An experimental investigation was made of misfit dislocation generation mechanisms at the hetero-interface. The InGaAs epitaxial layers were grown, by using low-pressure organometallic vapor-phase epitaxy, onto patterned and unpatterned GaAs substrates which had etch-pit densities of 200, 1400, or 10000/cm2. After epitaxial growth, the samples were annealed at temperatures of between 650 and 750C, and were analyzed by using optical and transmission electron microscopy. It was found that the substrate etch-pit density controlled the onset of misfit dislocation generation in the case of low-temperature (less than 600C) epitaxial deposition onto unpatterned substrates. When the epilayers were annealed at 750C, the misfit dislocation density was independent of the substrate etch-pit density. These results also showed that the predominant misfit dislocation generation mechanism for films which were grown onto patterned substrates was nucleation at the growth-mesa edge. The density of pre-existing threading dislocations had little effect upon misfit dislocation generation in films which were selectively deposited within 100 x 100 growth windows. In the case of selective hetero-epitaxy, misfit dislocation generation depended strongly upon the crystallographic orientation of the growth-mesa edge.

J.Kui, W.A.Jesser, S.H.Jones: Journal of Applied Physics, 1994, 76[12], 7829-32