  Topological crystalline insulators (TCIs) are interesting for their
topological surface states, which hold great promise for scattering-free
transport channels and fault-tolerant quantum computing. A promising TCI is
SnTe. However, Sn-vacancies form in SnTe, causing a high hole density,
hindering topological transport from the surface being measured. This issue
could be relieved by using nanowires with a high surface-to-volume ratio.
Furthermore, SnTe can be alloyed with Pb reducing the Sn-vacancies while
maintaining its topological phase. Here we present the catalyst-free growth of
monocrystalline PbSnTe in molecular beam epitaxy (MBE). By the addition of a
pre-deposition stage before the growth, we have control over the nucleation
phase and thereby increase the nanowire yield. This facilitates tuning the
nanowire aspect ratio by a factor of four by varying the growth parameters.
These results allow us to grow specific morphologies for future transport
experiments to probe the topological surface states in a Pb1-xSnxTe-based
platform.
