The Young's modulus and fracture strength of silicon nanowires with diameters between 15 and 60 nm and lengths between 1.5 and 4.3 µm were measured. The nanowires, grown by the vapor-liquid-solid process, were subjected to tensile tests in situ inside a scanning electron microscope. The Young's modulus decreased while the fracture strength increased up to 12.2 GPa, as the nanowire diameter decreased. The fracture strength also increased with the decrease of the side surface area; the increase rate for the chemically synthesized silicon nanowires was found to be much higher than that for the microfabricated silicon thin films. Repeated loading and unloading during tensile tests demonstrated that the nanowires are linear elastic until fracture without appreciable plasticity.Silicon (Si) nanowires (NWs) are one of the key building blocks for nanoelectronic and nanoelectromechanical devices. 1 They exhibit excellent mechanical, 2,3 electrical, 4 and optical 5 properties, in addition to interesting multifunctional properties such as piezoresistivity 6 and thermoelectricity. [7][8][9] As such, Si NWs have been used in a broad range of applications including nanoelectronics, 10-12 nanosensors, 13 nanoresonators, 14 light-emitting diodes, 15 and thermoelectric energy scavengers. 7,8 The operation and reliability of these nanodevices depend on the mechanical properties of Si NWs, which are expected to be different from their bulk counterparts due to their increasing surface-to-volume ratio.Existing techniques for measuring the mechanics of individual NWs include observing the vibration (or resonance) of cantilevered NWs inside a transmission or scanning electron microscope (TEM/SEM), [16][17][18] measuring the lateral bending of suspended NWs with an atomic force microscope (AFM), 3,19-21 measuring uniaxial tension of suspended NWs in SEM or TEM, 2,22-26 and nanoindentation of NWs on a substate. 27 Available experimental results on Si NWs exhibit significant scatter including the following: (1) some reported a decrease in Young's modulus with decreasing size, 2,9,24,28 while others showed an opposite trend; 20,21 (2) the reported strength values of vapor-liquid-solid (VLS) grown Si NWs ranged from 500 MPa to 12 GPa; 3,28 (3) Han et al. 2 observed pronounced plastic deformation of Si NWs by in situ TEM tensile tests at room temperature, while Gordon et al. 21 reported linear elastic behavior followed by brittle fracture using AFM bending tests.Moreover the experimental data show large discrepancy with the simulation results. 29 For instance, the experimentally measured Young's moduli started deviating from the bulk value at diameters of about 200 nm; 28 conversely, computational studies using both density functional theory (DFT) and classical molecular dynamics (MD) indicated that the transition diameter for Young's modulus of Si NWs is less than 10 nm. [30][31][32] The experimentally observed plasticity at room temperature occurred for Si NWs with diameter less than 60 nm, while MD simulations 33 predicted a simi...

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 ...

We investigate the low-temperature magneto-transport properties of individual Ge/Si core/shell nanowires. Negative magneto-conductance was observed, which is a signature of one-dimensional weak antilocalization of holes in the presence of strong spin--orbit coupling. The temperature and back gate dependences of phase coherence length, spin--orbit relaxation time, and background conductance were studied. Specifically, we show that the spin--orbit coupling strength can be modulated by more than five folds with an external electric field. These results suggest the Ge/Si nanowire system possesses strong and tunable spin--orbit interactions and may serve as a candidate for spintronics applications.

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