Defect reduction in heteroepitaxial InP on Si by epitaxial lateral overgrowth

Epitaxial lateral overgrowth of InP has been grown by hydride vapor phase epitaxy on Si substrates with a thin seed layer of InP masked with SiO2. Openings in the form of multiple parallel lines as well as mesh patterns from which growth occurred were etched in the SiO2 mask and the effect of different growth conditions in terms of V/III ratio and growth temperature on defects such as threading dislocations and stacking faults in the grown layers was investigated. The samples were characterized by cathodoluminescence and by transmission electron microscopy. The results show that the cause for threading dislocations present in the overgrown layers is the formation of new dislocations, attributed to coalescence of merging growth fronts, possibly accompanied by the propagation of pre-existing dislocations through the mask openings. Stacking faults were also pre-existing in the seed layer and propagated to some extent, but the most important reason for stacking faults in the overgrown layers was concluded to be formation of new faults early during growth. The formation mechanism could not be unambiguously determined, but of several mechanisms considered, incorrect deposition due to distorted bonds along overgrowth island edges was found to be in best agreement with observations.