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1.
Scanning tunneling microscopy of carbon nanotubes 总被引:1,自引:0,他引:1
W. Clauss 《Applied Physics A: Materials Science & Processing》1999,69(3):275-281
This article reports on the application of scanning tunneling microscopy for the study of surface structures and electronic
properties of carbon nanotubes. Geometric effects resulting from the cylindrical shape of the tubes as well as the particular
band structure of the graphitic crystal lattice can lead to a variety of contrast patterns. On the atomic scale, it is sometimes
possible to see the full honeycomb lattice structure but often different structures are observed. Besides distortions caused
by tip–sample interactions, we find that a complex superstructure superimposed on the simple atomic contrast pattern arises
from elastic scattering of the Fermi states at defects or impurities. From a careful analysis of high-resolution images it
is possible to extract information about elastic strain of individual tubes. A new combination of scanning tunneling and scanning
force microscopy enables near-atomic point resolution of the force signal the tubes can be identified without the need of
a conducting substrate. This imaging mode is a crucial step for the characterization of electronic devices based on individual
single-wall tubes. This mode can be further enhanced by the use of single-walled tubes as probe tips.
Received: 17 May 1999 / Accepted: 18 May 1999 / Published online: 4 August 1999 相似文献
2.
Mechanical properties of carbon nanotubes 总被引:26,自引:0,他引:26
J.-P. Salvetat J.-M. Bonard N.H. Thomson A.J. Kulik L. Forró W. Benoit L. Zuppiroli 《Applied Physics A: Materials Science & Processing》1999,69(3):255-260
A variety of outstanding experimental results on the elucidation of the elastic properties of carbon nanotubes are fast appearing.
These are based mainly on the techniques of high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy
(AFM) to determine the Young’s moduli of single-wall nanotube bundles and multi-walled nanotubes, prepared by a number of
methods. These results are confirming the theoretical predictions that carbon nanotubes have high strength plus extraordinary
flexibility and resilience. As well as summarising the most notable achievements of theory and experiment in the last few
years, this paper explains the properties of nanotubes in the wider context of materials science and highlights the contribution
of our research group in this rapidly expanding field. A deeper understanding of the relationship between the structural order
of the nanotubes and their mechanical properties will be necessary for the development of carbon-nanotube-based composites.
Our research to date illustrates a qualitative relationship between the Young’s modulus of a nanotube and the amount of disorder
in the atomic structure of the walls. Other exciting results indicate that composites will benefit from the exceptional mechanical
properties of carbon nanotubes, but that the major outstanding problem of load transfer efficiency must be overcome before
suitable engineering materials can be produced.
Received: 17 May 1999 / Accepted: 18 May 1999 / Published online: 29 July 1999 相似文献
3.
G.S. Duesberg J. Muster H.J. Byrne S. Roth M. Burghard 《Applied Physics A: Materials Science & Processing》1999,69(3):269-274
Production methods for carbon nanotubes are now well established and allow their synthesis on a scale of grams per day. For
many potential applications of this unique material, its purification still remains a crucial problem. In this article various
purification methods for single- and multi-wall carbon nanotubes are reviewed. These methods are compared in terms of their
capacity, efficiency, and effects on the tubes. In addition, the use of Raman spectroscopy for monitoring the chromatographic
purification of single-wall nanotubes is described.
Received: 17 May 1999 / Accepted: 18 May 1999 / Published online: 29 July 1999 相似文献
4.
Y-branching of single walled carbon nanotubes 总被引:1,自引:0,他引:1
P. Nagy R. Ehlich L.P. Biró J. Gyulai 《Applied Physics A: Materials Science & Processing》2000,70(4):481-483
Y-branching was observed by scanning tunnelling microscopy (STM) in single wall carbon nanotubes grown by thermal decomposition
of C60 fullerene in the presence of transition metals. These novel carbon nanostructures may play an important role in carbon-based
nanoelectronics.
Received: 18 November 1999 / Accepted: 20 January 2000 / Published online: 8 March 2000 相似文献
5.
L. Palacio P. Prádanos A. Hernández M.J. Ariza J. Benavente M. Nyström 《Applied Physics A: Materials Science & Processing》2001,73(5):555-560
The surfaces of three commercial urea formaldehyde polysulfone membranes from Dow DenmarkTM (GR51, GR61 and GR81) are characterised both topographically and chemically. Their topography is studied by scanning force
microscopy to obtain the corresponding pore-size distributions, which are in fair agreement with nominal molecular weight
cut-offs.
The composition of the surfaces of the membranes is analysed by X-ray photoelectron spectroscopy. The resulting percentage
content of nitrogen, which could be attributed probably to an additive used in the manufacturing process, is shown to correlate
with the portion of the total surface with different viscoelastic properties as investigated by using phase-contrast scanning
force microscopy. Both parameters are increasing for membranes with decreasing molecular weight cut-off. Also, the additive
seems to be more sparsely distributed for the membranes with bigger pores, according to fractal analysis. Finally, all the
membranes are very similarly wettable.
Received: 22 May 2001 / Accepted: 30 May 2001 / Published online: 25 July 2001 相似文献
6.
C. Schönenberger A. Bachtold C. Strunk J.-P. Salvetat L. Forró 《Applied Physics A: Materials Science & Processing》1999,69(3):283-295
We report equilibrium electric resistance R and tunneling spectroscopy (dI/dV)measurements obtained on single multi-wall nanotubes
contacted by four metallic Au fingers from above. At low temperature quantum interference phenomena dominate the magnetoresistance.
The phase-coherence (lφ)and elastic-scattering lengths (le)are deduced. Because le is of order of the circumference of the nanotubes, transport is quasi-ballistic. This result is supported by a dI/dV spectrum
which is in good agreement with the density of states (DOS) due to the one-dimensional subbands expected for a perfect single-wall
tube. As a function of temperature T the resistance increases on decreasing T and saturates at ≈1–10 Kfor all measured nanotubes.
R(T) cannot be related to the energy-dependent DOS of graphene but is mainly caused by interaction and interference effects.
On a relatively small voltage scale of the order ≈10 meV, a pseudogap is observed in dI/dV which agrees with Luttinger-liquid
theories for nanotubes. Because we have used quantum diffusion based on Fermi-liquid as well as Luttinger-liquid theory in
trying to understand our results, a large fraction of this paper is devoted to a careful discussion of all our results.
Received: 17 May 1999 / Accepted: 18 May 1999 / Published online: 4 August 1999 相似文献
7.
Chemical, morphological and accumulation phenomena in ultrashort-pulse laser ablation of TiN in air 总被引:1,自引:0,他引:1
J. Bonse H. Sturm D. Schmidt W. Kautek 《Applied Physics A: Materials Science & Processing》2000,71(6):657-665
Ultrashort-pulse laser ablation (τ=130 fs, λ=800 nm, repetition rate 2–20 Hz) of titanium nitride was investigated for laser
fluences between 0.3 and 4.5 J/cm2 using the direct focusing technique in air. The influence of the laser pulse number and the peak fluence was investigated
by means of several surface analytical techniques (optical microscopy, dynamic friction atomic force microscopy, scanning
Auger electron microscopy and small-spot electron spectroscopy for chemical analysis). The correlation of the results about
optical, physical and chemical properties of the irradiated areas allows us to propose a simple oxidation model, which explains
different observed phenomena associated with surface damage such as mound formation and crater widening and clarifies the
incubation behavior reported earlier for this material.
Received: 8 May 2000 / Accepted: 9 May 2000 / Published online: 13 September 2000 相似文献
8.
A. Yamada K.P. Ho T. Maruyama K. Akimoto 《Applied Physics A: Materials Science & Processing》1999,69(1):89-92
The feasibility of MoS2 layered compound as a substrate for GaN growth was investigated. GaN films were successfully grown on MoS2 by plasma-enhanced molecular beam epitaxy and the crystal quality of GaN on MoS2 was compared with that on Al2O3. For GaN grown on MoS2 substrate, it was found that the surface flatness observed by atomic force microscopy, stress in the film measured by Raman
spectroscopy, optical properties measured by photoluminescence spectroscopy, and threading dislocation density observed by
transmission electron microscopy show superior properties compared with that grown on Al2O3. These results suggest the layered compound such as MoS2, which has no dangling bonds on the surface and has lattice mismatching of 0.9% to GaN, has high potential for a substrate
of GaN growth.
Received: 1 March 1999 / Accepted: 8 March 1999 / Published online: 26 May 1999 相似文献
9.
J. Nygard D.H. Cobden M. Bockrath P.L. McEuen P.E. Lindelof 《Applied Physics A: Materials Science & Processing》1999,69(3):297-304
We review transport measurements on single-walled carbon nanotubes contacted by metal electrodes. At room temperature some
devices show transistor action similar to that of p-channel field effect transistors, while others behave as gate-voltage
independent wires. At low temperatures transport is usually dominated by Coulomb blockade. In this regime the quantum eigenstates
of the finite-length tubes can be studied. At higher temperatures power law behaviour is observed for the temperature and
bias dependence of the conductance. This is consistent with tunneling into a one-dimensional Luttinger liquid in a nanotube.
We also discuss recent developments in contacting nanotubes which should soon allow study of their intrinsic transport properties.
Received: 17 May 1999 / Accepted 18 May 1999 / Published online: 4 August 1999 相似文献
10.
W.M. Steffens S. Heisig U.D. Keil E. Oesterschulze 《Applied physics. B, Lasers and optics》1999,69(5-6):455-458
We report on the fabrication process of a scanning force microscopy (SFM) cantilever probe suitable for the investigation
of ultrafast transient signals in microwave integrated circuits. High temporal resolution is achieved by integrating a laser-gated
photoconductive switch within a coplanar waveguide structure onto a low-temperature GaAs cantilever. This is demonstrated
by temporal and spatio-temporal measurements performed on a coplanar strip line.
Received: 17 February 1999 / Revised version: 22 April 1999 / Published online: 29 July 1999 相似文献
11.
Synthesis, integration, and electrical properties of individual single-walled carbon nanotubes 总被引:4,自引:0,他引:4
J. Kong C. Zhou A. Morpurgo H.T. Soh C.F. Quate C. Marcus H. Dai 《Applied Physics A: Materials Science & Processing》1999,69(3):305-308
High-quality single-walled carbon nanotubes (SWNTs) are synthesized by chemical vapor deposition (CVD) of methane on silicon-dioxide
substrates at controlled locations using patterned catalytic islands. With the synthesized nanotube chips, microfabrication
techniques are used to reliably contact individual SWNTs and obtain low contact resistance. The combined chemical synthesis
and microfabrication approaches enable systematic characterization of electron transport properties of a large number of individual
SWNTs. Results of electrical properties of representative semiconducting and metallic SWNTs are presented. The lowest two-terminal
resistance for individual metallic SWNTs (≈5 μm long) is ≈16.5 kΩ measured at 4.2 K.
Received: 17 May 1999 / Accepted: 18 May 1999 / Published online: 14 July 1999 相似文献
12.
J. Ferber U.C. Fischer N. Hagedorn H. Fuchs 《Applied Physics A: Materials Science & Processing》1999,69(6):581-589
An internal reflection mode is introduced for scanning near-field optical microscopy (SNOM) with the tetrahedral tip. A beam
of light is coupled into the tip and the light specularly reflected out of the tip is detected as a photosignal for SNOM.
An auxiliary STM mode is used to control the distance during the scanning process and to record the topography of the sample
simultaneously with the SNOM image. Images were obtained of different metallic samples which show a contrast in the order
of 10% of the total reflected photosignal. In images of metallic samples an inverted contrast is consistently obtained compared
to images previously obtained of comparable samples in a transmission mode. The contrast shows a pronounced dependence on
the polarization of the incident beam with respect to the orientation of the edges of the tip. In the case of gold surfaces,
the photosignal as a function of distance between the tip and the surface shows a pronounced peak in the near-field range
of 0–20 nm which is tentatively attributed to the excitation of surface plasmons on the gold surface. The pronounced near-field
effects and the strong contrast in the near-field images and the resolution well below 50 nm are an indication of a highly
efficient coupling of the incident beam to a local excitation of the tip apex which is essential for the function of the tip
as a probe for SNOM.
Received: 17 May 1999 / Accepted: 18 May 1999 / Published online: 21 October 1999 相似文献
13.
Field emission from carbon nanotubes: perspectives for applications and clues to the emission mechanism 总被引:15,自引:0,他引:15
J.-M. Bonard J.-P. Salvetat T. Stöckli L. Forró A. Châtelain 《Applied Physics A: Materials Science & Processing》1999,69(3):245-254
We report on the extensive characterization of carbon nanotube electron field emitters. We studied the emission behavior of
single-wall, closed and opened arc-discharge multi-wall, and catalytically grown multi-wall nanotubes, as single emitters
and in film form. The nanotube field emitters show excellent field emission properties, but significant differences were observed
between the different types of nanotubes. To obtain good performances as well as long emitter lifetimes, the nanotubes should
be multi-walled and have closed, well-ordered tips. Complementary results such as energy distribution and luminescence induced
by the field emission give further precious indications on the field emission mechanism. The large field amplification factor,
arising from the small radius of curvature of the nanotube tips, is partly responsible for the good emission characteristics.
Additional evidence however shows that the density of states at the tip is non-metallic, appearing in the form of localized
states with well-defined energy levels.
Received: 15 May 1999 / Accepted: 18 May 1999 / Published online: 29 July 1999 相似文献
14.
L. Minati G. Speranza S. Torrengo L. Toniutti C. Migliaresi D. Maniglio M. Ferrari A. Chiasera 《Surface science》2010,604(17-18):1414-1419
Multi-walled carbon nanotubes were functionalized with thiol groups by chemical route. Exploiting the chemical affinity between thiol and gold an assembly of carbon nanotubes was obtained by spontaneous chemical adsorption to gold using Au–S bonds. The multi-walled carbon nanotubes were first chemically cut by acid treatment and then functionalized with short chain thiol (2-aminoethanethiol). Substrate dipping in a suspension of functionalized carbon nanotubes allows them to bond to the gold surface. The resultant products, as well as the intermediate were characterized by means of X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, visible spectroscopy, scanning electron microscopy and atomic force microscopy. 相似文献
15.
C. Thomsen S. Reich H. Jantoljak I. Loa K. Syassen M. Burghard G.S. Duesberg S. Roth 《Applied Physics A: Materials Science & Processing》1999,69(3):309-312
The pressure dependence of the high-energy Raman modes in single- and multi-walled carbon nanotubes was measured in the range
0–10 GPa. We found the pressure coefficient to be linear in both materials but 25% smaller in MWNT. Given that the curvature
effects on vibrational properties of the rolled-up graphene sheets are small, we can explain this difference simply with elasticity
theory.
Received: 17 May 1999 / Accepted 18 May 1999 / Published online: 4 August 1999 相似文献
16.
M. Andersson A. Iline F. Stietz F. Träger 《Applied Physics A: Materials Science & Processing》1999,68(5):609-614
Gold films with a nominal thickness of 5–40 monolayers were grown on dielectric substrates and imaged by scanning force microscopy
(SFM). The films originally consisted of well-separated or densely packed clusters. During imaging in contact mode, the morphology
of the films changed drastically. At low coverage, i.e. Θ<10 monolayers, the well-known stripes originating from mobile clusters,
eventually accumulated into larger aggregates, were observed. In contrast, at larger coverage, highly ordered structures consisting
of one-dimensional wires evolved during scanning. They often were parallel with equal separation, i.e. well-defined periodicity,
over distances of several μm. Typically, the wires were 5–10 nm high and 50–100 nm wide. Investigations of Au films prepared
at varying temperature on different dielectric substrates allow us to suggest a self-assembling mechanism for wire formation
in which gold is periodically collected by the SFM tip and redeposited as soon as a critical amount is reached.
Received: 22 February 1999 / Accepted: 2 March 1999 / Published online: 7 April 1999 相似文献
17.
A. Berlinger 《Applied Physics A: Materials Science & Processing》1999,68(4):403-405
x surface of Si(111) wafers was studied as a function of annealing time at relatively low annealing temperatures (50 and 100 °C)
by application of scanning force microscopy. A fast increase in cluster diameter and height as a function of annealing time
was detected. After more than 3 h of annealing depletion zones and nucleation exclusion zones were observed.
Received: 13 August 1998 / Published online: 10 February 1999 相似文献
18.
J. Jersch F. Demming I. Fedotov K. Dickmann 《Applied Physics A: Materials Science & Processing》1999,68(6):637-641
Time-resolved dependence of the transient current through a ns laser pulse illuminated scanning tunneling microscope (STM)
tip/sample gap in tunneling mode and out of tunneling range is presented. A self-designed fast STM-preamplifier (bandwidth
35 MHz) allows one to resolve the fine structure of the transient signal as well as the observation of some effects that are
undetectable by using conventional low-band preamplifiers. The dependence of the threshold laser pulse intensity, which corresponds
to the beginning of electron emission from tip (in non-tunneling mode), as a function of the tip/sample distance was investigated.
At tip/sample distances from tunnel contact up to approximately 1 μm a linear dependence is found. This behavior is in good
agreement with the theory for field enhancement in a STM tip/sample system. In tunneling mode a ns (fast component) as well
as a μs (slow component) current response was found as a result of the laser pulse illumination. These data suggest the tip
bending to be an important factor in clarifying the thermal/mechanical mechanism of laser-assisted surface nanomodification.
Received: 4 May 1998 / Accepted: 29 January 1999 / Published online: 28 April 1999 相似文献
19.
H.S. Nagaraja F. Ohnesorge D.K. Avasthi R. Neumann P. Mohan Rao 《Applied Physics A: Materials Science & Processing》2000,71(3):337-341
Single crystals of the amino acid benzoyl glycine (hippuric acid) are irradiated normal to the as-grown surface by highly
charged Bi ions with a kinetic energy of 2.38 GeV and a fluence of 1×1010 ions/cm2. The projectiles create circular craters with a mean diameter of 40 (10) nm on the surface of the crystal as observed by
scanning force microscopy (SFM). The mean depth amounts to 4 (1) nm, this value being considered as a lower limit due to the
finite radius of curvature of the force cantilever tip. Thus, on the average, each single-ion projectile seems to eject about
104 molecules. On the surface of non-irradiated crystals, SFM reveals terraces of a few monolayers in height. In water, it was
possible to visualize the lattice periodicity. Terraces were also observed on the irradiated crystal surface in the presence
of the craters, indicating that the crystal is still intact at the given dose.
Received: 25 May 2000 / Accepted: 26 May 2000 / Published online: 13 July 2000 相似文献
20.
Investigation of the thermal conductivity of diamond film on aluminum nitride ceramic 总被引:1,自引:0,他引:1
Y. Liao R.C. Fang Z.Y. Ye N.G. Shang S.J. Han Q.Y. Shao S.Z. Ji 《Applied Physics A: Materials Science & Processing》1999,69(1):101-103
Diamond films were successfully synthesized on aluminum nitride(AlN) ceramic substrates by hot-filament chemical vapor deposition
(HFCVD) method. The thermal conductivity of the diamond film/aluminum nitride ceramic (DF/AlN) composites was studied by photothermal
deflection (PTD) technique. It has reached 2.04 W/cm K, 73% greater than that of AlN ceramic. Compared with the measurement
of scanning electron microscopy (SEM) and Raman spectroscopy, the influence of diamond films on the thermal conductivity of
the composites was pointed out. The adhesion and the stresses were also studied. The unusual stability and very good adhesion
of the diamond film on AlN ceramic substrate obtained is attributed to the formation of aluminum carbide.
Received: 24 March 1998 / Accepted: 8 March 1999 / Published online: 5 May 1999 相似文献