Early stages of IBAD-film growth: Differences between (100) and polycrystalline Mo substrates

The effects of 250 eV Ar+ ion assistance on the growth of ultrathin molybde num films on Mo (1 00) and on well-annealed polycrystalline molybdenum subs trates (largely (110)-oriented) are investigated by concurrent thermal deso rption spectrometry of incorporated Ar and He, the latter species brought i nto the film after deposition as probe particles to decorate the point defe cts. Ar entrapment. defect concentration. and the transition From planar to columnar growth are quantitatively determined. The overall defect creation rate of 250 eV Ar+ assistance is 0.1 defects per ion, including self-trapp ing. The difference between the substrate orientations shows up mainly in t he growth morphology, the defect concentration, and the immediate subsurfac e trapping of Ar and He. (C) 1999 Elsevier Science B.V. All rights reserved .