High-Performance Transparent Conducting Oxide Nanowires

Abstract

We report the growth and characterization of single-crystalline Sn-doped In 2 O 3 (ITO) and Mo-doped In 2 O 3 (IMO) nanowires. Epitaxial growth of vertically aligned ITO nanowire arrays was achieved on ITO/yttria-stabilized zirconia (YSZ) substrates. Optical transmittance and electrical transport measurements show that these nanowires are high-performance transparent metallic conductors with transmittance of ∼85% in the visible range, resistivities as low as 6.29 × 10 -5 Ω·cm and failure-current densities as high as 3.1 × 10 7 A/cm 2 . Such nanowires will be suitable in a wide range of applications including organic light-emitting devices, solar cells, and field emitters. In addition, we demonstrate the growth of branched nanowire structures in which semiconducting In 2 O 3 nanowire arrays with variable densities were grown epitaxially on metallic ITO nanowire backbones.One-dimensional (1D) nanostructures such as nanowires, nanorods, and nanobelts have become the focus of intensive investigation in the past decade as potential building blocks for nanoscale devices and sensors. 1-5 Along with group IV and III-V materials, metal oxide (including In 2 O 3 , SnO 2 and ZnO) nanowires have been widely studied due to their excellent electrical and optical properties and ease of fabrication. [6][7][8] In these studies the metal oxide nanowires are typically not intentionally doped, and the carriers are normally generated by structural defects such as oxygen deficiencies. As a result, the devices behave as wide band gap semiconductors whose performance is influenced by the surrounding environment. 8 On the other hand, intentional doping can greatly modify the device properties and yield new device applications. One such example is tin-doped indium oxide (ITO), in which metal-like behavior is achieved when In 2 O 3 is degenerately doped by Sn. Due to its high conductivity and high transmittance in the visible spectral region, 9 ITO has become by far the most important transparent conducting oxide material, and ITO films have found applications in various optoelectronic devices such as flatpanel displays, solar cells, and light-emitting diodes. [10][11][12] The ability to obtain highly transparent and highly conducting ITO nanowires may potentially further enhance the performance of such devices due to the increased effective device area using nanowire electrodes. Furthermore, similar to NiSi and TaSi 2 nanowires, 13,14 the highly conducting ITO nanowires may also be used as interconnects in integrated nanocsale devices.The growth of ITO nanowires/nanorods has been reported by several groups since the first study on In 2 O 3 nanobelts in 2001. [15][16][17][18][19][20][21] However, detailed electrical characterizations have not been reported, and it is not clear whether these ITO nanowire/nanorods have the desired electrical properties. For example, the only reported resistivity value is ∼0.4 Ω‚cm, 18 which is several orders higher than that can be obtained in commercially available ITO films 9 and clearly too high ...

Bottom-up growth of fully transparent contact layers of indium tin oxide nanowires for light-emitting devices

“…We conducted electrical measurements on a series of nanowire-containing segments using corner contacts to areas of the nanowire layer in the van der Pauw geometry [18]. The conductivity of the pure (In 1.875 Sn 0.125 )O 3 branched nanowires is typically measured to be 1053.5 ± 42.3 S cm -1 at room temperature, which is similar to the values previously reported for other individual nanowires and two orders of magnitude greater than individual In 2 O 3 or SnO 2 nanowires [2]. We note that our conductivity values are similar to those reported previously [16] for Sn-doped (5-8 atom%) In 2 O 3 nanowires, whereas that of In 2 O 3 nanowires without intentional doping is of the order of 1 S cm -1 .…”

Indium tin oxide nanowires growth by dc sputtering

“…Although ITO used in practical applications is mainly in the thin film form, there is considerable interest in ITO nanostructures [4][5][6][7][8][9][10][11][12][13][14][15][16], since they can result in very low resistivity [4], as well as enable improved performance of solar cells due to improved charge collection [6]. Growth of ITO nanostructures using different methods has been reported [4][5][6][7][8][9][10][11][12][13][14][15][16], such as chemical vapor deposition [4,8,10,14,15], chemical synthesis [5], oblique-incidence electron-beam (ebeam) deposition [6,13], sol electrophoresis [7], sputtering [9,11], and thermal treatment [12].…”

Complex Nanostructures: Synthesis and Energetic Applications

“…In a slight variation, this strategy has also been applied to solution phase synthesis such as the solution-liquid-solid (SLS) growth [32]. Importantly, the branches of complex nanostructures created by this approach can be of different composition from that of the trunk, as has been demonstrated in examples of ZnO/In 2 O 3 [33], ZnO/SnO 2 [32], CdS/ZnS [34], In 2 O 3 /ITO [35] and carbon nanotube/SiC [36]. …”