Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session Y6: Nanotubes and Nanowires (non-carbon): Transport and Optical Phenomena |
Hide Abstracts |
Sponsoring Units: DCMP Chair: Jonathan Spanier, Drexel University Room: 302 |
Friday, March 22, 2013 8:00AM - 8:12AM |
Y6.00001: Surface Passivation and Orientation Dependence in the Electronic Properties of Silicon Nanowires Keenan Zhuo, Mei-Yin Chou Different surface passivation configurations for silicon nanowires (SiNWs) have previously been studied for expanding their technological applications. Of note, methyl (CH$_3$) passivated SiNWs have enhanced ambient stability, while electronegative atoms/groups such as halogens are useful in band gap engineering and chemical post-processing. Thus far though, fundamental mechanisms for how such passivations alter the electronic properties of SiNWs have not been rigorously scrutinized. In this work, we address this issue through first-principles calculations on CH$_3$, fluorine (F) and hydrogen (H) passivated [110] and [111] SiNWs. In comparison to H passivation, we explain how CH$_3$ and F passivations cause significant band gap reductions in [110] SiNWs, through strain and quantum confinement respectively. Furthermore, we discuss how structural differences in [111] SiNWs mitigate these effects, thereby giving the electronic properties of [111] SiNWs greater stability against various surface passivations than those of [110] SiNWs. [Preview Abstract] |
Friday, March 22, 2013 8:12AM - 8:24AM |
Y6.00002: Axial Si/Ge hetero-nanowires for tunneling transistors Son Le, Daniel Perea, Pooya Jannaty, Xu Luo, Shadi Dayeh, Alexander Zaslavsky, Thomas Picraux Modern vapor-liquid-solid (VLS) growth based on alloy catalysts can grow SiGe heteronanowires (hetero-NWs) with controlled axial heterojunction abruptness [1] combined with simultaneous control of material composition (Si and Ge) and doping profile. Previously, we reported on axial in-situ doped Ge NW pn junction tunneling field effect transistors (TFETs) with effective backgate control of the tunneling current [2]. In this presentation, we report on tri-gated p-Ge/i-Si/n-Si axial hetero-NWs TFET with on-state tunneling occuring in the Ge drain section and off-state leakage dominated by the Si junction in the source. The devices have high Ion of 2 uA/um, suppressed ambipolarity, and a sub-threshold slope SS of 140 mV/decade over 4 decades of current with lowest SS of 50 mV/decade. Device operation in the tunneling mode is confirmed by three-dimensional TCAD simulation. In addition, our devices work standard as NW FETs with good Ion/Ioff ratio when the source-drain junction is forward-biased [3]. [1] D. E. Perea et al., Nano Lett 11, 3117 (2011). [2] Son T. Le et al., Appl. Phys. Lett. 96, 262102 (2010). [3] Son T. Le et al., accepted to Nano Lett. (10/2012). [Preview Abstract] |
Friday, March 22, 2013 8:24AM - 8:36AM |
Y6.00003: Probing Interface Band Edge Discontinuity in Single Core-shell Nanowire by Photocurrent Spectroscopy Guannan Chen, Guan Sun, Yujie Ding, Ilio Maccoli, Nico Lovergine, Paola Prete, Jonathan Spanier Group III-V co-axial core-shell semiconducting nanowire (NW) heterostructures possess unique advantages over their planar counterparts in logic, photovoltaic and light-emitting devices. Dimensional confinement of electronic carriers and interface complexity in NWs are known to produce local electronic potential landscapes along the radial direction that deviate from those along the normal to planar heterojunction interfaces. However, understanding of electronic and optoelectronic carrier transport properties and device characteristics remains lacking without a direct measurement of band alignment in individual NWs. Photocurrent spectroscopy has proven to be effective in investigating the effects of quantum confinement and surface related properties such as bandgaps, surface adsorption/desorption, and polarization anisotropy. Here, we report on, using the GaAs/Al$_{x}$Ga$_{1-x}$As core-shell NW system ($x$ = 0.24 and 0.33), how photocurrent and photoluminescence spectroscopies can be used together to construct a band diagram of an individual heterostructure NW with high spectral resolution. This approach and results are relevant for the study of tunable hot electron transfer across NW core-shell interfaces. [Preview Abstract] |
Friday, March 22, 2013 8:36AM - 8:48AM |
Y6.00004: Capacitance of Nanowire with different cross sections and different materials at different frequencies Abbas Arab, Qiliang Li During the past half century, feature-size of electronic elements has been reduced dramatically. Semiconductor industry expects this down-scaling to be continued for at least next decade. Among different approaches proposed for reducing the size of electronic elements, is nanowire (NW) based elements such as nanowire field effect transistor (NW-FET). NW approach offers a coaxial gate-dielectric-channel geometry that has advantage of electrostatic control in down-scaling the electronic elements. NWs can be grown in different cross sections depending on the material used as the core of the coaxial structure. Despite so much interest and research on this field, a complete set of study on nanowire capacitance will be very useful for nanoelectronics. In this work, we are going to study different NW structures with different materials and cross sections including: square, triangular, circular and hexagonal in different frequencies. We will study the effect of oxide thickness, oxide material and rotation of cross section, in cases that are not symmetric to rotation, on NW behavior. [Preview Abstract] |
Friday, March 22, 2013 8:48AM - 9:00AM |
Y6.00005: ABSTRACT WITHDRAWN |
Friday, March 22, 2013 9:00AM - 9:12AM |
Y6.00006: Discrete random distribution of source dopants in nanowire tunnel transistors (TFETs) Somaia Sylvia, M. Abul Khayer, Khairul Alam, Hong-Hyun Park, Gerhard Klimeck, Roger Lake InAs and InSb nanowire (NW) tunnel field effect transistors (TFETs) require highly degenerate source doping to support the high electric fields in the tunnel region. For a target on-current of 1 $\mu A$, the doping requirement may be as high as $1.5\times10^{20}~ \mathrm{cm^{-3}}$ in a NW with diameter as low as 4 nm. The small size of these devices demand that the dopants near tunneling region be treated discretely. Therefore, the effects resulting from the random distribution of dopant atoms in the source of a TFET are studied for 30 test devices. Comparing with the transfer characteristics of the same device simulated with a continuum doping model, our results show (1) a spread of $I-V$ toward the positive gate voltage axis, (2) the same average threshold voltage, (3) an average 62\% reduction in the on current, and (4) a slight degradation of the subthreshold slope. Random fluctuations in both the number and placement of dopants will be discussed. Also, as the channel length is scaled down, direct tunneling through the channel starts limiting the device performance. Therefore, a comparison of materials is also performed, showing their ability to block direct tunneling for sub-10 nm channel FETs and TFETs. [Preview Abstract] |
Friday, March 22, 2013 9:12AM - 9:24AM |
Y6.00007: Observation of defect-induced Photoresponse and charge carrier transport in single GeSe2 nanobelt devices Bablu Mukherjee, Eng Soon Tok, Chorng Haur Sow Single crystal GeSe2 nanobelts were grown using chemical vapor deposition techniques. Morphology of the nanostructures was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Raman spectroscopy. Electronic transport properties, impedance spectroscopy, photoconductive characteristics and temperature-dependent electrical resistivity measurements were carried out on individual GeSe2 nanobelt devices. The photosensitivity of single GeSe2 nanobelt (NB) devices was examined with two different excitation wavelengths of laser beams with photon energies above band gap and at sub-band gap of the NB. A maximum photoconductive gain 10$^6$ \% was achieved at a wavelength of 808 nm. The magnitude of the photocurrent and response time of the individual GeSe2 NB device indicate that the photoresponse could be attributed to the presence of isolated mid band gap defect levels. Temperature dependent photocurrent measurements indicate the rough estimation of the energy levels for the defect states. Localized photostudy shows that the large photoresponse of the device primarily occurs at the metal-NB contact regions. [Preview Abstract] |
Friday, March 22, 2013 9:24AM - 9:36AM |
Y6.00008: Finite Element Analysis of lateral charge distribution in ZnO nanowire Javad Usefie Mafahim, Arkadii Krokhin, Arup Neogi The coupling of piezoelectric and semiconducting properties in zinc oxide creates a strain field and charge separation across a nanowire (NW) as a result of an external or internally induced strain. The potential drop along the transverse section of a hexagonal ZnO NW is simulated by the finite element analysis method. The NW is considered to be fixed at one end and laterally deflected at the other with a uniform force on a constant area of cross-section. We numerically simulate the potential drop across a direction transverse to the growth of the NW attached to the substrate. The piezoelectric potentials difference is analyzed as a function of the lateral force, thickness, and aspect ratio of the NW. It is observed that due to a change in the component of the shear force in the transverse direction with respect to the length of the NW, a significant variation of strain in observed in the direction of the lateral force. Our analysis explains previously observed experimental results. It is also shown that the potential difference is influenced by the changing aspect ratio. The charge distribution is also analyzed in a fluid medium with a lateral flow of the liquid. Our results can be used for the design of novel biosensors. [Preview Abstract] |
Friday, March 22, 2013 9:36AM - 9:48AM |
Y6.00009: Tailoring electronic properties of SnO$_2$ nanobelts via thermal annealing Timothy Keiper, Jorge Barreda, Joon-Il Kim, Jim P. Zheng, Peng Xiong Metal oxide semiconductors nanowires are a viable option for the fabrication of transistors with desirable characteristics for nanoelectronic and sensing applications. SnO$_2$ nanobelts (NBs) have been synthesized using catalyst-free chemical vapor deposition. The growth parameters have been explored, producing NBs as long as millimeters. These NBs have been demonstrated as effective channel-limited gas [1], pH [2] and protein [3] field-effect transistor (FET) sensors. Through modification of O$_2$ and vacuum thermal annealing conditions, we investigate the control and optimization of the electronic properties of the NBs to achieve desired device characteristics for biosensing applications. A pronounced increase in conductance, up to the order of microsiemens, has been observed in annealed NBs under O$_2$ environment at elevated temperatures above 600$^\circ$C. We also examine the properties of the electrical contacts with different metallization and varying NB conductivity. Optimal device characteristics for various sensing applications will be tested and discussed.\\[4pt] [1] L.L. Fields et al., Appl. Phys. Lett. 88, 263102 (2006).\\[0pt] [2] Yi Cheng et al., Nano Lett. 8, 4179–4184 (2008).\\[0pt] [3] Yi Cheng et al., Biosensors and Bioelectronics 26, 4538-4544 (2011). [Preview Abstract] |
Friday, March 22, 2013 9:48AM - 10:00AM |
Y6.00010: Gated nonlocal transport in sketched oxide nanostructures Shicheng Lu, Guanglei Cheng, Joshua P. Veazey, Patrick Irvin, Feng Bi, Mengchen Huang, Jeremy Levy, Chung-Wung Bark, Sangwoo Ryu, Kwang-Hwan Cho, Chang-Beom Eom The oxide heterostructure LaAlO$_3$/SrTiO$_3$ supports a two-dimensional electron liquid (2DEL) with a variety of competing phases including magnetism, superconductivity and weak antilocalization due to Rashba spin-orbit coupling. Further confinement of this 2DEL into quasi-one-dimensional regime can provide insight into the underlying physics of this system and reveal new behavior. Prior magnetotransport experiments on narrow LaAlO$_3$/SrTiO$_3$ structures created by a conductive atomic force microscope lithography technique have revealed large nonlocal resistances (as large as 10$^4$$\Omega$), with separations between current and voltage that are large compared to the 2D mean-free path. To help understand the origin of this remarkable behavior, we perform electric gating of nanowire structures in order to vary the carrier density and possibly other interactions such as spin-orbit coupling strength. [Preview Abstract] |
Friday, March 22, 2013 10:00AM - 10:12AM |
Y6.00011: ABSTRACT WITHDRAWN |
Friday, March 22, 2013 10:12AM - 10:24AM |
Y6.00012: ABSTRACT WITHDRAWN |
Friday, March 22, 2013 10:24AM - 10:36AM |
Y6.00013: Atomic Hydrogen and Oxygen Adsorptions in Single-Walled Zigzag Silicon Nanotubes Haoliang Chen, Asok Ray \textit{Ab initio }calculations have been performed to study the electronic and geometric structure properties of zigzag Si nanotubes. Full geometry and spin optimizations have been performed without any symmetry constraints with an all electron 3-21G* basis set and the B3LYP functional. The largest zigzag silicon nanotube (12, 0) studied has a binding energy per atom of 3.584eV. Atomic hydrogen and oxygen adsorption on (9, 0) and (10, 0) nanotubes have been studied by optimizing the distances of the adatoms from both inside and outside the tube. The adatom can be placed initially in four adsorption sites- parallel bridge, zigzag bridge, hollow, and on-top site. The on-top site is the most preferred site for hydrogen atom adsorbed on (9, 0) with an adsorption energy of 3.0eV and an optimized distance of 1.49{\AA}. For oxygen adsorption on (9, 0), the most preferred site is the zigzag bridge site with an adsorption energy of 5.987eV. For atomic hydrogen adsorption on (10, 0), the most preferred site is also the on-top site with an adsorption energy of 2.974eV and an optimized distance of 1.49 {\AA}. For adsorption of atomic oxygen on (10, 0), the most preferred site is parallel bridge site with an adsorption energy of 6.275eV. [Preview Abstract] |
Friday, March 22, 2013 10:36AM - 10:48AM |
Y6.00014: Topological Effect to Surface Plasmon Excitation in Topological Insulator Nanowires Mingda Li, Wenping Cui, Ju Li, Yimei Zhu, Lijun Wu, Qingping Meng, Weishu Liu, Zhifeng Ren, Ferhat Katmis, Peng Wei, Jagadeesh Moodera, Yong Zhang We present a theoretical investigation of the surface plasmon at the interface between topologically-non-trivial cylindrical core and topological-trivial surrounding material, from the axion electrodynamics and modified constitutive relations. We find that the topological effect lowers the SP energy in any case, while as the diameter of the core becomes smaller, the topological modification to SP energy is reduced. A qualitative picture based on perturbation theory of shifted boundary is given to explain these phenomena, from which we also infer that in order to amplify the topological effect, the difference between the inverse of dielectric constants of two materials must be increased. We also find that when the surrounding material goes magnetic, the magnetism overcomes topological effect, makes the latter seemingly suppressed. What's more, bulk plasmon energy at 17.5 $\pm$ 0.2eV for semiconducting Bi2Se3 nanoparticle is observed from high-resolution Electron Energy Loss Spectrum Image measurements. [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