Generating and Imaging Dislocations in Topologically-Insulating Bi_1-xSb_x Alloys

Dislocations in electronic materials are typically undesirable due to their tendency to trap or scatter carriers, impeding current flow. In topological insulators, however, certain dislocations are instead predicted to host 1D topological states and act as spin state-preserving paths of conduction. Edge dislocations in the slip system {011}<100> of Bi_1-xSb_x (0.07 < x < 0.22) are predicted to have these properties, while those in the primary slip system {011}<1-10> are not. In this work, we explore the generation of dislocations in Bi_1-xSb_x via uniaxial strain, as well as imaging dislocations via electron channeling contrast imaging (ECCI) in a scanning electron microscope. Following alignment via Laue diffraction for precision cutting and cleavage to expose (111) surfaces, we apply >2% uniaxial strain along [-211] to bulk Bi_1-xSb_x (x = 0.12) single crystals. Following the application of strain, we collect ECCI in various {1-10} and {-211} alignments and attempt to identify the Burgers vectors of imaged dislocations via g·b invisibility criterion analysis. In-situ uniaxial strain during ECCI and nanoindentation of Bi_1-xSb_x (111) surfaces will also be discussed.