Development of Phase-Field Models for Simulating the Vapor Deposition and Microstructure Evolution of Thin Films
Student: James Stewart
Degree: Ph.D., May 2016
Major Professor: Dr. Douglas Spearot
Research Area(s):
Conventional Materials & Processes
Modeling & Simulation
Background/Relevance
- Develop and employ mesoscale simulations to investigate microstructure evolution (e.g., phase distribution, GBs, grain orientation, etc.) in thin films during physical vapor deposition
- Construct virtual structure zone diagrams to predict thin film microstructures for improved advanced materials design
Innovation
- Development of descriptive models that incorporates simultaneous thin film growth and microstructure evolution
- Construction of virtual SZDs for polymorphic & polycrystalline materials
Approach
- Models are developed using the phase-field methodology: field variables describe physical quantities of system with evolution described by conserved or non-conserved differential equations
- PVD simulations are performed with various substrate temperatures, phase distributions, grain sizes, and vapor flux rates
Key Results
- PVD and grain evolution models have been coupled together — columnar & porous growth of a polycrystalline material below
- Developed novel free energy functional for PVD
Conclusions
- Current models capture arbitrary surface formation, shadowing effects, incident vapor fluxes, grain coarsening, GB migration, solid state phase transformations, phase nucleation, temperature evolution and latent heat release / consumption
Future Work
- Dimensionalize novel free energy functional to determine length and times scales for experimental comparison
- Extend novel free energy functional to include: anisotropic growth kinetics, multiple phases, and temperature evolution