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Heteroepitaxial growth of strained thin film in sub-micron patterned substrates: an elastoplastic phase field model

An elastoplastic phase field model has been developed to study the effect of lateral confinements on growth of heteroepitaxial thin films. The governing equations used in this modeling can be categorized in two groups. First, the evolution equation, which is a fourth order partial differential equation known as Cahn-Hilliard equation. Second, the elastoplastic governing equation, which consists of equilibrium, constitutive and compatibility equations, in addition to the flow rule, hardening rule and yield function. The parameters used in this model correspond to InGaAs for the thin film, GaAs for the substrate and SiO2 for the confining walls. Effects of lattice mismatch between film and the substrate, non-uniform deposition flux and plastic deformation in the film have been investigated on the morphology of thin film. Our results showed that morphology of the InGaAs thin film varies non-monotonically with the indium concentration of the alloy. Low indium concentration (0%-40%) causes formation and growth of two islands near the wall. By increasing indium concentration to (40%-75%) surface diffusion dominates the kinetic effects of overflow flux that leads to formation of a single island away from the walls. By further increase in indium concentration up to 100%, plastic deformation relaxes most of the strain energy density of the film that leads to asymmetric formation of islands near the walls.

Author(s):

Mehrdad Arjmand    
University of Wisconsin-Madison
United States

Jie Deng    
University of Wisconsin-Madison
United States

Narasimhan Swaminathan    
University of Wisconsin-Madison
United States

Dane Morgan    
University of Wisconsin-Madison
United States

Izabela Szlufarska    
University of Wisconsin-Madison
United States