Naslov
Isotope effect for mega-electronvolt boron ions in amorphous silicon

Autori
Svensson, B.G. ; Ridgway, M.C. ; Petravić, Mladen

Izvornik
Journal of applied physics (0021-8979) 73 (1993), 10; 4836-4840

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
depth profiling ; SIMS ; boron in Si

Sažetak
The depth profiles of l”B and “B implanted into amorphous silicon have been analyzed by secondary ion mass spectrometry. Implantation energies between 0.4 and 5.0 MeV were used, and each sample was sequentially implanted with both ‘0s and “B without changing the acceleration voltage but only the field in the mass analyzing magnet. A shift between the two profiles is clearly resolved and has been carefully studied as a function of ion energy. A maximum shift of 3.5% in mean projected range (R ) If is revealed at 0.6-0.8 MeV IRJ”B> >R, (‘~)l, and for higher energiest he ratio Rp( B)/R, ( ‘@B)d ecreasess lowly to a value of - 1.006 at 5.0 MeV. This reverse shift (heavier isotope penetrates deeper) is attributed to a larger electronic stopping cross section (S, ) for t”B than for ilB at a given energy E where S, -, !#’ and p > 0. The experimental data for R, (“B)/R, (“B) and RP( “B) are compared with calculations, and it is demonstrated that the variation of R, (“B)/R, (‘“B) with ion energy hinges strongly on the S, vs E dependence. A close velocity proportional dependence (p=O.50*0.03) is found to be valid up to -300 keV, and then p decreasesg radually with a maximum in S, (p=O) at -2.0 to 2.5 MeV. A semiempirical expression is presented for S, and shown to yield excellent agreement with both the relative isotope shift and the absolute range values ; the deviations are less than 0.2% and 3.0%, respectively.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

POVEZANOST RADA