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The Mechanical Behavior of ALD‐Polymer Hybrid Films Under Tensile Strain
Author(s) -
Bulusu Anuradha,
Graham Samuel,
Bahre Hendrik,
Behm Henrik,
Böke Marc,
Dahlmann Rainer,
Hopmann Christian,
Winter Jörg
Publication year - 2015
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201400431
Subject(s) - materials science , nucleation , atomic layer deposition , polymer , x ray photoelectron spectroscopy , composite material , ultimate tensile strength , saturation (graph theory) , polyethylene terephthalate , chemical engineering , layer (electronics) , organic chemistry , chemistry , mathematics , combinatorics , engineering
Atomic layer deposition (ALD) is increasingly becoming commonplace to deposit high density, conformal films, as novel deposition techniques allow improved deposition rates on various substrates. Diffusion and miscibility of ALD precursors with polymers are known to affect film nucleation. To assess the influence of polymeric underlayer on the growth and mechanical behavior of ALD films, we deposited aluminum oxide (Al 2 O 3 ) and titanium dioxide (TiO 2 ) films on three different polymers with known reactivity to the ALD precursors and compared them to films on polyethylene terephthalate (PET). We present the trends in nucleation and penetration of the ALD films on the various polymers as well as the in situ mechanical behavior under tensile strain. X‐ray photoelectron spectroscopy (XPS) revealed that Cytop, a fluorinated polymer and polyethyleneimine ethoxylated (PEIE) delay the nucleation of Al 2 O 3 and TiO 2 films. Time‐of‐flight mass spectrometry (ToFSIMS) shows the extent of diffusion of the ALD precursors into the polymer underlayer, delaying nucleation. Tensile tests show that while the crack onset strain remained unchanged despite the various polymer underlayers, the crack saturation density decreased for ALD films on PEIE and polyhydroxystyrene (PHOST). Films on Cytop showed no crack saturation limit until the nucleation delay was overcome indicating that judicious choice of the ALD film and polymer underlayer will allow tailoring of the length of the diffusion zone and crack saturation, but not the crack onset strain, which will be addressed in future studies.