Catalyst-free MBE growth of PbSnTe nanowires with tunable aspect ratio

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