Thermomechanical Properties of Aluminum Alkoxide (Alucone) Films Created Using Molecular Layer Deposition

Abstract

Nanometer-scale-thick, polymer-like coatings deposited using the molecular layer deposition (MLD) technique constitute a new class of materials. The modulus and hardness of aluminum alkoxide ("alucone") films grown using either homobifunctional or heterobifunctional reactants were measured using nanoindentation. Because the coatings are brittle and possess a significant tensile film stress immediately after deposition, the influence of film stress on the indentation measurements was quantified using a numerical analysis protocol. The film stress and coefficient of thermal expansion for alucone were determined using the wafer curvature method. Film stress was found to stabilize within the first thermal cycle, demonstrating a repeatable hysteresis thereafter. Curvature/time measurements on coated microcantilever beams indicated that the most significant evolution in film stress for alucone occurred during the initial 2 weeks of storage in the ambient environment. The temporal behavior is attributed to the change in thickness and/or modulus of alucone, and is consistent with the film stress becoming more compressive over time. An encapsulating alumina film, coated using the atomic layer deposition technique, was found to suppress the evolution of stress within alucone. The studies here suggest that the alucones have a greater elastic modulus than traditional polymers, are at present quite brittle and are prone to environmental influence. The MLD technique however, possesses a rich wealth of options that enable the modulus, adhesion and chemical stability of the coatings to be tailored.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 2009
Accession Number
ADA552961

Entities

People

  • Byunghoon Yoon
  • David C. Miller
  • Dragos Seghete
  • Jacob A. Bertrand
  • Martin L. Dunn
  • Ross R. Foster
  • Shih-hui Jen
  • Steven M. George
  • Yung-cheng Lee

Organizations

  • University of Colorado Boulder

Tags

DTIC Thesaurus Topics

  • Anhydrides
  • Chemical Synthesis
  • Chemistry
  • Coefficients
  • Composite Materials
  • Curvature
  • Geometry
  • Hardness
  • Material Degradation Processes
  • Materials
  • Materials Laboratories
  • Materials Science
  • Measurement
  • Mechanical Properties
  • Mechanics
  • Modulus Of Elasticity
  • Numerical Analysis

Readers

  • Neurological Diseases/Conditions/Disorders
  • Polymer Science and Technology
  • Powder metallurgy of Titanium alloys.