High‐Density Sb2Te3 Nanopillars Arrays by Templated, Bottom‐Up MOCVD Growth

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2019-09, Vol.15 (37), p.n/a
• Main Authors: Cecchini, Raimondo, Gajjela, Raja S. R., Martella, Christian, Wiemer, Claudia, Lamperti, Alessio, Nasi, Lucia, Lazzarini, Laura, Nobili, Luca G., Longo, Massimo
• Format: Article
• Language: English
• Subjects: AAO templates; Aluminum oxide; Arrays; Chalcogenides; Chemical etching; Density; Mechanical polishing; Memory devices; Metalorganic chemical vapor deposition; MOCVD; nanopillars; Nanotechnology; Nanowires; Organic chemicals; Organic chemistry; Performance enhancement; Phase transitions; Sb2Te3; Substrates; Thermoelectricity
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201901743

Sb2Te3 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 Sb2Te3 NPs can be grown by metal organic chemical vapor deposition (MOCVD) on patterned substrates. In particular, crystalline Sb2Te3 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 Sb2Te3 can be followed either by mechanical polishing and chemical etching to produce Sb2Te3 NPs arrays with planar surfaces or by chemical dissolution of the AAO templates to obtain freestanding Sb2Te3 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. Sb2Te3 nanostructures are grown by metal organic chemical vapor deposition (MOCVD) to form dense arrays: 20 nm single‐crystal Sb2Te3 nanopillars are grown by MOCVD inside high density (5 × 1010 cm−2) pores of aluminum oxide membranes. High‐density forests of freestanding Sb2Te3 nanopillars are also obtained. These methods can be used for different chalcogenide alloys and substrates.