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

Abstract

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.

Recent Progress of Self‐Supported Metal Oxide Nano‐Porous Arrays in Energy Storage Applications

“…[40] The remarkably tunable properties of AAO templates have sparked increasing interest in integrating electrochemical anodization with template-assisted methods to form a diverse range of nanostructured materials. [36,45,46] Another extensively investigated structure is the TiO 2 nanotube array, which exhibits a highly ordered hole arrangement under specific preparation conditions. In 1991, Zwilling and colleagues synthesized highly ordered TiO 2 -NTs in a chromic acid electrolyte for the first time.…”

“…[ 40 ] The remarkably tunable properties of AAO templates have sparked increasing interest in integrating electrochemical anodization with template‐assisted methods to form a diverse range of nanostructured materials. [ 36,45,46 ]…”

“…Transitional metal oxide nanoarrays can be fabricated through various techniques, such as electrodeposition, [30,31] sol-gel synthesis, [32] hydrothermal methods, [33,34] template-assisted methods, [29,35,36] and so on. The hydrothermal method is widely applicable and has been employed in the synthesis of diverse transitional metal oxides such as TiO 2 , WO 3 , etc.…”

Fabrication of ordered Sb–Te and In–Ge–Te nanostructures by selective MOCVD

“…While this approach is effective in providing dense forests of nanowires with random position/orientation, in many applications, including the realization of PCMs industrial devices, the chalcogenide material would need to be grown at specific sites and with precise control over size and orientation. The bottom-up, MOCVD growth of ordered arrays of chalcogenide nanoplatelets [21], as well as of nanopillars with very high density [22], using Au nanoparticle catalysts has been demonstrated. However, an easier integration of such an MOCVD growth process in the typical industrial fabrication flow of, e.g.…”

Magnetic order in 3D topological insulators—Wishful thinking or gateway to emergent quantum effects?

“…In the context of thermoelectric applications and fundamental studies of the (Bi,Sb) 2 (Se,Te) 3 family of solid solutions, a number of single crystal, 27,28 nanostructure, [29][30][31][32][33][34] and thin film growth techniques have been employed; [35][36][37][38][39][40] however, for brevity and also given the versatility of the method, our review focuses solely on results obtained using molecular beam epitaxy (MBE) 41,42 (for reviews on TI thin film growth, see, e.g., Refs. [43][44][45].…”