Static analysis of off-axis crystal film growth onto a lattice-mismatched substrate

Abstract

The interface construction of tilt growth that is sometimes observed for epilayer growth on a lattice mismatched substrate is modeled on the basis that tilt relieves misfit strain in the epilayer. In this model off-axis misfit accommodation is assumed to be due to only tilt dislocations or tilt dislocations combined with misfit dislocations. The average interval between successive dislocations which are formed along the interface can be estimated using the lattice units of both materials and that of the epilayer in another principal axis direction; the tilt angle can also be calculated geometrically. The tilt angle predicted by this model agrees well with experimental results for several examples of mismatched epilayer growth by molecular-beam epitaxy. The model suggests a method to grow a single domain of stress-free epilayer by using a substrate cut to an angle that allows off-axis fit to the lattice unit of the epilayer. © 2001 American Institute of Physics.