Fast Diffusion and Segregation along Threading Dislocations in Semiconductor Heterostructures

Abstract

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 theepitaxy of these dissimilar materialsremain 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 needan accurate description of the structure of threading dislocationsin semiconductor heterostructures. We show that the composition around threading dislocations intechnologically important InGaAs/GaAs/Ge/Si heterostructures areindeed different from that of thematrix. Site-specific atom probe tomography enabled by electron channeling contrast imaging reveals this at individual dislocations.We present evidence for the simultaneousfast diffusion of germanium and indium up and down adislocation, 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 andprovide new tools for their study.