The effect of substrate growth area on misfit and threading dislocation densities in mismatched heterostructures

Abstract

We show that mismatched epitaxial growth on small growth areas results in metastable, low dislocation density films. By considering methods of dislocation nucleation in mismatched epitaxial films, we can explain the effect of growth area on the kinetics of misfit dislocation nucleation. We demonstrate this reduction of misfit dislocation density by growth on small areas using the InGaAs/GaAs system, and we also demonstrate a reduction in threading dislocation densities in the GeSi/Si system. InGaAs/GaAs interfaces which have a misfit dislocation density greater than 5000 dislocations/cm for large growth areas are grown nearly misfit-dislocation-free on small growth areas. GeSi/Si structures which have a threading dislocation density of approximately 1000 dislocations/cm2 are grown with a 100% threading dislocation density reduction for small growth areas. We discuss the limits of growth on small areas to reduce both interface dislocation densities as well as threading dislocation densities.