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Microstructure and Residual Stresses in Al2O3 Prepared by Ion Beam Assisted Deposition
Published online by Cambridge University Press: 22 February 2011
Abstract
Alumina films synthesized by ion beam assisted deposition (EBAD) were characterized in terms of their microstructure and residual stress. Normalized energy per deposited atom, En, ranged from 0 to 130 eV/atom. The microstructure of PVD films (En=0) is a mixture of crystalline (γ-Al2O3) and amorphous phases and IBAD films are amorphous. Density and stoichiometry vary between 2.6 and 3.1 g/cm3 and 1.3 and 1.6, respectively. Neither are dependent on either ion-to-atom arrival rate ratio, R, or En. The film porosity is in the form of small (4-6 nm) voids of density 1017 - 1018 cm-3. Bombarding gas is incorporated with 80% efficiency to levels of 4-5 at. %. A tensile residual stress of 0.3 GPa exists in PVD films. A rapid transition to high compressive stresses occurs with increased En, with a saturation of -0.4 GPa occurring at high En There is a strong correlation between gas incorporation and residual film stress. However, no existing models are capable of providing a quantitative explanation of the results.
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- Copyright © Materials Research Society 1994
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