Hi,

TRIM will give you the typical distance reach by He ions in you sample, after you can calculate your He proportions compared to Ta/CoFeB. For this, use the ion current and the time of exposition to recalculate the number of ion implanted in the area irradiated. A current in ampere multiply by the time of exposition give you a charge in coulomb, 1 C correspond to 6.242×10^18 elementary charge so that He ions in your case.

The distrubution must be statistic in your sample. I don't know if there is a better way to caracterise your alloy.

Hopping it was usefull,

Nicolas

Dear Rajnandini,

the answer to this question gives the theory of Rutherford backscattering and ionization cross section of the atom shell.

He+ ion on Ta gives a very effective backscattering cross section. Only ions which meet the inner shell of the atom have enough energy to shift the Ta-nucleus. In the rough approximation of the central kick of to hard spheres you find a transfer energy of 4*m1*10keV/m2 = 0,09 keV. This is enough to destroy the surface. But you must reach the inner shell. The K-shell binding energy after Mosley is 13,6eV*Z² = 72 keV. So, the probability is high to ionize the L-shell before the ion penetrates the shell. If you want to erase the surface, you need heavier ions like Argon. Such ions are used to polish the surface. Light ions on heavy atoms are mostly reflected. But I would after irradiation anneal the sample.

With Regard

R. Mitdank

Thank you, Nicolas Ludwig and Dr. Mitdank. Your answers helped me to understand my problem in a better way. Apart from being ionization of Ta, I want to know about the intermixing of layered Ta/CoFeB and its effect on magnetic property of CoFeB.