Morphological evolution during epitaxial lateral overgrowth of indium phosphide on silicon

Epitaxial lateral overgrowth of InP from mesh and line openings on masked InP seed layer on Si(0 0 1) wafer is investigated. Coalescence occurred more rapidly from the mesh openings than from the line openings. Lethargic coalescence in the line openings is attributed to the gradual formation of growth retarding boundary planes in the initial stages of growth. Extended growth leads to complete coalescence in both types of openings. The surface roughness of the coalesced layer is inversely proportional to its thickness. Cathodoluminescence studies on the uncoalesced islands show the emergence of facets with orientation-dependent dopant concentration, but reveal no defects, in contrast to the coalesced regions. The latter are relaxed and their dislocation density deduced from panchromatic cathodoluminescence mapping varies from 6×106 to 4×107 cm−2 depending on the layer thickness; the reduced density at higher thickness indicates partial self annihilation of dislocations. TEM cross-section studies show that most of the threading dislocations originating in the InP seed layer/Si interface are blocked by the mask, but new dislocations are generated. Some of these dislocations are associated with bounding planar defects such as stacking faults, possibly generated during lateral growth across the mask due to unevenness of the mask surface.

► Epitaxial lateral overgrowth of InP on Si from line and mesh openings studied.
► Surface roughness for mesh openings lower initially but alike later for both.
► Line openings have larger decrease in initial growth rate than mesh openings.
► Threading dislocations are filtered even above the openings of optimum size.
► Defects due to coalescence may be minimized with a smoother starting surface.