© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 3915 www.advmat.de www.MaterialsViews.com wileyonlinelibrary.com RESEARCH NEWS Low-Dimensional Te-Based Nanostructures Qisheng Wang, Muhammad Safdar, Zhenxing Wang, and Jun He* 1. Introduction Low-dimensional nanomaterials, with at least one physical dimension constrained to the nanometer scale, have attracted huge attention during the last few decades. Owing to their sur- face effect, quantum size effect, and macroscopic quantum-tun- neling effect, low-dimensional nanomaterials exhibit superior properties to those of their bulk counterparts and have opened up new and sometimes unexpected fields of applications in nanoscale electronic and optoelectronic devices such as ZnO- nanowire-based nanogenerators, [1] reduced graphene oxide field-effect-transistor (FET)-based biosensors, [2] CdS/Cu 2 S- core–shell nanowire-based solar cells, [3] and ZnSe-nanobelt- based photodetectors. [4] High-quality single-crystalline low-dimensional Te-based nanomaterials show fascinating surface-state properties: photo- electricity, phase-change memory, and thermoelectricity, owing to intrinsic novel properties of their bulk counterparts [5] and the unique morphology of their low-dimensional nanostructures. For example, due to crystal defects or environmental doping in a bulk topological insulator, contribution of the surface carriers to the charge-transport measurement is always masked in bulk materials. However, one- and two-dimensional Te-based nano- structures, such as Ag 2 Te, [6] Bi 2 Te 3 , [7] and Sb 2 Te 3 , [8] with large surface-to-volume ratios, strengthen electron transmission on the surface; this results in the successful observation of sur- face electronic properties. The one-dimensional (1D) ZnTe, [9] CdTe, [10] and In 2 Te 3 [11] nanostructure also shows enhanced photoelectrical performance such as high quantum efficiency due to the surface effect and high crystallinity of the 1D nanostructure. In addition, 1D GeTe-, [12] Sb 2 Te 3 -, [13] and Ge 2 Sb 2 Te 5 -based [14] phase- change memory devices show low power dissipation due to the lower melting point of the nanowire than of the bulk materials. Furthermore, a 1D PbTe-based thermo- electric material, which has the advantages of both quantum confinement to enhance the power factor and phonon scattering at the nanostructure surface to lower thermal conductivity, shows a much higher ther- moelectric figure of merit (ZT). [15] Thanks to the successful development of various growth methods such as van der Waals epitaxial growth, [16] Au-catalyzed vapor–liquid–solid deposition, [6] and template-directed growth, [17] high-quality and single-crystalline low-dimensional Te-based nanomaterials have been obtained, which pave the way for the observation of novel physical prop- erties. This article reviews recent development in the synthesis, properties, and applications of low-dimensional Te-based nanostructures. 2. Synthesis of Single-Crystalline Te-Based Nanostructures Controllable synthesis of high-quality and -mass single-crystal- line low-dimensional nanomaterials is very important for the exhibition of novel physical performance of nanoscale electronic and photoelectronic devices. In recent years, systematic synthesis technologies have been developed and successfully used for the growth of low-dimensional Te-based nanostructures, such as vapor-phase deposition, [16] the solvothermal method, [18] and the electrochemical deposition method. [19] Specifically, some unique growth mechanisms have been applied to synthesize Te-based nanomaterials, for example, van der Waals epitaxial growth of few-layer Bi 2 Te 3 nanoplates, [16] and Au-catalyzed vapor–liquid– solid growth of single-crystalline β-Ag 2 Te nanowires. [20] 2.1. Vapor-Phase Deposition Methods In layered-structure Bi 2 Te 3 and Sb 2 Te 3 , the quintuple layers (QLs) weakly interact by means of van der Waals forces. There- fore, the vapor–solid (VS) method is particularly suitable for growth of two-dimensional (2D) Sb 2 Te 3 and Bi 2 Te 3 nanostruc- tures. Few-layer Sb 2 Te 3 nanoplates have been successfully syn- thesized on various substrates such as SiO 2 /Si, Si (111), and Low-dimensional Te-based nanomaterials have attracted intense attention in recent years due to their novel physical properties including surface-state effects, photoelectricity, phase changes, and thermoelectricity. The recent development of synthesis methods of low-dimensional Te-based nanostruc- tures is reviewed, such as van der Waals expitaxial growth and template- assisted solution-phase deposition. In addition, the unique properties of these materials, such as tunable surface states, high photoresponsivity, fast phase change, and high thermoelectricity figure of merit, are reviewed. The potential applications of low-dimensional Te-based nanostructures are broad but particularly promising for nanoscale electronic and photoelectronic devices. Q. Wang, M. Safdar, Dr. Z. Wang, Prof. J. He National Center for Nanoscience and Technology Beijing 100190, P. R. China E-mail: hej@nanoctr.cn DOI: 10.1002/adma.201301128 Adv. Mater. 2013, 25, 3915–3921