The increasing dependence on fossil fuels and the consequent CO_(2)emissions have prompted urgent energy and environmental challenges[1,2].Solar-driven CO_(2)conversion into value-added fuels offers a sustainable and ...The increasing dependence on fossil fuels and the consequent CO_(2)emissions have prompted urgent energy and environmental challenges[1,2].Solar-driven CO_(2)conversion into value-added fuels offers a sustainable and promising solution to these issues[3].However,the practical implementation of CO_(2)photoreduction is constrained by low efficiency,primarily due to the rapid recombination of photogenerated electron-hole pairs[4].展开更多
In order to reduce deep level defects, the theory and process design of 4H-SiC homoepitaxial layer implanted by carbon ion are studied. With the Monte Carlo simulator TRIM, the ion implantation range, location of peak...In order to reduce deep level defects, the theory and process design of 4H-SiC homoepitaxial layer implanted by carbon ion are studied. With the Monte Carlo simulator TRIM, the ion implantation range, location of peak concentration and longitudinal straggling of carbon are calculated. The process for improving deep energy level in undoped 4H-SiC homoepitaxial layer by three times carbon ion-implantation is proposed, including implantation energy, dose, the SiO2 resist mask, annealing temperature, annealing time and annealing protection. The deep energy level in 4H-SiC material can be significantly improved by implantation of carbon atoms into a shallow surface layer. The damage of crystal lattice can be repaired well, and the carbon ions are effectively activated after 1 600 ℃ annealing, meanwhile, deep level defects are decreased.展开更多
Entanglement due to the interaction of a two level atom with a laser and quantized field is investigated. The role of the nonlinearity due to these interactions is discussed. It is found that the nonlinearity changes ...Entanglement due to the interaction of a two level atom with a laser and quantized field is investigated. The role of the nonlinearity due to these interactions is discussed. It is found that the nonlinearity changes strongly the behavior of the entanglement also the detuning parameters have important role in the structure of the measure of entanglement.展开更多
The influence of a deep-level-defect（DLD） band formed in a heavily Mg-doped GaN contact layer on the performance of Ni/Au contact to p-GaN is investigated. The thin heavily Mg-doped GaN（p^＋＋-GaN） contact layer w...The influence of a deep-level-defect（DLD） band formed in a heavily Mg-doped GaN contact layer on the performance of Ni/Au contact to p-GaN is investigated. The thin heavily Mg-doped GaN（p^＋＋-GaN） contact layer with DLD band can effectively improve the performance of Ni/Au ohmic contact to p-GaN. The temperature-dependent I–V measurement shows that the variable-range hopping（VRH） transportation through the DLD band plays a dominant role in the ohmic contact. The thickness and Mg/Ga flow ratio of p^＋＋-GaN contact layer have a significant effect on ohmic contact by controlling the Mg impurity doping and the formation of a proper DLD band. When the thickness of the p^＋＋-GaN contact layer is 25 nm thick and the Mg/Ga flow rate ratio is 10.29%, an ohmic contact with low specific contact resistivity of 6.97×10^-4Ω·cm^2 is achieved.展开更多
Focusing on the low open circuit voltage(V_(OC))and fill factor(FF)in flexible Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells,indium(In)ions are introduced into the CZTSSe absorbers near Mo foils to modify the back interface...Focusing on the low open circuit voltage(V_(OC))and fill factor(FF)in flexible Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells,indium(In)ions are introduced into the CZTSSe absorbers near Mo foils to modify the back interface and passivate deep level defects in CZTSSe bulk concurrently for improving the performance of flexible device.The results show that In doping effectively inhibits the formation of secondary phase(Cu(S,Se)_(2))and VSndefects.Further studies demonstrate that the barrier height at the back interface is decreased and the deep level defects(Cu_(Sn)defects)in CZTSSe bulk are passivated.Moreover,the carrier concentration is increased and the V_(OC) deficit(V_(OC,def))is decreased significantly due to In doping.Finally,the flexible CZTSSe solar cell with 10.01%power conversion efficiency(PCE)has been obtained.The synergistic strategy of interface modification and bulk defects passivation through In incorporation provides a new thought for the fabrication of efficient flexible kesterite-based solar cells.展开更多
Understanding the defect characteristics that occur near the space-charge regions(SCRs)of kesterite(CZTSSe)solar cells is important because the recombination loss at the CZTSSe/CdS interface is considered the main cau...Understanding the defect characteristics that occur near the space-charge regions(SCRs)of kesterite(CZTSSe)solar cells is important because the recombination loss at the CZTSSe/CdS interface is considered the main cause of their low efficiency.CZTSSe surfaces with different elemental compositions were formed without polishing(C00)and with polishing for 20 s(C20)and 60 s(C60).For C60,a specific region near the SCR was excessively Cu-rich and Zn-poor compared to C00 and C20.Various charged defects formed where the elemental variation was large.As the main deep acceptor defect energy level(E_(a2))near the SCR increased,the efficiency,open-circuit voltage deficit,and current density degraded,and this phenomenon was especially rapid for large E_(a2) values.As the E_(a2) near the SCR became deep,the carrier diffusion length decreased more for the CZTSSe solar cells with a low carrier mobility than for the CuInGaSe_(2)(CIGSe)solar cells.The large amplitude of the electrostatic potential fluctuation in the CZTSSe solar cells induced a high carrier recombination and a short carrier lifetime.Consequently,the properties of the CZTSSe solar cells were more strongly degraded by defects with deep energy levels near the SCR than those of the CIGSe solar cells.展开更多
Electrically active defects in the phosphor-doped single-crystal silicon, induced by helium-ion irradiation under thermal annealing, have been investigated. Isothermal charge-sensitive deep-level transient spectroscop...Electrically active defects in the phosphor-doped single-crystal silicon, induced by helium-ion irradiation under thermal annealing, have been investigated. Isothermal charge-sensitive deep-level transient spectroscopy was employed to study the activation energy and capture cross-section of helium-induced defects in silicon samples. It was shown that the activation energy levels produced by helium-ion irradiation first increased with increasing annealing temperature, with the maximum value of the activation energy occurring at 873 K, and reduced with further increase of the annealing temperature. The energy levels of defects in the samples annealed at 873 and 1073 K are found to be located near the mid-forbidden energy gap level so that they can act as thermally stable carrier recombination centres.展开更多
小型轮廓封装(Small Outline Package,SOP)和球形阵列封装(Ball Grad Array,BGA)元件作为贴片机常用的贴装元件,在其制造过程中可能会由于材料适配、工艺精细程度等而出现引脚变形等缺陷,进而给焊接过程造成不良影响,甚至使芯片功能失...小型轮廓封装(Small Outline Package,SOP)和球形阵列封装(Ball Grad Array,BGA)元件作为贴片机常用的贴装元件,在其制造过程中可能会由于材料适配、工艺精细程度等而出现引脚变形等缺陷,进而给焊接过程造成不良影响,甚至使芯片功能失效。本研究以SOP和BGA元件为研究对象,提出一种结合图像融合差分、缺陷连通域标记和基于倾斜前后引脚外边缘中心点距离变化比对方法的多级引脚缺陷检测方法,以实现元件引脚缺陷的准确检测。实验结果表明,矩形引脚元件SOP和球形引脚元件BGA的总体检测准确率达到了95%以上,且缺陷检测的整体平均耗时均在100ms以内,满足贴片机检测系统要求,为相关行业贴片机的检测系统提供一定工程应用参考价值。展开更多
The correct rate of detection for fabric defect is affected by low contrast of images. Aiming at the problem,frequencytuned salient map is used to detect the fabric defect. Firstly,the images of fabric defect are divi...The correct rate of detection for fabric defect is affected by low contrast of images. Aiming at the problem,frequencytuned salient map is used to detect the fabric defect. Firstly,the images of fabric defect are divided into blocks. Then,the blocks are highlighted by frequency-tuned salient algorithm. Simultaneously,gray-level co-occurrence matrix is used to extract the characteristic value of each rectangular patch. Finally,PNN is used to detect the defect on the fabric image. The performance of proposed algorithm is estimated off-line by two sets of fabric defect images. The theoretical argument is supported by experimental results.展开更多
文摘The increasing dependence on fossil fuels and the consequent CO_(2)emissions have prompted urgent energy and environmental challenges[1,2].Solar-driven CO_(2)conversion into value-added fuels offers a sustainable and promising solution to these issues[3].However,the practical implementation of CO_(2)photoreduction is constrained by low efficiency,primarily due to the rapid recombination of photogenerated electron-hole pairs[4].
基金Supported by the National Natural Science Foundation of China (No. 61006008)Xi'an Applied Materials Innovation Fund (No. XA-AM-200607)
文摘In order to reduce deep level defects, the theory and process design of 4H-SiC homoepitaxial layer implanted by carbon ion are studied. With the Monte Carlo simulator TRIM, the ion implantation range, location of peak concentration and longitudinal straggling of carbon are calculated. The process for improving deep energy level in undoped 4H-SiC homoepitaxial layer by three times carbon ion-implantation is proposed, including implantation energy, dose, the SiO2 resist mask, annealing temperature, annealing time and annealing protection. The deep energy level in 4H-SiC material can be significantly improved by implantation of carbon atoms into a shallow surface layer. The damage of crystal lattice can be repaired well, and the carbon ions are effectively activated after 1 600 ℃ annealing, meanwhile, deep level defects are decreased.
文摘Entanglement due to the interaction of a two level atom with a laser and quantized field is investigated. The role of the nonlinearity due to these interactions is discussed. It is found that the nonlinearity changes strongly the behavior of the entanglement also the detuning parameters have important role in the structure of the measure of entanglement.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61474110,61377020,61376089,61223005,and 61176126)the National Science Fund for Distinguished Young Scholars of China(Grant No.60925017)+1 种基金One Hundred Person Project of the Chinese Academy of Sciencesthe Basic Research Project of Jiangsu Province,China(Grant No.BK20130362)
文摘The influence of a deep-level-defect（DLD） band formed in a heavily Mg-doped GaN contact layer on the performance of Ni/Au contact to p-GaN is investigated. The thin heavily Mg-doped GaN（p^＋＋-GaN） contact layer with DLD band can effectively improve the performance of Ni/Au ohmic contact to p-GaN. The temperature-dependent I–V measurement shows that the variable-range hopping（VRH） transportation through the DLD band plays a dominant role in the ohmic contact. The thickness and Mg/Ga flow ratio of p^＋＋-GaN contact layer have a significant effect on ohmic contact by controlling the Mg impurity doping and the formation of a proper DLD band. When the thickness of the p^＋＋-GaN contact layer is 25 nm thick and the Mg/Ga flow rate ratio is 10.29%, an ohmic contact with low specific contact resistivity of 6.97×10^-4Ω·cm^2 is achieved.
基金supported by the National Natural Science Foundation of China(62074037)the Science and Technology Department of Fujian Province(2020I0006)the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ124)。
文摘Focusing on the low open circuit voltage(V_(OC))and fill factor(FF)in flexible Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells,indium(In)ions are introduced into the CZTSSe absorbers near Mo foils to modify the back interface and passivate deep level defects in CZTSSe bulk concurrently for improving the performance of flexible device.The results show that In doping effectively inhibits the formation of secondary phase(Cu(S,Se)_(2))and VSndefects.Further studies demonstrate that the barrier height at the back interface is decreased and the deep level defects(Cu_(Sn)defects)in CZTSSe bulk are passivated.Moreover,the carrier concentration is increased and the V_(OC) deficit(V_(OC,def))is decreased significantly due to In doping.Finally,the flexible CZTSSe solar cell with 10.01%power conversion efficiency(PCE)has been obtained.The synergistic strategy of interface modification and bulk defects passivation through In incorporation provides a new thought for the fabrication of efficient flexible kesterite-based solar cells.
基金the National Research Foundation of Korea(NRF)grant funded by the Ministry of Science and ICT(No.2022M3J1A1085371)the DGIST R&D programs of the Ministry of Science and ICT(23-ET-08 and 23-CoE-ET-01)the National Research Foundation of Korea(NRF),funded by the Korean Government(NRF-2021R1A2C1008598).
文摘Understanding the defect characteristics that occur near the space-charge regions(SCRs)of kesterite(CZTSSe)solar cells is important because the recombination loss at the CZTSSe/CdS interface is considered the main cause of their low efficiency.CZTSSe surfaces with different elemental compositions were formed without polishing(C00)and with polishing for 20 s(C20)and 60 s(C60).For C60,a specific region near the SCR was excessively Cu-rich and Zn-poor compared to C00 and C20.Various charged defects formed where the elemental variation was large.As the main deep acceptor defect energy level(E_(a2))near the SCR increased,the efficiency,open-circuit voltage deficit,and current density degraded,and this phenomenon was especially rapid for large E_(a2) values.As the E_(a2) near the SCR became deep,the carrier diffusion length decreased more for the CZTSSe solar cells with a low carrier mobility than for the CuInGaSe_(2)(CIGSe)solar cells.The large amplitude of the electrostatic potential fluctuation in the CZTSSe solar cells induced a high carrier recombination and a short carrier lifetime.Consequently,the properties of the CZTSSe solar cells were more strongly degraded by defects with deep energy levels near the SCR than those of the CIGSe solar cells.
基金Project supported by the National Natural Science Foundation of China (Grant No 10575124)
文摘Electrically active defects in the phosphor-doped single-crystal silicon, induced by helium-ion irradiation under thermal annealing, have been investigated. Isothermal charge-sensitive deep-level transient spectroscopy was employed to study the activation energy and capture cross-section of helium-induced defects in silicon samples. It was shown that the activation energy levels produced by helium-ion irradiation first increased with increasing annealing temperature, with the maximum value of the activation energy occurring at 873 K, and reduced with further increase of the annealing temperature. The energy levels of defects in the samples annealed at 873 and 1073 K are found to be located near the mid-forbidden energy gap level so that they can act as thermally stable carrier recombination centres.
文摘小型轮廓封装(Small Outline Package,SOP)和球形阵列封装(Ball Grad Array,BGA)元件作为贴片机常用的贴装元件,在其制造过程中可能会由于材料适配、工艺精细程度等而出现引脚变形等缺陷,进而给焊接过程造成不良影响,甚至使芯片功能失效。本研究以SOP和BGA元件为研究对象,提出一种结合图像融合差分、缺陷连通域标记和基于倾斜前后引脚外边缘中心点距离变化比对方法的多级引脚缺陷检测方法,以实现元件引脚缺陷的准确检测。实验结果表明,矩形引脚元件SOP和球形引脚元件BGA的总体检测准确率达到了95%以上,且缺陷检测的整体平均耗时均在100ms以内,满足贴片机检测系统要求,为相关行业贴片机的检测系统提供一定工程应用参考价值。
文摘The correct rate of detection for fabric defect is affected by low contrast of images. Aiming at the problem,frequencytuned salient map is used to detect the fabric defect. Firstly,the images of fabric defect are divided into blocks. Then,the blocks are highlighted by frequency-tuned salient algorithm. Simultaneously,gray-level co-occurrence matrix is used to extract the characteristic value of each rectangular patch. Finally,PNN is used to detect the defect on the fabric image. The performance of proposed algorithm is estimated off-line by two sets of fabric defect images. The theoretical argument is supported by experimental results.
