DISLOCATION REPLICATION AND ANNIHILATION IN INP HOMOEPITAXIAL LAYERS GROWN BY LIQUID-PHASE EPITAXY

The mechanisms associated with the replication and annihilation of dislocations during the homoepitaxial growth of indium phosphide layers by liquid phase epitaxy have been investigated. Two distinct situations develop during the growth of homoepitaxial layers on dislocated substrates: the Burgers vector of a substrate dislocation is either inclined or parallel to the growth surface. The replication of dislocations which have their Burger's vector parallel to the growth surface has been studied by cross-sectional transmission electron microscopy. Results suggest that perfect dislocations are incorporated into epitaxial layers without an increased separation between Shockley partials in contrast to observations in silicon homoepitaxial layers. In addition, their orientation is observed to change so as to align themselves parallel to the growth direction. In contrast, dislocations whose Burgers' vectors are inclined to the surface propagate in the usual 60° configuration. The annihilation of dislocations has been studied using X-ray topography and cross-sectional transmission electron microscopy. Results indicate that the annihilation that is observed in the absence of stress can be accounted for by chance impingement of dislocations during growth. This is facilitated by the climb of closely spaced dislocations. The effects of stress due to non-stoichiometric growth and isoelectronic doping have also been studied and have been found to be detrimental to the overall perfection of epitaxial layers. © 1990.