CoSi{sub 2} growth on Si(001) by reactive deposition epitaxy: Effects of high-flux, low-energy ion irradiation
- Department of Materials Science, Frederick Seitz Materials Research Laboratory, University of Illinois, 104 South Goodwin, Urbana, Illinois 61801 (United States)
CoSi{sub 2} layers, <40 nm thick, were grown on Si(001) by reactive deposition epitaxy (RDE) in which Co was deposited at 700 deg.C by magnetically unbalanced ultrahigh vacuum magnetron sputtering. X-ray diffraction pole figures and transmission electron microscopy (TEM) reveal that the layers, which exhibit a cube-on-cube epitaxial relationship with the substrate (001){sub CoSi{sub 2}}(parallel sign)(001){sub Si} and [100]{sub CoSi{sub 2}}(parallel sign)[100]{sub Si}, contain fourfold symmetric (111) twinned domains oriented such that (221){sub CoSi{sub 2}}(parallel sign)(001){sub Si} and <110>{sub CoSi{sub 2}}(parallel sign)[110]{sub Si}. We demonstrate that high-flux low-energy (E{sub Ar{sup +}}=9.6 eV) Ar{sup +} ion irradiation during deposition dramatically increases the area fraction f{sub u} of untwinned regions from 0.17 in films grown under standard magnetically balanced conditions in which the ratio J{sub Ar{sup +}}/J{sub Co} of the incident Ar{sup +} to Co fluxes is 1.4 to 0.72 with J{sub Ar{sup +}}/J{sub Co}=13.3. TEM analyses show that the early stages of RDE CoSi{sub 2}(001) film growth proceed via the Volmer-Weber mode with independent nucleation of both untwinned and twinned islands. Increasing J{sub Ar{sup +}}/J{sub Co} results in larger values of both the number density and area of untwinned with respect to twinned islands. The intense Ar{sup +} ion bombardment creates additional low-energy adsorption sites that favor the nucleation of untwinned islands while collisionally enhancing Co surface mobilities which, in turn, increases the probability of itinerant Co adatoms reaching these sites.
- OSTI ID:
- 20879956
- Journal Information:
- Journal of Applied Physics, Vol. 100, Issue 1; Other Information: DOI: 10.1063/1.2213351; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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