Heterogeneous integration of semiconductors combines the functionality of different materials, enabling technologies such as III−V lasers and solar cells on silicon and GaN LEDs on sapphire. However, threading dislocations generated during the epitaxy of these dissimilar materials remain a key obstacle to the success of this approach due to reduced device efficiencies and reliability. Strategies to alleviate this and understand charge carrier recombination at threading dislocations now need an accurate description of the structure of threading dislocations in semiconductor heterostructures. We show that the composition around threading dislocations in technologically important InGaAs/GaAs/Ge/ Si heterostructures are indeed different from that of the matrix. Site-specific atom probe tomography enabled by electron channeling contrast imaging reveals this at individual dislocations. We present evidence for the simultaneous fast diffusion of germanium and indium up and down a dislocation, respectively, leading to unique compositional profiles. We also detect the formation of clusters of metastable composition at the interface between Ge and GaAs, driven by intermixing in these two nearly immiscible materials. Together, our results have important implications for the properties of dislocations and interfaces in semiconductors and provide new tools for their study.

III-V optoelectronics grown epitaxially on Si substrates have large networks of dislocations due to a lattice constant mismatch between the device layers and the substrate. Recombination-enhanced dislocation glide (REDG) allows these dislocations to move and increase in length during device operation, which degrades performance. In this paper, we study REDG dynamics of threading dislocations in situ in (In)AlGaAs double heterostructures grown on Si substrates using scanning electron microscopy cathodoluminescence. The driving force for REDG arises due to coefficient of thermal expansion differences between Si and the III-V layers leading to large residual strains in the films. Tracking of threading dislocations as moving dark spot defects reveals glide characteristics that vary based on the nature of the dislocation. Remarkably, the alloying of a few atom percent of indium using metamorphic structures arrests threading dislocation glide by more than two orders of magnitude. Finally, we present REDG-based filtering as a pathway to reducing the threading dislocation density in select areas, removing a large fraction of the mobile dislocations. Together, these techniques will enable the understanding of dislocation-dislocation and carrier-dislocation interactions that have so far remained elusive during device operation, leading to reliable III-V integrated optoelectronics on silicon.

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