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14 Jun 1999

Volume 74, Issue 24, pp. 3595-3737

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Evidence of Be3P2 formation during growth of Be-doped phosphorus-based semiconductor compounds

M. M. G. de Carvalho, J. Betinni, M. A. A Pudenzi, L. P. Cardoso, and M. A. Cotta

Appl. Phys. Lett. 74, 3669 (1999); http://dx.doi.org/10.1063/1.123216 (3 pages) | Cited 4 times

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In this work, we present evidence that Be3P2 microcrystals are formed in Be-doped phosphorus-based semiconductor compounds grown by chemical beam epitaxy. Our results suggest that microcrystal formation occurs when high Be concentrations (>1018 cm−3) and temperatures higher than 500 °C are used for crystal growth. The main consequence of Be3P2 formation is a high phosphorus consumption close to these microcrystals that causes a large density of P vacancies in the semiconductor layer. This results in reduced electrical mobility, lattice parameter reduction, and poor crystalinity of the film in general. © 1999 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.61.Ey III-V semiconductors
81.05.Ea III-V semiconductors
61.72.J- Point defects and defect clusters
72.20.Fr Low-field transport and mobility; piezoresistance
73.50.Dn Low-field transport and mobility; piezoresistance
68.35.Fx Diffusion; interface formation

Electrical simulation of scanning capacitance microscopy imaging of the pn junction with semiconductor probe tips

M. L. O’Malley, G. L. Timp, W. Timp, S. V. Moccio, J. P. Garno, and R. N. Kleiman

Appl. Phys. Lett. 74, 3672 (1999); http://dx.doi.org/10.1063/1.123217 (3 pages) | Cited 13 times

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Scanning capacitance microscopy (SCM) enables the imaging of the two-dimensional carrier profiles of small transistors. Initial imaging utilized metal-coated probe tips but the limited resolution achievable with these tips due to their size led us to investigate micromachined silicon tips with a smaller tip diameter. Electrical simulations of a pn junction structure probed with semiconducting tips indicate that image improvements result from the semiconductor nature of the silicon tips as well as from the smaller tip size. The tip becomes active in the imaging process as the capacitance–voltage responses of the tip and sample interact to improve image contrast and decrease the Vbias dependence of the pn junction locations. SCM images of a 60 nm gate length n-metal–oxide–semiconductor device, obtained using a boron-doped silicon tip, demonstrate these effects. © 1999 American Institute of Physics.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
07.79.-v Scanning probe microscopes and components
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Formation of double-monolayer-height islands on a Si(001) surface by alternating current heating in molecular beam epitaxy

Takahisa Doi, Masakazu Ichikawa, Shigeyuki Hosoki, and Hiroshi Kakibayashi

Appl. Phys. Lett. 74, 3675 (1999); http://dx.doi.org/10.1063/1.123218 (3 pages) | Cited 1 time

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Molecular beam epitaxy (MBE) of Si atoms onto a Si(001) 1×2 surface is investigated using reflection electron microscopy. A 1×2 surface with wide 1×2 and narrow 2×1 terraces is prepared by passing a direct current from the down side to the up side at the surface steps. After sample heating to 900 °C using an alternating current without deposited Si atoms, the 1×2 surface changes to a double-domain surface, where the width of the 2×1 terraces is approximately equal to that of the 1×2 terraces. With MBE, however, the 1×2 surface remains the 1×2 surface, and the double-monolayer-height islands with an approximately circular shape are stably formed on it. © 1999 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.05.Cy Elemental semiconductors
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.55.-a Thin film structure and morphology
68.35.Rh Phase transitions and critical phenomena
81.40.Gh Other heat and thermomechanical treatments

X-ray diffraction study of chalcopyrite ordering in epitaxial ZnSnP2 grown on GaAs

S. Francoeur, G. A. Seryogin, S. A. Nikishin, and H. Temkin

Appl. Phys. Lett. 74, 3678 (1999); http://dx.doi.org/10.1063/1.123219 (3 pages) | Cited 8 times

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We report on the structural characterization of epitaxial ZnSnP2 grown on GaAs (001). Ordering of Zn and Sn atoms in the cation sublattice is observed by high-resolution x-ray diffraction. By varying the growth conditions, samples with two distinct structures were obtained: one showing chalcopyrite ordering with the tetragonal axis oriented along the growth direction and the other showing no evidence of ordering. Chalcopyrite ordering was determined unambiguously by observing several characteristic reflections uniquely identifying this structure. © 1999 American Institute of Physics.
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68.55.-a Thin film structure and morphology
61.50.Ks Crystallographic aspects of phase transformations; pressure effects
64.70.K- Solid-solid transitions

Enhanced Mg doping efficiency in Al0.2Ga0.8N/GaN superlattices

Peter Kozodoy, Monica Hansen, Steven P. DenBaars, and Umesh K. Mishra

Appl. Phys. Lett. 74, 3681 (1999); http://dx.doi.org/10.1063/1.123220 (3 pages) | Cited 90 times

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High p-type conductivity of Mg-doped AlGaN/GaN superlattices is demonstrated. The measured hole concentration at room temperature is over 2.5×1018 cm−3, more than ten times that obtained in bulk AlGaN layers, and lateral resistivity as low as 0.2 Ω cm is realized. The temperature dependence of the resistivity is drastically reduced compared to bulk films, providing evidence of the formation of a confined hole gas. Valence band bending due primarily to piezoelectric and spontaneous polarization is identified as the origin of these effects. © 1999 American Institute of Physics.
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61.72.uj III-V and II-VI semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.61.Ey III-V semiconductors
77.65.-j Piezoelectricity and electromechanical effects
77.22.Ej Polarization and depolarization

Electrical and noise properties of thin-film transistors on very thin excimer laser annealed polycrystalline silicon films

C. T. Angelis, C. A. Dimitriadis, F. V. Farmakis, G. Kamarinos, J. Brini, and M. Miyasaka

Appl. Phys. Lett. 74, 3684 (1999); http://dx.doi.org/10.1063/1.123221 (3 pages) | Cited 2 times

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Thin-film transistors, fabricated on polycrystalline silicon films prepared by combined solid phase crystallization of amorphous silicon and excimer laser annealing processes, have been investigated by electrical and low frequency noise measurements in relation to the active layer thickness and the laser energy density. The device performance is improved with increasing the laser energy density until a critical value where the film is completely melted. By decreasing the active layer thickness from 50 to 25 nm, although the subthreshold characteristics are improved, the electron mobility and the threshold voltage are degraded. The noise data indicate that the degradation is related to electron trapping in both gate and substrate oxide interface traps. © 1999 American Institute of Physics.
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85.30.Tv Field effect devices
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
72.20.Ee Mobility edges; hopping transport
72.20.Fr Low-field transport and mobility; piezoresistance
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
81.40.Gh Other heat and thermomechanical treatments
81.40.Rs Electrical and magnetic properties related to treatment conditions
61.72.Cc Kinetics of defect formation and annealing
61.82.Fk Semiconductors

Analysis of contamination, hydrogen emission, and surface temperature variations using real time spectroscopic ellipsometry during p/i interface formation in amorphous silicon p-i-n solar cells

H. Fujiwara, Joohyun Koh, C. R. Wronski, and R. W. Collins

Appl. Phys. Lett. 74, 3687 (1999); http://dx.doi.org/10.1063/1.123230 (3 pages) | Cited 5 times

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The formation of p/i interfaces in hydrogenated amorphous silicon p-i-n solar cells prepared by plasma-enhanced chemical vapor deposition has been studied in detail using real time spectroscopic ellipsometry. With this technique, three effects have been successfully separated and quantified: (i) contaminant layer deposition at the p-layer surface with a sensitivity of ±0.1 Å, (ii) thermal emission of bonded hydrogen from the p layer with a sensitivity of ±0.1 at. % (±2 meV in optical gap), and (iii) surface temperature variations with a sensitivity of ±1 °C. The separation of these competing effects has yielded a better understanding of p/i interface formation and device optimization. © 1999 American Institute of Physics.
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84.60.Jt Photoelectric conversion
68.35.Dv Composition, segregation; defects and impurities
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
68.35.Ct Interface structure and roughness
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.66.Db Elemental semiconductors and insulators
81.05.Cy Elemental semiconductors
78.66.Jg Amorphous semiconductors; glasses
81.05.Gc Amorphous semiconductors
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Exchange-biased magnetic tunnel junctions: Dependence of offset field on junction width

K.-S. Moon, R. E. Fontana, and S. S. P. Parkin

Appl. Phys. Lett. 74, 3690 (1999); http://dx.doi.org/10.1063/1.123222 (3 pages) | Cited 20 times

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Magnetic tunnel junction structures comprising a ferromagnetic layer pinned by exchange biasing and a “free” ferromagnetic layer were prepared using dc-magnetron sputtering and patterned with conventional optical lithography. Structures were prepared, square and rectangular in shape, with various widths and lengths. It was observed that the magnetic properties of the free layer vary systematically with the size of the junction. In particular, the offset field of the free-layer magnetic hysteresis loop, as measured resistively, is controlled by a combination of magnetostatic and ferromagnetic coupling between the pinned and free layers. © 1999 American Institute of Physics.  
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.50.Bb Fe and its alloys
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Et Exchange and superexchange interactions
75.45.+j Macroscopic quantum phenomena in magnetic systems
81.15.Cd Deposition by sputtering

Microwave-induced current steps in intrinsic Josephson junctions patterned on Bi2Sr2CaCu2O8 single crystal

H. B. Wang, Y. Aruga, T. Tachiki, Y. Mizugaki, J. Chen, K. Nakajima, T. Yamashita, and P. H. Wu

Appl. Phys. Lett. 74, 3693 (1999); http://dx.doi.org/10.1063/1.123223 (3 pages) | Cited 13 times

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With a 10 μm×10 μm mesa patterned on Bi2Sr2CaCu2O8 single crystals, we measure the current–voltage (I–V) curves of a stack of intrinsic Josephson junctions. Current steps are observed at an equal voltage spacing of 4 mV when the sample is subjected to microwave radiation at around 7 GHz. With increase of the microwave power, more steps occur while the spacing between neighboring steps does not seem to change. The magnitude of each step depends on the microwave power in an oscillating way. Tuning the microwave frequency causes such steps to occur over separate frequency ranges, and each range is quite narrow. A temperature rise from 4.2 to 14.3 K completely quenches the step structures. Possible explanations for the step structures, based on resonances excited by microwave or geometric resonances in the junction cavity, are discussed. © 1999 American Institute of Physics.
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74.50.+r Tunneling phenomena; Josephson effects
74.72.-h Cuprate superconductors
74.25.F- Transport properties
74.25.N- Response to electromagnetic fields

Pulsed-laser-deposited epitaxial Sr2FeMoO6−y thin films: Positive and negative magnetoresistance regimes

H. Asano, S. B. Ogale, J. Garrison, A. Orozco, Y. H. Li, E. Li, V. Smolyaninova, C. Galley, M. Downes, M. Rajeswari, R. Ramesh, and T. Venkatesan

Appl. Phys. Lett. 74, 3696 (1999); http://dx.doi.org/10.1063/1.123224 (3 pages) | Cited 48 times

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Epitaxial thin films of ordered double-perovskite Sr2FeMoO6−y are deposited on (001) SrTiO3 substrates by pulsed-laser deposition using a two step growth process. Selection of growth conditions is found to lead to either highly conductive metallic thin films (residual resistivity of about 1 μΩ cm) or semiconducting films. The metallic films show a positive magnetoresistance (MR) as high as 35%, while the semiconducting films show a negative MR of −3%, at a temperature of 5 K and a field of 8 T. © 1999 American Institute of Physics.
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73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.61.Le Other inorganic semiconductors
73.61.At Metal and metallic alloys

Quantum constraints on technological superconductors

J. R. Thompson, J. G. Ossandon, L. Krusin-Elbaum, K. J. Song, D. K. Christen, and J. L. Ullmann

Appl. Phys. Lett. 74, 3699 (1999); http://dx.doi.org/10.1063/1.123225 (3 pages) | Cited 5 times

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Vortex pinning in textured Bi2Sr2CaCu2Ox/Ag superconducting tapes was enhanced by irradiation with 0.8 GeV protons, creating randomly oriented columnar defects. Measurements of the current density J versus time show that thermally-activated current decay was greatly decreased, compared with unirradiated tapes. However, temperature-independent quantum tunneling of vortices considerably limits J and its temporal stability, for a significant fraction of the finite-Jc region. © 1999 American Institute of Physics.
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84.71.Mn Superconducting wires, fibers, and tapes
74.72.-h Cuprate superconductors
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.25.Sv Critical currents
61.80.Jh Ion radiation effects
61.82.-d Radiation effects on specific materials
61.72.-y Defects and impurities in crystals; microstructure

Magnetic field biasing in Faraday effect sensors

H. Guerrero, R. Pérez del Real, R. Fernández de Caleya, and G. Rosa

Appl. Phys. Lett. 74, 3702 (1999); http://dx.doi.org/10.1063/1.123226 (3 pages) | Cited 2 times

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A method for improving the performances of Faraday effect sensors, which is based in the passive magnetic field biasing of a Faraday rotator, is described. It allows obtaining reflective optical fiber sensor architectures, based on a single polarizer and a mirror-coated Faraday rotator, which exhibit linear response and maximum sensitivity. It can be achieved by means of a permanent magnet providing a 45° rotation of the polarization of the optical beam propagating through a Faraday rotator. Operation of this method in both a point magnetic field sensor and a current sensor, with a ferromagnetic ring as concentrator, has been demonstrated. © 1999 American Institute of Physics.
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42.81.Pa Sensors, gyros
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
85.70.Sq Magnetooptical devices
07.60.Vg Fiber-optic instruments
07.55.Ge Magnetometers for magnetic field measurements
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
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Thermal stability of Ta2O5 in metal–oxide–metal capacitor structures

J. P. Chang, M. L. Steigerwald, R. M. Fleming, R. L. Opila, and G. B. Alers

Appl. Phys. Lett. 74, 3705 (1999); http://dx.doi.org/10.1063/1.123227 (3 pages) | Cited 17 times

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Using x-ray photoelectron spectroscopy and Rutherford backscattering spectrometry, we have studied structures used in metal–oxide–metal capacitors including Ta2O5/TiN/Ti, Ta2O5/Ti, Ta2O5/TaN/Ti, Ta2O5/WN/Ti, and Ta2O5/M, where M=Ta, Pt, W, Al, and Si. We find that Ti and Al are able to reduce the Ta2O5 to Ta, forming oxides of Ti and Al, respectively. The diffusion barriers TiN, TaN, and WN hamper the diffusion of oxygen and therefore postpone the reduction of Ta2O5 to higher temperatures. As judged by the temperatures at which the reduction of Ta2O5 occurs, TaN and WN are more effective oxygen-diffusion barriers than TiN. We observe no oxygen remaining in the diffusion barrier when a Ti layer is present underneath. We observe no reduction of Ta2O5 when M=Pt, W, or Si. © 1999 American Institute of Physics.
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84.32.Tt Capacitors
68.60.Dv Thermal stability; thermal effects
61.85.+p Channeling phenomena (blocking, energy loss, etc.)
79.60.Jv Interfaces; heterostructures; nanostructures

Temperature-accelerated dielectric breakdown in ultrathin gate oxides

C.-C. Chen, C.-Y. Chang, C.-H. Chien, T.-Y. Huang, H.-C. Lin, and M.-S. Liang

Appl. Phys. Lett. 74, 3708 (1999); http://dx.doi.org/10.1063/1.123228 (3 pages) | Cited 4 times

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Temperature-accelerated effects on dielectric breakdown of ultrathin gate oxide with thickness ranging from 8.7 to 2.5 nm are investigated and analyzed. Although superior reliability for ultrathin gate oxide at room temperature has been reported in recent literatures, a strong temperature-accelerated degradation of oxide reliability is observed in this study. Experimental results show that both charge-to-breakdown (Qbd) and breakdown field (Ebd) characteristics are greatly aggravated for ultrathin oxide at elevated temperature. The Arrhenius plot also confirms that the activation energies of Qbd and Ebd increase significantly as oxide thickness decreases, explaining the higher sensitivity to temperature for thinner oxides. © 1999 American Institute of Physics.
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85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology
85.30.-z Semiconductor devices
85.30.De Semiconductor-device characterization, design, and modeling
85.40.Qx Microcircuit quality, noise, performance, and failure analysis

Effects of a Bi4Ti3O12 buffer layer on SrBi2Ta2O9 thin films prepared by the metalorganic decomposition

G. D. Hu, J. B. Xu, I. H. Wilson, W. Y. Cheung, N. Ke, and S. P. Wong

Appl. Phys. Lett. 74, 3711 (1999); http://dx.doi.org/10.1063/1.123229 (3 pages) | Cited 7 times

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Ferroelectric SrBi2Ta2O9 thin films have been deposited on the Bi4Ti3O12 buffered Pt/Ti/SiO2/Si substrates using the metalorganic decomposition technique at annealing temperatures ranging from 600 to 750 °C. No pyrochlore phase was found in the SrBi2Ta2O9 thin films although the Bi2Ti2O7 phase appeared in the Bi4Ti3O12 buffer layers. A SrBi2Ta2O9 film with (200) predominant orientation was formed at 650 °C. The effects of the Bi4Ti3O12 buffer layer and post-annealing temperature on the structure, surface morphology, and electrical properties of SrBi2Ta2O9 thin films were analyzed. © 1999 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
77.80.Dj Domain structure; hysteresis
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
61.72.Cc Kinetics of defect formation and annealing
68.35.B- Structure of clean surfaces (and surface reconstruction)
77.22.Ej Polarization and depolarization
77.22.Ch Permittivity (dielectric function)
68.55.-a Thin film structure and morphology
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
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Optical studies of electric fields in poly(2-methoxy-5-ethyl (2′-hexyloxy) para-phenylene vinylene) light-emitting diodes

C. Giebeler, S. A. Whitelegg, A. J. Campbell, M. Liess, S. J. Martin, P. A. Lane, D. D. C. Bradley, G. Webster, and P. L. Burn

Appl. Phys. Lett. 74, 3714 (1999); http://dx.doi.org/10.1063/1.123238 (3 pages) | Cited 23 times

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We report electroabsorption studies of poly(2-methoxy-5-ethyl(2′-hexyloxy) para-phenylene vinylene) light-emitting diodes. An electric field develops during operation which opposes the field of the applied bias. The counter field builds up within 5 s of turning on the device, increases in magnitude with the operating voltage, and decays exponentially with a time constant between 15 and 32 s. We attribute the counter field to bulk carrier traps and discuss its relevance to the increase of the turn-on voltage as organic light-emitting diodes degrade. © 1999 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.20.Jq Electro-optical effects
42.70.Jk Polymers and organics

All-optical reflection modulator using a nonlinear heteronipi structure within an asymmetric Fabry–Perot optical cavity

P. F. Davies, C. C. Phillips, and C. Roberts

Appl. Phys. Lett. 74, 3717 (1999); http://dx.doi.org/10.1063/1.123231 (3 pages) | Cited 2 times

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Reflectivity changes of ∼ 40% and contrast ratios of ∼ 100% are reported at optical excitation densities less than 100 μW/cm2 in an AlAs/AlGaAs/GaAs reflection-mode optical modulator. Switching and in-plane transport dynamics as a function of pixel size are also reported. Optical modulation occurs via the quantum-confined Stark effect in GaAs quantum wells grown within a “nipi” doping superlattice and is controlled through microcavity étalon effects. Optical bistability without the need for external electronic biasing circuitry is projected. © 1999 American Institute of Physics.
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42.79.Hp Optical processors, correlators, and modulators
78.66.Fd III-V semiconductors
78.20.Jq Electro-optical effects
42.65.Pc Optical bistability, multistability, and switching, including local field effects

A vertical injection blue light emitting diode in substrate separated InGaN heterostructures

Y.-K. Song, M. Diagne, H. Zhou, A. V. Nurmikko, C. Carter-Coman, R. S. Kern, F. A. Kish, and M. R. Krames

Appl. Phys. Lett. 74, 3720 (1999); http://dx.doi.org/10.1063/1.123232 (3 pages) | Cited 26 times

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A vertical injection, light emitting InGaN quantum well diode has been demonstrated by separating the nitride heterostructure from its sapphire substrate by ultraviolet laser photoablation within a process scheme that allows transferring the devices to a host substrate. The incorporation of a dielectric multilayer stack to the device is shown to be a first practical step towards a resonant cavity light emitting diode. © 1999 American Institute of Physics.
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85.60.Jb Light-emitting devices
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Nonsteady-state photo-EMF effect in photorefractive polymers

Reinhard Bittner, Klaus Meerholz, and Serguei Stepanov

Appl. Phys. Lett. 74, 3723 (1999); http://dx.doi.org/10.1063/1.123233 (3 pages) | Cited 6 times

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The nonsteady-state photo-electromotive force (photo-EMF) effect has been observed in photorefractive (PR) polymer films based on poly(N-vinylcarbazole) (PVK). It was investigated in the typical tilted transmission configuration without and with application of moderate external direct current (dc) electric fields. The dependencies of the photo-EMF signals on the frequency and the amplitude of the phase modulation, the tilt angle, and the externally applied dc field are qualitatively explained using a simple model of the effect, developed earlier for unipolar photoconductive inorganic crystals without saturation of the trapping centers. The absolute value of the photo-EMF signal was two to three times larger than expected from this model and the experimental data on conventional photoconductivity of the polymer film. This was rationalized considering the presence of additional space-charge gratings appearing due to light reflectance from the rear surface of the thin-film device. © 1999 American Institute of Physics.
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72.40.+w Photoconduction and photovoltaic effects
73.61.Ph Polymers; organic compounds
42.70.Jk Polymers and organics
42.70.Gi Light-sensitive materials
73.50.Pz Photoconduction and photovoltaic effects
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Graphite lattice synthesis catalyzed by chromium-containing crystallites

Fumio Okuyama, Tatsuji Hayashi, and Yasutaka Fujimoto

Appl. Phys. Lett. 74, 3726 (1999); http://dx.doi.org/10.1063/1.123234 (3 pages) | Cited 4 times

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The encapsulation of chromium-containing crystallites in carbon nanocages is shown to occur on glow-discharge anodes in the presence of an ac magnetic field. These encapsulants catalytically promote the synthesis of nanodimensional graphite lattices in their nearby free space as well as on their surface. The minimum unit of graphite crystals thus synthesized is “rail-like,” with a spacing somewhat larger than the (002) spacing of graphite. © 1999 American Institute of Physics.
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61.48.-c Structure of fullerenes and related hollow and planar molecular structures
81.05.ub Fullerenes and related materials
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Imposed layer-by-layer growth by pulsed laser interval deposition

Gertjan Koster, Guus J. H. M. Rijnders, Dave H. A. Blank, and Horst Rogalla

Appl. Phys. Lett. 74, 3729 (1999); http://dx.doi.org/10.1063/1.123235 (3 pages) | Cited 57 times

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Pulsed laser deposition has become an important technique to fabricate novel materials. Although there is the general impression that, due to the pulsed deposition, the growth mechanism differs partially from continuous physical and chemical deposition techniques, it has hardly been used. Here, we will introduce a growth method, based on a periodic sequence: fast deposition of the amount of material needed to complete one monolayer followed by an interval in which no deposition takes place and the film can reorganize. This makes it possible to grow in a layer-by-layer fashion in a growth regime (temperature, pressure) where otherwise island formation would dominate the growth. © 1999 American Institute of Physics.
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81.15.Fg Pulsed laser ablation deposition
68.55.-a Thin film structure and morphology
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)

Control of morphology changes in self-assembled Mn-based nanostructures overgrown with mismatched material

A. Bonanni, H. Seyringer, H. Sitter, D. Stifter, and K. Hingerl

Appl. Phys. Lett. 74, 3732 (1999); http://dx.doi.org/10.1063/1.123236 (3 pages) | Cited 4 times

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Reproducibility of size and shape for epitaxially grown self-assembling Mn-based nanostructures was achieved by tracing the formation process via reflectance difference spectroscopy. Pure Mn crystallites were at first fabricated on a CdTe(001) Te-terminated surface and, in a second stage, a variety of well-controlled strain-induced island morphologies was obtained with the deposition of semiconducting materials on the magnetic precursors. © 1999 American Institute of Physics.
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81.07.-b Nanoscale materials and structures: fabrication and characterization
61.46.-w Structure of nanoscale materials
78.66.Bz Metals and metallic alloys

Detection of ultrasound using an apertureless near-field scanning optical microscope

David W. Blodgett and James B. Spicer

Appl. Phys. Lett. 74, 3735 (1999); http://dx.doi.org/10.1063/1.123237 (3 pages) | Cited 1 time

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A method for the detection of ultrasonic vibrations using the apertureless near-field scanning optical microscope (ANSOM) is presented. Due to the changes in tip-sample separation, ultrasonic vibrations are seen as perturbations on the near-field signal. Both contact transducer (5 MHz) and laser-generated ultrasound have been successfully transduced. The linear dependence of the near-field signal on tip-sample separation makes the interpretation of these wave forms similar to that for conventional ultrasonic techniques. © 1999 American Institute of Physics.
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43.35.Yb Ultrasonic instrumentation and measurement techniques
43.58.-e Acoustical measurements and instrumentation
07.79.Fc Near-field scanning optical microscopes
43.38.Zp Acoustooptic and photoacoustic transducers
43.35.Ud Thermoacoustics, high temperature acoustics, photoacoustic effect
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