The sharp luminescent peaks in Yb and Er-implanted InP,SI-InP,GaAs,and n-GaAs were observed at 77K.The peaks at 1.0 and 1.5μm come from(4f)~2F_(5/2)→~2F_(7/2)of Yb^(3+)and ~4I_(13/2)→~4I_(15/2)of Er^(3+), respectiv...The sharp luminescent peaks in Yb and Er-implanted InP,SI-InP,GaAs,and n-GaAs were observed at 77K.The peaks at 1.0 and 1.5μm come from(4f)~2F_(5/2)→~2F_(7/2)of Yb^(3+)and ~4I_(13/2)→~4I_(15/2)of Er^(3+), respectively.The optimum luminescent intensities can be obtained from Yb-implanted and Er-implanted sam- ples which were annealed at 800 and 750℃,respectively.A ccording to the analyses of PL and the rocking curve of X-ray double crystal diffraction,the best crystal structure of implanted InP layer has been obtained by an- nealing at 850℃.The interaction between Yb^(3+)and Er^(3+)in the SI-InP has been investigated for the first time. The quenching effect of Yb^(3+)and Er^(3+)with each other has been observed when the doses of Yb and Er-im- planted SI-InP are equal.展开更多
The epitaxial techniques are the most important processes in the production of semiconductor materials and optoelectronic devices. Liquid phase epitaxy (LPE) and metal organic vapor phase epitaxy (MOVPE) particularly...The epitaxial techniques are the most important processes in the production of semiconductor materials and optoelectronic devices. Liquid phase epitaxy (LPE) and metal organic vapor phase epitaxy (MOVPE) particularly have many applications.The process characteristics and crystalline properties of both LPE and MOVPE techniques were introduced briefly, the compositional space suitable for LPE and MOVPE growth was discussed from the view point of thermodynamic equilibrium. The analysis and comparison show that on the one hand LPE and MOVPE have some advantages and characteristics in common; on the other hand, they may overcome each other′s weaknesses and deficiencies by offering their own special features.展开更多
Long-term societal prosperity depends on addressing the world’s energy and environmental problems,and photocatalysis has emerged as a viable remedy.Improving the efficiency of photocatalytic processes is fundamentall...Long-term societal prosperity depends on addressing the world’s energy and environmental problems,and photocatalysis has emerged as a viable remedy.Improving the efficiency of photocatalytic processes is fundamentally achieved by optimizing the effective utilization of solar energy and enhancing the efficient separation of photogenerated charges.It has been demonstrated that the fabrication ofⅢ–Ⅴsemiconductor-based photocatalysts is effective in increasing solar light absorption,long-term stability,large-scale production and promoting charge transfer.This focused review explores on the current developments inⅢ–Ⅴsemiconductor materials for solar-powered photocatalytic systems.The review explores on various subjects,including the advancement ofⅢ–Ⅴsemiconductors,photocatalytic mechanisms,and their uses in H2 conversion,CO_(2)reduction,environmental remediation,and photocatalytic oxidation and reduction reactions.In order to design heterostructures,the review delves into basic concepts including solar light absorption and effective charge separation.It also highlights significant advancements in green energy systems for water splitting,emphasizing the significance of establishing eco-friendly systems for CO_(2)reduction and hydrogen production.The main purpose is to produce hydrogen through sustainable and ecologically friendly energy conversion.The review intends to foster the development of greener and more sustainable energy source by encouraging researchers and developers to focus on practical applications and advancements in solar-powered photocatalysis.展开更多
Efficient light generation and amplification has long been missing on the silicon platform due to its well-known indirect bandgap nature.Driven by the size,weight,power and cost(SWaP-C)requirements,the desire to fully...Efficient light generation and amplification has long been missing on the silicon platform due to its well-known indirect bandgap nature.Driven by the size,weight,power and cost(SWaP-C)requirements,the desire to fully realize integrated silicon electronic and photonic integrated circuits has greatly pushed the effort of realizing high performance on-chip lasers and amplifiers moving forward.Several approaches have been proposed and demonstrated to address this issue.In this paper,a brief overview of recent progress of the high-performance lasers and amplifiers on Si based on different technology is presented.Representative device demonstrations,including ultra-narrow linewidthⅢ-Ⅴ/Si lasers,fully integratedⅢ-Ⅴ/Si/Si3N4 lasers,high-channel count mode locked quantum dot(QD)lasers,and high gain QD amplifiers will be covered.展开更多
An explicit expression of reflection magnetic circular dichroism （RMCD） has been derived, taking into account the interference effect that arises from multiple internal reflections in an air/Ga1-xMnxAs/GaAs dielectr...An explicit expression of reflection magnetic circular dichroism （RMCD） has been derived, taking into account the interference effect that arises from multiple internal reflections in an air/Ga1-xMnxAs/GaAs dielectric layered system. It unambiguously shows that the RMCD signal is composed by three terms. In addition to the conventional term, which is sufficient in the absence of interference, an oscillatory term is required. Both of them are related to the imaginary part εxy of the off-diagonal element of the dielectric tensor. One also becomes aware that in this case RMCD is not actually determined only by the imaginary part εxy of the off-diagonal element of the dielectric tensor, as has been widely accepted. In fact, the real part εxy of the off-diagonal element will substantially mix into the measured RMCD results by another oscillatory cos θ form. It can even reverse the sign of RMCD, when the Gal_xMnxAs layer becomes thicker. The main aspects of these predictions were used to reasonably explain the RMCD results measured in three different types of samples. Our work will bring about a reconsideration of how to correctly explain RMCD results.展开更多
Multijunction solar cells are the highest efficiency photovoltaic devices yet demonstrated for both space and terrestrial applications.In recent years five-junction cells based on the direct semiconductor bonding tech...Multijunction solar cells are the highest efficiency photovoltaic devices yet demonstrated for both space and terrestrial applications.In recent years five-junction cells based on the direct semiconductor bonding technique(SBT),demonstrates space efficiencies>35%and presents application potentials.In this paper,the major challenges for fabricating SBT 5J cells and their appropriate strategies involving structure tunning,band engineering and material tailoring are stated,and 4-cm235.4%(AM0,one sun)5J SBT cells are presented.Further efforts on detailed optical managements are required to improve the current generating and matching in subcells,to achieve efficiencies 36%-37%,or above.展开更多
A 240-nm thick Al0.4In0.02Ga0.58N layer is grown by metal organic chemical vapour deposition, with an over 1-μm thick GaN layer used as a buffer layer on a substrate of sapphire （0001）. Rutherford backscattering an...A 240-nm thick Al0.4In0.02Ga0.58N layer is grown by metal organic chemical vapour deposition, with an over 1-μm thick GaN layer used as a buffer layer on a substrate of sapphire （0001）. Rutherford backscattering and channeling are used to characterize the microstructure of AlInGaN. The results show a good crystalline quality of AIInGaN （χmin = 1.5%） with GaN buffer layer. The channeling angular scan around an off-normal {1213} axis in the {1010} plane of the AlInGaN layer is used to determine tetragonal distortion eT, which is caused by the elastic strain in the AIInGaN. The resulting AlInGaN is subjected to an elastic strain at interracial layer, and the strain decreases gradually towards the near-surface layer. It is expected that an epitaxial AlInGaN thin film with a thickness of 850 nm will be fully relaxed （^eT = 0）.展开更多
Although tuning band structure of optoelectronic semiconductor-based materials by means of doping single defect is an important approach for potential photocatalysis application,C-doping or oxygen vacancy(Vo)as a sing...Although tuning band structure of optoelectronic semiconductor-based materials by means of doping single defect is an important approach for potential photocatalysis application,C-doping or oxygen vacancy(Vo)as a single defect in ZnO still has limitations for photocatalytic activity.Meanwhile,the influence of co-existence of various defects in ZnO still lacks sufficient studies.Therefore,we investigate the photocatalytic properties of ZnOx C0.0625(x=0.9375,0.875,0.8125),confirming that the co-effect of various defects has a greater enhancement for photocatalytic activity driven by visible-light than the single defect in ZnO.To clarify the underlying mechanism of co-existence of various defects in ZnO,we perform systematically the electronic properties calculations using density functional theory.It is found that the coeffect of C-doping and Vo in ZnO can achieve a more controllable band gap than doping solely in ZnO.Moreover,the impact of the effective masses of ZnO_(x)C_(0.0625)(x=0.9375,0.875,0.8125)is also taken into account.In comparison with heavy Vo concentrations,the light Vo concentration(x=0.875)as the optimal component together with C-doping in ZnO,can significantly improve the visible-light absorption and benefit photocatalytic activity.展开更多
Wide spectral white light emitting diodes have been designed and grown on a sapphire substrate by using a metal-organic chemical vapor deposition system. Three quantum wells with blue-light-emitting, green-light-emitt...Wide spectral white light emitting diodes have been designed and grown on a sapphire substrate by using a metal-organic chemical vapor deposition system. Three quantum wells with blue-light-emitting, green-light-emitting and red-light-emitting structures were grown according to the design. The surface morphology of the film was observed by using atomic force microscopy. The films were characterized by their photoluminescence measurements. X-ray diffraction t9/2/9 scan spectroscopy was carried out on the multi-quantum wells. The secondary fringes of the symmetric ω/2θ X-ray diffraction scan peaks indicate that the thicknesses and the alloy compositions of the individual quantum wells are repeatable throughout the active region. The room temperature photoluminescence spectra of the structures indicate that the white light emission of the multi-quantum wells is obtained. The light spectrum covers 400 700 nm, which is almost the whole visible light spectrum.展开更多
The structural and magnetic properties, as well as the mechanism of magnetization, of Ni-implanted A1N films were studied. A1N was deposited on A1203 substrates by metalorganic chemical vapor deposition （MOCVD）, and...The structural and magnetic properties, as well as the mechanism of magnetization, of Ni-implanted A1N films were studied. A1N was deposited on A1203 substrates by metalorganic chemical vapor deposition （MOCVD）, and subsequently Ni ions were implanted into the A1N films by Metal Vapor Arc （MEVVA） sources at an energy of 100 keV for 3 h. The films were annealed at 900~C for 1 h in the furnace in order to transfer the Ni ions from interstitial sites to substitutional sites in A1N, thus activating the Ni3＋ ions. Characterizations were performed in situ using X-ray diffraction （XRD）, X-ray photoemis- sion spectroscopy （XPS）, and vibrating sample magneto- metry （VSM）, which showed that the films have a wurtzite structure without the formation of a secondary phase after implanting and annealing. Ni ions were successfully implanted into substitutional sites of AlN films, and the chemical bonding states are Ni-N. The apparent hysteresis loops prove that the films exhibited magnetism at 300 K. The room temperature （RT） saturation magnetization moment （Ms） and eoercivity （He） values were about 0.36 emu/g and 35.29 Oe, respectively. From the first-principles calculation, a total magnetic moment of 2.99 ~tB per supercell is expected, and the local magnetic moment of a NiN4 tetrahedron, 2.45 gB, makes the primary contribu- tion. The doped Ni atom hybridizes with four nearby N atoms in a NiN4 tetrahedron; then the electrons of the N atoms are spin-polarized and couple with the electrons of the Ni atom with strong magnetization, which results in magnetism. Therefore, the p-d exchange mechanism between Ni-3d and N-2p can be the origin of the magnetism. It is expected that these room temperature, ferromagnetic, Ni-doped A1N films will have many potential applications as diluted magnetic semiconductors.展开更多
基金Project supported by the National Natural Science Foundation of China
文摘The sharp luminescent peaks in Yb and Er-implanted InP,SI-InP,GaAs,and n-GaAs were observed at 77K.The peaks at 1.0 and 1.5μm come from(4f)~2F_(5/2)→~2F_(7/2)of Yb^(3+)and ~4I_(13/2)→~4I_(15/2)of Er^(3+), respectively.The optimum luminescent intensities can be obtained from Yb-implanted and Er-implanted sam- ples which were annealed at 800 and 750℃,respectively.A ccording to the analyses of PL and the rocking curve of X-ray double crystal diffraction,the best crystal structure of implanted InP layer has been obtained by an- nealing at 850℃.The interaction between Yb^(3+)and Er^(3+)in the SI-InP has been investigated for the first time. The quenching effect of Yb^(3+)and Er^(3+)with each other has been observed when the doses of Yb and Er-im- planted SI-InP are equal.
基金Projects(06YFJZJC01100,08JCYBJC14800)supported by Applied Basic Study Foundation of Tianjin,ChinaProject(2006AA03Z413)supported by the Hi-tech Research and Development Program of China
文摘The epitaxial techniques are the most important processes in the production of semiconductor materials and optoelectronic devices. Liquid phase epitaxy (LPE) and metal organic vapor phase epitaxy (MOVPE) particularly have many applications.The process characteristics and crystalline properties of both LPE and MOVPE techniques were introduced briefly, the compositional space suitable for LPE and MOVPE growth was discussed from the view point of thermodynamic equilibrium. The analysis and comparison show that on the one hand LPE and MOVPE have some advantages and characteristics in common; on the other hand, they may overcome each other′s weaknesses and deficiencies by offering their own special features.
基金supported by the Nano&Material Technology Development Program through the National Research Foundation of Korea(NRF)funded by Ministry of Science and ICT(No.2022M3H4A1A04096380)and(No.2022M3H4A3A01082883)。
文摘Long-term societal prosperity depends on addressing the world’s energy and environmental problems,and photocatalysis has emerged as a viable remedy.Improving the efficiency of photocatalytic processes is fundamentally achieved by optimizing the effective utilization of solar energy and enhancing the efficient separation of photogenerated charges.It has been demonstrated that the fabrication ofⅢ–Ⅴsemiconductor-based photocatalysts is effective in increasing solar light absorption,long-term stability,large-scale production and promoting charge transfer.This focused review explores on the current developments inⅢ–Ⅴsemiconductor materials for solar-powered photocatalytic systems.The review explores on various subjects,including the advancement ofⅢ–Ⅴsemiconductors,photocatalytic mechanisms,and their uses in H2 conversion,CO_(2)reduction,environmental remediation,and photocatalytic oxidation and reduction reactions.In order to design heterostructures,the review delves into basic concepts including solar light absorption and effective charge separation.It also highlights significant advancements in green energy systems for water splitting,emphasizing the significance of establishing eco-friendly systems for CO_(2)reduction and hydrogen production.The main purpose is to produce hydrogen through sustainable and ecologically friendly energy conversion.The review intends to foster the development of greener and more sustainable energy source by encouraging researchers and developers to focus on practical applications and advancements in solar-powered photocatalysis.
文摘Efficient light generation and amplification has long been missing on the silicon platform due to its well-known indirect bandgap nature.Driven by the size,weight,power and cost(SWaP-C)requirements,the desire to fully realize integrated silicon electronic and photonic integrated circuits has greatly pushed the effort of realizing high performance on-chip lasers and amplifiers moving forward.Several approaches have been proposed and demonstrated to address this issue.In this paper,a brief overview of recent progress of the high-performance lasers and amplifiers on Si based on different technology is presented.Representative device demonstrations,including ultra-narrow linewidthⅢ-Ⅴ/Si lasers,fully integratedⅢ-Ⅴ/Si/Si3N4 lasers,high-channel count mode locked quantum dot(QD)lasers,and high gain QD amplifiers will be covered.
基金supported by the National Basic Research Program of China(Grant No.2011CB932901)
文摘An explicit expression of reflection magnetic circular dichroism （RMCD） has been derived, taking into account the interference effect that arises from multiple internal reflections in an air/Ga1-xMnxAs/GaAs dielectric layered system. It unambiguously shows that the RMCD signal is composed by three terms. In addition to the conventional term, which is sufficient in the absence of interference, an oscillatory term is required. Both of them are related to the imaginary part εxy of the off-diagonal element of the dielectric tensor. One also becomes aware that in this case RMCD is not actually determined only by the imaginary part εxy of the off-diagonal element of the dielectric tensor, as has been widely accepted. In fact, the real part εxy of the off-diagonal element will substantially mix into the measured RMCD results by another oscillatory cos θ form. It can even reverse the sign of RMCD, when the Gal_xMnxAs layer becomes thicker. The main aspects of these predictions were used to reasonably explain the RMCD results measured in three different types of samples. Our work will bring about a reconsideration of how to correctly explain RMCD results.
基金supported by the National Nature Science Foundation of China(Grant No.62004126)Shanghai Rising-Star Program(Grant No.19QB1403800).
文摘Multijunction solar cells are the highest efficiency photovoltaic devices yet demonstrated for both space and terrestrial applications.In recent years five-junction cells based on the direct semiconductor bonding technique(SBT),demonstrates space efficiencies>35%and presents application potentials.In this paper,the major challenges for fabricating SBT 5J cells and their appropriate strategies involving structure tunning,band engineering and material tailoring are stated,and 4-cm235.4%(AM0,one sun)5J SBT cells are presented.Further efforts on detailed optical managements are required to improve the current generating and matching in subcells,to achieve efficiencies 36%-37%,or above.
基金Project supported by the National Natural Science Foundation of China(Grant No.10875004)the National Basic Research Program of China(Grant No.2010CB832904)
文摘A 240-nm thick Al0.4In0.02Ga0.58N layer is grown by metal organic chemical vapour deposition, with an over 1-μm thick GaN layer used as a buffer layer on a substrate of sapphire （0001）. Rutherford backscattering and channeling are used to characterize the microstructure of AlInGaN. The results show a good crystalline quality of AIInGaN （χmin = 1.5%） with GaN buffer layer. The channeling angular scan around an off-normal {1213} axis in the {1010} plane of the AlInGaN layer is used to determine tetragonal distortion eT, which is caused by the elastic strain in the AIInGaN. The resulting AlInGaN is subjected to an elastic strain at interracial layer, and the strain decreases gradually towards the near-surface layer. It is expected that an epitaxial AlInGaN thin film with a thickness of 850 nm will be fully relaxed （^eT = 0）.
基金Project supported by the National Natural Science Foundation of China(Grant No.11874038)the State Key Laboratory of Advanced Metallurgy Foundation in China(Grant No.KF19-03)。
文摘Although tuning band structure of optoelectronic semiconductor-based materials by means of doping single defect is an important approach for potential photocatalysis application,C-doping or oxygen vacancy(Vo)as a single defect in ZnO still has limitations for photocatalytic activity.Meanwhile,the influence of co-existence of various defects in ZnO still lacks sufficient studies.Therefore,we investigate the photocatalytic properties of ZnOx C0.0625(x=0.9375,0.875,0.8125),confirming that the co-effect of various defects has a greater enhancement for photocatalytic activity driven by visible-light than the single defect in ZnO.To clarify the underlying mechanism of co-existence of various defects in ZnO,we perform systematically the electronic properties calculations using density functional theory.It is found that the coeffect of C-doping and Vo in ZnO can achieve a more controllable band gap than doping solely in ZnO.Moreover,the impact of the effective masses of ZnO_(x)C_(0.0625)(x=0.9375,0.875,0.8125)is also taken into account.In comparison with heavy Vo concentrations,the light Vo concentration(x=0.875)as the optimal component together with C-doping in ZnO,can significantly improve the visible-light absorption and benefit photocatalytic activity.
基金supported by the National Natural Science Foundation of China(11327901 and 11127404)the Project of Construction of Innovative Teams and Teacher Career Development for Universities and Colleges Under Beijing Municipality(IDHT20140504)
基金supported by the Special Funds for Major State Basic Research Project,China(Grant No.2011CB301900)the Hi-tech Research Project,China(Grant No.2009AA03A198)+2 种基金the National Natural Science Foundation of China(Grant Nos.60990311, 60721063,60906025,60936004,60731160628,and 60820106003)the Nature Science Foundation of Jiangsu Province,China (Grant Nos.BK2008019,BK2010385,BK2009255,and BK2010178)the Research Funds from NJU-Yangzhou Institute of Opto-electronics,China
文摘Wide spectral white light emitting diodes have been designed and grown on a sapphire substrate by using a metal-organic chemical vapor deposition system. Three quantum wells with blue-light-emitting, green-light-emitting and red-light-emitting structures were grown according to the design. The surface morphology of the film was observed by using atomic force microscopy. The films were characterized by their photoluminescence measurements. X-ray diffraction t9/2/9 scan spectroscopy was carried out on the multi-quantum wells. The secondary fringes of the symmetric ω/2θ X-ray diffraction scan peaks indicate that the thicknesses and the alloy compositions of the individual quantum wells are repeatable throughout the active region. The room temperature photoluminescence spectra of the structures indicate that the white light emission of the multi-quantum wells is obtained. The light spectrum covers 400 700 nm, which is almost the whole visible light spectrum.
文摘The structural and magnetic properties, as well as the mechanism of magnetization, of Ni-implanted A1N films were studied. A1N was deposited on A1203 substrates by metalorganic chemical vapor deposition （MOCVD）, and subsequently Ni ions were implanted into the A1N films by Metal Vapor Arc （MEVVA） sources at an energy of 100 keV for 3 h. The films were annealed at 900~C for 1 h in the furnace in order to transfer the Ni ions from interstitial sites to substitutional sites in A1N, thus activating the Ni3＋ ions. Characterizations were performed in situ using X-ray diffraction （XRD）, X-ray photoemis- sion spectroscopy （XPS）, and vibrating sample magneto- metry （VSM）, which showed that the films have a wurtzite structure without the formation of a secondary phase after implanting and annealing. Ni ions were successfully implanted into substitutional sites of AlN films, and the chemical bonding states are Ni-N. The apparent hysteresis loops prove that the films exhibited magnetism at 300 K. The room temperature （RT） saturation magnetization moment （Ms） and eoercivity （He） values were about 0.36 emu/g and 35.29 Oe, respectively. From the first-principles calculation, a total magnetic moment of 2.99 ~tB per supercell is expected, and the local magnetic moment of a NiN4 tetrahedron, 2.45 gB, makes the primary contribu- tion. The doped Ni atom hybridizes with four nearby N atoms in a NiN4 tetrahedron; then the electrons of the N atoms are spin-polarized and couple with the electrons of the Ni atom with strong magnetization, which results in magnetism. Therefore, the p-d exchange mechanism between Ni-3d and N-2p can be the origin of the magnetism. It is expected that these room temperature, ferromagnetic, Ni-doped A1N films will have many potential applications as diluted magnetic semiconductors.
