The oxygen-related defects in CZ silicon during electron irradiation(1.5 MeV)and subsequent annealing in the range of 150-600℃were investigated by means of FTIR.In the electron irradiation CZ-Si,vacancy-oxygen comple...The oxygen-related defects in CZ silicon during electron irradiation(1.5 MeV)and subsequent annealing in the range of 150-600℃were investigated by means of FTIR.In the electron irradiation CZ-Si,vacancy-oxygen complex is one of the dominant defects and its concentration is proportional to electron dose but not related to oxygen concentration.In this work,it was focused on the identification of the weak band at 860 cm^(-1)which was originated from asymmetrical stretching vibrations of an oxygen atom in the negative VO complex.It exhibits the same thermal stability with neutral VO band at 830 cm^(-1).In addition,the intensity of 889 cm-1 band has never been observed to exceed that of the A-center,implying that only a partial transformation of VO into VO_(2)does occur.展开更多
Fast-neutron irradiated nitrogen-doped Czochralski silicon(NCZ-Si)was annealed at 1100℃for different time,then FTIR and optical microscope were used to study the behavior of oxygen.It is found that[Oi]increase at the...Fast-neutron irradiated nitrogen-doped Czochralski silicon(NCZ-Si)was annealed at 1100℃for different time,then FTIR and optical microscope were used to study the behavior of oxygen.It is found that[Oi]increase at the early stage then decrease along with the increasing of anneal time.High density induced-defects can be found in the cleavage plane.By comparing NCZ-Si with Czochralski silicon(CZ-Si),[Oi]in NCZ-Si decrease more after anneal 24 h.展开更多
Growth of Czochralski (CZ) silicon crystals under the magnetic field induced by a cusp-shaped permanent magnet of NdFeB has been investigated. It is found that the mass transport in silicon melt was controlled by its ...Growth of Czochralski (CZ) silicon crystals under the magnetic field induced by a cusp-shaped permanent magnet of NdFeB has been investigated. It is found that the mass transport in silicon melt was controlled by its diffusion while the magnetic intensity at the edge of a crucible was over 0.15 T. In comparison with the growth of conventional CZ silicon without magnetic field, the resistivity homogeneity of the CZ silicon under the magnetic field was improved. Furthermore, the Marangoni convection which has a significant influence on the control of oxygen concentration was observed on the surface of silicon melt. It is suggested that the crystal growth mechanism in magnetic field was similar to that in micro-gravity if a critical value was reached, named the growth of equivalent micro-gravity. The relationship of the equivalent micro-gravity and the magnetic intensity was derived as g=(v0/veff)g0. Finally, the orders of the equivalent micro-gravity corresponding to two crucibles with characteristic sizes were calculated.展开更多
The influence of stresses on martensitic transformation in Ni50Mn19Fe6Ga25 melt-spun ribbons was studied. X-ray diffraction examination shows that the ribbon has a pure cubic L21 phase at room temperature and that the...The influence of stresses on martensitic transformation in Ni50Mn19Fe6Ga25 melt-spun ribbons was studied. X-ray diffraction examination shows that the ribbon has a pure cubic L21 phase at room temperature and that the ribbon surface exhibits [100] preferentially oriented texture, while the [110] axis is about 45° tilted from the normal of the ribbon. By calculating the d spacing at different angles with the length direction of the ribbon, the tension was observed. It was found that the direction of the stress was along [010] direction of the oriented textured grains. During cooling, there is no obvious structural transition observed in as-spun ribbons. However, when the ribbons were annealed at 900 K for 24 h, the tension along [010] direction disappeared and the structural transition from cubic to tetragonal occurred obviously during cooling. It indicates that it is the tension along [010] direction to suppress the martensitic transformation in the as-spun ribbons.展开更多
基金The work was financially supported by the National Natural Science Foundation of China(No.50472034)Natural Science Foundation of Hebei Province(No.E2005000048)Specialized Research Fundforthe Doctoral Program of Higher Education(No.20050080006).
文摘The oxygen-related defects in CZ silicon during electron irradiation(1.5 MeV)and subsequent annealing in the range of 150-600℃were investigated by means of FTIR.In the electron irradiation CZ-Si,vacancy-oxygen complex is one of the dominant defects and its concentration is proportional to electron dose but not related to oxygen concentration.In this work,it was focused on the identification of the weak band at 860 cm^(-1)which was originated from asymmetrical stretching vibrations of an oxygen atom in the negative VO complex.It exhibits the same thermal stability with neutral VO band at 830 cm^(-1).In addition,the intensity of 889 cm-1 band has never been observed to exceed that of the A-center,implying that only a partial transformation of VO into VO_(2)does occur.
基金Project supported by the National Nature Science Foundation of China(50472034)the Natural Science Foundation of Hebei Province(E2005000048)Education Ministry Doctoral Program Foundation of China(20050080006)
文摘Fast-neutron irradiated nitrogen-doped Czochralski silicon(NCZ-Si)was annealed at 1100℃for different time,then FTIR and optical microscope were used to study the behavior of oxygen.It is found that[Oi]increase at the early stage then decrease along with the increasing of anneal time.High density induced-defects can be found in the cleavage plane.By comparing NCZ-Si with Czochralski silicon(CZ-Si),[Oi]in NCZ-Si decrease more after anneal 24 h.
基金the National Natural Science Foundation of China (Grant No. 59972007) the Ministry of National Science and Technology and the Natural Science Foundation of Hebei Province (No.599033).
文摘Growth of Czochralski (CZ) silicon crystals under the magnetic field induced by a cusp-shaped permanent magnet of NdFeB has been investigated. It is found that the mass transport in silicon melt was controlled by its diffusion while the magnetic intensity at the edge of a crucible was over 0.15 T. In comparison with the growth of conventional CZ silicon without magnetic field, the resistivity homogeneity of the CZ silicon under the magnetic field was improved. Furthermore, the Marangoni convection which has a significant influence on the control of oxygen concentration was observed on the surface of silicon melt. It is suggested that the crystal growth mechanism in magnetic field was similar to that in micro-gravity if a critical value was reached, named the growth of equivalent micro-gravity. The relationship of the equivalent micro-gravity and the magnetic intensity was derived as g=(v0/veff)g0. Finally, the orders of the equivalent micro-gravity corresponding to two crucibles with characteristic sizes were calculated.
基金the National Natural Science Foundation of China (Grant No.50271023) the Natural Science Foundation of Hebei Province (Grant No. 503031).
文摘The influence of stresses on martensitic transformation in Ni50Mn19Fe6Ga25 melt-spun ribbons was studied. X-ray diffraction examination shows that the ribbon has a pure cubic L21 phase at room temperature and that the ribbon surface exhibits [100] preferentially oriented texture, while the [110] axis is about 45° tilted from the normal of the ribbon. By calculating the d spacing at different angles with the length direction of the ribbon, the tension was observed. It was found that the direction of the stress was along [010] direction of the oriented textured grains. During cooling, there is no obvious structural transition observed in as-spun ribbons. However, when the ribbons were annealed at 900 K for 24 h, the tension along [010] direction disappeared and the structural transition from cubic to tetragonal occurred obviously during cooling. It indicates that it is the tension along [010] direction to suppress the martensitic transformation in the as-spun ribbons.
