Uniaxially oriented Te/SexTe1−x van der Waals heterojunction nanowire arrays grown by molecular beam epitaxy

Abstract

Elemental tellurium (Te), with chiral atom chains held together by van der Waals (vdW) force, has recently gained significant attention due to its intriguing physical properties. However, the controlled synthesis of its vdW heterostructures remains challenging. Here, we synthesize uniaxially oriented Te/SexTe1−x vdW heterojunction nanowire (vdWHN) arrays with tunable composition (x = 0–0.45) using molecular beam epitaxy. By employing a molecular engineering strategy, we first obtained well-aligned Te nanowire nuclei, which then served as the basis for the growth of Te/SexTe1−x vdWHNs. Compositional and structural characterizations confirm the epitaxial relationship between Te and SexTe1−x and reveal atomically sharp heterointerfaces without observable defects. Building on this, we demonstrate the synthesis of bi-periodic Te/SexTe1−x vdWHNs. Furthermore, periodic stripes are observed on the nanowires, which are attributed to the combined effect of moiré patterns and interfacial lattice mismatch between Te and SexTe1−x. Field-effect transistors based on four-period Te/SexTe1−x vdWHNs demonstrate an on/off current ratio of 5 × 104 at 160 K. This study expands the controlled synthesis of vdW heterostructures and provides a foundation for the application of Te-based one-dimensional layered materials.