The lack of effective charge transfer driving force and channel limits the electron directional migration in nanoclusters(NC)-based heterostructures,resulting in poor photocatalytic performance.Herein,a Z-scheme NC-ba...The lack of effective charge transfer driving force and channel limits the electron directional migration in nanoclusters(NC)-based heterostructures,resulting in poor photocatalytic performance.Herein,a Z-scheme NC-based heterojunction(Pt1Ag28-BTT/CoP,BTT=1,3,5-benzenetrithiol)with strong internal electric field is constructed via interfacial Co-S bond,which exhibits an absolutely superiority in photocatalytic performance with 24.89 mmol·h^(−1)·g−1 H_(2)production rate,25.77%apparent quantum yield at 420 nm,and~100%activity retention in stability,compared with Pt1Ag28-BDT/CoP(BDT=1,3-benzenedithiol),Ag29-BDT/CoP,and CoP.The enhanced catalytic performance is contributed by the dual modulation strategy of inner core and outer shell of NC,wherein,the center Pt single atom doping regulates the band structure of NC to match well with CoP,builds internal electric field,and then drives photogenerated electrons steering;the accurate surface S modification promotes the formation of Co-S atomic-precise interface channel for further high-efficient Z-scheme charge directional migration.This work opens a new avenue for designing NC-based heterojunction with matchable band structure and valid interfacial charge transfer.展开更多
Vacancy engineering and Mott-Schottky heterostructure can accelerate charge transfer,regulate adsorption energy of reaction intermediates,and provide additional active sites,which are regarded as valid means for impro...Vacancy engineering and Mott-Schottky heterostructure can accelerate charge transfer,regulate adsorption energy of reaction intermediates,and provide additional active sites,which are regarded as valid means for improving catalytic activity.However,the underlying mechanism of synergistic regulation of interfacial charge transfer and optimization of electrocatalytic activity by combining vacancy and Mott-Schottky junction remains unclear.Herein,the growth of a bifunctional NiCo/NiCoP Mott-Schottky electrode with abundant phosphorus vacancies on foam nickel(NF)has been synthesized through continuous phosphating and reduction processes.The obtained NiCo/NiCoP heterojunctions show remarkable OER and HER activities,and the overpotentials for OER and HER are as low as 117 and 60 mV at 10 mA/cm^(2) in 1 mol/L KOH,respectively.Moreover,as both the cathode and anode of overall water splitting,the voltage of the bifunctional NiCo/NiCoP electrocatalyst is 1.44 V at 10 mA/cm^(2),which are far exceeding the benchmark commercial electrodes.DFT theoretical calculation results confirm that the phosphorus vacancies and build-in electric field can effectively accelerate ion and electron transfer between NiCo alloy and NiCoP semiconductor,tailor the electronic structure of the metal centers and lower the Gibbs free energy of the intermediates.Furthermore,the unique self-supported integrated structure is beneficial to facilitate the exposure of the active site,avoid catalyst shedding,thus improving the activity and structural stability of NiCo/NiCoP.This study provides an avenue for the controllable synthesis and performance optimization of Mott-Schottky electrocatalysts.展开更多
Hafnia-based ferroelectrics have greatly revived the field of ferroelectric memory(FeRAM),but certain reliability issues must be satisfactorily resolved before they can be widely applied in commercial memories.In part...Hafnia-based ferroelectrics have greatly revived the field of ferroelectric memory(FeRAM),but certain reliability issues must be satisfactorily resolved before they can be widely applied in commercial memories.In particular,the imprint phenomenon severely jeopardizes the read-out reliability in hafnia-based ferroelectric capacitors,but its origin remains unclear,which hinders the development of its recovery schemes.In this work,we have systematically investigated the imprint mechanism in TiN/Hf_(0.5)Zr_(0.5)O_(2)(HZO)/TiN ferroelectric capacitors using experiments and first-principles calculations.It is shown that carrier injection-induced charged oxygen vacancies are at the heart of imprint in HZO,where other mechanisms such as domain pinning and dead layer are less important.An imprint model based on electron de-trapping from oxygen vacancy sites has been proposed that can satisfactorily explain several experimental facts such as the strong asymmetric imprint,leakage current variation,and so forth.Based on this model,an effective imprint recovery method has been proposed,which utilizes unipolar rather than bipolar voltage inputs.The remarkable recovery performances demonstrate the prospect of improved device reliability in hafnia-based FeRAM devices.展开更多
The doping profile function of a double base epilayer is constructed according to drift-diffusion theory. Then an analytical model for the base transit time τb is developed assuming a small-level injection based on t...The doping profile function of a double base epilayer is constructed according to drift-diffusion theory. Then an analytical model for the base transit time τb is developed assuming a small-level injection based on the characteristics of the 4H-SiC material and the principle of the 4H-SiC BJTs. The device is numerically simulated and validated based on two-dimensional simulation models. The results show that the built-in electric field generated by the double base epilayer configuration can accelerate the carriers when transiting the base region and reduce the base transit time. From the simulation results, the base transit time reaches a minimal value when the ratio of L2/L1 is about 2.展开更多
Through-silicon via(TSV)is a key enabling technology for the emerging 3-dimension(3 D)integrated circuits(ICs).However,the crosstalk between the neighboring TSVs is one of the important sources of the soft faults.To s...Through-silicon via(TSV)is a key enabling technology for the emerging 3-dimension(3 D)integrated circuits(ICs).However,the crosstalk between the neighboring TSVs is one of the important sources of the soft faults.To suppress the crosstalk,the Fibonacci-numeral-system-based crosstalk avoidance code(FNS-CAC)is an effective scheme.Meanwhile,the self-repair schemes are often used to deal with the hard faults,but the repaired results may change the mapping between signals to TSVs,thus may reduce the crosstalk suppression ability of FNS-CAC.A TSV self-repair technique with an improved FNS-CAC codec is proposed in this work.The codec is designed based on the improved Fibonacci numeral system(FNS)adders,which are adaptive to the health states of TSVs.The proposed self-repair technique is able to suppress the crosstalk and repair the faulty TSVs simultaneously.The simulation and analysis results show that the proposed scheme keeps the crosstalk suppression ability of the original FNS-CAC,and it has higher reparability than the local self-repair schemes,such as the signal-switching-based and the signal-shifting-based counterparts.展开更多
Organometallic perovskite is a new generation photovoltaic material with exemplary properties such as high absorption co-efficient,optimal bandgap,high defect tolerance factor and long carrier diffusion length.However...Organometallic perovskite is a new generation photovoltaic material with exemplary properties such as high absorption co-efficient,optimal bandgap,high defect tolerance factor and long carrier diffusion length.However,suitable electrodes and charge transport materials are required to fulfill photovoltaic processes where interfaces between hole transport material/perovskite and perovskite/electron transport material are affected by phenomena of charge carrier separation,transportation,collection by the interfaces and band alignment.Based on recent available literature and several strategies for minimizing the recombination of charge carriers at the interfaces,this review addresses the properties of hole transport materials,relevant working mechanisms,and the interface engineering of perovskite solar cell(PSC)device architecture,which also provides significant insights to design and development of PSC devices with high efficiency.展开更多
基金the Natural Science research project of Universities in Anhui Province(No.KJ2021ZD0001)the Natural Science Foundation of Anhui Province(No.2208085MB20)the National Natural Science Foundation of China(No.22101001).
文摘The lack of effective charge transfer driving force and channel limits the electron directional migration in nanoclusters(NC)-based heterostructures,resulting in poor photocatalytic performance.Herein,a Z-scheme NC-based heterojunction(Pt1Ag28-BTT/CoP,BTT=1,3,5-benzenetrithiol)with strong internal electric field is constructed via interfacial Co-S bond,which exhibits an absolutely superiority in photocatalytic performance with 24.89 mmol·h^(−1)·g−1 H_(2)production rate,25.77%apparent quantum yield at 420 nm,and~100%activity retention in stability,compared with Pt1Ag28-BDT/CoP(BDT=1,3-benzenedithiol),Ag29-BDT/CoP,and CoP.The enhanced catalytic performance is contributed by the dual modulation strategy of inner core and outer shell of NC,wherein,the center Pt single atom doping regulates the band structure of NC to match well with CoP,builds internal electric field,and then drives photogenerated electrons steering;the accurate surface S modification promotes the formation of Co-S atomic-precise interface channel for further high-efficient Z-scheme charge directional migration.This work opens a new avenue for designing NC-based heterojunction with matchable band structure and valid interfacial charge transfer.
基金financially supported by the National Natural Science Foundation of China(NSFC,Nos.22269015,22205119)Natural Science Foundation of Inner Mongolia Autonomous Region of China(Nos.2021ZD11,2019BS02015).
文摘Vacancy engineering and Mott-Schottky heterostructure can accelerate charge transfer,regulate adsorption energy of reaction intermediates,and provide additional active sites,which are regarded as valid means for improving catalytic activity.However,the underlying mechanism of synergistic regulation of interfacial charge transfer and optimization of electrocatalytic activity by combining vacancy and Mott-Schottky junction remains unclear.Herein,the growth of a bifunctional NiCo/NiCoP Mott-Schottky electrode with abundant phosphorus vacancies on foam nickel(NF)has been synthesized through continuous phosphating and reduction processes.The obtained NiCo/NiCoP heterojunctions show remarkable OER and HER activities,and the overpotentials for OER and HER are as low as 117 and 60 mV at 10 mA/cm^(2) in 1 mol/L KOH,respectively.Moreover,as both the cathode and anode of overall water splitting,the voltage of the bifunctional NiCo/NiCoP electrocatalyst is 1.44 V at 10 mA/cm^(2),which are far exceeding the benchmark commercial electrodes.DFT theoretical calculation results confirm that the phosphorus vacancies and build-in electric field can effectively accelerate ion and electron transfer between NiCo alloy and NiCoP semiconductor,tailor the electronic structure of the metal centers and lower the Gibbs free energy of the intermediates.Furthermore,the unique self-supported integrated structure is beneficial to facilitate the exposure of the active site,avoid catalyst shedding,thus improving the activity and structural stability of NiCo/NiCoP.This study provides an avenue for the controllable synthesis and performance optimization of Mott-Schottky electrocatalysts.
基金This work was supported in part by the the National Natural Science Foundation of China(Nos.61974049,61922083,61804167,61834009,61904200,61821091,and 92064003)in part by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB44000000).
文摘Hafnia-based ferroelectrics have greatly revived the field of ferroelectric memory(FeRAM),but certain reliability issues must be satisfactorily resolved before they can be widely applied in commercial memories.In particular,the imprint phenomenon severely jeopardizes the read-out reliability in hafnia-based ferroelectric capacitors,but its origin remains unclear,which hinders the development of its recovery schemes.In this work,we have systematically investigated the imprint mechanism in TiN/Hf_(0.5)Zr_(0.5)O_(2)(HZO)/TiN ferroelectric capacitors using experiments and first-principles calculations.It is shown that carrier injection-induced charged oxygen vacancies are at the heart of imprint in HZO,where other mechanisms such as domain pinning and dead layer are less important.An imprint model based on electron de-trapping from oxygen vacancy sites has been proposed that can satisfactorily explain several experimental facts such as the strong asymmetric imprint,leakage current variation,and so forth.Based on this model,an effective imprint recovery method has been proposed,which utilizes unipolar rather than bipolar voltage inputs.The remarkable recovery performances demonstrate the prospect of improved device reliability in hafnia-based FeRAM devices.
基金Project supported by the National Natural Science Foundation of China (No.60876061)the Pre-Research Project (No.51308040302)
文摘The doping profile function of a double base epilayer is constructed according to drift-diffusion theory. Then an analytical model for the base transit time τb is developed assuming a small-level injection based on the characteristics of the 4H-SiC material and the principle of the 4H-SiC BJTs. The device is numerically simulated and validated based on two-dimensional simulation models. The results show that the built-in electric field generated by the double base epilayer configuration can accelerate the carriers when transiting the base region and reduce the base transit time. From the simulation results, the base transit time reaches a minimal value when the ratio of L2/L1 is about 2.
基金supported in part by the Key-Area Research and Development Program of Guangdong Province(2019B010155002)the National Key Research and Development Project(2018YFB2202600)the Research and Development Project of Shenzhen Government(ZDSYS201802061805105).
文摘Through-silicon via(TSV)is a key enabling technology for the emerging 3-dimension(3 D)integrated circuits(ICs).However,the crosstalk between the neighboring TSVs is one of the important sources of the soft faults.To suppress the crosstalk,the Fibonacci-numeral-system-based crosstalk avoidance code(FNS-CAC)is an effective scheme.Meanwhile,the self-repair schemes are often used to deal with the hard faults,but the repaired results may change the mapping between signals to TSVs,thus may reduce the crosstalk suppression ability of FNS-CAC.A TSV self-repair technique with an improved FNS-CAC codec is proposed in this work.The codec is designed based on the improved Fibonacci numeral system(FNS)adders,which are adaptive to the health states of TSVs.The proposed self-repair technique is able to suppress the crosstalk and repair the faulty TSVs simultaneously.The simulation and analysis results show that the proposed scheme keeps the crosstalk suppression ability of the original FNS-CAC,and it has higher reparability than the local self-repair schemes,such as the signal-switching-based and the signal-shifting-based counterparts.
基金R.D.(CSIR Award No:09/1001(0074)/2020-EMR-I)thanks Council of Scientific and Industrial Research(CSIR)for the financial assistance through Research Associates(CSIR-RA)programme.
文摘Organometallic perovskite is a new generation photovoltaic material with exemplary properties such as high absorption co-efficient,optimal bandgap,high defect tolerance factor and long carrier diffusion length.However,suitable electrodes and charge transport materials are required to fulfill photovoltaic processes where interfaces between hole transport material/perovskite and perovskite/electron transport material are affected by phenomena of charge carrier separation,transportation,collection by the interfaces and band alignment.Based on recent available literature and several strategies for minimizing the recombination of charge carriers at the interfaces,this review addresses the properties of hole transport materials,relevant working mechanisms,and the interface engineering of perovskite solar cell(PSC)device architecture,which also provides significant insights to design and development of PSC devices with high efficiency.
