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25 Sep 2000

Volume 77, Issue 13, pp. 1925-2071

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Photonic band gaps in dusty plasma crystals

M. J. Keskinen and R. Fernsler

Appl. Phys. Lett. 77, 1925 (2000); http://dx.doi.org/10.1063/1.1312200 (3 pages) | Cited 3 times

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A two-dimensional model for electromagnetic wave propagation in a dusty plasma crystal is solved using plane wave expansion techniques. We show that photonic band gaps, where propagation is forbidden, can occur for a range of Debye length scale sizes with respect to the dust particle size. We find that band gap features are dependent on the plasma sheath characteristics of the dusty plasma crystal. In addition we compute the damping due to the conductivity of the dusty plasma crystal.
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52.27.Lw Dusty or complex plasmas; plasma crystals
42.70.Qs Photonic bandgap materials
52.40.Db Electromagnetic (nonlaser) radiation interactions with plasma
52.40.Hf Plasma-material interactions; boundary layer effects
42.50.-p Quantum optics
52.25.Fi Transport properties

Terahertz quantum cascade structures: Intra- versus interwell transition

J. Ulrich, R. Zobl, W. Schrenk, G. Strasser, K. Unterrainer, and E. Gornik

Appl. Phys. Lett. 77, 1928 (2000); http://dx.doi.org/10.1063/1.1312864 (3 pages) | Cited 26 times

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Terahertz quantum cascade structures (emission around 20 meV) based on intra- and interwell transitions have been compared in magnetotransport and intersubband-electroluminescence experiments. The interwell transition exhibits a Stark shift of up to 6 meV. We also observe a smaller energy shift of the intrawell transition which is attributed to the tunnel splitting, when the initial and final subbands mix with those of the injectors. The electric field induced narrowing of the emission line and our band structure calculations support this interpretation. The quantum efficiency of the electroluminescence is of similar magnitude for the two transitions, despite their large difference in the spatial subband overlap. © 2000 American Institute of Physics.
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78.66.Fd III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.60.Fi Electroluminescence
78.70.Gq Microwave and radio-frequency interactions
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
78.20.Jq Electro-optical effects
73.61.Ey III-V semiconductors

Performance and degradation of continuous-wave InGaN multiple-quantum-well laser diodes on epitaxially laterally overgrown GaN substrates

Michael Kneissl, David P. Bour, Linda Romano, Chris. G. Van de Walle, John E. Northrup, William S. Wong, David W. Treat, Mark Teepe, Tanya Schmidt, and Noble M. Johnson

Appl. Phys. Lett. 77, 1931 (2000); http://dx.doi.org/10.1063/1.1312860 (3 pages) | Cited 21 times

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The performance and degradation characteristics of continuous-wave (cw) InGaN multiple-quantum-well laser diodes are reported. A cw threshold current as low as 62 mA was obtained for ridge-waveguide laser diodes on epitaxially laterally overgrown GaN on sapphire substrates grown by metalorganic chemical vapor deposition. Transmission electron microscopy reveals a defect density <5×107 cm−2 in the active region. The emission wavelength was near 400 nm with output powers greater than 20 mW per facet. Under cw conditions, laser oscillation was observed up to 70 °C. The room-temperature cw operation lifetimes, measured at a constant output power of 2 mW, exceeded 15 h. From the temperature dependence of the laser diode lifetimes, an activation energy of 0.50 eV±0.05 eV was determined. © 2000 American Institute of Physics.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Pk Continuous operation
42.55.Px Semiconductor lasers; laser diodes
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

All selective metalorganic vapor phase epitaxy grown buried-heterostructure laser diodes with selectively oxidized AlInAs current-confinement layer

Hyun-Chul Ko, Takahiro Nakamura, Tomoaki Koui, Naofumi Suzuki, Kazuhiro Shiba, and Kenichi Kobayashi

Appl. Phys. Lett. 77, 1934 (2000); http://dx.doi.org/10.1063/1.1313374 (3 pages)

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A laser diode structure, consisting of a 1.3 μm all selective metalorganic vapor phase epitaxy grown buried-heterostructure (ASM-BH) laser diode with a selectively oxidized-AlInAs current-confinement layer, is proposed and demonstrated. As the lateral oxidization is automatically stopped near the active layer by self-aligned AlInAs, a narrow current aperture with excellent controllability is realized. The fabricated laser diode shows low continuous-wave threshold current of 2.5 and 7.5 mA at 25 and 85 °C, respectively, for 250-μm-long devices with HR(75%)/HR(95%) coatings. The maximum operating temperature is higher than 145 °C. © 2000 American Institute of Physics.
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42.60.By Design of specific laser systems
42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.65.Mq Oxidation
42.60.Pk Continuous operation

Waveguiding in planar photonic crystals

Marko Lončar, Dušan Nedeljković, Theodor Doll, Jelena Vučković, Axel Scherer, and Thomas P. Pearsall

Appl. Phys. Lett. 77, 1937 (2000); http://dx.doi.org/10.1063/1.1311604 (3 pages) | Cited 169 times

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Photonic crystal planar circuits designed and fabricated in silicon on silicon dioxide are demonstrated. Our structures are based on two-dimensional confinement by photonic crystals in the plane of propagation, and total internal reflection to achieve confinement in the third dimension. These circuits are shown to guide light at 1550 nm around sharp corners where the radius of curvature is similar to the wavelength of light. © 2000 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
42.82.Et Waveguides, couplers, and arrays
42.79.Gn Optical waveguides and couplers
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Memorized polarization-dependent light scattering in rare-earth-ion-doped glass

Jianrong Qiu, P. G. Kazanski, Jinhai Si, K. Miura, T. Mitsuyu, K. Hirao, and Alexander L. Gaeta

Appl. Phys. Lett. 77, 1940 (2000); http://dx.doi.org/10.1063/1.1311956 (3 pages) | Cited 14 times

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We report the observation of memorized polarization-dependent light scattering in a Eu2+-doped fluoroaluminate glass sample. Anisotropic light scattering along the plane of the light polarization was observed in the glass sample after the excitation of a focused 800 nm, 150 fs laser beam at a repetition rate of 200 kHz. When we changed the direction of the light polarization and irradiated the same location, we observed an anisotropic light-scattering pattern identical to the original one at the beginning, but then observed a new pattern along the new direction of the light polarization while the original light-scattering pattern disappeared gradually with the passage of time. This observed phenomenon was considered to be due to the light scattering of the polarization-dependent permanent microstructure induced by the polarized ultrashort pulsed laser itself. © 2000 American Institute of Physics.
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78.35.+c Brillouin and Rayleigh scattering; other light scattering
42.70.Ce Glasses, quartz
61.43.Fs Glasses
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Demonstration of near-field scanning photoreflectance spectroscopy

Charles Paulson, A. B. Ellis, Leon McCaughan, Brian Hawkins, Jingxi Sun, and T. F. Kuech

Appl. Phys. Lett. 77, 1943 (2000); http://dx.doi.org/10.1063/1.1312253 (3 pages) | Cited 2 times

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A near-field scanning optical microscope (NSOM) was developed to perform photoreflectance (PR) spectroscopy experiments at high spatial resolution ( ∼ 1 μm). Representative PR spectra are shown, along with an image illustrating the capability of observing contrast in images due to the strength of a PR feature. It was found that sufficiently high intensity light from the NSOM tip can produce photovoltages large enough to limit the spatial resolution of the electric field determination by PR. The photovoltage effect is measured as a function of light intensity, and the results are discussed in terms of a simple photovoltage expression. © 2000 American Institute of Physics.
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07.60.Rd Visible and ultraviolet spectrometers
07.79.Fc Near-field scanning optical microscopes
42.62.Fi Laser spectroscopy
73.20.-r Electron states at surfaces and interfaces

GaN0.011P0.989 red light-emitting diodes directly grown on GaP substrates

H. P. Xin, R. J. Welty, and C. W. Tu

Appl. Phys. Lett. 77, 1946 (2000); http://dx.doi.org/10.1063/1.1311957 (3 pages) | Cited 23 times

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Red light-emitting diodes (LEDs) emitting at 670 nm and employing GaN0.011P0.989 p–n homojunction grown on a (100) GaP substrate by gas-source molecular beam epitaxy with a rf plasma nitrogen source have been obtained. The integrated photoluminescence intensity of GaNP p–n homojunction LED is 5 times stronger than that of Ga0.51In0.49P bulk layer, but the peak width is much broader. Compared to conventional high-brightness AlGaInP red LEDs, our LED structure saves two process steps of etch removing of the GaAs absorbing substrate and wafer bonding to a GaP transparent substrate. © 2000 American Institute of Physics.
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85.60.Jb Light-emitting devices
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.05.Ea III-V semiconductors
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors

Semiconducting boron carbonitride nanostructures: Nanotubes and nanofibers

J. Yu, J. Ahn, S. F. Yoon, Q. Zhang, Rusli, B. Gan, K. Chew, M. B. Yu, X. D. Bai, and E. G. Wang

Appl. Phys. Lett. 77, 1949 (2000); http://dx.doi.org/10.1063/1.1311953 (3 pages) | Cited 33 times

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Highly oriented boron carbonitride (BCN) nanostructures consisting of nanotubes and nanofibers have been synthesized by bias-assisted hot-filament chemical vapor deposition from the source gases of B2H6, CH4, N2, and H2. It is found that the B concentration of the BCN nanostructures increases with increasing B2H6 in the gas mixture, and the highest B concentration is 45 at. %. Photoluminescence spectrum shows that the BCN nanostructures, identified as B0.34C0.42N0.24, are semiconductors with a band gap energy of around 1.0 eV. © 2000 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
73.22.-f Electronic structure of nanoscale materials and related systems
81.07.-b Nanoscale materials and structures: fabrication and characterization
78.55.Hx Other solid inorganic materials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Determination of precipitate nucleation and growth rates from ultrasonic harmonic generation

John H. Cantrell and William T. Yost

Appl. Phys. Lett. 77, 1952 (2000); http://dx.doi.org/10.1063/1.1311951 (3 pages) | Cited 10 times

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An analytical model based on precipitate-dislocation interactions is presented that predicts a decrease in ultrasonic harmonic generation during the nucleation of precipitates and an increase during precipitate growth up to the point of precipitate-matrix coherency loss. The opposing effects allow independent, indirect assessments of nucleation and growth rates from a curve fit of the model equation to experimental data. Application to the assessment of S′ precipitation during the artificial aging of AA2024 yields a constant nucleation rate of 5.4×1015 m−3 s−1 and a growth rate increasing as the 1.2 power of time in the range 72–432 min during heat treatment at 463 K.
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81.30.Mh Solid-phase precipitation
64.75.-g Phase equilibria
43.25.Dc Nonlinear acoustics of solids
62.65.+k Acoustical properties of solids
81.40.Gh Other heat and thermomechanical treatments
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
61.72.Yx Interaction between different crystal defects; gettering effect

Shape transition of calcium islands formed by electron-stimulated desorption of fluorine from a CaF2(111) surface

M. Batzill and K. J. Snowdon

Appl. Phys. Lett. 77, 1955 (2000); http://dx.doi.org/10.1063/1.1311949 (3 pages) | Cited 4 times

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Extremely low-energy electrons emitted from a heated filament have been used to deplete fluorine from a cleaved CaF2(111) surface. Calcium left behind on the surface reorganizes itself in islands. A shape transition for the islands from a compact shape to an elongated shape has been observed for islands larger than ∼20 nm in diameter. Some cleavage steps show preferential fluorine erosion, which leads to the formation of very long calcium nanowires of uniform width ∼15 nm parallel to the step edge. The observed island and wire morphology is explained by energy minimization of strained commensurate islands. © 2000 American Institute of Physics.
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79.20.La Photon- and electron-stimulated desorption
68.55.-a Thin film structure and morphology
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.35.Rh Phase transitions and critical phenomena

Phonon lifetimes in bulk AlN and their temperature dependence

M. Kuball, J. M. Hayes, Ying Shi, and J. H. Edgar

Appl. Phys. Lett. 77, 1958 (2000); http://dx.doi.org/10.1063/1.1311948 (3 pages) | Cited 34 times

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We report on the Raman analysis of the phonon lifetimes of the A1(LO) (longitudinal optical) and E2(high) phonons in bulk AlN crystals and their temperature dependence from 10 to 1275 K. Our experimental results show that amongst the various possible decay channels, the A1(LO) phonons decay primarily into two phonons of equal energy (Klemens model), most likely longitudinal-acoustic phonons, whereas the E2(high) phonon decays asymmetrically into a high-energy and a low-energy phonon. Possible decay channels of the E2(high) phonon have been shown to include combinations of E2(low) and acoustic phonons. Phonon lifetimes of the A1(LO) phonon and the E2(high) phonon of 0.75 and 2.9 ps, respectively, were measured at 10 K. © 2000 American Institute of Physics.
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63.20.D- Phonon states and bands, normal modes, and phonon dispersion
78.30.Fs III-V and II-VI semiconductors

Simple and high-yield method for synthesizing single-crystal GaN nanowires

C. C. Tang, S. S. Fan, H. Y. Dang, P. Li, and Y. M. Liu

Appl. Phys. Lett. 77, 1961 (2000); http://dx.doi.org/10.1063/1.1312853 (3 pages) | Cited 54 times

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A simple and high-yield method involving vapor-liquid-solid wire-like growth mechanism was developed for the synthesis of GaN nanowires. In this process, the mixture of Ga and SiO2 reacted with ammonia in the presence of the Fe2O3 catalyst supported by Al2O3. The x-ray powder diffraction measurement and transmission electron microscopy observations confirmed that the synthesized GaN nanowires are single-crystal hexagonal wurtzite structure with diameters ranged from 10 to 50 nm and lengths up to several micrometers. Based on the fact that a small Fe dominant particle attached to one end of some nanowires, a growth model of the GaN nanowires was proposed. © 2000 American Institute of Physics.
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81.07.-b Nanoscale materials and structures: fabrication and characterization
81.05.Ea III-V semiconductors
61.46.-w Structure of nanoscale materials
81.05.Cy Elemental semiconductors
82.30.Vy Homogeneous catalysis in solution, polymers and zeolites

Phase change in Ge2Sb2Te5 films investigated by coherent phonon spectroscopy

M. Först, T. Dekorsy, C. Trappe, M. Laurenzis, H. Kurz, and B. Béchevet

Appl. Phys. Lett. 77, 1964 (2000); http://dx.doi.org/10.1063/1.1312861 (3 pages) | Cited 28 times

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Amorphous and crystalline phases of Ge2Sb2Te5 films are investigated by coherent phonon spectroscopy. By heating amorphous films above specific temperatures, the coherent phonon signatures exhibit pronounced changes due to the crystallization of the amorphous phase into a cubic lattice and the transition from the cubic to a hexagonal crystal structure. The phonon modes observed are identified by comparison with coherent phonon spectra of the binary Sb2Te3 and GeTe constituents. © 2000 American Institute of Physics.
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61.43.Fs Glasses
68.55.-a Thin film structure and morphology
81.05.Gc Amorphous semiconductors
64.70.K- Solid-solid transitions

Evolving shock-wave profiles measured in a silicon crystal by picosecond time-resolved x-ray diffraction

Yoichiro Hironaka, Akio Yazaki, Fumikazu Saito, Kazutaka G. Nakamura, Ken-ichi Kondo, Hisataka Takenaka, and Masatake Yoshida

Appl. Phys. Lett. 77, 1967 (2000); http://dx.doi.org/10.1063/1.1313297 (3 pages) | Cited 22 times

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Picosecond time-resolved x-ray diffraction is used to probe single-crystal silicon under pulsed-laser irradiation (300 ps pulse at 1.4 J/cm2) at an interval of 60 ps. The observed rocking curves show shock compression of the silicon lattice by the laser irradiation. Uniaxial strain profiles perpendicular to the Si(111) plane are estimated using dynamical x-ray diffraction theory. The temporal and spatial evolution of the profiles indicates a propagating shock wave with the velocity of 9.4 km/s inside the silicon crystal. The observed maximum compression is 1.05%, which corresponds to a pressure of 2.18 GPa. © 2000 American Institute of Physics.
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81.05.Cy Elemental semiconductors
78.47.-p Spectroscopy of solid state dynamics
62.50.-p High-pressure effects in solids and liquids
61.82.Fk Semiconductors
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
79.20.Ds Laser-beam impact phenomena

Relation between short-range order and crystallization behavior in Zr-based amorphous alloys

L. Q. Xing, T. C. Hufnagel, J. Eckert, W. Löser, and L. Schultz

Appl. Phys. Lett. 77, 1970 (2000); http://dx.doi.org/10.1063/1.1313255 (3 pages) | Cited 75 times

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We have examined the effect of Ti and cooling rate on the crystallization of Zr62−xTixCu20Ni8Al10(0 ⩽ x ⩽ 10) amorphous alloys. Ti stabilizes an icosahedral phase in Zr62−xTixCu20Ni8Al10(0 ⩽ x ⩽ 10) alloys. Without Ti (x = 0), crystallization produces cubic and tetragonal intermetallic phases, and the crystallization temperature shows no dependence on the cooling rate at which the amorphous alloy was produced. The alloys containing Ti (3 ⩽ x ⩽ 10) precipitate an icosahedral quasicrystalline phase upon annealing, and show a significant reduction of crystallization temperatures with decreasing cooling rates of casting. We propose that the undercooled melts and amorphous alloys have icosahedral short-range order. The degree of short-range order or medium-range order in the amorphous alloys increases with decreasing cooling rate. Crystallization is easier when the precipitating phase resembles the short-range order of the amorphous solid. Therefore, the crystallization temperature is reduced when the precipitates are icosahedral. The dissimilarity between the structures of the precipitates and the short-range order in amorphous Zr62Cu20Ni8Al10 may be one of the reasons for its very wide supercooled liquid region. © 2000 American Institute of Physics.
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61.43.Fs Glasses
61.44.Br Quasicrystals
64.75.-g Phase equilibria
81.30.Mh Solid-phase precipitation

Chemical ordering around open-volume regions in bulk metallic glass Zr52.5Ti5Al10Cu17.9Ni14.6

P. Asoka-Kumar, J. Hartley, R. Howell, P. A. Sterne, and T. G. Nieh

Appl. Phys. Lett. 77, 1973 (2000); http://dx.doi.org/10.1063/1.1313367 (3 pages) | Cited 21 times

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We provide direct experimental evidence for a nonrandom distribution of atomic constituents in Zr52.5Ti5Al10Cu17.9Ni14.6 bulk metallic glass using positron annihilation spectroscopy. The Ti content around the open-volume regions is significantly enhanced at the expense of Ni and Cu. Our results indicate that Ni and Cu atoms closely occupy the volume bounded by their neighboring atoms while Al, Ti, and Zr are less closely packed, and more likely to be associated with the open-volume regions. The overall distribution of elements seen by the positron is not significantly altered by annealing or by crystallization. Theoretical calculations indicate that the observed elemental distribution is not consistent with the known crystalline phases Zr2Cu and NiZr2, while Al3Zr4 shows some of the characteristics seen in the experiment. © 2000 American Institute of Physics.
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61.43.Fs Glasses
71.23.Cq Amorphous semiconductors, metallic glasses, glasses
78.70.Bj Positron annihilation
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis

Accurate measurements of the intrinsic diffusivities of boron and phosphorus in silicon

Yaser M. Haddara, Brennan T. Folmer, Mark E. Law, and Temel Buyuklimanli

Appl. Phys. Lett. 77, 1976 (2000); http://dx.doi.org/10.1063/1.1313248 (3 pages) | Cited 36 times

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All activity in modeling transient diffusion behavior relies on knowledge of the inert intrinsic diffusivities of dopants in Si. The measurements upon which these values are based were conducted over 15 years ago. Since then, the quality of wafers used in industrial applications has significantly changed. This will affect the effective diffusivity through changes in trap concentrations. The reliability of measurement techniques has also changed dramatically from tracer and staining methods to secondary ion mass spectrometry (SIMS) measurements that are dominant today. Finally, our understanding of diffusion behavior has changed significantly. For example, we now understand that the extraction of diffusivities from implanted samples with no pre-anneal includes a significant transient effect. We have measured the inert intrinsic diffusivities of As, B, P, and Sb in different substrates in defect-free Czochralski and float zone wafers and epitaxially grown layers. All samples underwent a 30 min anneal at 1000 °C in dry oxygen in order to grow a cap oxide and eliminate transient enhanced diffusion. We performed SIMS analysis on an initial batch of samples to evaluate the different factors that may affect the diffusivity in a nonideal manner and concluded that there are no transient effects but that surface effects are important. Hence, for the fast moving dopants (B, P) we restrict our data extraction to the deep implants. Our data show that B and P diffusivities are different than the values commonly assumed in the literature at low temperatures. We compare our results to previously published data in light of the factors mentioned here. © 2000 American Institute of Physics.
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81.05.Cy Elemental semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
66.30.J- Diffusion of impurities
61.72.S- Impurities in crystals

Insights into the structure of BN nanotubes

D. Golberg, Y. Bando, L. Bourgeois, K. Kurashima, and T. Sato

Appl. Phys. Lett. 77, 1979 (2000); http://dx.doi.org/10.1063/1.1313251 (3 pages) | Cited 64 times

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The following features of multiwalled BN nanotubes were discovered using a field emission high-resolution analytical transmission electron microscope: (i) coexistence of hexagonal and rhombohedral stacking in nanotube shell assembly; (ii) flattening of nanotube cross section, which makes possible clear atomic resolution of the core structure in a three-shelled nanotube; and (iii) change in chirality of tubular layers from armchair to zigzag arrangement in a 30° double-walled nanotube kink, as revealed by atomically resolved images of tube wall segments. © 2000 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
68.37.Vj Field emission and field-ion microscopy
79.20.Kz Other electron-impact emission phenomena

Piezoelectric-induced quantum-confined Stark effect in self-assembled InAs quantum dots grown on (N11) GaAs substrates

S. Sanguinetti, M. Gurioli, E. Grilli, M. Guzzi, and M. Henini

Appl. Phys. Lett. 77, 1982 (2000); http://dx.doi.org/10.1063/1.1311814 (3 pages) | Cited 26 times

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We investigate the optical properties of InAs self-assembled quantum dots grown on (N11)A/B GaAs substrates, by means of cw photoluminescence under different excitation power densities. We observe a sizeable blue-shift of photoluminescence band induced by increasing the photogenerated carrier density. The shift depends on the substrate orientation and exhibits a strong asymmetric dependence on the substrate termination. We attribute the photoluminescence blue-shift to a reverse quantum confined Stark shift of ground state transition energies in the quantum dots. This effect arises from the photogenerated charge screening of the built-in piezoelectric field present in such strained structures grown on high index planes. © 2000 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.20.Jq Electro-optical effects
78.55.Cr III-V semiconductors
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

Microstructure of BaRuO3 thin films grown on (001) SrTiO3

W. Tian, X. Q. Pan, M. K. Lee, and C. B. Eom

Appl. Phys. Lett. 77, 1985 (2000); http://dx.doi.org/10.1063/1.1289059 (3 pages) | Cited 2 times

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BaRuO3 thin films with hexagonal 4H structure were grown on (001) SrTiO3 by a 90° off-axis rf-sputtering technique. The thin films were epitaxially grown on the (001) surface of SrTiO3, with (20math3) planes parallel to the surface of the substrate. Within the growth plane, the film consists of four different crystallographic orientations with respect to the substrate, defined by the surface symmetry of the (001) SrTiO3 substrate. BaRuO3 grains of all four orientations show an anisotropic shape elongated along the [math2math0] direction. The reason for the anisotropic growth is that the lattice mismatch between BaRuO3 and SrTiO3 is smaller along the [math2math0] direction of SrTiO3 in comparison to that along its perpendicular direction. Stacking faults and intergrowths of the 9R structure were observed in small local regions of the film. © 2000 American Institute of Physics.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Cd Deposition by sputtering
61.72.Nn Stacking faults and other planar or extended defects
68.60.Dv Thermal stability; thermal effects
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Preparation of air-stable, low recombination velocity Si(111) surfaces through alkyl termination

William J. Royea, Agnes Juang, and Nathan S. Lewis

Appl. Phys. Lett. 77, 1988 (2000); http://dx.doi.org/10.1063/1.1312203 (3 pages) | Cited 57 times

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A two-step, chlorination/alkylation procedure has been used to convert the surface Si–H bonds on NH4F(aq)-etched (111)-oriented Si wafers into Si–alkyl bonds of the form Si–CnH2n+1 (n ≥ 1). The electrical properties of such functionalized surfaces were investigated under high-level and low-level injection conditions using a contactless rf apparatus. The charge carrier recombination velocities of the alkylated surfaces were <25 cm s−1 under high-level and low-level injection conditions, implying residual surface trap densities of <3×109 cm−2. Although the carrier recombination velocity of hydrogen-terminated Si(111) surfaces in contact with aqueous acids is <20 cm s−1, this surface deteriorates within 30 min in an air ambient, yielding a high surface recombination velocity. In contrast, methylated Si(111) surfaces exhibit low surface recombination velocities in air for more than 4 weeks. Low surface recombination velocities were also observed for Si surfaces that had been modified with longer alkyl chains. © 2000 American Institute of Physics.
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73.61.Cw Elemental semiconductors
73.25.+i Surface conductivity and carrier phenomena
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
81.65.Cf Surface cleaning, etching, patterning
81.05.Cy Elemental semiconductors
73.20.At Surface states, band structure, electron density of states

Fabrication of extremely narrow metal wires

D. Natelson, R. L. Willett, K. W. West, and L. N. Pfeiffer

Appl. Phys. Lett. 77, 1991 (2000); http://dx.doi.org/10.1063/1.1312256 (3 pages) | Cited 33 times

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A robust technique for fabrication of metal wires with controlled widths substantially below 10 nm is presented. By etching a cleaved molecular-beam epitaxy grown substrate, a mechanical template is produced with surface relief of atomic lateral definition. Using metal deposition and directional ion etching of such a substrate, electrically continuous wires are formed from AuPd alloy with diameters as small as 3 nm and lengths greater than 1 μm. This technique can be used with a variety of materials and makes metallic nanostructures on a previously inaccessible size scale. © 2000 American Institute of Physics.
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81.65.Cf Surface cleaning, etching, patterning
85.40.Ls Metallization, contacts, interconnects; device isolation
68.55.-a Thin film structure and morphology
73.61.At Metal and metallic alloys
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
81.07.-b Nanoscale materials and structures: fabrication and characterization

Local capacitance measurements on InAs dot-covered GaAs surfaces by scanning capacitance microscopy

H. Yamamoto, T. Takahashi, and I. Kamiya

Appl. Phys. Lett. 77, 1994 (2000); http://dx.doi.org/10.1063/1.1312257 (3 pages) | Cited 9 times

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Capacitance images responsible for surface depletion were observed on an InAs dot-covered GaAs surface by scanning capacitance microscopy. We performed local capacitance versus bias voltage measurements on quantum dots (QDs) and a wetting layer (WL) as well as conductance versus bias voltage (G–V) measurements. Both results indicate that the surface depletion is more suppressed beneath the QDs than under the WL. In addition, the conventional thermionic equation theory fitted to the measured G–V curves shows that the interface barrier height between the GaAs and the InAs QD increases as the QD size is reduced. We ascribe this result to the influence of the surrounding WL, whose surface Fermi level is strongly pinned at the midgap of the n-GaAs. © 2000 American Institute of Physics.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.61.Ey III-V semiconductors
73.20.At Surface states, band structure, electron density of states

Athermal annealing of phosphorus-ion-implanted silicon

J. Grun, R. P. Fischer, M. Peckerar, C. L. Felix, B. C. Covington, W. J. DeSisto, D. W. Donnelly, A. Ting, and C. K. Manka

Appl. Phys. Lett. 77, 1997 (2000); http://dx.doi.org/10.1063/1.1312259 (3 pages) | Cited 5 times

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A 1 cm2 area in phosphorus-implanted silicon samples is annealed by irradiation of a much smaller 0.002 cm2 area with a single laser pulse. Resistivity of the annealed region is uniform and similar to that measured after thermal annealing. Electrically activated donors did not diffuse into the sample and only slightly towards the sample surface. The process is 100% reproducible. We present evidence that the annealing is not caused by heat. © 2000 American Institute of Physics.
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61.72.Cc Kinetics of defect formation and annealing
61.72.uf Ge and Si
61.82.Fk Semiconductors
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
72.20.Fr Low-field transport and mobility; piezoresistance
72.80.Cw Elemental semiconductors
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