Interfacial roughening in lattice-matched GaInP/GaAs heterostructures

The microstructure of solid source molecular beam epitaxy (MBE) lattice-mat ched GaInP-GaAs heterostructures has been studied by transmission electron microscopy (TEM). It is shown that atomic-scale roughening occurs in the fi rst several (similar to five) interfaces, and beyond which roughening is de veloped into micrometer-scale. The {131} faceted roughening occurs in the G aInP-on-GaAs interfaces, leading to the formation of V-shaped grooves. Disl ocation dipoles are observed in the top, facet surface and bottom regions o f the grooves, and there is no obvious difference. For GaInP layers exhibit ing atomic-scale roughening, a small number of dislocations, mostly 60 degr ees -type and in a dipole configuration, are confined in a zone of approxim ately 5.0 nm in width along the interface, and dislocations are rare deep i nside the layers. For GaInP layers, in contrast, there is a high density of dislocations in both the regions, and it has remarkable interfacial roughe ning. Based on their distribution and configurations, the dislocations are believed to result from the compositional modulation occurred in the GaInP layers. The interplay of roughening, dislocations and compositional modulat ion has been discussed in the light of the morphological features. (C) 2001 Elsevier Science B.V. All rights reserved.