Merging nanowires and formation dynamics of bottom-up grown InSb nanoflakes

Indium Antimonide (InSb) is a semiconductor material with unique properties, that are suitable for studying new quantum phenomena in hybrid semiconductor-superconductor devices. The realization of such devices with defect-free InSb thin films is challenging, since InSb has a large lattice mismatch with most common insulating substrates. Here, the controlled synthesis of free-standing 2D InSb nanostructures, termed as 'nanoflakes', on a highly mismatched substrate is presented. The nanoflakes originate from the merging of pairs of InSb nanowires grown in V-groove incisions, each from a slanted and opposing {111}B facet. The relative orientation of the two nanowires within a pair, governs the nanoflake morphologies, exhibiting three distinct ones related to different grain boundary arrangements: no boundary (type-I), Σ3- (type-II), and Σ9-boundary (type-III). Low-temperature transport measurements indicate that type-III nanoflakes are of a relatively lower quality compared to type-I and type-II, based on field-effect mobility. Moreover, type-III nanoflakes exhibit a conductance dip attributed to an energy barrier pertaining to the Σ9-boundary. Type-I and type-II nanoflakes exhibit promising transport properties, suitable for quantum devices. This platform hosting nanoflakes next to nanowires and nanowire networks can be used to selectively deposit the superconductor by inter-shadowing, yielding InSb-superconductor hybrid devices with minimal post-fabrication steps. (© 2023 The Authors. Advanced Functional Materials published by Wiley‐VCH GmbH)