundation of Nanotechnology (No. 1052nm07300)+1 种基金Shanghai Education Development Foundation (No. 08SG41)Shanghai Leading Academic Disciplines (No. S30107)
文摘PbZr0.53Ti0.47O3 (PZT) ferroelectric thin films were deposited on LaNiO3 (LNO) by sol-gel method. The PbTiO3 (PT) seed layer was depos-ited between the LNO buffer layer and stainless steel (SS) substrate, which effectively decreased the annealing temperature of LNO layer from 750 C to 650 C. X-ray diffraction (XRD) reveals that LNO layers with PT layer crystallize into a perovskite phase on annealing at 650 C for 10 min. PZT deposited on LNO buffer layer with PT seed layer exhibits good ferroelectric property.
基金Project supported by the National Key Research and Development Program of China(Grant No.2021YFA1400300)the National Natural Science Foundation of China(Grant Nos.22271309,12304268,12261131499,and 11921004)the China Postdoctoral Science Foundation(Grant No.2023M743741)。
文摘BiMeO_(3)–PbTiO_(3)(where Me represents transition metals)perovskite-type thin films have been widely studied due to their superior ferroelectric properties,including robust ferroelectric polarization and high Curie temperatures.In this study,PbTiO_(3)-based perovskite thin films of xBi(Cu_(1/2)Zr_(1/2))O_(3)–(1-x)PbTiO_(3)(xBCZ–(1-x)PT)were designed and prepared on Pt(111)/Ti/SiO_(2)/Si substrates using the conventional sol–gel method.The x BCZ–(1-x)PT thin films demonstrate remarkable crystallinity,characterized by a perovskite structure and a dense microstructure,which contribute to their highperformance ferroelectric and fatigue properties.Notably,the thin films exhibit large remnant polarization(2P_(r0))values,reaching 98μC·cm^(-2)and 74μC·cm^(-2)for the 0.05BCZ–0.95PT and 0.1BCZ–0.9PT compositions,respectively.Furthermore,the thin films also demonstrate a high Curie temperature(T_(C)=510℃),as well as favorable fatigue properties and low leakage current,suggesting their potential applicability in ferroelectric devices.
基金supported by the National Natural Science Foundation of China(Nos.12372331,12072307)the Department of Education Project of Hunan Province,China(No.21B0112)+1 种基金the fund of Innovation Center of Radiation Application(No.KFZC2022020602)the Outstanding Youth Science Foundation of Hunan Province,China(No.2021JJ20041).
文摘As the core component of ferroelectric memories,HfO_(2)-based ferroelectric thin films play a crucial role in achieving their excellent storage performance.Here,we improved the ferroelectric properties and domain switching properties through in situ stress loading during annealing.The thin films are annealed under different bending states by applying different stress actions,and it is observed that,within a certain range of stress bending,the optimization of the ferroelectric properties of the annealed thin films can reach an extreme value.Specifically,under the influence of a small electric field,the 2Pr values of thin films annealed at+10 and-10 mm increased by 87.1%and 71.1%,respectively,compared with the unbent films.Additionally,these thin films exhibit extremely high domain wall mobility and excellent domain switching capabilities.Once the ferroelectric phase is formed through in situ stress modulation,it remains stable even under multiple service environments.
基金supported by the Scientific Research Innovation Capability Support Project for Young Faculty(Grant No.ZYGXQNJSKYCXNLZCXM-M22)the National Natural Science Foundation of China(Grant Nos.52122205,51901166,12302429,12474092 and 52250308)+4 种基金the National Key Research and Development Program of China(Grant No.2024YFA1208603)the Natural Science Basic Research Program of Shaanxi(Program No.2024JC-YBQN-0583)the Guangdong Basic and Applied Basic Research Foundation(No.2022A1515110116)the Fundamental Research Funds for the Central Universitiesthe Innovation Fund of Xidian University.
文摘High-scalability HfO_(2)-based ferroelectric thin films are promising for application in fast,energy-efficient,and high-density non-volatile memories.This ferroelectricity is believed to originate from the metastable orthorhombic phase,which is difficult to obtain.Post-metallization annealing with a top electrode capping layer is a useful method for stabilizing the ferroelectric orthorhombic phase.However,direct physical evidence of the top electrode role is lacking.In this study,we visualized the dynamic process of the phase transition in Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films with TiN and Pt top electrodes during the heating and cooling processes through in-situ scanning transmission electron microscopy(STEM).The TiN top electrode stabilized the orthorhombic phase,whereas the Pt top electrode induced a phase transition to the monoclinic phase.Subsequently,we elucidated the phase transition mechanism in HZO thin films using the kinetic effect and revealed that it was related to the concentration of oxygen vacancies induced by the top electrode.This study provides valuable insights into the stabilization of the orthorhombic phase in HfO_(2)-based ferroelectric thin films and contributes to the elucidation of the phase transition mechanism of HfO_(2)-based ferroelectric thin films.
基金National Key Research and Development Program of China(2022YFA1404601)National Natural Science Foundation of China(62293520,62293521,12074400,62205363,12104442,12404446,12293052)+4 种基金Shanghai Science and Technology Innovation Action Plan Program(20JC1416200,22JC1403300)CAS Project for Young Scientists in Basic Research(YSBR-69)Natural Science Foundation of Anhui Province(2408085QA010)China Postdoctoral Science Foundation(2024M753078)Postdoctoral Fellowship Program of CPSF(GZC20232560)。
文摘Chip-based soliton frequency microcombs combine compact size,broad bandwidth,and high coherence,presenting a promising solution for integrated optical telecommunications,precision sensing,and spectroscopy.Recent progress in ferroelectric thin films,particularly thin-film lithium niobate(LiNbO_(3))and thin-film lithium tantalate(LiTaO_(3)),has significantly advanced electro-optic(EO)modulation and soliton microcombs generation,leveraging their strong third-order nonlinearity and high Pockels coefficients.However,achieving soliton frequency combs in X-cut ferroelectric materials remains challenging due to the competing effects of thermo-optic and photorefractive phenomena.These issues hinder the simultaneous realization of soliton generation and high-speed EO modulation.Here,following the thermal-regulated carrier behavior and auxiliary-laser-assisted approach,we propose a convenient mechanism to suppress both photorefractive and thermal dragging effects at once,and implement a facile method for soliton formation and its longterm stabilization in integrated X-cut LiTaO_(3) microresonators for the first time,to the best of our knowledge.The resulting mode-locked states exhibit robust stability against perturbations,enabling new pathways for fully integrated photonic circuits that combine Kerr nonlinearity with high-speed EO functionality.
基金Wen Dong acknowledges National Key R&D Program of China(No.2024YFA1409703)National Natural Science Foundation of China(No.52202134)+4 种基金Hubei Nature Science Foundation(No.2022CFB595)Biaolin Peng acknowledges the Key Research and Development Program of Shandong Province of China(No.2022CXGC020203)National Natural Science Foundation of China(No.62271362)Shenglin Jiang acknowledges National Natural Science Foundation of China(No.61971459)the Analytical and Testing Center of Huazhong University of Science and Technology,Electron Microscopy Center of Yunnan University(No.2022CFB595).
文摘Ferroelectric materials are highly promising for next-generation electro-optic(EO)modulators because of their ultrafast and efficient light modulation.However,efforts to maximize polarization freedom for large refractive index modulation—through domain engineering,epitaxial strain,and defect engineering—have hit limitations,leaving intrinsic polarization mechanisms largely unexplored.Here,we report a giant effective EO coefficient(~233.5 pm/V)in PbZr_(0.52)Ti_(0.48)O_(3)(PZT)films,which surpasses all reported values measured under an in-plane electric field and significantly exceeds the theoretical limit(~13 pm/V)as well as the value of LiNbO_(3)(~31 pm/V).Beyond conventional domain switching,phase transitions and domain wall variations critically enhance the EO effect.The highly relaxed structure of the PZT film,with mixed[001]and[100]orientations and disordered nanoscale phases,enables unprecedented polarization control.This unique configuration breaks the theoretical EO coefficient limit,bridging the gap between predictions and experimental results.Owing to its high Curie temperature and compatibility with wafer-scale fabrication,PZT has emerged as a promising candidate for next-generation high-performance EO modulators.Our findings not only advance the frontiers of ferroelectric EO materials but also pave the way for exploring other ferroelectric thin-film devices,such as those for energy storage and electrocaloric cooling,by leveraging enhanced polarization modulation mechanisms.
