High-Density Sb₂ Te₃ Nanopillars Arrays by Templated, Bottom-Up MOCVD Growth

Sb₂ Te₃ exhibits several technologically relevant properties, such as high thermoelectric efficiency, topological insulator character, and phase change memory behavior. Improved performances are observed and novel effects are predicted for this and other chalcogenide alloys when synthetized in the form of high-aspect-ratio nanostructures. The ability to grow chalcogenide nanowires and nanopillars (NPs) with high crystal quality in a controlled fashion, in terms of their size and position, can boost the realization of novel thermoelectric, spintronic, and memory devices. Here, it is shown that highly dense arrays of ultrascaled Sb₂ Te₃ NPs can be grown by metal organic chemical vapor deposition (MOCVD) on patterned substrates. In particular, crystalline Sb₂ Te₃ NPs with a diameter of 20 nm and a height of 200 nm are obtained in Au-functionalized, anodized aluminum oxide (AAO) templates with a pore density of ≈5 × 10¹⁰ cm^-2 . Also, MOCVD growth of Sb₂ Te₃ can be followed either by mechanical polishing and chemical etching to produce Sb₂ Te₃ NPs arrays with planar surfaces or by chemical dissolution of the AAO templates to obtain freestanding Sb₂ Te₃ NPs forests. The illustrated growth method can be further scaled to smaller pore sizes and employed for other MOCVD-grown chalcogenide alloys and patterned substrates.