Critical thickness of epitaxial thin films using Finite Element Method

In the paper, finite element methodology applied to critical thickness calculation has been presented. Semiconductor heterostructures have been applied to many electronic and optoelectronic devices. The performance and properties of epitaxial semiconductor thin film depend on the defects structure and stress-state of the film. During epitaxial growth first few layers are coherent with a substrate crystalline structure. As film thickness increases, growing stress causes nucleation of dislocations. This partially relaxes the strain due to lattice mismatch. A thickness at which this occurs is defined as a critical thickness. Calculation of critical thickness for the nucleation has been a subject of considerable study since the pioneering work of Frank and Van der Merve. Finite Element Method (FEM) is used to simulate the strained epitaxial layer and the substrate. Finally, approach to calculate the critical thickness on the basis of energy balance approach is presented.