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Depth profiling of low-energy ions implanted into metals using the field ion microscope/imaging atom probe

Thesis/Dissertation ·
OSTI ID:7231858

The implantation depth is an important parameter if properties are to be modified in a controllable and reproducible fashion by ion implantation. The Field Ion Microscope/Imaging Atom Probe (FIM/IAP) is superb for depth profiling, having depth resolutions on the order of a crystal lattice spacing of the metal under investigation. This study involves the application of the FIM/IAP in obtaining depth profiles of low-energy ions (<20keV) implanted into metals. Two technologically important ion species were used, nitrogen and deuterium. It was found that the deuterium partial pressure was not a problem when a properly differentially pumped ion gun was used. Specific problems of applying FIM/IAP to these species were reported. The results of nitrogen implanted into nickel showed that the nitrogen resists field evaporation even though the nickel was removed. Range and straggling values for nitrogen implanted into tungsten with energies of 2.5-9 keV were found and compared to Monte Carlo computer calculations. Two special Transmission Electron Microscope (TEM) sample holders were developed for use with FIM specimens. Using these holders, it was shown that there was little or no influence of the high electric field on the implanted defect microstructure of the specimen. However, nickel was seen to be embrittled by deuterium implantation, but not by helium or nitrogen.

Research Organization:
Florida Univ., Gainesville (USA)
OSTI ID:
7231858
Country of Publication:
United States
Language:
English