In-Plane Nanowire Growth of Topological Crystalline Insulator Pb₁₋ₓSnₓTe

Predicted topological crystalline insulators such as Pb₁₋ₓSnₓTe are an interesting candidate for applications in quantum technology, as they can host spin-polarized surface states. Moreover, in the nanowire geometry, a quasi-1D system can be realized with potential applications exploiting Majorana fermions. Herein, the selective area growth of Pb₁₋ₓSnₓTe islands and nanowires over the full range of x is demonstrated, and their in-depth growth dynamics and faceting are analyzed. By transmission electron microscopy, the single-crystalline and defect-free nature of the grown material and the homogeneous, controllable Pb/Sn ratio in the nanowires is confirmed. With support of phase-field growth simulations, it is shown that the crystal faceting mainly follows the driving force of surface energy minimization, favoring the lowest energy {200} surfaces. A kinetic enhancement of adatom incorporation on {110} facets is recognized to limit their extension with respect to {200} and {111} facets. After inspecting all possible in-plane orientations, we identify the <110> directions as the optimal candidate for the growth of high-quality and perfectly straight Pb₁₋ₓSnₓTe nanowires, enabling the design of complex networks due to their threefold symmetry. This work opens the way to systematic transport investigation of the carrier density in Pb₁₋ₓSnₓTe nanowires and can facilitate further optimization of the Pb₁₋ₓSnₓTe system.