Bulletin of the American Physical Society
APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016; Baltimore, Maryland
Session L8: Electron Transport in NanowiresFocus
|
Hide Abstracts |
Sponsoring Units: DMP Chair: Jonathan Baugh, University of Waterloo Room: 304 |
Wednesday, March 16, 2016 11:15AM - 11:27AM |
L8.00001: 1D Coulomb drag between coupled nanowires formed at oxide interfaces Yuhe Tang, Michelle Tomczyk, Mengchen Huang, Hyungwoo Lee, Chang-Beom Eom, Patrick Irvin, Jeremy Levy ``Coulomb drag'' is a transport phenomenon where Coulomb interaction between two close but electrically isolated conductors induces voltage in one conductor when an electric current is injected in the other conductor. It is a powerful approach to probe electronic correlations. Here we examine 1D electronic correlations in a proximally coupled nanowire system where two parallel nanowires are created with conductive atomic force microscopy at the LaAlO$_3$/SrTiO$_3$ interface. Coulomb drag measurements are made by injecting current into one wire (drive wire) and measuring the induced voltage in the other wire (drag wire). This geometry offers experimental insights into the interplay of electron pairing and superconductivity in reduced dimensions. [Preview Abstract] |
Wednesday, March 16, 2016 11:27AM - 11:39AM |
L8.00002: 1D-1D Coulomb drag in a ~6 Million Mobility Bi-layer Heterostructure Simon Bilodeau, Dominique Laroche, Jian-Sheng Xia, Mike Lilly, John Reno, Loren Pfeiffer, Ken West, Guillaume Gervais We report Coulomb drag measurements in vertically-coupled quantum wires. The wires are fabricated in GaAs/AlGaAs bilayer heterostructures grown from two different MBE chambers: one at Sandia National Laboratories (1.2M mobility), and the other at Princeton University (6M mobility). The previously observed positive and negative drag signals are seen in both types of devices, demonstrating the robustness of the result. However, attempts to determine the temperature dependence of the drag signal in the 1D regime proved challenging in the higher mobility heterostructure (Princeton), in part because of difficulties in aligning the wires within the same transverse subband configuration. Nevertheless, this work, performed at the Microkelvin laboratory of the University of Florida, is an important proof-of-concept for future investigations of the temperature dependence of the 1D-1D drag signal down to a few mK. Such an experiment could confirm the Luttinger charge density wave interlocking predicted to occur in the wires. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL8500. [Preview Abstract] |
Wednesday, March 16, 2016 11:39AM - 11:51AM |
L8.00003: Electronic structure and transport properties of III-V core/shell nanowires Florinda Vi\~nas, Martin Leijnse We have modeled electron structure and low-temperature transport in III-V core/shell nanowires to establish a relationship between electron-hole hybridization and signatures in thermoelectrical measurements. Nanowires with a GaSb core and an InAs shell (and inverted) are interesting for studies of hybridization effects due to the bulk broken band gap alignment at the material interface. By varying the core radius and shell thickness of such wires we can modify the size of the band gap and create wires with band structures that exhibit hole-electron hybridization states. \\ The band structures are obtained using 8-band $k\cdot p$ theory together with the envelope function approximation. The calculated energy dispersions are used as input to the Boltzmann equation to study thermoelectric transport quantities such as the Seebeck coefficient, in the diffusive limit. [Preview Abstract] |
Wednesday, March 16, 2016 11:51AM - 12:03PM |
L8.00004: Visualizing One-Dimensional Electronic States and their Scattering in Semi-conducting Nanowires Haim Beidenkopf, Jonathan Reiner, Andrew Norris, Abhay Kumar Nayak, Nurit Avraham, Hadas Shtrikman One-dimensional electronic systems constitute a fascinating playground for the emergence of exotic electronic effects and phases, within and beyond the Tomonaga-Luttinger liquid paradigm. More recently topological superconductivity and Majorana modes were added to that long list of phenomena. We report scanning tunneling microscopy and spectroscopy measurements conducted on pristine, epitaxialy grown InAs nanowires. We resolve the 1D electronic band structure manifested both via Van-Hove singularities in the local density-of-states, as well as by the quasi-particle interference patterns, induced by scattering from surface impurities. By studying the scattering of the one-dimensional electronic states off various scatterers, including crystallographic defects and the nanowire end, we identify new one-dimensional relaxation regimes and yet unexplored effects of interactions.~Some of these may bear implications on the topological superconducting state and Majorana modes therein. [Preview Abstract] |
Wednesday, March 16, 2016 12:03PM - 12:15PM |
L8.00005: Electrical characterization of surface passivation in III-V nanowires Gregory Holloway, Ray LaPierre, Jonathan Baugh III-V nanowires are promising for implementing many useful technologies including optical sensing and quantum information processing. However, most native nanowires have a significant density of surface states, which cause electron accumulation at the surface and make the optoelectronic characteristics very sensitive to surface conditions and variable from device to device. To achieve optimum device performance it is imperative to decrease the density of these defects, since they are responsible for charge noise (e.g. random telegraph noise) and decreased carrier mobility. Here we report on experimental results from low temperature transport studies of a series of InAs nanowire field effect transistors, each fabricated with a different surface passivation technique. The different surface treatments include combinations of chemical passivation, growth of a thermal oxide, and deposition of a high-\textit{k} dielectric to determine the optimum process for passivating the surface states. To better quantify the density of surface states, we also study the axial field magnetoconductance of short-channel nanowire transistors, and show how the results can be used to estimate the degree of surface band-bending. [Preview Abstract] |
Wednesday, March 16, 2016 12:15PM - 12:27PM |
L8.00006: Electron transport in doped GaAs nanowires contacted by evaporated metal films Zhuting Sun, Andrei Kogan, Timothy Burgess, Chennupati Jagadish We present electron transport measurements in doped GaAs nanowire samples contacted by metal interfaces as function of temperature. We show that the contact resistance is strongly dependent on T ($5K |
Wednesday, March 16, 2016 12:27PM - 12:39PM |
L8.00007: Electrostatically-tuned dimensional crossover in nanowires Michelle Tomczyk, Guanglei Cheng, Mengchen Huang, Hyungwoo Lee, Chang-Beom Eom, Patrick Irvin, Jeremy Levy The electron system at the interface of two complex oxides, LaAlO$_3$ and SrTiO$_3$, exhibits a number of interesting strongly-correlated electronic properties, such as superconductivity and spin-orbit coupling. Reduced dimensionality is made accessible through nanowire devices created with conducting AFM lithography. Here, we describe an electrostatically-controlled dimensionality crossover in weak antilocalization behavior of LaAlO$_3$/SrTiO$_3$ nanowires at low temperature. These measurements give insight to the interplay of spin-orbit coupling and dimensionality. Characterizing the behavior of the strongly-correlated electronic properties in these reduced dimensions is necessary in order to develop this system as a multifunctional nanoelectronics platform. [Preview Abstract] |
Wednesday, March 16, 2016 12:39PM - 12:51PM |
L8.00008: Transport studies of quantum dots sensitized single Mn-ZnO nanowire field effect transistors Keshab R Sapkota, Francis Scott Maloney, Gaurab Rimal, Uma Poudyal, Jinke Tang, Wenyong Wang We present opto-electrical transport properties of Mn-CdSe quantum dots (QDs) sensitized single Mn-ZnO nanowire (NW) field effect transistors (FET). The ZnO NWs with 2 atomic {\%} of Mn doping are grown by chemical vapor deposition. The NWs are ferromagnetic at low temperature. The as grown nanowires are transferred to clean SiO2/Si substrate and single nanowire field effect transistors (FET) are fabricated by standard e-beam lithography. Mobility and carrier concentration of Mn-ZnO NWs are estimated from FET device measurement which shows NWs are n-type semiconductors. Pulse laser deposition of Mn-CdSe QDs on the single NW FET significantly increases carrier concentration of the QD-NW system in dark where the QD monolayer conduction is negligibly small. The photoconductivity study of QD sensitized NW FET enlightens the conduction spectrum of QD-NW system and QD to NW carrier transfer mechanism. [Preview Abstract] |
Wednesday, March 16, 2016 12:51PM - 1:03PM |
L8.00009: Thermally Active Screw Dislocations in Si, SiC, PbSe, and SiGe Nanowires. Jihong Al-Ghalith, Yuxiang Ni, Shiyun Xiong, Sebastian Volz, Traian Dumitrica We elucidate thermal conductivity along the screw dislocation line, which represents a transport direction inaccessible to classical theories. By using equilibrium and non-equilibrium molecular dynamics simulations, and the atomistic Green function method, we uncover a Burgers vector dependent thermal conductivity reduction in Si, SiC, PbSe, and SiGe nanowires. The effect is uncorrelated with the classical theory of Klemens. The influence of dislocations on thermal transport originates in the highly deformed core region, which represents a significant source of anharmonic phonon-phonon scattering. High strain reduces the phonon relaxation time, especially in the longitudinal acoustic branches, and creates an effective internal thermal resistance around the dislocation axis. The effect can be distinguished from the thermal transport reduction caused by the nanowire surface imperfections and vacancies. Our results have implications for designing materials useful for high-temperature electronics and thermoelectric applications. [Preview Abstract] |
Wednesday, March 16, 2016 1:03PM - 1:15PM |
L8.00010: A New One-dimensional Quantum Material - Ta$_{2}$Pd$_{3}$Se$_{8}$ Atomic Chain Xue Liu, Jinyu Liu, Jin Hu, Chunlei Yue, Zhiqiang Mao, Jiang Wei, Liubov Antipina, Pavel Sorokin, Ana Sanchez Since the discovery of carbon nanotube, there has been a persistent effort to search for other one dimensional (1D) quantum systems. However, only a few examples have been found. We report a new 1D example - semiconducting Ta$_{2}$Pd$_{3}$Se$_{8}$. We demonstrate that the Ta$_{2}$Pd$_{3}$Se$_{8}$ nanowire as thin as 1.3nm can be easily obtained by applying simple mechanical exfoliation from its bulk counterpart. High resolution TEM shows an intrinsic 1D chain-like crystalline morphology on these nano wires, indicating weak bonding between these atomic chains. Theoretical calculation shows a direct bandgap structure, which evolves from 0.53eV in the bulk to 1.04eV in single atomic chain. The field effect transistor based on Ta$_{2}$Pd$_{3}$Se$_{8}$ nanowire achieved a promising performance with 10$^{4\, }$On/Off ratio and 80 cm$^{2}$V$^{-1}$s$^{-1}$ mobility. Low temperature transport study reflects two different mechanisms, variable range hopping and thermal activation, which dominate the transport properties at different temperature regimes. Ta$_{2}$Pd$_{3}$Se$_{8}$ nanowire provides an intrinsic 1D material system for the study low dimensional condensed matter physics. [Preview Abstract] |
Wednesday, March 16, 2016 1:15PM - 1:27PM |
L8.00011: Gate field induced switching of electronic current in Si-Ge Core-Shell nanowire quantum dots: A first principles study Kamal B Dhungana, Meghnath Jaishi, Ranjit Pati Core-shell nanowires are formed by varying the radial composition of the nanowires. One of the most widely studied core-shell nanowire groups in recent years is the Si-Ge and Ge-Si core-shell nanowires. Compared to their pristine counterparts, they are reported to have superior electronic properties. For example, the scaled ON state current value in a Ge-Si core-shell nanowire field effect transistor (FET) is reported to be three to four times higher than that observed in state-of-the-art-metal oxide semiconductor FET (MOSFET) ({\it Nature, 441, 489 (2006)}). Here, we study the transport properties of the pristine Si and Si-Ge core-shell nanowire quantum dots of similar dimension to understand the superior performance of Si-Ge core-shell nanowire field effect transistor. Our calculations yield excellent gate field induced switching behavior in current for both pristine Si and Si-Ge core-shell hetero-structure nanowire quantum dots. The threshold gate bias for ON/OFF switching in the Si-Ge core-shell nanowire is found to be much smaller than that found in the pristine Si nanowire. A single particle many-body Green's function approach in conjunction with density functional theory is employed to calculate the electronic current. [Preview Abstract] |
Wednesday, March 16, 2016 1:27PM - 1:39PM |
L8.00012: Exploring Dynamics and Band Structure in Mid Infrared GaAsSb and GaAsSb/InP Nanowire Heterostructures Leigh Smith, Yuda Wang, Nadeeka Wickramasuriya, Samuel Linser, Howard Jackson, Xiaoming Yuan, Philippe Caroff, Hoe Tan, Chennupati Jagadish We study the carrier recombination dynamics and band structure of GaAs$_{1-x}$Sb$_{x}$ and GaAs$_{1-x}$Sb$_{x}$/InP core/shell nanowires (NWs) grown by MOCVD. Using Transient Rayleigh Scattering (TRS) measurements and Raman scattering measurements in single unstrained bare core and strained core-shell NWs, we measure the strain distributions in the core and shell and its effect on band structures. At 10 K, the band gap of the GaAs$_{0.7}$Sb$_{0.3}$ core is seen using TRS to move to lower energy because of the tensile strain from the InP shell. This tensile strain is confirmed by micro-Raman which show the InP phonons shift to higher frequencies while the GaAs$_{0.7}$Sb$_{0.3}$ phonons move to lower frequencies. The recombination lifetimes in bare GaAs$_{0.7}$Sb$_{0.3}$ NWs are found to be less than the 50 ps at all temperatures, which is limited by our system response. In contrast, the lifetimes measured in the GaAs$_{0.7}$Sb$_{0.3}$/InP core/shell NWs are 820ps at 10K and 130ps at 300K. This significant lifetime enhancement reflects the effectiveness of the InP shell surface passivation. We infer that the surface recombination velocity reduces from \textasciitilde 100,000 cm/s to \textasciitilde 3,000 cm/s in the core-shell NW. [Preview Abstract] |
Wednesday, March 16, 2016 1:39PM - 1:51PM |
L8.00013: ABSTRACT WITHDRAWN |
Wednesday, March 16, 2016 1:51PM - 2:03PM |
L8.00014: WHY A MAGNETIZED QUANTUM WIRE CAN ACT AS AN OPTICAL AMPLIFIER Manvir Kushwaha We discuss the fundamental issues associated with the magnetoplasmon excitations in a semiconducting quantum wire characterized by a harmonic confining potential and subjected to an applied (perpendicular) magnetic field. The problem involves two length scales: ${\it l}_0=\sqrt{\hbar/m^*\omega_0}$ and ${\it l}_c=\sqrt{\hbar/m^*\omega_c}$, which characterize the strengths of the confinement and the magnetic field ($B$). Essentially, we focus on the device aspects of the intersubband collective (magnetoroton) excitation, which observes a negative group velocity between maxon and roton. Existence of the negative group velocity is a clear manifestation of a medium with population inversion brought about due to a metastable state caused by the magnetic field that satisfies the condition $B> B_{th}$; $B_{th}$ being the threshold value below which the magnetoroton does not exist. A medium with an inverted population has the remarkable ability of amplifying a small optical signal of definite wavelength. An extensive scrutiny of the gain coefficient suggests an interesting and important application: the electronic device designed on the basis of such magnetoroton modes can act as an optical amplifier$^{1}$. 1. M.S. Kushwaha, J. Appl. Phys.{\bf 109}, 106102 (2011). [Preview Abstract] |
Wednesday, March 16, 2016 2:03PM - 2:15PM |
L8.00015: Focused Gold Ion Implantation for Conducting Wires Todd Brintlinger With the advent of non-Ga ion sources in commercial focused-ion-beam (FIB) systems, new possibilities have arisen for lithographic devices. We demonstrate that focused gold ions can be directly implanted into silicon nitride to form conducting wires. The focused gold ion beam is formed from a binary alloy AuSi source with a deep eutectic temperature, where the gold ions are sorted from the silicon ions with in an ExB filter. Using a 15 pA beam, single-pass lines (dose 1.0-1.5 nC/cm) are written to create several wires in the gap between existing gold electrodes on a silicon nitride membrane. To allow for overlap between the deposited gold wires and the electrodes, the lines are written on top of the existing gold electrodes, as well as in the gap, giving rise to rapid gold-on-gold sputtering in the electrodes, but leaving behind the aforementioned gold wire in the silicon nitride. Full-width, half-max linewidth of wires is 110-140 nm. Atomic force microscopy reveals significant ion sputtering in existing gold electrodes, as already seen in scanning electron microscope, but shows that implanted gold ion wires exist in subsurface with minimal topographic distortion to silicon nitride membrane. Voltage sweeps reveal linear, length-dependent, currents passing through the gold wires. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700