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28 Jan 2008

Volume 92, Issue 4, Articles (04xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 92, 041901 (2008); http://dx.doi.org/10.1063/1.2831926 (3 pages)

M. A. Avila, K. Suekuni, K. Umeo, H. Fukuoka, S. Yamanaka, and T. Takabatake
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Enhanced localized fluorescence in plasmonic nanoantennae

Reuben M. Bakker, Hsiao-Kuan Yuan, Zhengtong Liu, Vladimir P. Drachev, Alexander V. Kildishev, Vladimir M. Shalaev, Rasmus H. Pedersen, Samuel Gresillon, and Alexandra Boltasseva

Appl. Phys. Lett. 92, 043101 (2008); http://dx.doi.org/10.1063/1.2836271 (3 pages) | Cited 61 times

Online Publication Date: 28 January 2008

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Pairs of gold elliptical nanoparticles form antennae, resonant in the visible. A dye, embedded in a dielectric host, coats the antennae; its emission excites plasmon resonances in the antennae and is enhanced. Far-field excitation of the dye-nanoantenna system shows a wavelength-dependent increase in fluorescence that reaches 100 times enhancement. Near-field excitation shows enhanced fluorescence from a single nanoantenna localized in a subwavelength area of ∼ 0.15 μm2. The polarization of enhanced emission is along the main antenna axis. These observed experimental results are important for increasing light extraction from emitters localized around antennae and for potential development of a subwavelength sized laser.
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78.60.-b Other luminescence and radiative recombination
73.22.Lp Collective excitations
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters

High temperature surface imaging using atomic force microscopy

Joska Broekmaat, Alexander Brinkman, Dave H. A. Blank, and Guus Rijnders

Appl. Phys. Lett. 92, 043102 (2008); http://dx.doi.org/10.1063/1.2836943 (3 pages) | Cited 3 times

Online Publication Date: 28 January 2008

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Atomic force microscopy (AFM) is one of the most important tools in nanotechnology and surface science. Because of recent developments, nowadays, it is also used to study dynamic processes, such as thin film growth and surface reaction mechanisms. These processes often take place at high temperature and there is a clear need to extend the current operating temperature range of AFM. This letter describes a heating stage and a modified AFM that extends the maximum operating temperature to 750 °C. Atomic step resolution is obtained up to 500 °C in ambient and even up to 750 °C in vacuum.
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68.37.Ps Atomic force microscopy (AFM)

Carbon diffusion around the edge region of nickel nanoparticles

Young-Han Shin and Suklyun Hong

Appl. Phys. Lett. 92, 043103 (2008); http://dx.doi.org/10.1063/1.2836265 (3 pages) | Cited 8 times

Online Publication Date: 29 January 2008

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Adsorption and diffusion of carbon atoms in nickel are studied by density-functional theory calculations to understand the growth mechanism of carbon nanotubes in its initial stage. Combined with the results for surface and subsurface diffusions, the diffusion behaviors around the edges between low-index nickel surfaces reveal that the growth of carbon nanotubes is related to the diffusion barriers across these edge regions of nickel nanoparticles in addition to the growth temperature. We explain these results in terms of the reaction mechanisms which are kinetically or thermodynamically controlled depending on the temperature at which the carbon nanotubes grow.
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81.07.De Nanotubes
68.43.Mn Adsorption kinetics
68.43.Jk Diffusion of adsorbates, kinetics of coarsening and aggregation

The formation of pentagon-heptagon pair defect by the reconstruction of vacancy defects in carbon nanotube

Gun-Do Lee, C. Z. Wang, Euijoon Yoon, Nong-Moon Hwang, and K. M. Ho

Appl. Phys. Lett. 92, 043104 (2008); http://dx.doi.org/10.1063/1.2837632 (3 pages) | Cited 12 times

Online Publication Date: 29 January 2008

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The reconstruction process of vacancy hole in carbon nanotube is investigated by tight-binding molecular dynamics simulations and by ab initio total energy calculations. In the molecular dynamics simulation, a vacancy hole is found to reconstruct into two separated pentagon-heptagon pair defects. As the result of reconstruction, the radius of the carbon nanotube is reduced and the chirality of the tube is partly changed. During the vacancy hole healing process, the formation of pentagonal and heptagonal rings is proceeded by the subsequent Stone-Wales [Chem. Phys. Lett. 128, 501 (1986) ] transformation.
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61.72.jd Vacancies
61.46.Fg Nanotubes

Carbon nanotube surface attenuated infrared absorption

Kristina Setyowati, Ming Jun Piao, Jian Chen, and Haiying Liu

Appl. Phys. Lett. 92, 043105 (2008); http://dx.doi.org/10.1063/1.2837808 (3 pages) | Cited 8 times

Online Publication Date: 29 January 2008

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The carbon nanotube (CNT) surface quality plays a critical role in defining the molecule-nanotube, macromolecule-nanotube, metal/semiconductor-nanotube, and nanotube-nanotube interfaces, which are at the heart of numerous potential CNT-based applications in electronics, sensors, nanocomposites, thermal management, actuators, energy storage and conversion, and drug delivery. We report that the infrared vibrations of adsorbed molecules/macromolecules that give rise to dipole changes parallel to the highly polarizable CNT surface are diminished significantly in intensity. The CNT surface attenuated infrared absorption provides a mechanism to probe and compare the overall surface qualities of various bulk CNT materials.
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61.48.De Structure of carbon nanotubes, boron nanotubes, and other related systems
78.66.Tr Fullerenes and related materials
78.30.Na Fullerenes and related materials
68.43.-h Chemisorption/physisorption: adsorbates on surfaces

Resonating modes of vibrating microcantilevers in liquid

Murali Krishna Ghatkesar, Thomas Braun, Viola Barwich, Jean-Pierre Ramseyer, Christoph Gerber, Martin Hegner, and Hans Peter Lang

Appl. Phys. Lett. 92, 043106 (2008); http://dx.doi.org/10.1063/1.2838295 (3 pages) | Cited 26 times

Online Publication Date: 29 January 2008

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A study of nanomechanical cantilevers vibrating at various resonating modes in liquid is presented. Resonant frequency spectrum with 16 well resolved flexural modes is obtained. The quality factor increased from 1 at mode 1 to 30 at mode 16. The theoretical estimate of eigenfrequency using the Elmer–Dreier model [ F.-J. Elmer and M. Dreier, J. Appl. Phys. 81, 12 (1997) ] and Sader’s extended viscous model [ C. A. Van Eysden and J. E. Sader, J. Appl. Phys. 101, 044908 (2007) ] matched well with the experimental data. The apparent mass of the liquid comoved by the oscillating cantilevers decreased asymptotically with mode number.
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46.40.Ff Resonance, damping, and dynamic stability

Au–ZnO: A tunable localized surface plasmonic nanocomposite

Y. K. Mishra, S. Mohapatra, R. Singhal, D. K. Avasthi, D. C. Agarwal, and S. B. Ogale

Appl. Phys. Lett. 92, 043107 (2008); http://dx.doi.org/10.1063/1.2838302 (3 pages) | Cited 21 times

Online Publication Date: 29 January 2008

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In this letter, we report the thermal processing controlled tunability of localized surface plasmon resonance (LSPR) of Au nanoparticles embedded in ZnO matrix. Au–ZnO nanocomposite films were prepared by atom beam cosputtering and were annealed from 200 to 600 °C in Ar. A regular redshift ∼ 110 nm (from 505 to 615 nm) in LSPR peak with increase in annealing temperature up to 600 °C is observed. Transmission electron microscopy results confirm the formation of Au nanoparticles supported by ZnO nanorods at annealing temperature of 600 °C. The Au–ZnO nanocomposite exhibits significant enhancement in the Raman signal for C70 molecules.
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73.22.Lp Collective excitations
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
81.40.Gh Other heat and thermomechanical treatments

Nanofluid with tunable thermal properties

John Philip, P. D. Shima, and Baldev Raj

Appl. Phys. Lett. 92, 043108 (2008); http://dx.doi.org/10.1063/1.2838304 (3 pages) | Cited 41 times

Online Publication Date: 29 January 2008

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We experimentally demonstrate the tunable thermal property of a magnetically polarizable nanofluid that consists of a colloidal suspension of magnetite nanoparticles with average diameter of 6.7 nm. Controlling the linear aggregation length from nano- to micron scales, the thermal conductivity (TC) of the nanofluid has been enhanced up to 216%, using 4.5 vol % of nanoparticles. Repeated magnetic cycling shows that the TC enhancement is reversible. It has been confirmed that the large enhancement in TC is due to the efficient transport of heat through percolating nanoparticle paths. Our findings offer promising applications in “smart” cooling devices.
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66.25.+g Thermal conduction in nonmetallic liquids
75.50.Mm Magnetic liquids
75.50.Tt Fine-particle systems; nanocrystalline materials
82.70.Kj Emulsions and suspensions

A generalized heat transfer model for thin film bearings at head-disk interface

W. D. Zhou, B. Liu, S. K. Yu, W. Hua, and C. H. Wong

Appl. Phys. Lett. 92, 043109 (2008); http://dx.doi.org/10.1063/1.2838454 (3 pages) | Cited 17 times

Online Publication Date: 30 January 2008

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The physics of the heat transfer process from the slider of a hard disk drive to its disk is discussed. A generalized heat transfer model, which incorporates various molecular dynamics models, is proposed to solve the heat transfer problem in thin film bearings at head-disk interface. The proposed model considers the impact of molecular collisions between film molecules and solid surfaces, which plays an important role in the heat transfer of thin film bearings and is expected to improve the accuracy of predicting the thermal protrusion caused by the heating of the slider at the head-disk interface of hard disk drives.
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85.70.Li Other magnetic recording and storage devices (including tapes, disks, and drums)

One-step grown suspended n-type semiconducting single wall carbon nanotube field effect transistors with carbon nanotube electrodes

Yun-Hi Lee, Jong-Hee Lee, and Ji-Young Noh

Appl. Phys. Lett. 92, 043110 (2008); http://dx.doi.org/10.1063/1.2838736 (3 pages) | Cited 2 times

Online Publication Date: 30 January 2008

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The authors report on the in situ formation of n-type ferromagnetic single wall carbon nanotube field effect transistors for the first time using a rapid heating process with a continuous flow of H2 gas under a vacuum of millitorr and their electromagnetic transport properties. The suspended n-type single wall carbon nanotube (SWNT) bridge including nanosized Fe catalyst impurities also shows gate controlled magnetic field dependent field effect behavior. The interesting features of these devices can be understood qualitatively based on the influence of the nonoxidant interface and nano Fe residing at the growth site of the SWNT bridge.
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85.30.Tv Field effect devices
85.35.Kt Nanotube devices

The influence of a Cu buffer layer on the self-assembly of iron silicide nanostructures on Si(111)

K. Paredis, K. Vanormelingen, and A. Vantomme

Appl. Phys. Lett. 92, 043111 (2008); http://dx.doi.org/10.1063/1.2838737 (3 pages) | Cited 7 times

Online Publication Date: 30 January 2008

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The role of a Cu buffer layer on the formation of iron silicide nanostructures is investigated using scanning tunneling microscopy and Mössbauer spectroscopy. The deposition of 1 Å Fe on the Si(111)-7×7 and the Si(111)-5×5-Cu surfaces results in the self-organization of nanoscale islands. Increasing the deposition temperature (300-600 °C) leads to an exponential decrease in island density and to an increase of the average island size. At 475 °C, the preferential nucleation site changes from the terrace to the step edges, i.e., step flow growth is observed. The self-assembled nanostructures exhibit the metastable CsCl–FeSi1+x structure. Due to the enhanced diffusion, nanodots formed on the 5×5 surface are significantly larger and more separated compared to growth on the bare 7×7 surface. These results show that a buffer layer provides an additional, experimentally controllable parameter, besides temperature, to tailor the size and distribution of nanodots.
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81.07.Bc Nanocrystalline materials
81.16.Dn Self-assembly
76.80.+y Mössbauer effect; other γ-ray spectroscopy
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.35.Fx Diffusion; interface formation

High-frequency metallic nanomechanical resonators

T. F. Li, Yu. A. Pashkin, O. Astafiev, Y. Nakamura, J. S. Tsai, and H. Im

Appl. Phys. Lett. 92, 043112 (2008); http://dx.doi.org/10.1063/1.2838749 (3 pages) | Cited 16 times

Online Publication Date: 30 January 2008

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We developed a technology to fabricate fully metallic doubly clamped beams working as nanomechanical resonators. Measured with a magnetomotive detection scheme, the beams, made of polycrystalline metal films, show as good quality as previously reported ones made of single crystal materials, such as Si, GaAs, AlN, and SiC. Our method is compatible with the conventional fabrication process for nanoscale electronic circuits and thus offers a possibility of easily integrating the beams into superconducting charge and flux qubits and single-electron transistors as well as coupling them to coplanar waveguide resonators.
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07.10.Cm Micromechanical devices and systems
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices

Polarization of intersubband transitions in self-assembled quantum dots

Weidong Sheng

Appl. Phys. Lett. 92, 043113 (2008); http://dx.doi.org/10.1063/1.2838755 (3 pages) | Cited 3 times

Online Publication Date: 30 January 2008

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Intersubband transitions in self-assembled quantum dots are studied by using a multiband tight-binding method. A picture different from that by the single-band effective-mass approximation is presented to reveal the origin of the polarization of the intersubband transitions. It is shown that the symmetry of those minor components from the valence bands in the electronic states accounts for the polarization of the intersubband transitions. A microscopic theory is presented to explain the pattern of symmetry of these minor components in the electronic states. The result is compared with a recent experiment.
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73.21.La Quantum dots
78.67.Hc Quantum dots
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)

Discretely guided electromagnetic effective medium

K. Kempa, X. Wang, Z. F. Ren, and M. J. Naughton

Appl. Phys. Lett. 92, 043114 (2008); http://dx.doi.org/10.1063/1.2839320 (3 pages) | Cited 3 times

Online Publication Date: 30 January 2008

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A material comprised of an array of subwavelength coaxial waveguides decomposes incident electromagnetic waves into spatially discrete wave components, propagates these components without frequency cutoff, and reassembles them on the far side of the material. The propagation of these wave components is fully controlled by the physical properties of the waveguides and their geometrical distribution in the array. This allows for an exceptional degree of control over the electromagnetic response of this effective medium, with numerous potential applications. With the development of nanoscale subwavelength coaxial waveguides, these applications (including metamaterial functionality) can be enabled in the visible frequency range.
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84.40.Az Waveguides, transmission lines, striplines
41.20.Jb Electromagnetic wave propagation; radiowave propagation

First-principles calculations of the dielectric properties of silicon nanostructures

S. Hamel, A. J. Williamson, H. F. Wilson, F. Gygi, G. Galli, E. Ratner, and D. Wack

Appl. Phys. Lett. 92, 043115 (2008); http://dx.doi.org/10.1063/1.2839332 (3 pages) | Cited 8 times

Online Publication Date: 30 January 2008

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We have investigated the static dielectric properties of silicon rods and slabs below 10 nm, in the long wavelength limit, by using first-principles density functional theory calculations. Surface structure is found to be the most important factor affecting the changes of the dielectric response at the nanoscale, compared to that of bulk Si, with significant differences observed between slabs and finite rods of similar lateral dimensions.
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77.22.Ch Permittivity (dielectric function)
73.20.At Surface states, band structure, electron density of states
77.55.-g Dielectric thin films
81.05.Cy Elemental semiconductors

A surface-enhanced Raman spectroscopy substrate for highly sensitive label-free immunoassay

Ming-Liang Zhang, Chang-Qing Yi, Xia Fan, Kui-Qing Peng, Ning-Bew Wong, Meng-Su Yang, Rui-Qin Zhang, and Shuit-Tong Lee

Appl. Phys. Lett. 92, 043116 (2008); http://dx.doi.org/10.1063/1.2833695 (3 pages) | Cited 15 times

Online Publication Date: 30 January 2008

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Large-scale uniform silicon nanowires (SiNWs) array was fabricated by chemical etching on n-Si(111) wafer. Silver nanoparticles (AgNPs) were loaded on their surfaces. The AgNPs on SiNWs (AgNPs@SiNWs) array exhibit strong surface-enhanced Raman effect. On the substrate surfaces, characteristic Raman signals are generated with trace amount of mouse immunoglobulin G (mIgG), goat-anti-mouse immunoglobulin G (gamIgG), and immune complexes formed from 4 ng each of mIgG and gamIgG. The shifted positions and changed intensities in Raman bands indicate the occurrence of immunoreactions. This AgNPs@SiNWs array is a unique substrate for surface-enhanced Raman spectroscopy to show the immune reagents and immunoreactions at higher sensitivity.
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87.64.kp Raman
87.85.Rs Nanotechnologies-applications
78.68.+m Optical properties of surfaces
78.67.Lt Quantum wires
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.30.-j Infrared and Raman spectra

Controlling the alignment of neutral iodine molecules in the elliptical channels of AlPO4-11 crystals

J. P. Zhai, I. L. Li, S. C. Ruan, H. F. Lee, and Z. K. Tang

Appl. Phys. Lett. 92, 043117 (2008); http://dx.doi.org/10.1063/1.2839374 (3 pages) | Cited 7 times

Online Publication Date: 30 January 2008

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AlPO4-11 (AEL) single crystal provides well-aligned one-dimensional elliptical nanochannels, wherein neutral iodine molecules can be trapped and aligned. Since the iodine molecules are well accommodated in the matrix of the AEL single crystal, it offers us a good example for studying polarized Raman spectra in a controllable way. Polarization dependence of Raman intensity of the iodine molecular vibration modes indicates that the iodine molecules are strictly oriented in two directions, either along the long axis of the elliptical channel or along the AEL channel direction.
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78.30.Hv Other nonmetallic inorganics
78.67.-n Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials

Strain development in nanoporous metallic foils formed by dealloying

Eleanor J. Schofield, Bridget Ingham, Alan Turnbull, Michael F. Toney, and Mary P. Ryan

Appl. Phys. Lett. 92, 043118 (2008); http://dx.doi.org/10.1063/1.2838351 (3 pages) | Cited 7 times

Online Publication Date: 30 January 2008

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Nanoporous Au foils were formed by dealloying a Ag–Au alloy in concentrated HNO3. The resultant foils, which have a “spongelike” morphology with interconnecting ligaments, were studied using synchrotron-based diffraction. A three-dimensional visualization of the nanostructure is generated from small angle experiments and the lattice parameter is derived from diffraction. The data show the development of two interspersed nanoscale strained regions within the material: one in significant tension and one in compression. We interpret this by considering regions of high positive and negative curvatures in the material; this curvature decreases with increasing pore size resulting in a relaxation in lattice strain.
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81.40.Jj Elasticity and anelasticity, stress-strain relations
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
78.70.Ck X-ray scattering
61.43.Gt Powders, porous materials

Optically isotropic-nanostructured liquid crystal composite with high Kerr constant

Suk-Won Choi, Shin-Ichi Yamamoto, Yasuhiro Haseba, Hiroki Higuchi, and Hirotsugu Kikuchi

Appl. Phys. Lett. 92, 043119 (2008); http://dx.doi.org/10.1063/1.2838352 (3 pages) | Cited 53 times

Online Publication Date: 30 January 2008

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The relationship between material parameters of host nematic liquid crystals (LCs) and Kerr constant of their nanostructured chiral LC composites was investigated. We made certain that the Kerr constant of nanostrutured chiral LC composites was closely related to the parameters of their host LCs, such as value of the difference of refractive index (Δn), the dielectric anisotropy (Δε), and bend to splay elastic constant ratio (K33/K11).
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61.30.-v Liquid crystals
78.20.Ls Magneto-optical effects
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.70.Df Liquid crystals
62.10.+s Mechanical properties of liquids

Molecular dynamics simulations of the torsional instability of carbon nanotubes filled with hydrogen or silicon atoms

Q. Wang, K. M. Liew, and V. K. Varadan

Appl. Phys. Lett. 92, 043120 (2008); http://dx.doi.org/10.1063/1.2840165 (3 pages) | Cited 7 times

Online Publication Date: 31 January 2008

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Torsional buckling of single-walled carbon nanotubes filled with hydrogen or silicon atoms via molecular dynamics is reported. The formation of a concentric layered atomic cluster in the tubes with the half filled atoms is observed at a lower torsional angle. However, a spill-over phenomenon accompanied by torsional buckling is found at a higher torsional angle that reveals the effect that being fully filled with hydrogen and silicon atoms has on the stability of carbon nanotubes. The higher critical torsional angle of carbon nanotubes fully filled with foreign atoms is attributed to the extra energy necessary to break the atomic chain structure.
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81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity

Interference enhancement of Raman signal of graphene

Y. Y. Wang, Z. H. Ni, Z. X. Shen, H. M. Wang, and Y. H. Wu

Appl. Phys. Lett. 92, 043121 (2008); http://dx.doi.org/10.1063/1.2838745 (3 pages) | Cited 45 times

Online Publication Date: 31 January 2008

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Raman spectroscopic studies of graphene have attracted much interest. The G-band Raman intensity of a single layer graphene on Si substrate with 300 nm SiO2 capping layer is surprisingly strong and is comparable to that of bulk graphite. To explain this Raman intensity anomaly, we show that in addition to the interference due to multiple reflection of the incident laser, the multiple reflection of the Raman signal inside the graphene layer must be also accounted for. Further studies of the role of SiO2 layer in the enhancement Raman signal of graphene are carried out and an enhancement factor of ∼ 30 is achievable, which is very significant for the Raman studies. Finally, we discuss the potential application of this enhancement effect on other ultrathin films and nanoflakes and a general selection criterion of capping layer and substrate is given.
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78.30.-j Infrared and Raman spectra

High resolution vacuum scanning thermal microscopy of HfO2 and SiO2

M. Hinz, O. Marti, B. Gotsmann, M. A. Lantz, and U. Dürig

Appl. Phys. Lett. 92, 043122 (2008); http://dx.doi.org/10.1063/1.2840186 (3 pages) | Cited 14 times

Online Publication Date: 31 January 2008

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We present scanning thermal microscopy (SThM) measurements on a sample consisting of regions of 3 nm thick HfO2 film and 2 nm thick SiO2 on a silicon substrate. The experiments were preformed in high vacuum conditions using microfabricated silicon cantilevers with sharp heatable tips, facilitating the unprecedented achievement of a lateral SThM image resolution of 25 nm. In addition, the heat transfer through the tip to the sample was investigated using approach curves and used to determine the thermal conductivity of the 3 nm thick HfO2 layer.
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66.70.Lm Other systems such as ionic crystals, molecular crystals, nanotubes, etc.

Local tuning of photonic crystal cavities using chalcogenide glasses

Andrei Faraon, Dirk Englund, Douglas Bulla, Barry Luther-Davies, Benjamin J. Eggleton, Nick Stoltz, Pierre Petroff, and Jelena Vučković

Appl. Phys. Lett. 92, 043123 (2008); http://dx.doi.org/10.1063/1.2839308 (3 pages) | Cited 34 times

Online Publication Date: 31 January 2008

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We demonstrate a method to locally change the refractive index in planar optical devices by photodarkening of a thin chalcogenide glass layer deposited on top of the device. The method is used to tune the resonance of GaAs-based photonic crystal cavities by up to 3 nm at 940 nm. The method has broad applications for postproduction tuning of photonic devices.
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42.70.Qs Photonic bandgap materials
42.25.Gy Edge and boundary effects; reflection and refraction

Controlled focused electron beam-induced etching for the fabrication of sub-beam-size nanoholes

Hiroyuki Miyazoe, Ivo Utke, Johann Michler, and Kazuo Terashima

Appl. Phys. Lett. 92, 043124 (2008); http://dx.doi.org/10.1063/1.2839334 (3 pages) | Cited 6 times

Online Publication Date: 31 January 2008

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Sub-beam-size focused electron beam-induced etching of amorphous carbon membranes was achieved. The size of the tungsten filament generated electron beam was determined from the in situ stage current monitoring and verified by knife edge measurements. The in situ time resolved stage current measurements as an end point detection allowed the fabrication of nanoholes with a diameter of sub-20 nm, corresponding to 20%–40% of the full width at half maximum of the incident beam.
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81.65.Cf Surface cleaning, etching, patterning
81.16.-c Methods of micro- and nanofabrication and processing
81.07.-b Nanoscale materials and structures: fabrication and characterization
61.46.-w Structure of nanoscale materials

Influence of phonon scattering on the performance of p-i-n band-to-band tunneling transistors

Siyuranga O. Koswatta, Mark S. Lundstrom, and Dmitri E. Nikonov

Appl. Phys. Lett. 92, 043125 (2008); http://dx.doi.org/10.1063/1.2839375 (3 pages) | Cited 16 times

Online Publication Date: 31 January 2008

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Power dissipation has become a major obstacle in performance scaling of modern integrated circuits and has spurred the search for devices operating at lower voltage swing. In this letter, we study p-i-n band-to-band tunneling field effect transistors taking semiconducting carbon nanotubes as the channel material. The on current of these devices is mainly limited by the tunneling barrier properties, and phonon-scattering has only a moderate effect. We show, however, that the off current is limited by phonon absorption assisted tunneling, and thus is strongly temperature dependent. Subthreshold swings below the 60 mV/decade conventional limit can be readily achieved even at room temperature. Interestingly, although subthreshold swing degrades due to the effects of phonon scattering, it remains low under practical biasing conditions.
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85.30.Tv Field effect devices
85.35.Kt Nanotube devices
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