Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session X65: 1D Materials: Nanowires, Nanotubes, and Nanoribbons |
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Sponsoring Units: DCMP Chair: Paula Fekete, US Military Academy Room: Mile High Ballroom 4F |
Friday, March 6, 2020 11:15AM - 11:27AM |
X65.00001: Designing nano-biocomposite materials using CVD grown CNTs and ZnO nanostructures for hybrid interfaces and hydrogel environments with future biomedical applications Nicholas Schaper, Brannan Hutchinson, Silviya Zustiak, Irma Kuljanishvili One dimensional (1D) nanostructures, carbon nanotubes (CNTs) and other nanowires, have been proven useful for many biomedical applications. Their high aspect ratio allows for functionalization with specific biological molecules or other nanoscale moieties through covalent bonding, physisorption or chemisorption. Controlled production of CNTs and zinc oxide nanowires (ZnO NWs) has been shown to provide avenues for tailoring interfaces at the nanoscale. These materials are excellent candidates for biomedical use due to unique physical/electrical properties and biocompatibility. When incorporated into nonconductive environments, CNTs/ZnO NW will efficiently transmit electrical signals to biological cells and improve the mechanical strength of composite materials. |
Friday, March 6, 2020 11:27AM - 11:39AM |
X65.00002: Unfolding the temperature induced dual bandgap in TiO2 nanotubes with improved photocatalytic application Sangita Bhowmick, Chetan prakash Saini, Saif Khan, Mukul Gupta, Rahul Singhal, Raja Sen, Aloke Kanjilal Since the discovery of photocatalytic water splitting, TiO2 has gained enormous interest in improving efficiency by generating stable electron-hole (e-h) pairs upon proper light illumination [1]. In particular, anodic TiO2 nanotubes have attracted wide interest not only for their high surface-to-volume ratio with scalable structures [2]. However, the overall efficiency is limited by the recombination of the photo-generated (e-h) pairs in the bulk and electrode/electrolyte interfaces. To overcome this tuning the crystallinity and the bandgap of them are required. Among various approaches, thermal annealing dependent control over the anatase/rutile phase ratio of TiO2 and their inter-granular charge transfer process exhibit a relatively high photocatalytic performance. Here, we report the efficacy of dual-phase mediated bandgap modulation and the subsequent improvement of photocatalytic activity of TiO2 nanotubes as a function of temperature by various complementary techniques like UV-Vis, XRD, XPS, XAS, Raman, etc. and supported by DFT calculations. |
Friday, March 6, 2020 11:39AM - 11:51AM |
X65.00003: Modulation Doping of Template-Defined InGaAs Nanowires Kristopher Cerveny, Martin Friedl, Mohammad Samani, Didem Dede, Chunyi Huang, Lincoln J Lauhon, Anna Fontcuberta i Morral, Dominik Zumbuhl Templated semiconductor nanowires with strong Rashba spin-orbit interaction are a great platform to create and study novel quantum states of matter, such as helical states and spin helices, Majorana- and para-fermions. Here, we report recent results on templated InGaAs nanowire Y-junctions grown on GaAs nanomembranes[1] with modulation doping. Modulation doping has been successfully used in many high-performance systems to create structures with enhanced mobility and higher carrier concentrations. We investigate modulation doping in GaAs nanomembranes grown via molecular beam epitaxy in a selective area growth approach. In a novel process, the dopants migrate up through the GaAs membrane during growth. This remote doping process has enabled major improvements in notable system parameters such as mean free path, coherence length, and spin-orbit length. With a top gate, we can tune between weak localization and antilocalization. The improvements suggest ballistic transport may be within reach. Further, experiments with superconducting contacts for proximitizing and Majorana zero modes can be envisioned. |
Friday, March 6, 2020 11:51AM - 12:03PM |
X65.00004: Reflection of light from gold coated InP NW arrays ChiaWei Tu, Qian Gao, Hoe Tan, Chennupati Jagadish, Masoud Kaveh, Heidrun Schmitzer, Martin Fraenzl, Hans-Peter Wagner To optimize light coupling into a plasmonic nanowire (NW) array as a function of incident angle and excitation wavelength, we investigated the reflection of light from two different bare and gold coated InP NW arrays. The NWs in the arrays have a diameter of 180 nm, heights of 2 and 1 micrometers and pitches of 666 and 500 nm. A nominally 10 nm thick gold film was deposited around the NWs to investigate the influence of plasmonic effects. The arrays were irradiated with s- and p- polarized light. The spectral reflectance was measured with an incandescent light source ranging from 500 to 1000 nm and the angle resolved reflectance was investigated with a cw laser at 880 nm. The p-polarized angle resolved reflectance of gold deposited NW arrays significantly differs from the reflectance of uncoated InP NW arrays. The differences are attributed to surface plasmon polariton effects. The measured spectrally and angle resolved reflectance was compared with finite-difference-time-domain (FDTD) simulations. The simulations show very good agreement when an air-gold effective medium according to the granularity of the deposited gold films was used. |
Friday, March 6, 2020 12:03PM - 12:15PM |
X65.00005: Enhanced Dresselhaus spin-orbit interaction in low-symmetry nanowires Miguel Carballido, Christoph Kloeffel, Dominik Zumbuhl, Daniel Loss Semiconducting nanowires (NWs) are promising building blocks for solid-state quantum computers, since they allow for conventional spin and charge qubits as well as for topological quantum computing schemes. Such systems often rely on spin-orbit interaction (SOI), which is a crucial mechanism in modern fields of condensed matter physics. |
Friday, March 6, 2020 12:15PM - 12:27PM |
X65.00006: Investigating the magneto-optics in quantum wires for designing the optical amplifiers Manvir Kushwaha Quantum wires occupy a unique status among the semiconducting nanostructures with reduced dimensionality |
Friday, March 6, 2020 12:27PM - 12:39PM |
X65.00007: Mid-infrared photoconductivity of tellurium nanowire devices Pengke Li, Ian Appelbaum Elemental tellurium is a narrow bandgap (0.34 eV) semiconductor, whose trigonal lattice is composed of weakly-bound, three-fold helical atomic chains. This unusual lattice allows the formation of nanowires with highly anisotropic electronic and optical properties. Here, we present photocurrent spectroscopy of single tellurium nanowire devices in the mid-infrared range close to the band gap, demonstrating interesting anisotropic features closely related to the linear polarization of the incident light and the resonant modes of the nanowires. It is found that the photosensitivity is strongly dependent on the temperature and the back-gate bias. |
Friday, March 6, 2020 12:39PM - 12:51PM |
X65.00008: Quantum confinement and edge effects in zigzag green phosphorene nanoribbons Chi Ma, Tianxing Ma, Xihong Peng Ab initio calculations were carried out to study size and edge effects on the electronic properties of zigzag green phosphorene nanoribbons (ZGPNRs) with edge chemical functionalization including H, OH, F, Cl, O, and S for the ribbon width up to 3.7 nm. The electronic properties of the ZGPNRs are strongly dependent on the ribbon width and edge chemical species. The ribbons are either semiconducting or metallic depending on the edge functionalization species. The ZGPNRs demonstrate semiconducting behavior with the edge passivation of H, OH, F, or Cl (Group I), while show metallic feather with pristine or O, S edges (Group II). The conduction band minimum (CBM) and valence band maximum (VBM) of the ZGPNRs with the Group I edges are mainly contributed by the inner P atoms and the edge P and functionalization atoms have little contribution. However, for the Group II edges, the electronic bands crossing the Fermi level are dominantly located at the edge atoms. It was also found that the band gap and work function of the ZGPNRs are tunable by varying ribbon width and edge functionalization species. |
Friday, March 6, 2020 12:51PM - 1:03PM |
X65.00009: Lifetime analysis of quasistationary states of an electron in open quantum wires Ruei-Fu Jao, Hua-Yi Hsu, Ming-Chieh Lin The quasistationary states of an electron in a cylindrically N-layered open quantum wire are investigated. A complex eigen-solver is developed to determine both the resonant states ER and the corresponding lifetimes τ of the system. Here, we solve the eigenvalue equations for the quasibound states of an electron in open quantum wires using the adaptive finite element method (FEM). We have carefully examined the convergence of this approach for the desired accuracy and efficiency. All the quasistationary states of the system can be determined via this eigen-solver. For illustration, the numerical calculations are carried out for the GaAs/AlxGa1-xAs/GaAs multi-layered open quantum wire. Both the energy levels and the lifetimes of the quasistationary states are found as functions of the geometric parameters of the system. The lifetime of an electron in such a system is very sensitive to the geometric characteristics. Figure 1 shows our preliminary results are in good agreement with a previous work done by M. Tkach et al. which analyzed the cases of the quasiparticle lifetimes using the S-matrix theory. |
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