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3 Nov 1997

Volume 71, Issue 18, pp. 2557-2712

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Phase contrast hard x-ray microscopy with submicron resolution

S. Lagomarsino, A. Cedola, P. Cloetens, S. Di Fonzo, W. Jark, G. Soullié, and C. Riekel

Appl. Phys. Lett. 71, 2557 (1997); http://dx.doi.org/10.1063/1.119324 (3 pages) | Cited 36 times

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In this letter we present a hard x-ray phase contrast microscope based on the divergent and coherent beam exiting an x-ray waveguide. It uses lensless geometrical projection to magnify spatial variations in optical path length more than 700 times. Images of a nylon fiber and a gold test pattern were obtained with a resolution of 0.14 μm in one direction. Exposure times as short as 0.1 s gave already visible contrast, opening the way to high resolution, real time studies. © 1997 American Institute of Physics.
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07.85.-m X- and γ-ray instruments

Bright high efficiency blue organic light-emitting diodes with Al2O3/Al cathodes

H. Tang, F. Li, and J. Shinar

Appl. Phys. Lett. 71, 2560 (1997); http://dx.doi.org/10.1063/1.119325 (3 pages) | Cited 67 times

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The behavior of bright, efficient, low-driving-voltage blue organic light-emitting diodes based on amino-oxadiazole-fluorenes (AODFs) with Al2O3/Al cathodes is described. It is shown that the thin Al2O3 buffer layer sharply enhances current injection, increases the device efficiency, and reduces the driving voltage; the performance of devices with the optimal oxide buffer layer thickness approaches those with Mg0.9Ag0.1 cathodes. The effects of the Al2O3 buffer layer are believed to result from the removal of interface gap states induced by defects and chemical bonds between the AODF and Al, which trap carriers and quench singlet excitons nonradiatively. © 1997 American Institute of Physics.
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85.60.Jb Light-emitting devices
73.20.At Surface states, band structure, electron density of states
71.35.-y Excitons and related phenomena

Orientation-controlled organic electroluminescence of p-sexiphenyl films

H. Yanagi and S. Okamoto

Appl. Phys. Lett. 71, 2563 (1997); http://dx.doi.org/10.1063/1.119331 (3 pages) | Cited 79 times

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A multilayered electroluminescent device was constructed with epitaxially oriented films of p-sexiphenyl with its molecular axis lying or standing next to the substrate surface. The films with the lying and standing orientations were prepared by vapor deposition onto the KCl (001) surface kept at 20 and 150 °C, respectively. After successive depositions of electron-transport layer and Al cathode, the films were removed from the KCl substrate and transferred on an indium tin oxide coated glass anode. The cell with lying molecules emitted a higher electroluminescence with a narrowed spectrum at remarkably low driving voltages, as compared to one with standing molecules. This electroluminescent behaviors depend upon anisotropic distribution of the polarized emission light as well as efficiency of the carrier transport in the ordered molecular arrays with different orientation modes. © 1997 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.66.Qn Polymers; organic compounds
78.60.Fi Electroluminescence

Blue green stimulated emission from a high gain conjugated polymer

C. Zenz, W. Graupner, S. Tasch, G. Leising, K. Müllen, and U. Scherf

Appl. Phys. Lett. 71, 2566 (1997); http://dx.doi.org/10.1063/1.119332 (3 pages) | Cited 72 times

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An optically pumped waveguide structure has been fabricated with methyl substituted conjugated laddertype poly(paraphenylene) as the active material. The choice of the device parameters allows one to observe a high directionality, a small beam divergence, a complete linear polarization, and a linewidth with an upper limit of 1.7 nm at a considerable low threshold of 3 kW/cm2 at room temperature. © 1997 American Institute of Physics.
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78.45.+h Stimulated emission
42.55.Rz Doped-insulator lasers and other solid state lasers

Intracavity gain and absorption dynamics of hybrid modelocked semiconductor lasers using multiple quantum well saturable absorbers

S. Gee, R. Coffie, P. J. Delfyett, G. Alphonse, and J. Connolly

Appl. Phys. Lett. 71, 2569 (1997); http://dx.doi.org/10.1063/1.119333 (3 pages) | Cited 12 times

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Time resolved intracavity gain, saturable absorption dynamics, intracavity intensity pulse profiles, and their corresponding spectrograms, were measured in an external cavity hybrid mode-locked semiconductor diode laser. These measurements were performed to obtain fundamental information of the mode-locking dynamics and to determine their role in the pulse shaping and chirping dynamics. The results of these experiments show that the integrating nonlinearity associated with gain depletion, coupled with group velocity dispersion, leads to asymmetric intensity pulse profiles with predominantly cubic temporal phase, while saturable absorption coupled with group velocity dispersion tends to linearize the chirp. Exploitation of these dynamics may allow researchers to generate optical pulses with higher peak intensities than previously reported. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Fc Modulation, tuning, and mode locking
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
78.47.-p Spectroscopy of solid state dynamics

Absorption coefficient, energy gap, exciton binding energy, and recombination lifetime of GaN obtained from transmission measurements

J. F. Muth, J. H. Lee, I. K. Shmagin, R. M. Kolbas, H. C. Casey, B. P. Keller, U. K. Mishra, and S. P. DenBaars

Appl. Phys. Lett. 71, 2572 (1997); http://dx.doi.org/10.1063/1.120191 (3 pages) | Cited 173 times

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The absorption coefficient for a 0.4-μm-thick GaN layer grown on a polished sapphire substrate was determined from transmission measurements at room temperature. A strong, well defined exciton peak for the A and B excitons was obtained. The A, B, and C excitonic features are clearly defined at 77 K. At room temperature, an energy gap Eg = 3.452±0.001 eV and an exciton binding energy ExA,B = 20.4±0.5 meV for the A and B excitons and ExC = 23.5±0.5 meV for the C exciton were determined by analysis of the absorption coefficient. From this measured absorption coefficient, together with the detailed balance approach of van Roosbroek and Shockley, the radiative constant B = 1.1×10−8 cm3/s was obtained. © 1997 American Institute of Physics.
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78.66.Fd III-V semiconductors
71.20.Nr Semiconductor compounds
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
73.61.Ey III-V semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Temperature independent performance of organic semiconductor lasers

V. G. Kozlov, V. Bulović, and S. R. Forrest

Appl. Phys. Lett. 71, 2575 (1997); http://dx.doi.org/10.1063/1.120186 (3 pages) | Cited 42 times

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Characteristics of lasing in optically pumped, vacuum deposited organic semiconductor thin films of tris-(8-hydroxyquinoline) aluminum doped with DCM laser dye are studied as a function of DCM concentration and ambient temperature. In contrast to inorganic laser diodes, the lasing wavelength, output power, differential quantum efficiency, and threshold pump energy of organic lasers are found to be independent of temperature in the range from 0 to 140 °C. In addition, no degradation in laser performance was observed at temperatures approaching 160 °C. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
78.66.Li Other semiconductors
78.66.Qn Polymers; organic compounds

Two-photon optical beam induced current imaging through the backside of integrated circuits

Chris Xu and Winfried Denk

Appl. Phys. Lett. 71, 2578 (1997); http://dx.doi.org/10.1063/1.119334 (3 pages) | Cited 21 times

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Two-photon optical beam induced current (TOBIC) images were acquired through the polished backsides of integrated circuits. An excitation beam with a photon energy below the band gap can traverse even thick substrates virtually unattenuated. At the focus—and only there—two-photon absorption generates electron-hole pairs very efficiently when using a sub-picosecond light source. An additional advantage of TOBIC is a significant increase in spatial resolution. With high numerical aperture objective lense features smaller than 1 μm are easily discernible. © 1997 American Institute of Physics.
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85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology
72.40.+w Photoconduction and photovoltaic effects

Evidence for strong spatially localized band-filling effects at interface islands

Y. J. Ding, D. C. Reynolds, S. J. Lee, J. B. Khurgin, W. S. Rabinovich, and D. S. Katzer

Appl. Phys. Lett. 71, 2581 (1997); http://dx.doi.org/10.1063/1.119335 (3 pages) | Cited 4 times

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We have observed saturation of photoluminescence peak at extremely low pump intensities in growth-interrupted and undoped asymmetric-coupled quantum-well structures. We believe the saturation is due to filling of the exciton states localized at the interface islands. The exciton density required to completely fill the localized exciton states at the interface islands for one of the samples is two orders of magnitude lower than that for the previous sample. We have demonstrated that even under the same growth condition, two samples with the same structure exhibit distinctly different photoluminescence spectra and saturation characteristics. © 1997 American Institute of Physics.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors

Bound-free vacuum uv emissions of (XeCs)+ and (KrCs)+ ionic excimers by relativistic electron beam excitation

Da Xing, Qi Wang, Shi-ci Tan, and Ken-ichi Ueda

Appl. Phys. Lett. 71, 2584 (1997); http://dx.doi.org/10.1063/1.120187 (3 pages) | Cited 2 times

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Bound-free vacuum uv emissions from rare-gas alkali ionic excimers were observed by relativistic electron beam pumping of gas mixtures of Xe or Kr with hot cesium vapor. The observed two diffuse emission bands centered at 159 and 131 nm are assigned to be the 2 1Σ+→1 1Σ+ transition of (XeCs)+ and (KrCs)+ ionic excimers, respectively. © 1997 American Institute of Physics.
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34.80.Gs Molecular excitation and ionization
31.30.J- Relativistic and quantum electrodynamic (QED) effects in atoms, molecules, and ions
33.50.Dq Fluorescence and phosphorescence spectra

Δn = 0.22 birefringence measurement by surface emitting second harmonic generation in selectively oxidized GaAs/AlAs optical waveguides

A. Fiore, V. Berger, E. Rosencher, S. Crouzy, N. Laurent, and J. Nagle

Appl. Phys. Lett. 71, 2587 (1997); http://dx.doi.org/10.1063/1.119336 (3 pages) | Cited 15 times

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We have measured the birefringence enhancement due to lateral selective oxidation of AlAs in GaAs/AlAs optical waveguides. The birefringence was measured by imaging the surface-emitted second harmonic generated by the nonlinear interaction of counterpropagating TE and TM modes. In a waveguide containing a single AlAs layer the birefringence is enhanced from Δn = 0.017 (before oxidation) to Δn = 0.038 (after oxidation). In an oxidized multilayer GaAs/AlAs waveguide, a birefringence as high as Δn = 0.22 is measured. This birefringence is sufficient to phase-match the difference frequency generation of 3–5 μm infrared radiation from two near-infrared pumps. © 1997 American Institute of Physics.
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42.79.Gn Optical waveguides and couplers
42.65.Wi Nonlinear waveguides
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
78.20.Fm Birefringence
42.81.Gs Birefringence, polarization
81.65.Mq Oxidation
42.82.Et Waveguides, couplers, and arrays

Thermal lens determination of end-pumped solid-state lasers using primary degeneration modes

Bernd Ozygus and Qincheng Zhang

Appl. Phys. Lett. 71, 2590 (1997); http://dx.doi.org/10.1063/1.119337 (3 pages) | Cited 14 times

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A simple method using the singularities of an optical resonator to determine the thermal lens of end-pumped laser crystals is reported in this letter. At certain resonator parameters the transverse structures of the laser beam become a superposition of many transverse cavity modes of equal resonance frequencies. Because the resonator parameters depend on the thermally induced lens in the active medium, the strength of the lens can be determined by means of measuring the shift of the degeneration resonator length depending on the pumping power. The method is applied to an end-pumped Nd:YAG laser. © 1997 American Institute of Physics.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.79.Bh Lenses, prisms and mirrors

Gas-source molecular beam epitaxy growth of an 8.5 μm quantum cascade laser

S. Slivken, C. Jelen, A. Rybaltowski, J. Diaz, and M. Razeghi

Appl. Phys. Lett. 71, 2593 (1997); http://dx.doi.org/10.1063/1.119338 (3 pages) | Cited 13 times

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We demonstrate preliminary results for an 8.5 μm laser emission from quantum cascade lasers grown in a single step by gas-source molecular beam epitaxy. 70 mW peak power per two facets is recorded for all devices tested at 79 K with 1 μs pulses at 200 Hz. For a 3 mm cavity length, lasing persists up to 270 K with a T0 of 180 K. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.05.Ea III-V semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Temperature-dependent electroluminescence from (Eu, Gd) coordination complexes

Xianmin Zhang, Runguang Sun, Qianbing Zheng, Takayoshi Kobayashi, and Wenlian Li

Appl. Phys. Lett. 71, 2596 (1997); http://dx.doi.org/10.1063/1.119339 (3 pages) | Cited 20 times

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Light emission from single-layered electroluminescent devices is described in which (Eu, Gd) coordination complexes, (Eu0.1Gd0.9)(TTA)3(TPPO)2, and electron transport material oxadiazole derivative, 2-(4-biphenyl)-5-(4-t-butylphenylyl)-1,3,4-oxadiazole, are dispersed in a hole-transporting host polymer poly(N-vinylcarbazole) film. The color of the emitted electroluminescence changes smoothly from green-white to red with temperature varying from 77 to 300 K. This phenomenon is discussed in terms of temperature dependent yields of phosphorescence from the triplet state of the Gd and Eu chelates and the intermolecular energy transfer from Gd-chelate to Eu-chelate cages. © 1997 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.60.Fi Electroluminescence
71.35.-y Excitons and related phenomena

Electro-optic birefringence in semiconductor vertical-cavity lasers

R. F. M. Hendriks, M. P. van Exter, J. P. Woerdman, A. van Geelen, L. Weegels, K. H. Gulden, and M. Moser

Appl. Phys. Lett. 71, 2599 (1997); http://dx.doi.org/10.1063/1.119340 (3 pages) | Cited 15 times

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Birefringence induced by the electro-optic effect is demonstrated in vertical-cavity surface-emitting lasers (VCSEL). This is done by comparing two types of optically pumped VCSELs: VCSELs with standard pin-doping and VCSELs with symmetrical pip-doping. The observed birefringence in these VCSELs differs by an order of magnitude, a difference that we ascribe to the presence and absence, respectively, of electro-optic birefringence. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
78.20.Jq Electro-optical effects
78.20.Fm Birefringence

Pressure-induced blueshift of Nd3+ fluorescence emission in YAlO3: Near infrared pressure sensor

Hong Hua and Yogesh K. Vohra

Appl. Phys. Lett. 71, 2602 (1997); http://dx.doi.org/10.1063/1.119341 (3 pages) | Cited 4 times

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Pressure-induced shift of fluorescence emission in garnets and other oxides is investigated for applications as optical pressure sensors. We report high pressure studies on the fluorescence emission from neodymium-doped yttrium aluminum perovskite (Nd3+:YAlO3) to 80 GPa at room temperature. Unusual nonlinear blueshift of wavelength with pressure was found for several fluores cence peaks in the wavelength region of 850–900 nm. These peaks are identified as the lines associated with transition Nd3+:4F3/2→4I9/2 in YAlO3. The blueshift of these emissions is compared with the redshift of the same system in neodymium-doped yttrium aluminum garnet (Nd3+:Y3Al5O12). The shift with pressure is related to the change in the Stark level splitting with pressure. In view of the strong red emission from diamond anvils at ultrahigh pressures, this near infrared emission of Nd3+:YAlO3 holds promise as an ultrahigh pressure sensor. © 1997 American Institute of Physics.
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78.55.Hx Other solid inorganic materials
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
06.30.-k Measurements common to several branches of physics and astronomy
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
62.50.-p High-pressure effects in solids and liquids
42.79.Pw Imaging detectors and sensors
42.70.Hj Laser materials
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment

Enhanced harmonic emission from ionized clusters in intense laser pulses

S. X. Hu and Z. Z. Xu

Appl. Phys. Lett. 71, 2605 (1997); http://dx.doi.org/10.1063/1.119342 (3 pages) | Cited 30 times

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We present a two-dimensional model to simulate the enhanced harmonic emission from ionized argon clusters irradiated by an ultrashort ( ∼ 25 fs) laser pulse at moderate intensity ( ∼ 1014 W/cm2). The low-order harmonics (below the 15th) are enhanced by nearly two orders of magnitude relative to those of monomer argon. Furthermore, the harmonic plateau is extended to a higher frequency. The clustering environment is responsible for the enhancement of harmonic emission. © 1997 American Institute of Physics.
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36.40.-c Atomic and molecular clusters
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
33.80.Be Level crossing and optical pumping

Microscopic theory of gain for an InGaN/AlGaN quantum well laser

W. W. Chow, A. F. Wright, A. Girndt, F. Jahnke, and S. W. Koch

Appl. Phys. Lett. 71, 2608 (1997); http://dx.doi.org/10.1063/1.120155 (3 pages) | Cited 29 times

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This letter describes a microscopic gain theory for an InGaN/AlGaN quantum well laser. The approach, which is based on the semiconductor Bloch equations, with carrier correlations treated at the level of quantum kinetic theory in the Markovian limit, gives a consistent treatment of plasma and excitonic effects, both of which are important under lasing conditions. Inhomogeneous broadening due to spatial variations in quantum well thickness or composition is taken into account by a statistical average of the homogeneously broadened spectra. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
71.35.-y Excitons and related phenomena

Local atomic environment of Cu ions in ion-exchanged silicate glass waveguides: An x-ray absorption spectroscopy study

F. D’Acapito, S. Colonna, S. Mobilio, F. Gonella, E. Cattaruzza, and P. Mazzoldi

Appl. Phys. Lett. 71, 2611 (1997); http://dx.doi.org/10.1063/1.120156 (3 pages) | Cited 17 times

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We present an x-ray absorption spectroscopy study at the Cu K edge on Cu-doped soda-lime and BK7 glass waveguides obtained by ion exchange under various preparation conditions. The total electron yield and x-ray fluorescence yield collection modes were used to evidence the chemical behavior of surfacial and deep Cu ions. In all the samples copper is found preferentially as Cu+ throughout the whole exchanged region. The first coordination shell is formed by two to three oxygen atoms at 1.86 Å, much shorter than the Na–O bond (2.3 Å) in soda-lime glasses. © 1997 American Institute of Physics.
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42.70.Ce Glasses, quartz
42.79.Gn Optical waveguides and couplers
42.82.Et Waveguides, couplers, and arrays
78.70.Dm X-ray absorption spectra
82.30.Hk Chemical exchanges (substitution, atom transfer, abstraction, disproportionation, and group exchange)

Sensitivity of Bragg surface diffraction to analyze ion-implanted semiconductors

M. A. Hayashi, S. L. Morelhão, L. H. Avanci, L. P. Cardoso, J. M. Sasaki, L. C. Kretly, and S. L. Chang

Appl. Phys. Lett. 71, 2614 (1997); http://dx.doi.org/10.1063/1.120157 (3 pages) | Cited 10 times

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A special case of the x-ray multiple diffraction phenomenon, the Bragg surface diffraction (BSD), has been investigated under lattice damage due to ion implantation in GaAs (001) samples. The BSD profile is very sensitive to the diffraction regime (dynamical or kinematical) and provides information regarding crystalline perfection and lattice strains in both directions—parallel and perpendicular—to the sample surface. Results from grazing-incidence x-ray diffraction and reciprocal space mapping are also reported. © 1997 American Institute of Physics.
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61.72.uj III-V and II-VI semiconductors
61.80.Jh Ion radiation effects
61.05.cp X-ray diffraction

Epitaxial liftoff of thin oxide layers: Yttrium iron garnets onto GaAs

M. Levy, R. M. Osgood, A. Kumar, and H. Bakhru

Appl. Phys. Lett. 71, 2617 (1997); http://dx.doi.org/10.1063/1.120192 (3 pages) | Cited 32 times

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We report on the implementation of epitaxial liftoff in magnetic garnets. Deep-ion implantation is used to create a buried sacrificial layer in single-crystal yttrium iron garnet (YIG) and bismuth-substituted YIG epilayers grown on gadolinium gallium garnet. The damage generated by the implantation induces a large etch selectivity between the sacrificial layer and the rest of the garnet. 10-μm-thick films of excellent quality are lifted off and bonded to silicon and GaAs substrates. No noticeable degradation in magnetic coercivity due to domain pinning is observed. Stress-induced microfracturing in the thin oxide layers is also addressed. © 1997 American Institute of Physics.
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75.50.Gg Ferrimagnetics
81.65.Cf Surface cleaning, etching, patterning
85.40.Ry Impurity doping, diffusion and ion implantation technology
85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology
61.72.up Other materials
61.80.Jh Ion radiation effects
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.70.Kw Domain structure (including magnetic bubbles and vortices)

Epitaxial carbon nanotube film self-organized by sublimation decomposition of silicon carbide

Michiko Kusunoki, Masumi Rokkaku, and Toshiyuki Suzuki

Appl. Phys. Lett. 71, 2620 (1997); http://dx.doi.org/10.1063/1.120158 (3 pages) | Cited 63 times

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A film of well-oriented carbon nanotubes was produced by sublimation decomposition of silicon carbide at 1700 °C by using YAG laser heating in a transmission electron microscope (TEM). The processes of SiC decomposition and the formation of carbon nanotubes were observed successively by high-resolution electron microscopy (HREM). Carbon nanotubes were mostly oriented along the [111] direction on the (111) surface plane of β-SiC single crystal. The interface between them was observed by HREM. © 1997 American Institute of Physics.
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81.07.-b Nanoscale materials and structures: fabrication and characterization
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
81.05.ub Fullerenes and related materials
61.46.-w Structure of nanoscale materials
64.70.Hz Solid-vapor transitions

On the initial unloading slope in indentation of elastic-plastic solids by an indenter with an axisymmetric smooth profile

Che-Min Cheng (Zheng Zhemin) and Yang-Tse Cheng

Appl. Phys. Lett. 71, 2623 (1997); http://dx.doi.org/10.1063/1.120159 (3 pages) | Cited 37 times

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A simple relationship between the initial unloading slope, the contact area, and the elastic modulus is derived for indentation in elastic-plastic solids by an indenter with an arbitrary axisymmetric smooth profile. Although the same expression was known to hold for elastic solids, the new derivation shows that it is also true for elastic-plastic solids with or without work hardening and residual stress. These results should provide a sound basis for the use of the relationship for mechanical property determination using indentation techniques. © 1997 American Institute of Physics.
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46.55.+d Tribology and mechanical contacts
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
46.25.-y Static elasticity

Evidence for layered growth of (100) textured diamond films

V. P. Godbole, A. V. Sumant, R. B. Kshirsagar, and C. V. Dharmadhikari

Appl. Phys. Lett. 71, 2626 (1997); http://dx.doi.org/10.1063/1.120160 (3 pages) | Cited 4 times

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The growth of diamond films synthesized by the hot filament chemical vapor deposition method has been studied by scanning tunneling microscopy (STM). The smooth (100) faces of micron-sized diamond crystallites were found to exhibit pyramidal shaped architecture at the nano level. The STM data for chemical vapor deposited diamond is analyzed in the light of recently developed dynamical scaling approach. The value of the scaling exponent α ≅ 0.85 signifies a growth primarily driven by the transport of reacting species on the surface rather than molecular diffusion in gas phase. © 1997 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.-a Thin film structure and morphology
81.05.ub Fullerenes and related materials
68.35.B- Structure of clean surfaces (and surface reconstruction)
81.05.Cy Elemental semiconductors

Length control of individual carbon nanotubes by nanostructuring with a scanning tunneling microscope

Liesbeth C. Venema, J. W. G. Wildöer, H. L. J. Temminck Tuinstra, C. Dekker, A. G. Rinzler, and R. E. Smalley

Appl. Phys. Lett. 71, 2629 (1997); http://dx.doi.org/10.1063/1.120161 (3 pages) | Cited 67 times

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We present a technique to control the length of carbon nanotubes. Individual carbon nanotubes can be locally cut by applying a voltage pulse to the tip of a scanning tunneling microscope (STM). Topographic imaging and STM spectroscopy are subsequently used to investigate the result. The electronic properties of a nanotube can be strongly changed by reducing the size. Current-voltage curves obtained by STM spectroscopy on a 30 nm short tube created from a longer nanotube show a stepwise increase of the current, which is attributed to quantum size effects. © 1997 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
68.35.B- Structure of clean surfaces (and surface reconstruction)
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