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3 May 2010

Volume 96, Issue 18, Articles (18xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 96, 183102 (2010); http://dx.doi.org/10.1063/1.3419932 (3 pages)

Bernard Aufray, Abdelkader Kara, Sébastien Vizzini, Hamid Oughaddou, Christel Léandri, Benedicte Ealet, and Guy Le Lay
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Parallel laser microfabrication of large-area asymmetric split ring resonator metamaterials and its structural tuning for terahertz resonance

Z. C. Chen, M. H. Hong, C. S. Lim, N. R. Han, L. P. Shi, and T. C. Chong

Appl. Phys. Lett. 96, 181101 (2010); http://dx.doi.org/10.1063/1.3424793 (3 pages) | Cited 2 times

Online Publication Date: 3 May 2010

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Large-area asymmetric split ring resonator (ASRR) arrays are fabricated by femtosecond laser microlens array lithography. The double square ASRR consists of two gaps at the outer edge. The resonance properties of this ASRR under structural symmetry breaking conditions are investigated in the terahertz region by changing gap size at one side. The resonance of the ASRR shows blueshift from 0.85 to 0.98 THz when the one gap size increases from 2 to 14 μm. Numerical simulations reveal that the electric field enhancement at the fixed gap increases from 152 to 206 times as the degree of asymmetry increases.
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42.82.Cr Fabrication techniques; lithography, pattern transfer
42.70.-a Optical materials

In search of the elusive lossless metal

J. B. Khurgin and G. Sun

Appl. Phys. Lett. 96, 181102 (2010); http://dx.doi.org/10.1063/1.3425890 (3 pages) | Cited 9 times

Online Publication Date: 3 May 2010

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We show that when one looks beyond the Drude model of metal conductivity, the metals that may be extremely lossy for low frequency electromagnetic waves can become perfectly lossless in the mid-IR region or higher, while retaining the essential metallic characteristic of negative permittivity even at those frequencies. We identify that the transition to the lossless regime occurs when the interatomic distances in the lattice exceed certain values, typically a factor of two larger than those occurring in nature. We believe that advances in nanoassembly may render lossless metals feasible with revolutionary implications for the fields of plasmonics and metamaterials.
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42.70.-a Optical materials
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials

Electrically pumped photonic crystal nanocavity light sources using a laterally doped p-i-n junction

Bryan Ellis, Tomas Sarmiento, Marie Mayer, Bingyang Zhang, James Harris, Eugene Haller, and Jelena Vuckovic

Appl. Phys. Lett. 96, 181103 (2010); http://dx.doi.org/10.1063/1.3425663 (3 pages) | Cited 14 times

Online Publication Date: 4 May 2010

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A technique to electrically pump photonic crystal nanocavities using a lateral p-i-n junction is described. Ion implantation doping is used to form the junction, which under forward bias pumps a gallium arsenide photonic crystal nanocavity with indium arsenide quantum dots. Efficient cavity-coupled electroluminescence is demonstrated and the electrical characteristics of the diode are presented. The fabrication improvements necessary for making an electrically pumped nanocavity laser using a lateral junction are discussed.
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42.55.Tv Photonic crystal lasers and coherent effects
42.55.Px Semiconductor lasers; laser diodes
42.72.-g Optical sources and standards
42.82.-m Integrated optics
42.60.By Design of specific laser systems
42.70.Qs Photonic bandgap materials

Broad area lasers with monolithically integrated transverse mode selector

D. Hoffmann, K. Huthmacher, C. Döring, and H. Fouckhardt

Appl. Phys. Lett. 96, 181104 (2010); http://dx.doi.org/10.1063/1.3425898 (3 pages) | Cited 1 time

Online Publication Date: 4 May 2010

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AlGaInAsSb-based multiple quantum well broad area lasers (BALs) with a monolithically integrated Fourier-optical 4f spatial-frequency-filter for transverse mode selection (TMS) are realized. Laser samples with filters for the selection of the fundamental transverse mode (no. 0; TMS0) and—for proof of principle-higher order modes, here exemplarily mode no. 8 (TMS8), are prepared; their emission characteristics are investigated. The concept of BAL and TMS integration within the active laser chip is verified.
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42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.60.By Design of specific laser systems
42.82.-m Integrated optics
42.79.Ci Filters, zone plates, and polarizers
42.30.Kq Fourier optics

Gyrotropic band gap optical sensors

Neluka K. Dissanayake, Miguel Levy, Amir A. Jalali, and V. J. Fratello

Appl. Phys. Lett. 96, 181105 (2010); http://dx.doi.org/10.1063/1.3427404 (3 pages) | Cited 2 times

Online Publication Date: 6 May 2010

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Faraday-effect-active photonic band gap structures fabricated in iron garnet films are shown to provide a platform for optical sensing based on refractive index detection. Strong near-band gap-edge polarization rotations serve as a sensitive probe to cover-index changes in birefringent magneto-optic waveguides. A wide index range from air to n = 1.6 is explored. Device sensitivity is found to improve with cover index increase. Theoretical analysis of Bloch modes polarization state shows large near stop-band edge rotations and strong sensitivity to cover index. The combined effects of geometrical waveguide birefringence and Faraday rotation contribute to the strength of the sensor response.
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07.60.Hv Refractometers and reflectometers
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
42.79.Gn Optical waveguides and couplers
42.70.Qs Photonic bandgap materials

Resonant cavity-enhanced absorption for optical refrigeration

D. V. Seletskiy, M. P. Hasselbeck, and M. Sheik-Bahae

Appl. Phys. Lett. 96, 181106 (2010); http://dx.doi.org/10.1063/1.3397989 (3 pages) | Cited 2 times

Online Publication Date: 6 May 2010

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A 20-fold increase over the single path optical absorption is demonstrated with a low loss medium placed in a resonant cavity. This is applied to laser cooling of ytterbium-doped fluorozirconate glass resulting in 90% absorption of the incident pump light. A coupled-cavity scheme to achieve active optical impedance matching is analyzed.
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42.50.Wk Mechanical effects of light on material media, microstructures and particles

Spatially direct and indirect transitions of self-assembled GeSi/Si quantum dots studied by photoluminescence excitation spectroscopy

B. Adnane, K. F. Karlsson, G. V. Hansson, P. O. Holtz, and W.-X. Ni

Appl. Phys. Lett. 96, 181107 (2010); http://dx.doi.org/10.1063/1.3424789 (3 pages) | Cited 4 times

Online Publication Date: 6 May 2010

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Well-resolved photoluminescence excitation (PLE) spectra are reported for self-assembled GeSi dots grown on Si(001) by molecular beam epitaxy. The observation of two excitation resonance peaks is attributed to two different excitation/de-excitation routes of interband optical transitions connected to the spatially direct and indirect recombination processes. It is concluded that two dot populations are addressed by each monitored luminescence energy for the PLE acquisition.
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81.07.Ta Quantum dots
78.67.Hc Quantum dots
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.60.-b Other luminescence and radiative recombination

Ghost diffraction without a beamsplitter

Shibei He, Xia Shen, Hui Wang, Wenlin Gong, and Shengsheng Han

Appl. Phys. Lett. 96, 181108 (2010); http://dx.doi.org/10.1063/1.3425887 (3 pages)

Online Publication Date: 6 May 2010

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Many significant results have been achieved in the fields of ghost imaging, in which the beamsplitter is an indispensable optical component. This paper introduces a scheme to realize ghost diffraction without a beamsplitter. The experimental results and theoretical analysis are presented, and the possibility of some practical applications of this imaging scheme is also discussed.
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42.50.-p Quantum optics
42.25.Fx Diffraction and scattering
42.30.-d Imaging and optical processing

Peculiar features of confinement factors in a metal-semiconductor waveguide

D. B. Li and C. Z. Ning

Appl. Phys. Lett. 96, 181109 (2010); http://dx.doi.org/10.1063/1.3425896 (3 pages) | Cited 4 times

Online Publication Date: 6 May 2010

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The concept of confinement factor (CF) is analyzed for a metal-semiconductor-metal (MSM) waveguide near the surface plasmon resonance. We show that the CF is inversely proportional to the average energy velocity, and thus can be enhanced by the slowing down of energy propagation. This slowing down in the MSM waveguide results in a value of CF as high as 105, as opposed to a value of smaller than 1 in a typically dielectric structure. Contrary to the CF in pure dielectric waveguide where it is independent of material gain, the CF in MSM waveguide shows a resonancelike dependence on material gain near the surface plasmon resonance.
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42.79.Gn Optical waveguides and couplers
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Enhanced light extraction in light-emitting diodes with photonic crystal structure selectively grown on p-GaN

Chu-Young Cho, Se-Eun Kang, Ki Seok Kim, Sang-Jun Lee, Yong-Seok Choi, Sang-Heon Han, Gun-Young Jung, and Seong-Ju Park

Appl. Phys. Lett. 96, 181110 (2010); http://dx.doi.org/10.1063/1.3427352 (3 pages) | Cited 2 times

Online Publication Date: 7 May 2010

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We report on the properties of green light-emitting diodes (LEDs) with a photonic crystal (PC) structure on p-GaN. A PC structure was fabricated by the selective area epitaxy of p-GaN using SiO2 nanopillars. The electrical characteristics of LEDs with PC were not degraded and the optical output power of green LEDs with PC was increased by 70% at 20 mA of injection current compared with that of conventional LEDs without PC. This enhancement of optical output power was attributed to the improvement in light extraction efficiency by the SiO2/p-GaN PC layer on p-GaN.
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85.60.Jb Light-emitting devices
42.70.Qs Photonic bandgap materials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
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Nonlinear frequency coupling in dual radio-frequency driven atmospheric pressure plasmas

J. Waskoenig and T. Gans

Appl. Phys. Lett. 96, 181501 (2010); http://dx.doi.org/10.1063/1.3425668 (3 pages) | Cited 9 times

Online Publication Date: 3 May 2010

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Plasma ionization, and associated mode transitions, in dual radio-frequency driven atmospheric pressure plasmas are governed through nonlinear frequency coupling in the dynamics of the plasma boundary sheath. Ionization in low-power mode is determined by the nonlinear coupling of electron heating and the momentary local plasma density. Ionization in high-power mode is driven by electron avalanches during phases of transient high electric fields within the boundary sheath. The transition between these distinctly different modes is controlled by the total voltage of both frequency components.
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52.80.-s Electric discharges
52.25.-b Plasma properties
52.40.Kh Plasma sheaths
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Suppression of concentration quenching of Er-related luminescence in Er-doped GaN

Shaoqiang Chen, Benjamin Dierre, Woong Lee, Takashi Sekiguchi, Shigeo Tomita, Hiroshi Kudo, and Katsuhiro Akimoto

Appl. Phys. Lett. 96, 181901 (2010); http://dx.doi.org/10.1063/1.3421535 (3 pages) | Cited 5 times

Online Publication Date: 3 May 2010

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Erbium-doped GaN with different doping concentrations were grown by ammonia-source molecular beam epitaxy. The intra-4f-shell transitions related green luminescence were observed by both photoluminescence (PL) and cathodoluminescence (CL) measurements. It was found that concentration quenching of Er-related luminescence was observed in PL measurements while not in CL measurements. The different excitation and relaxation processes are suggested as the cause of the concentration quenching characteristics between PL and CL. The strong Er-related CL intensity in highly doped GaN demonstrates that high energy excitation is a promising approach to suppress the concentration quenching in Er-doped GaN.
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81.05.Ea III-V semiconductors
61.72.uj III-V and II-VI semiconductors
78.55.Cr III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.A- Nucleation and growth
78.66.Fd III-V semiconductors

Ellipsometric study of single-crystal γ-InSe from 1.5 to 9.2 eV

S. G. Choi, D. E. Aspnes, A. L. Fuchser, C. Martinez-Tomas, V. Muñoz Sanjosé, and D. H. Levi

Appl. Phys. Lett. 96, 181902 (2010); http://dx.doi.org/10.1063/1.3420080 (3 pages) | Cited 1 time

Online Publication Date: 6 May 2010

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We report the component math⊥math of the pseudodielectric-function tensor 〈ε(E)〉 = 〈ε1(E)〉+i〈ε2(E)〉 of γ-phase single-crystal InSe, obtained from 1.5 to 9.2 eV by vacuum-ultraviolet spectroscopic ellipsometry with the sample at room temperature. Overlayer artifacts were reduced as far as possible by measuring fresh surfaces prepared by cleavage. Accurate critical-point energies of observed structures were obtained by a combined method of spectral analysis.
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81.05.Hd Other semiconductors
78.66.Li Other semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
77.22.Ch Permittivity (dielectric function)
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
78.40.Fy Semiconductors

Comparison of optical absorption in Si nanowire and nanoporous Si structures for photovoltaic applications

Zhiqiang Xiong, Fangyuan Zhao, Jiong Yang, and Xinhua Hu

Appl. Phys. Lett. 96, 181903 (2010); http://dx.doi.org/10.1063/1.3427407 (3 pages) | Cited 6 times

Online Publication Date: 6 May 2010

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We numerically study the optical absorption in Si nanowire and nanoporous Si structures that have potential applications in solar cells. It is found that for the same thickness and filling ratio of Si, thin nanoporous structures can have much higher absorption than thin Si nanowire arrays. Above a critical filling ratio of Si (0.25), the nanoporous structures can have higher absorption even than thin films with the same thickness. For solar cells based on thin nanoporous Si structures, the maximal ultimate efficiency occurs when the filling ratio is around 0.3.
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61.46.-w Structure of nanoscale materials
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
72.40.+w Photoconduction and photovoltaic effects
78.66.Db Elemental semiconductors and insulators
88.40.H- Solar cells (photovoltaics)
61.43.Gt Powders, porous materials

Investigation of E1(LO) phonon-plasmon coupled modes and critical points in In1−xGaxN thin films by optical reflectance measurements

J. S. Thakur, A. Dixit, Y. V. Danylyuk, C. Sudakar, V. M. Naik, W. J. Schaff, and R. Naik

Appl. Phys. Lett. 96, 181904 (2010); http://dx.doi.org/10.1063/1.3428368 (3 pages) | Cited 1 time

Online Publication Date: 6 May 2010

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Low energy optical modes of molecular beam epitaxy-grown In1−xGaxN thin films with 0 ≤ x ≤ 0.6 are investigated using infrared reflectance measurements. We found that the reflectance of the films for wave vectors in the range from 600 to 800 cm−1 is determined by the high energy E1(LO)-plasmon coupled modes. In the higher energy regime of the UV-visible reflectance spectrum of InN, critical points with energies 4.75, 5.36, and 6.12 eV belonging to A and B structures are observed. The energies of these critical points increase with increasing values of x, similar to the band gap energy of these films.
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63.22.Dc Free films
78.66.Fd III-V semiconductors
78.30.Fs III-V and II-VI semiconductors
78.40.Fy Semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.ag Semiconductors

Structural effects on the lattice thermal conductivity of ternary antimony- and bismuth-containing chalcogenide semiconductors

Eric J. Skoug, Jeffrey D. Cain, and Donald T. Morelli

Appl. Phys. Lett. 96, 181905 (2010); http://dx.doi.org/10.1063/1.3425886 (3 pages) | Cited 3 times

Online Publication Date: 6 May 2010

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The lattice thermal conductivities Cu3SbSe4 and Cu3SbSe3 have been measured. While the former compound exhibits classical behavior, the lattice thermal conductivity of Cu3SbSe3 is anomalously low. We speculate that, similar to the case of AgSbTe2, the low thermal conductivity in Cu3SbSe3 has its origin in strong anharmonicity induced by the presence of the two additional nonbonding electrons in the valence shell of the Sb3+ ions. Anomalously low thermal conductivity is also demonstrated in compounds in which Bi occurs in the trivalent state. The results have implications in the design of thermoelectric semiconductors with intrinsically low thermal conductivity.
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72.20.Pa Thermoelectric and thermomagnetic effects
66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
65.60.+a Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.

Effects of oxide-shell structures on the dynamics of oxidation of Al nanoparticles

Weiqiang Wang, Richard Clark, Aiichiro Nakano, Rajiv K. Kalia, and Priya Vashishta

Appl. Phys. Lett. 96, 181906 (2010); http://dx.doi.org/10.1063/1.3425888 (3 pages)

Online Publication Date: 6 May 2010

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Effects of the crystalline and amorphous structure of alumina shells on the dynamics of oxidation of an aluminum nanoparticle (ANP) are studied using multimillion-atom molecular dynamics simulations. With an amorphous shell, formation of oxidized nanocluster fragments produced by the shattering of the shell, combined with the fragmentation and dispersion of the nanoparticle, catalyzes faster oxidation reactions. Consequently, the energy release rate of an ANP with an amorphous shell is much higher than that with a crystalline shell. Analysis on the formation of oxygen-rich fragments further confirms an enhanced reaction rate with an amorphous shell.
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81.65.Mq Oxidation
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Indium kinetics during the plasma-assisted molecular beam epitaxy of semipolar (11−22) InGaN layers

A. Das, S. Magalhães, Y. Kotsar, P. K. Kandaswamy, B. Gayral, K. Lorenz, E. Alves, P. Ruterana, and E. Monroy

Appl. Phys. Lett. 96, 181907 (2010); http://dx.doi.org/10.1063/1.3427310 (3 pages) | Cited 4 times

Online Publication Date: 7 May 2010

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We report on the growth kinetics of semipolar (11−22) InGaN layers by plasma-assisted molecular beam epitaxy. Similarly to (0001)-oriented InGaN, optimum growth conditions for this crystallographic orientation correspond to the stabilization of two atomic layers of In on the growing InGaN surface, and the limits of this growth window in terms of substrate temperature and In flux lie at same values for both polar and semipolar material. However, in semipolar samples, the incorporation of In is inhibited, even for growth temperatures within the Ga-limited regime of polar InGaN growth.
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81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
52.77.Dq Plasma-based ion implantation and deposition
68.55.ag Semiconductors

In-plane thermal and thermoelectric properties of misfit-layered [(PbSe)0.99]x(WSe2)x superlattice thin films

Anastassios Mavrokefalos, Qiyin Lin, Matthew Beekman, Jae Hun Seol, Yong J. Lee, Huijun Kong, Michael T. Pettes, David C. Johnson, and Li Shi

Appl. Phys. Lett. 96, 181908 (2010); http://dx.doi.org/10.1063/1.3428577 (3 pages) | Cited 4 times

Online Publication Date: 7 May 2010

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The in-plane thermal conductivity is measured to be three times lower in misfit-layered [(PbSe)0.99]x(WSe2)x superlattice thin films than disordered-layered WSe2 because of interface scattering despite a higher cross-plane value in the former than the latter. While having little effect on the in-plane thermal conductivity, annealing the p-type [(PbSe)0.99]2(WSe2)2 films in Se increases the in-plane Seebeck coefficient and electrical conductivity because of decreased defect and hole concentrations. Increasing interface density of the annealed films by decreasing x from 4 to 2 has weak influence on the in-plane thermal conductivity but increases the Seebeck coefficient and decreases the room-temperature electrical conductivity.
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73.61.Le Other inorganic semiconductors
68.55.ag Semiconductors
72.80.Jc Other crystalline inorganic semiconductors
66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
72.20.Pa Thermoelectric and thermomagnetic effects
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Microscopic studies of metal-induced lateral crystallization in SiGe

Masaru Itakura, Shunji Masumori, Noriyuki Kuwano, Hiroshi Kanno, Taizoh Sadoh, and Masanobu Miyao

Appl. Phys. Lett. 96, 182101 (2010); http://dx.doi.org/10.1063/1.3422477 (3 pages) | Cited 2 times

Online Publication Date: 4 May 2010

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Metal-induced lateral crystallization (MILC) in amorphous SiGe films on insulating substrates is an important technique for future thin-film-transistor fabrication. Growth features of low and/or high temperature MILC have been investigated based on the microscopic crystal observation. In the initial stage of MILC, precipitation of hemispherical Ni(Si,Ge) with orthorhombic structure is found at the growth front. This leads to the formation of long needlelike SiGe crystallites. And then, the spontaneous nucleation and growth of SiGe take place around the needlelike crystals, resulting in long rod-shaped SiGe crystals. In this way, the role of Ge atoms on MILC is clarified.
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68.55.ag Semiconductors
61.43.Dq Amorphous semiconductors, metals, and alloys
81.05.Gc Amorphous semiconductors
68.35.bj Amorphous semiconductors, glasses
81.30.Mh Solid-phase precipitation

Sulfur gradient-driven Se diffusion at the CdS/CuIn(S,Se)2 solar cell interface

L. Weinhardt, M. Bär, S. Pookpanratana, M. Morkel, T. P. Niesen, F. Karg, K. Ramanathan, M. A. Contreras, R. Noufi, E. Umbach, and C. Heske

Appl. Phys. Lett. 96, 182102 (2010); http://dx.doi.org/10.1063/1.3425666 (3 pages) | Cited 3 times

Online Publication Date: 4 May 2010

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The diffusion behavior of Se at the CdS/Cu(In,Ga)(S,Se)2 thin film solar cell interface was investigated by x-ray photoelectron spectroscopy and x-ray excited Auger electron spectroscopy. Buffer/absorber structures with S/Se ratios between zero and three at the initial Cu(In,Ga)(S,Se)2 surface were analyzed. Samples from a high-efficiency laboratory process (NREL) as well as from an industrial large-area process (AVANCIS) were investigated. We find selenium diffusion into the CdS buffer layer, the magnitude of which strongly depends on the S content at the absorber surface. The associated modification of the heterojunction partners has significant impact on the electronic structure at the interface.
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88.40.jm Thin film III-V and II-VI based solar cells
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Epitaxially stabilized iridium spinel oxide without cations in the tetrahedral site

Hiromichi Kuriyama, Jobu Matsuno, Seiji Niitaka, Masaya Uchida, Daisuke Hashizume, Aiko Nakao, Kunihisa Sugimoto, Hiroyuki Ohsumi, Masaki Takata, and Hidenori Takagi

Appl. Phys. Lett. 96, 182103 (2010); http://dx.doi.org/10.1063/1.3374449 (3 pages)

Online Publication Date: 4 May 2010

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Single-crystalline thin film of an iridium dioxide polymorph Ir2O4 has been fabricated by the pulsed laser deposition of LixIr2O4 precursor and the subsequent Li-deintercalation using soft chemistry. Ir2O4 crystallizes in a spinel (AB2O4) without A cations in the tetrahedral site, which is isostructural to λ-MnO2. Ir ions form a pyrochlore sublattice, which is known to give rise to a strong geometrical frustration. This Ir spinel was found to be a narrow gap insulator, in remarkable contrast to the metallic ground state of rutile-type IrO2. We argue that an interplay of a strong spin-orbit coupling and a Coulomb repulsion gives rise to an insulating ground state as in a layered perovskite Sr2IrO4.
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68.55.aj Insulators
81.15.Fg Pulsed laser ablation deposition
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect

p-type Bi0.4Sb1.6Te3 nanocomposites with enhanced figure of merit

Shufen Fan, Junnan Zhao, Jun Guo, Qingyu Yan, Jan Ma, and Huey Hoon Hng

Appl. Phys. Lett. 96, 182104 (2010); http://dx.doi.org/10.1063/1.3427427 (3 pages) | Cited 8 times

Online Publication Date: 6 May 2010

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We report enhanced figure of merit, ZT, in p-type Bi0.4Sb1.6Te3 nanocomposites fabricated by a rapid and high throughput method of mixing nanostructured Bi0.4Sb1.6Te3 particles obtained through melt spinning with micronsized particles obtained via solid state reaction. Due to effective scattering of phonons over a wide wavelength spectrum, low thermal conductivity, and moderately good power factor were obtained in the nanocomposites to achieve ZT above 1.5 at room temperature. A maximum ZT of 1.80 was attained at 43 °C for the nanocomposite consisting 40 wt % nanoinclusions. This was a 56% increment over the bulk sample, and the highest ZT reported for Bi2Te3-based materials.
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81.05.uj Diamond/nanocarbon composites
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)
64.70.Nd Structural transitions in nanoscale materials
61.72.Qq Microscopic defects (voids, inclusions, etc.)
66.70.Lm Other systems such as ionic crystals, molecular crystals, nanotubes, etc.
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials

High thermal stability and low electrical resistivity carbon-containing Cu film on barrierless Si

L. F. Nie, X. N. Li, J. P. Chu, Q. Wang, C. H. Lin, and C. Dong

Appl. Phys. Lett. 96, 182105 (2010); http://dx.doi.org/10.1063/1.3427408 (3 pages) | Cited 2 times

Online Publication Date: 7 May 2010

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Interfacial structures and electrical resistivities of a carbon-doped Cu film at different annealing temperatures and times were investigated. The film was prepared by magnetron sputtering on barrierless silicon. After annealing, grain growth was distinctly hindered and a carbon-containing nanometer thick passive amorphous layer was formed at the film/substrate interface. The film had a resistivity of about 2.7 μΩ cm after annealing at 400 °C for 1 h and maintained a low resistivity of 3.8 μΩ cm even after 9 h annealing at 400 °C. The low electrical resistivity in combination with the high thermal stability makes carbon doping a promising technique for future Cu interconnects on barrierless Si.
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68.60.Dv Thermal stability; thermal effects
81.15.Cd Deposition by sputtering
68.55.A- Nucleation and growth
81.40.Gh Other heat and thermomechanical treatments
73.61.At Metal and metallic alloys
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Giant magnetoelectric coefficients in (Fe90Co10)78Si12B10-AlN thin film composites

Henry Greve, Eric Woltermann, Hans-Joachim Quenzer, Bernhard Wagner, and Eckhard Quandt

Appl. Phys. Lett. 96, 182501 (2010); http://dx.doi.org/10.1063/1.3377908 (3 pages) | Cited 18 times

Online Publication Date: 3 May 2010

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Thin film magnetoelectric (ME) two–two composites consisting of AlN and amorphous (Fe90Co10)78Si12B10 layers were fabricated by magnetron sputtering on Si (100) substrates. Upon magnetic field annealing they show an extremely high ME coefficient of 737 V/cm Oe at mechanical resonance at 753 Hz and 3.1 V/cm Oe out of resonance at 100 Hz. These are the highest reported ME coefficients in thin film composites ever. Furthermore, the induced magnetic anisotropy by field annealing serves the possibility to obtain a sensor element with a pronounced sensitivity in only one dimension, which allows the realization of a three-dimensional vector field sensor.
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75.85.+t Magnetoelectric effects, multiferroics
77.55.Nv Multiferroic/magnetoelectric films
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
85.75.Ss Magnetic field sensors using spin polarized transport
75.30.Gw Magnetic anisotropy
75.60.Nt Magnetic annealing and temperature-hysteresis effects
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