Skip to main content Accessibility help

Density Reduction: A Mechanism for Amorphization at High Ion Doses

  • E.D. Specht (a1), D.A. Walko (a2) and S.J. Zinkle (a1)


At cryogenic temperatures, the accumulation of vacancy-interstitial pairs in Al2O3 from atomic displacements associated with ion implantation produces amorphization. At room temperature, these pairs recombine, and amorphization occurs only at high doses. X-ray reflectivity measurements show that amorphization of the surface of Al2O3 implanted at room temperature with 160 keV Cr+ ions is preceded by a progressive reduction in near-surface density. Monte Carlo simulations show that this density reduction can be accounted for by high-energy-transfer collisions which knock atoms deep into the target, leaving widely separated vacancies and interstitials, which do not recombine. Electron microscopy shows that at least some of these vacancies condense into voids. We propose that this reduction in near-surface density can lead to amorphization at high doses. We present simple approximations for the density reduction expected for different ions and targets.



Hide All
1 Burnett, P.J. and Page, T.F., Radiat. Eff. 97, 283 (1986).
2 Glaser, E., Götz, G., Sobolev, N., and Wesch, W., Phys. Status Solidi A 69, 603 (1982).
3 White, C.W., McHargue, C.J., Sklad, P.S., Boatner, L.A., and Farlow, G.C., Mater. Sci. Rep. 4, 41 (1989).
4 Brimhall, J.L. and Simonen, E.P., Nucl. Instrum. and Meth. B16, 187 (1986).
5 Burnett, P.J. and Page, T.F., J. Mater. Sci. 20, 4624 (1985).
6 O'ern, M.E., McHargue, C.J., White, C.W., and Farlow, G.C., Nucl. Instrum. and Meth. B46, 171 (1990).
7 Noda, S., Doi, H., and Kamigaito, O., J. Mater. Res. 4, 671 (1989).
8 Bull, S.J., J. Mater. Sci. 26, 3086 (1991).
9 McHargue, C.J., et al. , Nucl. Instrum. and Meth. B16, 212 (1986).
10 Specht, E.D., Walko, D.A., and Zinkle, S.J., Nucl. Instrum. and Meth. B (in press).
11 Parratt, L.G., Phys. Rev. 95, 359 (1954).
12 Hioki, T., Itoh, A., Ohkubo, M., Noda, S., Doi, H., Kawamoto, J., and Kaigaito, O., J. Mater. Sci. 21, 1321 (1986).
13 Specht, E.D., Sparks, C.J., and McHargue, C.J., Appl. Phys. Lett. 60, 2216 (1992).
14 See Biersack, J.P. and Haggmark, L.G., Nucl. Instrum. and Meth. 174, 257 (1980) for the original TRIM program. TRIM89 has been modified by T.P. Sjoreen (unpublished) to include different displacement thresholds for elements in compound materials.
15 Sigmund, P., Rev. Roum. Phys. 17, 823 (1972).
16 Oishi, Y. and Kingery, W.D., J. Chem. Phys. 33, 480 (1960).
17 Paladino, A.E. and Kingery, W.D., J. Chem. Phys. 37, 957 (1962).
18 Gulden, T.D., Philos. Mag. 15, 453 (1966).
19 Lee, W.E., Jenkins, M.L., and Pells, G.P., Phil. Mag. A51, 639 (1985).

Density Reduction: A Mechanism for Amorphization at High Ion Doses

  • E.D. Specht (a1), D.A. Walko (a2) and S.J. Zinkle (a1)


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed