The laser-induced damage threshold(LIDT)of plate laser beam splitter(PLBS)coatings is closely related to the subsurface absorption defects of the substrate.Herein,a two-step deposition temperature method is proposed t...The laser-induced damage threshold(LIDT)of plate laser beam splitter(PLBS)coatings is closely related to the subsurface absorption defects of the substrate.Herein,a two-step deposition temperature method is proposed to understand the effect of substrate subsurface impurity defects on the LIDT of PLBS coatings.Firstly,BK7 substrates are heat-treated at three different temperatures.The surface morphology and subsurface impurity defect distribution of the substrate before and after the heat treatment are compared.Then,a PLBS coating consisting of alternating HfO2–Al2O3 mixture and SiO2 layers is designed to achieve a beam-splitting ratio(transmittance to reflectance,s-polarized light)of approximately 50:50 at 1053 nm and an angle of incidence of 45◦,and it is prepared under four different deposition processes.The experimental and simulation results show that the subsurface impurity defects of the substrate migrate to the surface and accumulate on the surface during the heat treatment,and become absorption defect sources or nodule defect seeds in the coating,reducing the LIDT of the coating.The higher the heat treatment temperature,the more evident the migration and accumulation of impurity defects.A lower deposition temperature(at which the coating can be fully oxidized)helps to improve the LIDT of the PLBS coating.When the deposition temperature is 140◦C,the LIDT(s-polarized light,wavelength:1064 nm,pulse width:9 ns,incident angle:45◦)of the PLBS coating is 26.2 J/cm2,which is approximately 6.7 times that of the PLBS coating deposited at 200◦C.We believe that the investigation into the laser damage mechanism of PLBS coatings will help to improve the LIDT of coatings with partial or high transmittance at laser wavelengths.展开更多
p -type CZ silicon crystals annealed at 450℃ have been investigated by low temperature infrared spectroscopy with high resolusion. It has been shown that the 2p± and 3p± bands of neutral thermal donors TD~&...p -type CZ silicon crystals annealed at 450℃ have been investigated by low temperature infrared spectroscopy with high resolusion. It has been shown that the 2p± and 3p± bands of neutral thermal donors TD~° are all split into two bands, which have not been reported before. In addition, the concentrations ofindi- vidual TD_i and total TD have been derived from the heights of 2po bands, and the boron concentrations de- rived from that of 320 cm^(-1) band. The room temperature resistivities of samples have been evaluated and the comparison with practically measured resistivities have been made.展开更多
Stable nitrogen doping is an important issue in p-type ZnO research for device applications.In this paper,beryllium and magnesium are systematically compared as a dopant in ZnO to reveal their nitrogen-stabilizing abi...Stable nitrogen doping is an important issue in p-type ZnO research for device applications.In this paper,beryllium and magnesium are systematically compared as a dopant in ZnO to reveal their nitrogen-stabilizing ability.Secondary ion mass spectrum shows that Be and Mg can both enhance the stability of nitrogen in ZnO while Be has a better performance.Zn 2p and O 1s electron binding energies change in both MgZnO and Be ZnO thin films.Donor-acceptor luminescence is observed in the BeZnO samples.We conclude that Be is a better co-doping element than Mg for p-type ZnO:N.展开更多
The single-particle Green's function for a dc-biased superlattices with single impurity potential varying harmonically with time has been obtained in the framework of U(t,t') method and Floquet-Green's function. ...The single-particle Green's function for a dc-biased superlattices with single impurity potential varying harmonically with time has been obtained in the framework of U(t,t') method and Floquet-Green's function. The calculation of the local density of states shows that new states will emerge between the resonant Wannier-Stark states as a result of the intervention of time-dependent impurity potential, and the increase in electric field strength of impurity will result in the growing of the number of new states between the gaps of neighbouring Stark ladders.展开更多
A high-performance multicrystalline silicon (mc-Si) ingot was produced by seed-assisted directional solidification, and the minority carrier lifetime of the periphery edge region was evaluated. The defects and impur...A high-performance multicrystalline silicon (mc-Si) ingot was produced by seed-assisted directional solidification, and the minority carrier lifetime of the periphery edge region was evaluated. The defects and impurities in the periphery edge region of the silicon wafers were systematically studied with photoluminescence (PL) imaging, minority carrier lifetime mapping, and Fourier transform infrared (FTIR) spectroscopy. Their relationships with the minority carrier lifetime were investigated. The concentration of substitutional carbon, interstitial oxygen, and dislocation clusters is not directly correlated with the low minority carrier lifetime of the edge zone of the mc-Si ingot. Inhomogeneous grain size distribution and contamination with iron impurities were demonstrated to be the main factors affecting the low minority carrier lifetime. By controlling the impurities and improving the grain size distribution, a modified furnace was designed and a higher-quality mc-Si ingot was manufactured.展开更多
基金This study was supported by the National Natural Science Foundation of China(61975215)Youth Innovation Promotion Association of the Chinese Academy of Sciences,Strategic Priority Research Program of the Chinese Academy of Sciences(XDA25020206)the Science and Technology Planning Project of Shanghai Municipal Science&Technology Commission(21DZ1100400).
文摘The laser-induced damage threshold(LIDT)of plate laser beam splitter(PLBS)coatings is closely related to the subsurface absorption defects of the substrate.Herein,a two-step deposition temperature method is proposed to understand the effect of substrate subsurface impurity defects on the LIDT of PLBS coatings.Firstly,BK7 substrates are heat-treated at three different temperatures.The surface morphology and subsurface impurity defect distribution of the substrate before and after the heat treatment are compared.Then,a PLBS coating consisting of alternating HfO2–Al2O3 mixture and SiO2 layers is designed to achieve a beam-splitting ratio(transmittance to reflectance,s-polarized light)of approximately 50:50 at 1053 nm and an angle of incidence of 45◦,and it is prepared under four different deposition processes.The experimental and simulation results show that the subsurface impurity defects of the substrate migrate to the surface and accumulate on the surface during the heat treatment,and become absorption defect sources or nodule defect seeds in the coating,reducing the LIDT of the coating.The higher the heat treatment temperature,the more evident the migration and accumulation of impurity defects.A lower deposition temperature(at which the coating can be fully oxidized)helps to improve the LIDT of the PLBS coating.When the deposition temperature is 140◦C,the LIDT(s-polarized light,wavelength:1064 nm,pulse width:9 ns,incident angle:45◦)of the PLBS coating is 26.2 J/cm2,which is approximately 6.7 times that of the PLBS coating deposited at 200◦C.We believe that the investigation into the laser damage mechanism of PLBS coatings will help to improve the LIDT of coatings with partial or high transmittance at laser wavelengths.
文摘p -type CZ silicon crystals annealed at 450℃ have been investigated by low temperature infrared spectroscopy with high resolusion. It has been shown that the 2p± and 3p± bands of neutral thermal donors TD~° are all split into two bands, which have not been reported before. In addition, the concentrations ofindi- vidual TD_i and total TD have been derived from the heights of 2po bands, and the boron concentrations de- rived from that of 320 cm^(-1) band. The room temperature resistivities of samples have been evaluated and the comparison with practically measured resistivities have been made.
基金Project supported by the National Key Basic Research Program of China(Grant No.2011CB302000)the National Natural Science Foundation of China(Grant Nos.51232009 and 51202299)+2 种基金the Fundamental Research Funds for the Central Universities,China(Grant No.11lgpy16)the Natural Science Foundation for Jiangsu Provincial Higher Education,Institutions of China(Grant No.15KJB510005)the Talent Fund of Jiangsu University,China(Grant No.15JDG042)
文摘Stable nitrogen doping is an important issue in p-type ZnO research for device applications.In this paper,beryllium and magnesium are systematically compared as a dopant in ZnO to reveal their nitrogen-stabilizing ability.Secondary ion mass spectrum shows that Be and Mg can both enhance the stability of nitrogen in ZnO while Be has a better performance.Zn 2p and O 1s electron binding energies change in both MgZnO and Be ZnO thin films.Donor-acceptor luminescence is observed in the BeZnO samples.We conclude that Be is a better co-doping element than Mg for p-type ZnO:N.
基金Project supported by the Natural Science Foundation of Shanxi Province (Grant No 20031006).
文摘The single-particle Green's function for a dc-biased superlattices with single impurity potential varying harmonically with time has been obtained in the framework of U(t,t') method and Floquet-Green's function. The calculation of the local density of states shows that new states will emerge between the resonant Wannier-Stark states as a result of the intervention of time-dependent impurity potential, and the increase in electric field strength of impurity will result in the growing of the number of new states between the gaps of neighbouring Stark ladders.
文摘A high-performance multicrystalline silicon (mc-Si) ingot was produced by seed-assisted directional solidification, and the minority carrier lifetime of the periphery edge region was evaluated. The defects and impurities in the periphery edge region of the silicon wafers were systematically studied with photoluminescence (PL) imaging, minority carrier lifetime mapping, and Fourier transform infrared (FTIR) spectroscopy. Their relationships with the minority carrier lifetime were investigated. The concentration of substitutional carbon, interstitial oxygen, and dislocation clusters is not directly correlated with the low minority carrier lifetime of the edge zone of the mc-Si ingot. Inhomogeneous grain size distribution and contamination with iron impurities were demonstrated to be the main factors affecting the low minority carrier lifetime. By controlling the impurities and improving the grain size distribution, a modified furnace was designed and a higher-quality mc-Si ingot was manufactured.