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12 Jul 1999

Volume 75, Issue 2, pp. 151-304

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High-sensitivity quantitative Kelvin probe microscopy by noncontact ultra-high-vacuum atomic force microscopy

Ch. Sommerhalter, Th. W. Matthes, Th. Glatzel, A. Jäger-Waldau, and M. Ch. Lux-Steiner

Appl. Phys. Lett. 75, 286 (1999); http://dx.doi.org/10.1063/1.124357 (3 pages) | Cited 93 times

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We present quantitative measurements of the work function of semiconductor and metal surfaces prepared in ultrahigh vacuum (UHV) using a combination of UHV noncontact atomic force microscopy and Kelvin probe force microscopy. High energetic and lateral resolution is achieved by using the second resonance frequency of the cantilever to measure the electrostatic forces, while the first resonance frequency is used to simultaneously obtain topographic images by the frequency modulation technique. Spatially resolved work-function measurements reveal a reduced work function in the vicinity of steps on highly oriented pyrolytic graphite. On the GaAs(110) surface it could be demonstrated that defect states in the forbidden band gap cause a local pinning of the Fermi level along monolayer steps. On p-WSe2(0001) work-function variations due to the Coulomb potential of single dopant sites were resolved. © 1999 American Institute of Physics.
Show PACS
07.79.Lh Atomic force microscopes
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy
73.30.+y Surface double layers, Schottky barriers, and work functions
73.20.Hb Impurity and defect levels; energy states of adsorbed species
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.35.Dv Composition, segregation; defects and impurities

High-sensitivity piezoresistive cantilevers under 1000 Å thick

J. A. Harley and T. W. Kenny

Appl. Phys. Lett. 75, 289 (1999); http://dx.doi.org/10.1063/1.124350 (3 pages) | Cited 62 times

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Ultrathin, high-sensitivity piezoresistive cantilevers were constructed using vapor-phase epitaxy to grow the conducting layer. A fourfold reduction in thickness was achieved over the thinnest implanted piezoresistive cantilevers, allowing improved force or displacement sensitivity and increased bandwidth. In cantilevers 890 Å thick, the dopant is well confined to the surface, and the sensitivity is 70% of the theoretical maximum. A cantilever fabricated for high force resolution has a minimum detectable force of 8.6 fN/math in air. Additionally, the 1/f noise is shown to follow the relation proposed by Hooge [Phys. Lett A 29, 139 (1969)], increasing in inverse proportion to the number of carriers. © 1999 American Institute of Physics.
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77.55.-g Dielectric thin films
77.65.-j Piezoelectricity and electromechanical effects
81.15.Kk Vapor phase epitaxy; growth from vapor phase
07.79.Lh Atomic force microscopes
73.50.Td Noise processes and phenomena

Direct nanometer-scale patterning by the cantilever oscillation of an atomic force microscope

C. K. Hyon, S. C. Choi, S. W. Hwang, D. Ahn, Yong Kim, and E. K. Kim

Appl. Phys. Lett. 75, 292 (1999); http://dx.doi.org/10.1063/1.124351 (3 pages) | Cited 21 times

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A resistless nanostructure patterning technique using tip oscillation of an atomic force microscope (AFM) was systematically investigated. Commercial AFM cantilevers are used to successfully generate patterns as narrow as 10 nm on a GaAs surface, without further sharpening of the tips. Reliable patterns with fully controlled width and depth are achieved by adjusting the feedback gain and the scan speed. This process allows nanometer-scale patterning to be performed simply, and is well suited for nanodevice fabrication. © 1999 American Institute of Physics.
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81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices
07.79.Lh Atomic force microscopes
81.05.Ea III-V semiconductors

Measurement of fluid properties with a near-field acoustic sensor

R. Patois, P. Vairac, and B. Cretin

Appl. Phys. Lett. 75, 295 (1999); http://dx.doi.org/10.1063/1.124352 (3 pages) | Cited 9 times

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The proposed microsensor is derived from the electromechanical resonator of our ac force microscope: the scanning microdeformation microscope (SMM). A submillimetric spherical probe immersed in the fluid sample replaces the tip usually used in SMM. This sphere is connected to a cantilever, which is excited at the resonance frequency. The measurement of the resonance frequency and of the damping enables the quantitative characterization of the investigated fluid. A theoretical approach allows to model the system behavior. The model takes into account two aspects: the mechanical vibration of the cantilever and the fluid mechanics. The values predicted by the model are in good agreement with the experimental measurements performed for various viscous media. © 1999 American Institute of Physics.
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07.64.+z Acoustic instruments and equipment
07.79.-v Scanning probe microscopes and components
06.30.Dr Mass and density
47.80.-v Instrumentation and measurement methods in fluid dynamics
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.10.Cm Micromechanical devices and systems

Statistical modeling of pulse height spectrum of gamma-ray spectrometers limited by incomplete charge collection

Y. Nemirovsky

Appl. Phys. Lett. 75, 298 (1999); http://dx.doi.org/10.1063/1.124353 (3 pages) | Cited 6 times

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This letter presents an analytic approach to the calculation of the pulse height spectrum, using a statistical model, which simultaneously considers a random point of photon absorption (i.e., nonuniform absorption) and a random drift time for each carrier. The pulse height spectrum of gamma-ray spectrometers is calculated as a function of photon energy, electron and hole mobility-lifetime products and applied electric field. For spectrometers with a uniform electric field the pulse height spectrum is obtained by a single numerical integration of an analytical expression. © 1999 American Institute of Physics.
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07.85.Nc X-ray and γ-ray spectrometers
29.30.Kv X- and γ-ray spectroscopy
29.40.Wk Solid-state detectors
07.05.Tp Computer modeling and simulation
02.50.-r Probability theory, stochastic processes, and statistics
05.10.-a Computational methods in statistical physics and nonlinear dynamics
72.20.Fr Low-field transport and mobility; piezoresistance
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Fabrication of metallic electrodes with nanometer separation by electromigration

Hongkun Park, Andrew K. L. Lim, A. Paul Alivisatos, Jiwoong Park, and Paul L. McEuen

Appl. Phys. Lett. 75, 301 (1999); http://dx.doi.org/10.1063/1.124354 (3 pages) | Cited 282 times

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A simple yet highly reproducible method to fabricate metallic electrodes with nanometer separation is presented. The fabrication is achieved by passing a large electrical current through a gold nanowire defined by electron-beam lithography and shadow evaporation. The current flow causes the electromigration of gold atoms and the eventual breakage of the nanowire. The breaking process yields two stable metallic electrodes separated by ∼1 nm with high efficiency. These electrodes are ideally suited for electron-transport studies of chemically synthesized nanostructures, and their utility is demonstrated here by fabricating single-electron transistors based on colloidal cadmium selenide nanocrystals. © 1999 American Institute of Physics.
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66.30.Qa Electromigration
85.40.Hp Lithography, masks and pattern transfer
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.-a Thin film structure and morphology
85.40.Sz Deposition technology
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