A Hvem Study of the Electron Irradiated Defects in Nitrogen Doped FZ-Si Single Crystal
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A HVEM STUDY OF THE ELECTRON IRRADIATED DEFECTS IN NITROGEN DOPED FZ-Si SINGLE CRYSTAL Gao Yuzun* and T.Takeyama** *General Research Institute for Non-Ferrous Metals, Beijing, 100088 China; **HVEM Lab,Hokkaido University ,Sapporo, Hokkaido, Japan
ABSTRACT High voltage transmission electron microscope (JEM-1000) has been used to investigate the electron irradiated defects in in p-type FZ-Si and nitrogen doped p-type FZ-Si. It was found that when the irradiated conditions were the same ,the irradiated defects were easier to be produced in the FZ-Si than in nitrogen doped FZ-Si in the temperature range 573-773 K. The defect density was higher in the former. The migration energy of the vacancies in the temperature range 573-773 K was 0.34 and 0.58 eV for FZ-Si and nitrogen doped FZ-Si respectively. It seems to indicate that there was some interaction between vacancies and nitrogen atoms in the nitrogen doped FZ-Si. The results proved that the nitrogen doped FZ-Si has excellent property against electron irradiation.
INTRODUCTION The nitrogen doped FZ-Si single crystal has excellent strength properties against thermo-mechanical deformation (1). The X ray topograph technique has been used to investigate the defects in FZ-Si single crystal. It was pointed out there was interaction between nitrogen atoms and the defects in Si Nitrogen affected the electric properties of Si such as the resistivity and the lifetime. Tajima (2) has suggested that nitrogen and vacancies in Si matrix can form deep level defects. But the interaction between nitrogen and the point defects in Si is still not very clear. In the present work, high voltage transmission electron microscope (JEM-1000) has been used to investigate the electron irradiated defects in p-type (ill) FZ-Si and nitrogen doped ptype (111) FZ-Si. The difference of irradiation behavoir of the two type of Si under the same irradiated condition helped us to know the interaction between nitrogen and the point defects.
Experimental HVEM (JEM-1000) was used to investigate electron irradiated defects in Si. The specimens were p-type (111) FZ-Si and nitrogen doped p-type (111) FZ-Si. 3The concentration of nitrogen in the latter was IE+15 at/cm . The specimens were mechannically polished and chemically shinned to films with the thickness about 1000 nm. EM specimens were electron irradiated in HVEM at 573,623,673 and 723 K respectively. The specimens were irradiated in the EVEM at 1000 kV with the dose of 0.1 dpa/min.
Results Mat. Res. Soc. Symp. Proc. Vol. 163. ý 1990 Materials Research Society
938
The electron irradiated defects were easier to be produced in the FZ-Si than in nitrogen doped FZ-Si in the temperature range 573-623 K. When the irradiation temperature was 573 K,the bar-like defects have been observed only with the irradiated time 1 min in the FZ-Si. The defects density was 7E +9/cm at 573 K,2 min. However there weren't any irradiated defects in nitrogen doped FZ-Si at 573 K,8 min. The bar-like defects grew along directions of Si matrix. The EM image of bar-like defect
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