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5 Jan 1998

Volume 72, Issue 1, pp. 1-133

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Fuzzy controlled feedback applied to a combined scanning tunneling and force microscope

F. M. Battiston, M. Bammerlin, C. Loppacher, R. Lüthi, E. Meyer, H.-J. Güntherodt, and F. Eggimann

Appl. Phys. Lett. 72, 25 (1998); http://dx.doi.org/10.1063/1.120635 (3 pages) | Cited 5 times

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A feedback mechanism based on fuzzy logic has been applied to operate a combined atomic force microscope (AFM)/scanning tunneling microscope (STM), which is able to measure the resonance frequency shift Δf of the cantilever-type spring and the mean tunneling current Īt simultaneously. Using a decision making logic, the microscope can be scanned over a heterogeneous surface without tip crash. On the conductive parts of the sample, the STM mode is preferred, whereas the noncontact (nc)-AFM mode is used on the poorly conductive parts of the surface. The transition from the STM mode to nc-AFM mode is performed smoothly with the fuzzy logic feedback. © 1998 American Institute of Physics.
Show PACS
07.79.Cz Scanning tunneling microscopes
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
07.05.Mh Neural networks, fuzzy logic, artificial intelligence

Thermally activated electron capture by mobile protons in SiO2 thin films

K. Vanheusden, S. P. Karna, R. D. Pugh, W. L. Warren, D. M. Fleetwood, R. A. B. Devine, and A. H. Edwards

Appl. Phys. Lett. 72, 28 (1998); http://dx.doi.org/10.1063/1.121447 (3 pages) | Cited 11 times

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The annihilation of mobile protons in thin SiO2 films by capture of ultraviolet-excited electrons has been analyzed for temperatures between 77 and 500 K. We observe a strong increase in proton annihilation with increasing temperature, and derive an activation energy for electron capture of about 0.2 eV. Based on quantum chemical [(OH)3Si]2�O�H+ cluster calculations, we suggest photoexcitation of electrons from excited vibrational states of the ground electronic (valence band) state to a nearby excited electronic (SiO2 gap) state. It is argued that the latter excitation can result in H0 formation at elevated temperatures. © 1998 American Institute of Physics.
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73.61.Ng Insulators
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
71.55.Ht Other nonmetals

X-ray photoelectron spectroscopy study of excimer laser treated alumina films

D. G. Georgiev, K. Kolev, L. D. Laude, B. Mednikarov, and N. Starbov

Appl. Phys. Lett. 72, 31 (1998); http://dx.doi.org/10.1063/1.120636 (3 pages) | Cited 2 times

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Amorphous alumina layers are deposited on a single crystal Si substrate by a e-gun evaporation technique. These films are then thermally annealed in oxygen to be crystallized and, further, irradiated with an excimer laser beam. At each stage of the film preparation, an x-ray photoelectron spectroscopy analysis is performed at the film surface and in depth, upon ion beam grinding. Results give evidence for the formation of an aluminosilicate upon thermal annealing of the film in oxygen. At the surface itself, this compound is observed to decompose upon excimer laser irradiation at energy densities exceeding 1.75 J/cm2, giving rise to free Si atoms and SiO2, however with complete disappearance of Al atoms. Model photochemical reactions are proposed to explain such transformations. © 1998 American Institute of Physics.
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79.60.Bm Clean metal, semiconductor, and insulator surfaces
61.72.Cc Kinetics of defect formation and annealing
82.50.-m Photochemistry

Mesoscopic caverns and nucleation twins formed in the growth of Co on Cu

G. L. Zhou and C. P. Flynn

Appl. Phys. Lett. 72, 34 (1998); http://dx.doi.org/10.1063/1.120637 (3 pages) | Cited 1 time

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Mesoscopic caverns in the form of facetted voids are observed to form when Cu pumps through pinholes to the outer surface during the epitaxial growth of fcc Co(111) on Cu(111) near 500 °C. We prove that the pinholes are located mainly at boundaries between fcc twin domains that occur with ABC and ACB stacking. © 1998 American Institute of Physics.
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68.55.-a Thin film structure and morphology
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
61.72.Mm Grain and twin boundaries
61.72.Qq Microscopic defects (voids, inclusions, etc.)

Scanning Joule expansion microscopy at nanometer scales

J. Varesi and A. Majumdar

Appl. Phys. Lett. 72, 37 (1998); http://dx.doi.org/10.1063/1.120638 (3 pages) | Cited 41 times

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We report a new technique called scanning Joule expansion microscopy that can simultaneously image surface topography and material expansion due to Joule heating with vertical resolution in the 1 pm range and lateral resolution similar to that of an atomic force microscope. By coating the sample with a polymer film, we demonstrate that sample temperature distribution can be directly measured without the need of fabricating temperature-sensing scanning probes.© 1998 American Institute of Physics.  
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07.79.-v Scanning probe microscopes and components
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
07.20.Dt Thermometers
68.35.B- Structure of clean surfaces (and surface reconstruction)

Phase separation in InGaN grown by metalorganic chemical vapor deposition

N. A. El-Masry, E. L. Piner, S. X. Liu, and S. M. Bedair

Appl. Phys. Lett. 72, 40 (1998); http://dx.doi.org/10.1063/1.120639 (3 pages) | Cited 131 times

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We report on phase separation in thick InGaN films with up to 50% InN grown by metalorganic chemical vapor deposition from 690 to 780 °C. InGaN films with thicknesses of 0.5 μm were analyzed by θ–2θ x-ray diffraction, transmission electron microscopy (TEM), and selected area diffraction (SAD). Single phase InGaN was obtained for the as-grown films with <28% InN. However, for films with higher than 28% InN, the samples showed a spinodally decomposed microstructure as confirmed by TEM and extra spots in SAD patterns that corresponded to multiphase InGaN. © 1998 American Institute of Physics.
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68.55.Nq Composition and phase identification
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.05.Ea III-V semiconductors
64.75.-g Phase equilibria
81.30.Mh Solid-phase precipitation

Nanocrystalline-silicon superlattice produced by controlled recrystallization

L. Tsybeskov, K. D. Hirschman, S. P. Duttagupta, M. Zacharias, P. M. Fauchet, J. P. McCaffrey, and D. J. Lockwood

Appl. Phys. Lett. 72, 43 (1998); http://dx.doi.org/10.1063/1.120640 (3 pages) | Cited 125 times

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Nanocrystalline-silicon superlattices are produced by controlled recrystallization of amorphous-Si/SiO2 multilayers. The recrystallization is performed by a two-step procedure: rapid thermal annealing at 600–1000 °C, and furnace annealing at 1050 °C. Transmission electron microscopy, Raman scattering, x-ray and electron diffraction, and photoluminescence spectroscopy show an ordered structure with Si nanocrystals confined between SiO2 layers. The size of the Si nanocrystals is limited by the thickness of the a-Si layer, the shape is nearly spherical, and the orientation is random. The luminescence from the nc-Si superlattices is demonstrated and studied. © 1998 American Institute of Physics.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
61.72.Cc Kinetics of defect formation and annealing
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
78.66.Db Elemental semiconductors and insulators
78.30.Am Elemental semiconductors and insulators
78.55.Ap Elemental semiconductors

The role of second-neighbor effects in photoemission: Are silicon surfaces and interfaces special?

K. Z. Zhang, K. E. Litz, M. M. Banaszak Holl, and F. R. McFeely

Appl. Phys. Lett. 72, 46 (1998); http://dx.doi.org/10.1063/1.120641 (3 pages) | Cited 8 times

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A widely used assignment scheme for Si 2p core-level photoemission studies of silicon oxidation relies solely on the formal oxidation state of the silicon. The tacit assumption of this assignment methodology is that second-neighbor effects have no measurable effect on observed Si 2p binding energies. In this letter, new experiments are combined with literature precedents to make the case that the second-neighbor effects play an important role in determining binding energy shifts. © 1998 American Institute of Physics.
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79.60.Jv Interfaces; heterostructures; nanostructures
81.65.Mq Oxidation
73.20.At Surface states, band structure, electron density of states
79.60.Dp Adsorbed layers and thin films
79.60.Bm Clean metal, semiconductor, and insulator surfaces
81.05.Cy Elemental semiconductors
73.20.Hb Impurity and defect levels; energy states of adsorbed species
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