Article pubs.acs.org/JPCC
Lithographically Patterned p‑Type SbxTey Nanoribbons with Controlled Morphologies and Dimensions Hyunsung Jung,†,‡ Jae-Hong Lim,§ Hosik Park,‡ Jiwon Kim,‡ Yong-Ho Choa,∥ and Nosang V. Myung*,‡ †
Advanced Materials Convergence Division, Korea Institute of Ceramic Engineering & Technology, Seoul 153-801, Korea Department of Chemical and Environmental Engineering, University of CaliforniaRiverside, California 92521, United States § Electrochemistry Department, Korea Institute of Materials Science, Changwon 641-831, Korea ∥ Department of Fine Chemical Engineering, Hanyang University, Ansan 426-791, Korea ‡
ABSTRACT: Millimeter-long one-dimensional SbxTey nanoribbons with controlled composition and dimensions (down to 16 nm) were demonstrated using lithographically patterned electrodeposition at predetermined locations. The morphology of nanoribbons was tuned by applying a pulse plating technique and addition of surfactant (i.e., CTAB) in the electrolyte. Independent of geometry, the deposit Te content decreased from 69 to 51 at. % Te with an increase in the applied potential. The electrical resistivity and field effect hole mobility were strongly dependent on the composition of the nanoribbon where the lowest electrical resistivity (7.9 × 10−4 ohm m) with highest hole mobility (24.6 cm2/V s) was observed from the Sb2Te3 nanoribbon. The temperature-dependent electrical resistance measurement shows low-temperature phase transition behaviors in the temperatures between 333 and 351 K.
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INTRODUCTION One-dimensional (1-D) nanostructures have exhibited potentials for applications to various electronic and optoelectronic devices, since the 1-D nanostructures can demonstrate the anisotropically improved electronic and optic properties enabling the nanostructures to utilize themselves as building blocks of devices.1−9 Copious approaches, such as physical/ chemical vapor deposition and wet chemical methods, have been employed to synthesize 1-D nanostructures.10−15 However, the manipulability of dimension, composition and alignment of the 1-D nanostructure is still a challenging subject in the fabrication of devices. A lithographical patterned nanowire electrodeposition (LPNE) technique, which combines electrodeposition and photolithography, allows to batch fabricate high density ultralong nanostructure based devices with predetermined locations without postassembly.16−22 Additionally, the dimensions of nanoribbons can be precisely controlled with high reproducibility. Our group demonstrated the ability to fabricate continuous nanoribbons with the width of 100 nm using various electrodeposition mehods.19−22 Metal chalcogenide nanostructures with narrow energy band gaps have been attractive in various fields such as photovoltaic, thermoelectric, and memory devices. Among chalcogenides, antimony telluride nanostructures are of particular interest for the fabrication of high-performance phase change memory, thermoelectric, and topological insulating devices.9,23−29 A reversible phase transition between a rhombohedral crystal phase with lower resistance and an amorphous phase with higher resistance can be conducted at low temperatures below 351 K. Nonvolatile antimony telluride phase change memory © 2013 American Chemical Society
devices can be operated by the phase transition due to the heat arising from applying laser or pulsed current.9,23−25 Antimony telluride bulks as a p-type thermoelectric material have demonstrated high thermoelectric figure-of-merits at room temperature.26,27 Additionally, antimony telluride showed bulk band structures with the insulating gap originating from a large spin−orbit coupling, which is a topological insulator as next spintronics devices.28,29 Compared to 3-D bulk structures and 2-D thin film structures, the prominent properties of 1-D antimony telluride nanostructures due to high volume-to-ratio, quantum confinement and anisotropic properties have been expected in various applications such as gas/biosensors and high-performance electric/optical nanodevices. Especially, doped antimony telluride nanoline showed the improved phase transition properties as a nonvolatile memory device with a lower threshold voltage (
