Misfit stress in InGaAs/InP heteroepitaxial structures grown by vapor phase epitaxy.

The stress calculated from the measured radius of curvature was in all cases found to be smaller than the value predicted from the lattice mismatch using the simple beam theory and assuming a coherent interface. A simple argument is used to show that the parallel mismatch is directly related to the density of misfit dislocations. By taking into account both the presence of misfit dislocations and tetragonal distortion, relationships between the curvature, density of interfacial misfit dislocations, relaxed lattice mismatch, and measured tetragonally distorted vertical and parallel mismatches are derived. Predicted values for the radius of curvature agree very well with measured values. The results also indicate that in the presence of interfacial misfit dislocations the nature of the stress in the epitaxial layer is not uniquely determined by the mismatch. The stress can change sign depending upon the density of the misfit dislocations.