In the realm of optoelectronics,photodetectors play pivotal roles,with applications spanning from high-speed data communication to precise environmental sensing.Despite the advancements,conventional photodetectors gra...In the realm of optoelectronics,photodetectors play pivotal roles,with applications spanning from high-speed data communication to precise environmental sensing.Despite the advancements,conventional photodetectors grapple with challenges with response speed and dark current.In this study,we present a photodetector based on a lateral MoTe_(2)p-n junction,defined by a semi-floating ferroelectric gate.The strong ferroelectric fields and the depletion region of the p-n junction in the device are notably compact,which diminish the carrier transit time,thereby enhancing the speed of the photoelectric response.The non-volatile MoTe_(2)homojunction,under the influence of external gate voltage pulses,can alter the orientation of the intrinsic electric field within the junction.As a photovoltaic detector,it achieves an ultra-low dark current of 20 pA,and a fast photo response of 2μs.The spectral response is extended to the shortwave infrared range at 1550 nm.Furthermore,a logic computing system with light/no light as binary input is designed to convert the current signal to the voltage output.This research not only underscores the versatility of 2D materials in the realm of sophisticated photodetector design but also heralds new avenues for their application in energy-efficient,high-performance optoelectronic devices.展开更多
Vanadium oxide(VO_(x))has garnered significant attention in the realm of resistive random-access memory(RRAM)owing to its outstanding resistive switching characteristics.However,the ambiguous mechanisms of resistive s...Vanadium oxide(VO_(x))has garnered significant attention in the realm of resistive random-access memory(RRAM)owing to its outstanding resistive switching characteristics.However,the ambiguous mechanisms of resistive switching and inferior stability hinder its practical applications.Herein,an RRAM named VO_(x)/TiO_(2)/n^(++)Si device is prepared.It displays bipolar resistive switching behavior and shows superior cycle endurance(>200),a significantly high on/off ratio(>10^(2))and long-term stability.The tremendous improvement in the stability of the VO_(x)/TiO_(2)/n^(++)Si device compared with the Cu/VOx/n^(++)Si device is due to the p-i-n structure of VO_(x)/TiO_(2)/n^(++)Si.The switching mechanism of the VO_(x)/TiO_(2)/n^(++)Si device is attributed to the growth and annihilation of Cu conductive filaments.展开更多
The sluggish kinetics of the oxygen reduction reaction(ORR)and high over potential of oxygen evolution reaction(OER)are big challenges in the development of high-performance zinc-air batteries(ZABs)and fuel cells.In t...The sluggish kinetics of the oxygen reduction reaction(ORR)and high over potential of oxygen evolution reaction(OER)are big challenges in the development of high-performance zinc-air batteries(ZABs)and fuel cells.In this work,we report a rational design and a simple fabrication strategy of a photo-enhanced Co single-atom catalyst(SAC)comprising g-C3N4 coupled with cobalt-nitrogen-doped hierarchical mesoporous carbon(Co-N/MPC),forming a staggered p-n heterojunction that effectively improves charge separation and enhances electrocatalytic activity.The incorporation of Co SACs and g-C3N4 synergistically optimizes the photogenerated electron-hole pair separation,significantly boosting the intrinsic ORR-OER duplex activity.Under illumination,g-C_(3)N_(4)@Co-N/MPC exhibits an outstanding ORR half-wave potential(E1/2)of 0.841 V(vs.RHE)in 0.1 mol L^(–1)KOH and a low OER overpotential of 497.4 mV(vs.RHE)at 10 mA cm^(–2)in 1 mol L^(–1)KOH.Notably,the catalyst achieves an exceptional peak power density of 850.7 mW cm^(–2)in ZABs and of 411 mW cm^(–2)even in H_(2)-air fuel cell.In addition,g-C_(3)N_(4)@Co-N/MPC-based ZABs also show remarkable cycling stability exceeding 250 h.The advanced photo-induced charge separation at the p-n heterojunction facilitates faster electron transfer kinetics,and the mass transport owing to hierarchical mesoporous structure of Co-N-C,thereby reducing the overpotential and enhancing the overall energy conversion efficiency.This work provides a new perspective on designing next-generation of single-atom dispersed oxygen reaction catalysts,paving the way for high-performance photo-enhanced energy storage and conversion systems.展开更多
Formation of a p–n heterojunction rather than p-type or n-type semiconductors can enhance the separation of photogenerated electrons and holes and increase the quantum efficiency of photocatalytic reactions owing to ...Formation of a p–n heterojunction rather than p-type or n-type semiconductors can enhance the separation of photogenerated electrons and holes and increase the quantum efficiency of photocatalytic reactions owing to the difference of the electric potential in the inner electric field near the junction,pointing from n toward p. n-Ag3PO4/p-Ag2CO3 p–n heterojunction composites are prepared through a facile coprecipitation process. The obtained Ag3PO4/Ag2CO3 p–n heterojunctions exhibit excellent photocatalytic performance in the removal of rhodamine B（RhB） compared with Ag3PO4 and Ag2CO3. The 40%-Ag3PO4/Ag2CO3 composite photocatalyst（40 mol% Ag3PO4 and 60 mol% Ag2CO3） exhibits the best photocatalytic activity under visible light,demonstrating the ability to completely degrade RhB within 15 min. Transient photovoltage characterization and an active species trapping experiment further indicate that the formation of a p–n heterojunction structure can greatly enhance the separation efficiency of photogenerated carriers and produce more free h＋active species,which is the predominant contributor for RhB removal.展开更多
Microcystin-RR（MC-RR）,a form of microcystin with two arginine moieties,is a cyanobacterial toxin that has been detected across a wide geographic range.It is a great concern globally because of its potential liver to...Microcystin-RR（MC-RR）,a form of microcystin with two arginine moieties,is a cyanobacterial toxin that has been detected across a wide geographic range.It is a great concern globally because of its potential liver toxicity.Herein,the abilities of BiVO4,Ag-BiVO4,Ag2O-BiVO4 and Ag/Ag2O-BiVO4 to photocatalytically degrade MC-RR under visible-light irradiation（λ≥420 nm） were investigated and compared.The possible degradation pathways were explored through analysis of the reaction intermediates by high-performance liquid chromatography-mass spectrometry.The results showed that the presence of Ag^0 enhanced the photocatalytic efficiency of Ag/Ag2O-BiVO4 via a synergetic effect between Ag2O and Ag^0 at the p-n heterojunction.Moreover,the presence of Ag^0 also greatly promoted the adsorption of MC-RR on the photocatalyst surface.Toxicological experiments on mice showed that the toxicity of MC-RR was significantly reduced after photocatalytic degradation.展开更多
Highly oriented voids-free 3C-SiC heteroepitaxial layers are grown onφ50mm Si (100) substrates by low pressure chemical vapor deposition (LPCVD).The initial stage of carbonization and the surface morphology of carbon...Highly oriented voids-free 3C-SiC heteroepitaxial layers are grown onφ50mm Si (100) substrates by low pressure chemical vapor deposition (LPCVD).The initial stage of carbonization and the surface morphology of carbonization layers of Si (100) are studied using reflection high energy electron diffraction (RHEED) and scanning electron microscopy (SEM).It is shown that the optimized carbonization temperature for the growth of voids-free 3C-SiC on Si (100) substrates is 1100℃.The electrical properties of SiC layers are characterized using Van der Pauw method.The I-V,C-V,and the temperature dependence of I-V characteristics in n-3C-SiC/p-Si heterojunctions with AuGeNi and Al electrical pads are investigated.It is shown that the maximum reverse breakdown voltage of the n-3C-SiC/p-Si heterojunction diodes reaches to 220V at room temperature.These results indicate that the SiC/Si heterojunction diode can be used to fabricate the wide bandgap emitter SiC/Si heterojunction bipolar transistors (HBT's).展开更多
Single event transient of a real p-n junction in a 0.18μm bulk process is studied by 3D TCAD simulation. The impact of voltage, temperature, substrate concentration, and LET on SET is studied. Our simulation results ...Single event transient of a real p-n junction in a 0.18μm bulk process is studied by 3D TCAD simulation. The impact of voltage, temperature, substrate concentration, and LET on SET is studied. Our simulation results demonstrate that biases in the range 1.62 to 1.98V influence DSET current shape greatly and total collected charge weakly. Peak current and charge collection within 2ns decreases as temperature increases,and temperature has a stronger influence on SET currents than on total charge. Typical variation of substrate concentration in modern VDSM processes has a negligible effect on SEEs. Both peak current and total collection charge increases as LET increases.展开更多
Based on a new semi empirical analytical method, namely equivalent doping transformation, the breakdown voltage and the peak field of the epitaxial diffused punch through junction have been obtained. The basic prin...Based on a new semi empirical analytical method, namely equivalent doping transformation, the breakdown voltage and the peak field of the epitaxial diffused punch through junction have been obtained. The basic principle of this method is introduced and a set of breakdown voltage and peak field plots are provided for the optimum design of the low voltage power devices. It shows that the analytical results coincide with the previous numerical simulation well.展开更多
This report describes an equivalent doping profile transformation method with which the avalanche breakdown voltage of the asymmetric linearly graded junction was analytically predicted.The maximum breakdown voltage a...This report describes an equivalent doping profile transformation method with which the avalanche breakdown voltage of the asymmetric linearly graded junction was analytically predicted.The maximum breakdown voltage and the different depletion layer extension on the diffused side and substrate side are demonstrated in the report.The report shows the equivalent doping profile method is valid to predict the breakdown voltage of the complex P N junction.The analytical results agree with the experimental breakdown voltage in comparison with the abrupt junction and symmetric linearly graded junction approximations.展开更多
In this study,CuBi2O4 photocathodes were prepared using a simple electrodeposition method for photoelectrochemical(PEC)hydrogen production.The prepared photocathodes were modified with amorphous TiO2 and a Pt co‐cata...In this study,CuBi2O4 photocathodes were prepared using a simple electrodeposition method for photoelectrochemical(PEC)hydrogen production.The prepared photocathodes were modified with amorphous TiO2 and a Pt co‐catalyst,which resulted in the formation of CuBi2O4/TiO2 p‐n heterojunctions,and enhanced the activities of the as‐prepared photocathodes.The novel Pt/TiO2/CuBi2O4 photocathode exhibited a photocurrent of 0.35 mA/cm2 at 0.60 V vs.Reversible Hydrogen Electrode(RHE),which was nearly twice that of the Pt/CuBi2O4 photocathode.The present study provides a facile method for increasing the efficiency of photocathodes and provides meaningful guidance for the preparation of high‐performance CuBi2O4 photocathodes.展开更多
According to the plasma dispersion effect of silicon(Si),a silicon-on-insulator(SOI) based variable optical attenuator(VOA) with p-i-n lateral diode structure is demonstrated in this paper.A wire rib waveguide with su...According to the plasma dispersion effect of silicon(Si),a silicon-on-insulator(SOI) based variable optical attenuator(VOA) with p-i-n lateral diode structure is demonstrated in this paper.A wire rib waveguide with sub-micrometer cross section is adopted.The device is only about 2 mm long.The power consumption of the VOA is 76.3 mW(0.67 V,113.9 mA),and due to the carrier absorption,the polarization dependent loss(PDL) is 0.1dB at 20dB attenuation.The raise time of the VOA is 34.5 ns,the fall time is 37 ns,and the response time is 71.5 ns.展开更多
Effective spin-polarized injection from magnetic semiconductor （MS） to nonmagnetic semiconductor （NMS） has been highlighted in recent years. In this paper we study theoretically the dependence of nonequilibrium sp...Effective spin-polarized injection from magnetic semiconductor （MS） to nonmagnetic semiconductor （NMS） has been highlighted in recent years. In this paper we study theoretically the dependence of nonequilibrium spin polarization （NESP） in NMS during spin-polarized injection through the magnetic p-n junction. Based on the theory in semiconductor physics, a model is established and the boundary conditions are determined in the case of no external spin-polarized injection and low bias. The control parameters that may influence the NESP in NMS are indicated by calculating the distribution of spin polarization. They are the doping concentrations, the equilibrium spin polarization in MS and the bias. The effective spin-polarized injection can be realized more easily by optimizing the above parameters.展开更多
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0580000)Natural Science Foundation of China(62222413,62025405,62105100,62075228 and 62334001)+1 种基金Natural Science Foundation of Shanghai(23ZR1473400)Hundred Talents Program of the Chinese Academy of Sciences。
文摘In the realm of optoelectronics,photodetectors play pivotal roles,with applications spanning from high-speed data communication to precise environmental sensing.Despite the advancements,conventional photodetectors grapple with challenges with response speed and dark current.In this study,we present a photodetector based on a lateral MoTe_(2)p-n junction,defined by a semi-floating ferroelectric gate.The strong ferroelectric fields and the depletion region of the p-n junction in the device are notably compact,which diminish the carrier transit time,thereby enhancing the speed of the photoelectric response.The non-volatile MoTe_(2)homojunction,under the influence of external gate voltage pulses,can alter the orientation of the intrinsic electric field within the junction.As a photovoltaic detector,it achieves an ultra-low dark current of 20 pA,and a fast photo response of 2μs.The spectral response is extended to the shortwave infrared range at 1550 nm.Furthermore,a logic computing system with light/no light as binary input is designed to convert the current signal to the voltage output.This research not only underscores the versatility of 2D materials in the realm of sophisticated photodetector design but also heralds new avenues for their application in energy-efficient,high-performance optoelectronic devices.
基金National Natural Science Foundation of China(No.61376017)。
文摘Vanadium oxide(VO_(x))has garnered significant attention in the realm of resistive random-access memory(RRAM)owing to its outstanding resistive switching characteristics.However,the ambiguous mechanisms of resistive switching and inferior stability hinder its practical applications.Herein,an RRAM named VO_(x)/TiO_(2)/n^(++)Si device is prepared.It displays bipolar resistive switching behavior and shows superior cycle endurance(>200),a significantly high on/off ratio(>10^(2))and long-term stability.The tremendous improvement in the stability of the VO_(x)/TiO_(2)/n^(++)Si device compared with the Cu/VOx/n^(++)Si device is due to the p-i-n structure of VO_(x)/TiO_(2)/n^(++)Si.The switching mechanism of the VO_(x)/TiO_(2)/n^(++)Si device is attributed to the growth and annihilation of Cu conductive filaments.
文摘The sluggish kinetics of the oxygen reduction reaction(ORR)and high over potential of oxygen evolution reaction(OER)are big challenges in the development of high-performance zinc-air batteries(ZABs)and fuel cells.In this work,we report a rational design and a simple fabrication strategy of a photo-enhanced Co single-atom catalyst(SAC)comprising g-C3N4 coupled with cobalt-nitrogen-doped hierarchical mesoporous carbon(Co-N/MPC),forming a staggered p-n heterojunction that effectively improves charge separation and enhances electrocatalytic activity.The incorporation of Co SACs and g-C3N4 synergistically optimizes the photogenerated electron-hole pair separation,significantly boosting the intrinsic ORR-OER duplex activity.Under illumination,g-C_(3)N_(4)@Co-N/MPC exhibits an outstanding ORR half-wave potential(E1/2)of 0.841 V(vs.RHE)in 0.1 mol L^(–1)KOH and a low OER overpotential of 497.4 mV(vs.RHE)at 10 mA cm^(–2)in 1 mol L^(–1)KOH.Notably,the catalyst achieves an exceptional peak power density of 850.7 mW cm^(–2)in ZABs and of 411 mW cm^(–2)even in H_(2)-air fuel cell.In addition,g-C_(3)N_(4)@Co-N/MPC-based ZABs also show remarkable cycling stability exceeding 250 h.The advanced photo-induced charge separation at the p-n heterojunction facilitates faster electron transfer kinetics,and the mass transport owing to hierarchical mesoporous structure of Co-N-C,thereby reducing the overpotential and enhancing the overall energy conversion efficiency.This work provides a new perspective on designing next-generation of single-atom dispersed oxygen reaction catalysts,paving the way for high-performance photo-enhanced energy storage and conversion systems.
基金supported by the National Natural Science Foundation of China(2100705351302241)+1 种基金the Education Department of Henan Province(2012GGJS-174)Xuchang University Science Research Foundation(2015011)~~
文摘Formation of a p–n heterojunction rather than p-type or n-type semiconductors can enhance the separation of photogenerated electrons and holes and increase the quantum efficiency of photocatalytic reactions owing to the difference of the electric potential in the inner electric field near the junction,pointing from n toward p. n-Ag3PO4/p-Ag2CO3 p–n heterojunction composites are prepared through a facile coprecipitation process. The obtained Ag3PO4/Ag2CO3 p–n heterojunctions exhibit excellent photocatalytic performance in the removal of rhodamine B（RhB） compared with Ag3PO4 and Ag2CO3. The 40%-Ag3PO4/Ag2CO3 composite photocatalyst（40 mol% Ag3PO4 and 60 mol% Ag2CO3） exhibits the best photocatalytic activity under visible light,demonstrating the ability to completely degrade RhB within 15 min. Transient photovoltage characterization and an active species trapping experiment further indicate that the formation of a p–n heterojunction structure can greatly enhance the separation efficiency of photogenerated carriers and produce more free h＋active species,which is the predominant contributor for RhB removal.
基金supported by the National Natural Science Foundation of China (21677086, 21407092, 21377067, 21577078)the Natural Science Foundation for Innovation Group of Hubei Province, China (2015CFA021)~~
文摘Microcystin-RR（MC-RR）,a form of microcystin with two arginine moieties,is a cyanobacterial toxin that has been detected across a wide geographic range.It is a great concern globally because of its potential liver toxicity.Herein,the abilities of BiVO4,Ag-BiVO4,Ag2O-BiVO4 and Ag/Ag2O-BiVO4 to photocatalytically degrade MC-RR under visible-light irradiation（λ≥420 nm） were investigated and compared.The possible degradation pathways were explored through analysis of the reaction intermediates by high-performance liquid chromatography-mass spectrometry.The results showed that the presence of Ag^0 enhanced the photocatalytic efficiency of Ag/Ag2O-BiVO4 via a synergetic effect between Ag2O and Ag^0 at the p-n heterojunction.Moreover,the presence of Ag^0 also greatly promoted the adsorption of MC-RR on the photocatalyst surface.Toxicological experiments on mice showed that the toxicity of MC-RR was significantly reduced after photocatalytic degradation.
文摘Highly oriented voids-free 3C-SiC heteroepitaxial layers are grown onφ50mm Si (100) substrates by low pressure chemical vapor deposition (LPCVD).The initial stage of carbonization and the surface morphology of carbonization layers of Si (100) are studied using reflection high energy electron diffraction (RHEED) and scanning electron microscopy (SEM).It is shown that the optimized carbonization temperature for the growth of voids-free 3C-SiC on Si (100) substrates is 1100℃.The electrical properties of SiC layers are characterized using Van der Pauw method.The I-V,C-V,and the temperature dependence of I-V characteristics in n-3C-SiC/p-Si heterojunctions with AuGeNi and Al electrical pads are investigated.It is shown that the maximum reverse breakdown voltage of the n-3C-SiC/p-Si heterojunction diodes reaches to 220V at room temperature.These results indicate that the SiC/Si heterojunction diode can be used to fabricate the wide bandgap emitter SiC/Si heterojunction bipolar transistors (HBT's).
文摘Single event transient of a real p-n junction in a 0.18μm bulk process is studied by 3D TCAD simulation. The impact of voltage, temperature, substrate concentration, and LET on SET is studied. Our simulation results demonstrate that biases in the range 1.62 to 1.98V influence DSET current shape greatly and total collected charge weakly. Peak current and charge collection within 2ns decreases as temperature increases,and temperature has a stronger influence on SET currents than on total charge. Typical variation of substrate concentration in modern VDSM processes has a negligible effect on SEEs. Both peak current and total collection charge increases as LET increases.
文摘Based on a new semi empirical analytical method, namely equivalent doping transformation, the breakdown voltage and the peak field of the epitaxial diffused punch through junction have been obtained. The basic principle of this method is introduced and a set of breakdown voltage and peak field plots are provided for the optimum design of the low voltage power devices. It shows that the analytical results coincide with the previous numerical simulation well.
文摘This report describes an equivalent doping profile transformation method with which the avalanche breakdown voltage of the asymmetric linearly graded junction was analytically predicted.The maximum breakdown voltage and the different depletion layer extension on the diffused side and substrate side are demonstrated in the report.The report shows the equivalent doping profile method is valid to predict the breakdown voltage of the complex P N junction.The analytical results agree with the experimental breakdown voltage in comparison with the abrupt junction and symmetric linearly graded junction approximations.
基金the National Natural Science Foundation of China(51602179,21333006,21573135,11374190)the National Basic Research Program of China(973 Program,2013CB632401)~~
文摘In this study,CuBi2O4 photocathodes were prepared using a simple electrodeposition method for photoelectrochemical(PEC)hydrogen production.The prepared photocathodes were modified with amorphous TiO2 and a Pt co‐catalyst,which resulted in the formation of CuBi2O4/TiO2 p‐n heterojunctions,and enhanced the activities of the as‐prepared photocathodes.The novel Pt/TiO2/CuBi2O4 photocathode exhibited a photocurrent of 0.35 mA/cm2 at 0.60 V vs.Reversible Hydrogen Electrode(RHE),which was nearly twice that of the Pt/CuBi2O4 photocathode.The present study provides a facile method for increasing the efficiency of photocathodes and provides meaningful guidance for the preparation of high‐performance CuBi2O4 photocathodes.
基金supported by the National High Technology Research and Development Program of China(No.2013AA031402)
文摘According to the plasma dispersion effect of silicon(Si),a silicon-on-insulator(SOI) based variable optical attenuator(VOA) with p-i-n lateral diode structure is demonstrated in this paper.A wire rib waveguide with sub-micrometer cross section is adopted.The device is only about 2 mm long.The power consumption of the VOA is 76.3 mW(0.67 V,113.9 mA),and due to the carrier absorption,the polarization dependent loss(PDL) is 0.1dB at 20dB attenuation.The raise time of the VOA is 34.5 ns,the fall time is 37 ns,and the response time is 71.5 ns.
基金Project supported by the National Natural Science Foundation of China （Grant No 60606021）, the Specialized Research Fund for the Doctoral Program of Higher Education of China （Grant No 20060003067） and the Key Fundamental Research Foundation of Tsinghua University of China （Grant No Jz2001010）.
文摘Effective spin-polarized injection from magnetic semiconductor （MS） to nonmagnetic semiconductor （NMS） has been highlighted in recent years. In this paper we study theoretically the dependence of nonequilibrium spin polarization （NESP） in NMS during spin-polarized injection through the magnetic p-n junction. Based on the theory in semiconductor physics, a model is established and the boundary conditions are determined in the case of no external spin-polarized injection and low bias. The control parameters that may influence the NESP in NMS are indicated by calculating the distribution of spin polarization. They are the doping concentrations, the equilibrium spin polarization in MS and the bias. The effective spin-polarized injection can be realized more easily by optimizing the above parameters.
