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5 May 2008

Volume 92, Issue 18, Articles (18xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 92, 182104 (2008); http://dx.doi.org/10.1063/1.2917705 (3 pages)

Jiang Chen, Yibin Hu, Ke Xia, and Zhongshui Ma
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Electronic structure and optical gain of wurtzite ZnO nanowires

Xiu-Wen Zhang, Jingbo Li, Shu-Shen Li, and Jian-Bai Xia

Appl. Phys. Lett. 92, 181101 (2008); http://dx.doi.org/10.1063/1.2918445 (3 pages) | Cited 1 time

Online Publication Date: 5 May 2008

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The electronic structure and optical gain of wurtzite ZnO nanowires are investigated in the framework of effective-mass envelope-function theory. We found that as the elliptical aspect ratio e increases to be larger than a critical value, the hole ground states may change from optically dark to optically bright. The optical gain of ZnO nanowires increases as the hole density increases. For elliptical wire with large e, the y-polarized mode gain can be several thousand cm−1, while the x-polarized mode gain may be 26 times smaller than the former, so they can be used as ultraviolet linearly polarized lasers.
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73.22.-f Electronic structure of nanoscale materials and related systems
71.20.Nr Semiconductor compounds
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor
42.55.Px Semiconductor lasers; laser diodes
78.67.-n Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures

Advanced light trapping management by diffractive interlayer for thin-film silicon solar cells

Philipp Obermeyer, Christian Haase, and Helmut Stiebig

Appl. Phys. Lett. 92, 181102 (2008); http://dx.doi.org/10.1063/1.2919727 (3 pages) | Cited 15 times

Online Publication Date: 5 May 2008

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Thin-film silicon solar cells made of amorphous and microcrystalline silicon in tandem cell configuration enable high efficiency and low-cost production. Precise control of the absorption in each diode by a wavelength-selective and diffractive interlayer provides optimized current matching. For this purpose, intermediate reflectors with periodically textured interfaces are investigated. The propagation of electromagnetic waves is simulated using a three dimensional Maxwell solver which considers both near field and far field optics. Design rules for intermediate reflectors and textured interfaces are presented.
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84.60.Jt Photoelectric conversion

Continuous wave operation of injectorless quantum cascade lasers at low temperatures

Simeon Katz, Andrea Friedrich, Gerhard Boehm, and Markus-Christian Amann

Appl. Phys. Lett. 92, 181103 (2008); http://dx.doi.org/10.1063/1.2841704 (3 pages) | Cited 5 times

Online Publication Date: 6 May 2008

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A continuous wave operating quantum-cascade-laser without injector is presented. The core design was taken from a low-threshold pulsed staircase laser. The active zone of one sample was optimized for low threshold current densities, using 60 periods and a low doping of 2.4×1010 cm−2/period. The second sample consists of 50 periods and a high doping of 6.3×1010 cm−2/period. For the first (second) sample, the threshold current density at 77 K for continuous operation was measured with 0.13 (0.24) kA/cm2 and maximum output power of 16.2 (22.7) mW was observed. Continuous operation was maintained up to 140 K for both lasers.
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42.55.Px Semiconductor lasers; laser diodes

Terahertz-wave absorption in liquids measured using the evanescent field of a silicon waveguide

Li Cheng, Shin’ichiro Hayashi, Adrian Dobroiu, Chiko Otani, Kodo Kawase, Teruo Miyazawa, and Yuichi Ogawa

Appl. Phys. Lett. 92, 181104 (2008); http://dx.doi.org/10.1063/1.2916825 (3 pages) | Cited 6 times

Online Publication Date: 6 May 2008

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A technique is presented for the measurement of the absorption properties of liquids in the terahertz wave range, based on the interaction between the liquid and the evanescent wave covering the surface of a cylindrical waveguide made of high-resistivity silicon. The terahertz wave propagates inside the waveguide as the fundamental EH11 mode. The presence of a medium around the silicon rod has a measurable effect on the overall end-to-end transmission of the waveguide. As demonstration, we report the measurements of a D-glucose aqueous solution with a concentration ranging from 0% to 45%, using a backward-wave oscillator as the terahertz wave source.
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78.90.+t Other topics in optical properties, condensed matter spectroscopy and other interactions of particles and radiation with condensed matter (restricted to new topics in section 78)
61.25.Em Molecular liquids
41.20.Jb Electromagnetic wave propagation; radiowave propagation

Sensitized erbium emission from silicon-rich nitride/silicon superlattice structures

L. Dal Negro, R. Li, J. Warga, and S. N. Basu

Appl. Phys. Lett. 92, 181105 (2008); http://dx.doi.org/10.1063/1.2920435 (3 pages) | Cited 27 times

Online Publication Date: 7 May 2008

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Erbium-doped silicon-rich nitride/silicon superlattice structures were fabricated by direct magnetron cosputtering deposition on Si substrates. Rapid thermal annealing resulted in the nucleation of small amorphous Si clusters, which efficiently sensitize 1.54 μm emission via a nanosecond-fast nonresonant energy transfer process, providing an alternative route toward the fabrication of Si-compatible devices based on Er sensitization.
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81.15.Cd Deposition by sputtering
68.65.Cd Superlattices
61.72.Cc Kinetics of defect formation and annealing

Role of barrier layers in electroluminescence from SiN-based multilayer light-emitting devices

Rui Huang, Hengping Dong, Danqing Wang, Kunji Chen, Honglin Ding, Xiang Wang, Wei Li, Jun Xu, and Zhongyuan Ma

Appl. Phys. Lett. 92, 181106 (2008); http://dx.doi.org/10.1063/1.2920819 (3 pages) | Cited 16 times

Online Publication Date: 7 May 2008

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We report the effects of barrier layer on the electroluminescence properties of the SiN-based multilayer light-emitting devices (LEDs). It is found that the emission efficiency is significantly enhanced by more than one order of magnitude compared to that of LED without barrier layer. Meanwhile, the emission wavelength can also be tuned from 620 to 510 nm by controlling the Si/N ratio of the barrier layer. The improved performance of LEDs can be attributed to the variation in the band offset between the Si-rich SiN well layer and the N-rich SiN barrier layer.
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85.60.Jb Light-emitting devices

Laser action from Yb3+ ions in the ferroelectric and paraelectric phases of strontium barium niobate

E. Martín Rodríguez, D. Jaque, J. García Solé, and R. Pankrath

Appl. Phys. Lett. 92, 181107 (2008); http://dx.doi.org/10.1063/1.2924283 (3 pages) | Cited 8 times

Online Publication Date: 7 May 2008

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We report on continuous wave laser oscillation of trivalent ytterbium ions in the frequency converter Yb3+:Sr0.6Ba0.4Nb2O6 ferroelectric laser crystal. Pump induced thermal loading has been used to drive the crystal from its ferroelectric to paraelectric phase. Stable laser radiation at 1070 nm was found in both phases while a bistable laser output is observed through phase transition. In addition, diffuse green (535 nm) radiation was generated by self-frequency doubling of the fundamental laser radiation because of the random distribution of microferroelectric domains existing in the ferroelectric as grown crystal.
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42.60.By Design of specific laser systems
42.55.Rz Doped-insulator lasers and other solid state lasers
42.70.Hj Laser materials
42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

High peak power single frequency pulses using a short polarization-maintaining phosphate glass fiber with a large core

M. Leigh, W. Shi, J. Zong, Z. Yao, S. Jiang, and N. Peyghambarian

Appl. Phys. Lett. 92, 181108 (2008); http://dx.doi.org/10.1063/1.2917470 (3 pages) | Cited 14 times

Online Publication Date: 8 May 2008

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We report a high power, single frequency 1.5 μm pulsed fiber master oscillator-power amplifier laser source using a large core, polarization-maintaining phosphate glass fiber. The phosphate glass fiber produces high powers with low nonlinearities using high Er–Yb codoping and short length. Using this fiber, we were able to generate single frequency pulses with peak powers up to 51.5 kW. This is the highest reported peak pulse power for eye safe single frequency fiber laser systems.
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42.81.Gs Birefringence, polarization
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.70.Ce Glasses, quartz

Thin cell fringe-field-switching liquid crystal display with a chiral dopant

Zhibing Ge, Shin-Tson Wu, Seong Su Kim, Ji Woong Park, and Seung Hee Lee

Appl. Phys. Lett. 92, 181109 (2008); http://dx.doi.org/10.1063/1.2918838 (3 pages) | Cited 15 times

Online Publication Date: 8 May 2008

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A fringe-field-switching (FFS) liquid crystal display (LCD) using a thin cell doped with a reverse-handed chiral compound is proposed. Such a FFS LCD exhibits a fast response time ( ∼ 8 ms), high transmittance (>90%), low operating voltage (5 Vrms), and intrinsically wide viewing angle. Its application for LCD televisions in order to reduce image blurring is emphasized.
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42.79.Kr Display devices, liquid-crystal devices
85.60.Pg Display systems

Phasematching in semiconductor nonlinear optics by linear long-period gratings

Alex Hayat, Yotam Elor, Eran Small, and Meir Orenstein

Appl. Phys. Lett. 92, 181110 (2008); http://dx.doi.org/10.1063/1.2918013 (3 pages) | Cited 9 times

Online Publication Date: 9 May 2008

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We experimentally demonstrate a phasematching technique for frequency conversion in nonlinear semiconductor structures by employing linear long-period gratings. We designed a specific semiconductor photonic device for second harmonic generation using coupled-mode equations with parameters extracted from beam propagation method simulations. Optical frequency converters were fabricated according to the design with the main feature; linear long-period weak gratings imprinted on semiconductor waveguides, providing the required photon momentum difference for matching the phases of the different-wavelength photons. The measured nonlinear conversion efficiency and its spectrum comply with our theoretical predictions.
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42.79.Nv Optical frequency converters
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.Dj Gratings
42.15.Eq Optical system design
42.65.Wi Nonlinear waveguides
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials

A terahertz quantum cascade laser grown by low-pressure metalorganic vapor phase epitaxy

Lorenzo Sirigu, Alok Rudra, Eli Kapon, Maria I. Amanti, Giacomo Scalari, and Jérôme Faist

Appl. Phys. Lett. 92, 181111 (2008); http://dx.doi.org/10.1063/1.2924294 (3 pages) | Cited 9 times

Online Publication Date: 9 May 2008

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Demonstration of a terahertz quantum cascade laser grown by a low-pressure metalorganic vapor phase epitaxy is reported. The structural analysis of the grown structure shows a very high degree of vertical uniformity and sharp interfaces. Lasing emission at λ = 90 μm up to 93 K with a threshold current density Jth = 330 A/cm2 at 7 K was obtained in a structure incorporating a single plasmon waveguide.
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42.55.Px Semiconductor lasers; laser diodes

Irreversible redshift of transmission spectrum of gold nanoparticles doped in liquid crystals

Li-Hsuan Hsu, Kuang-Yao Lo, Shih-An Huang, Chi-Yen Huang, and Chung-Sung Yang

Appl. Phys. Lett. 92, 181112 (2008); http://dx.doi.org/10.1063/1.2926658 (3 pages) | Cited 6 times

Online Publication Date: 9 May 2008

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The absorption peak of gold (Au) nanoparticles doped in liquid crystal (ANDLC) is controllable by applying an external applied voltage before aggregation occurs. Au nanoparticles aggregate when the dielectrophoresis force, which is induced by the gradient of the square of the electric filed close to the sides of the host liquid crystal cell, overcomes the viscosity between Au nanoparticles and the LCs. This result leads to the irreversible redshift. A controllable filter with unpolarized light enables an ANDLC cell under the threshold voltage to prevent the aggregation effect.
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61.30.Gd Orientational order of liquid crystals; electric and magnetic field effects on order
66.20.-d Viscosity of liquids; diffusive momentum transport
78.30.C- Liquids
78.40.Dw Liquids
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Power scaling of an extreme ultraviolet light source for future lithography

Erik Wagenaars, Felix Küpper, Jürgen Klein, Willi Neff, Marcel Damen, Pieter van der Wel, Dominik Vaudrevange, and Jeroen Jonkers

Appl. Phys. Lett. 92, 181501 (2008); http://dx.doi.org/10.1063/1.2924299 (3 pages) | Cited 2 times

Online Publication Date: 8 May 2008

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For future lithography applications, high-power extreme ultraviolet (EUV) light sources are needed at a central wavelength of 13.5 nm within 2% bandwidth. We have demonstrated that from a physics point of view the Philips alpha-prototype source concept is scalable up to the power levels required for high-volume manufacturing (HVM) purposes. Scalability is shown both in frequency, up to 100 kHz, and pulse energy, up to 55 mJ collectable EUV per pulse, which allows us to find an optimal working point for future HVM sources within a wide parameter space.
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42.72.Bj Visible and ultraviolet sources
42.82.Cr Fabrication techniques; lithography, pattern transfer

Dynamic voltage-current characteristics for a water jet plasma arc

Jiaxiang Yang, Sheng Lan, and Zuoming Xu

Appl. Phys. Lett. 92, 181502 (2008); http://dx.doi.org/10.1063/1.2927475 (3 pages)

Online Publication Date: 8 May 2008

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A virtual instrument technology is used to measure arc current, arc voltage, dynamic V-I characteristics, and nonlinear conductance for a cone-shaped water jet plasma arc under ac voltage. Experimental results show that ac arc discharge mainly happens in water vapor evaporated from water when heated. However, due to water’s cooling effect and its conductance, arc conductance, reignition voltage, extinguish voltage, and current zero time are very different from those for ac arc discharge in gas work fluid. These can be valuable to further studies on mechanism and characteristics of plasma ac discharge in water, and even in gas work fluid.
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52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.25.Fi Transport properties
52.70.Ds Electric and magnetic measurements
52.75.Hn Plasma torches

Deposited debris characteristics and its reduction of a laser-produced plasma extreme ultraviolet source using a colloidal tin dioxide jet target

Masanori Kaku, Sumihiro Suetake, Yusuke Senba, Shoichi Kubodera, Masahito Katto, and Takeshi Higashiguchi

Appl. Phys. Lett. 92, 181503 (2008); http://dx.doi.org/10.1063/1.2924302 (3 pages) | Cited 3 times

Online Publication Date: 9 May 2008

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Debris characteristics and their reduction have been investigated for a laser-produced plasma extreme ultraviolet source by using a colloidal jet target containing tin dioxide nanoparticles. The amounts of deposited debris on a witness plate were determined by total laser energy irradiated onto a target. In situ low-temperature (100 °C) heating of a plate was effective to reduce the amounts of deposited debris, since colloidal debris was easily vaporized by the heat.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.50.Dg Plasma sources
52.70.-m Plasma diagnostic techniques and instrumentation
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Effects of a coating of spherically anisotropic material in core-shell particles

D. H. Liu, C. Xu, and P. M. Hui

Appl. Phys. Lett. 92, 181901 (2008); http://dx.doi.org/10.1063/1.2911724 (3 pages) | Cited 9 times

Online Publication Date: 6 May 2008

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We study the properties of a core-shell particle with a shell of spherically anisotropic material. Such material has a matrix dielectric function that is diagonal in the spherical coordinates. The electric field in the core region is found to be enhanced when compared to an isotropic shell material of comparable dielectric constant for large anisotropy. The enhanced field can drive an enhanced nonlinear response if the core region carries an intrinsic nonlinear susceptibility. For a metallic core, the surface plasmon resonance frequency is found to depend on the degree of anisotropy or the thickness of the shell.
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77.22.Ch Permittivity (dielectric function)
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Multifunctional liquid crystal elastomers: Large electromechanical and electro-optical effects

Shigehiro Hashimoto, Yusril Yusuf, Simon Krause, Heino Finkelmann, P. E. Cladis, Helmut R. Brand, and Shoichi Kai

Appl. Phys. Lett. 92, 181902 (2008); http://dx.doi.org/10.1063/1.2917465 (3 pages) | Cited 2 times

Online Publication Date: 6 May 2008

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A multifunctional main chain liquid crystal elastomer (MCLCE) with large mechanical and optical effects in applied electric fields is investigated, when MCLCE is swollen in a low molecular weight liquid crystal, 4-n-pentyl-4-cyanobiphenyl, a nematic solvent. The size change by the field effects is linearly proportional to the transmittancy change. This suggests the possibility of broad application as a field-induced-optical actuator device.
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61.30.Eb Experimental determinations of smectic, nematic, cholesteric, and other structures
78.20.Jq Electro-optical effects

Controlling the temperature coefficient of resistance and resistivity in RuO2–TiO2 thin films by the intermixing ratios between RuO2 and TiO2

Se-Hun Kwon, Sang-Won Kang, and Kwang-Ho Kim

Appl. Phys. Lett. 92, 181903 (2008); http://dx.doi.org/10.1063/1.2918989 (3 pages) | Cited 4 times

Online Publication Date: 6 May 2008

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The temperature coefficient of resistance (TCR) properties and resistivities, depending on the RuO2 intermixing ratios for RuO2–TiO2 thin films and their thermal stability in the temperature range of 200–700 °C, were investigated. The TCR values for the RuO2–TiO2 thin films ranged from −557.17 to −54.923 ppm/K for the RuO2 intermixing ratios ranging from 0.52 to 0.81, with resistivities remaining in the range of 2600–370 μΩ cm. Moreover, the high structural stability and its stable oxide form of the RuO2–TiO2 thin films resulted in minimal change in both TCR values and resistivities even after O2 annealing process at 700 °C.
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73.61.Le Other inorganic semiconductors
68.55.-a Thin film structure and morphology
81.40.Gh Other heat and thermomechanical treatments
68.60.Dv Thermal stability; thermal effects

Optical switching in VO2 films by below-gap excitation

M. Rini, Z. Hao, R. W. Schoenlein, C. Giannetti, F. Parmigiani, S. Fourmaux, J. C. Kieffer, A. Fujimori, M. Onoda, S. Wall, and A. Cavalleri

Appl. Phys. Lett. 92, 181904 (2008); http://dx.doi.org/10.1063/1.2921784 (3 pages) | Cited 22 times

Online Publication Date: 6 May 2008

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We study the photoinduced insulator-metal transition in VO2, correlating its threshold and dynamics with excitation wavelength. In single crystals, switching can only be induced with photon energies above the 670 meV gap. This contrasts with the case of polycrystalline films, where formation of the metallic state can be initiated also with photon energies as low as 180 meV, which are well below the bandgap. Perfection of this process may become conducive to schemes for optical switches, limiters, and detectors operating at room temperature in the mid-infrared.
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71.30.+h Metal-insulator transitions and other electronic transitions
78.66.Nk Insulators

Theoretical analysis of texture effects on the surface morphological stability of metallic thin films

Vivek Tomar, M. Rauf Gungor, and Dimitrios Maroudas

Appl. Phys. Lett. 92, 181905 (2008); http://dx.doi.org/10.1063/1.2912037 (3 pages) | Cited 10 times

Online Publication Date: 7 May 2008

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By using a nonlinear model of surface morphological evolution, linear stability analysis, and self-consistent dynamical simulations, we analyze the effects of surface crystallographic orientation of a metallic thin film on its surface morphological response to the simultaneous action of an electric field and mechanical stress. The analysis reveals improved surface morphological stability over a range of misorientation angles between the electric-field direction and “easy surface diffusion” directions; for ⟨111⟩-oriented surfaces in fcc metals, the surface morphological response is superior to that of ⟨110⟩- and ⟨100⟩-oriented surfaces. This finding provides an interpretation for the longer electromigration lifetime of {111}-textured metallic interconnects.
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68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
68.55.jm Texture
66.30.Qa Electromigration

The origin of the energy-dose window in separation-by-implanted-oxygen materials processing

R. Kögler, Xin Ou, W. Skorupa, and W. Möller

Appl. Phys. Lett. 92, 181906 (2008); http://dx.doi.org/10.1063/1.2917582 (3 pages) | Cited 5 times

Online Publication Date: 7 May 2008

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The energy-dose (ED) window (so called Izumi window) for the formation of a perfect planar and homogeneous buried oxide layer in silicon using ion implantation is controlled by the interaction of excess radiation defects and the local oxygen concentration. The ED window is defined by an appropriate correlation between the distribution of implantation-induced excess defects and the position of the finally formed oxide layer. A quantitative relation is established on the basis of collisional computer simulations. The findings are discussed in terms of oxide precipitation under the influence of defects.
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61.72.uf Ge and Si
61.72.jd Vacancies
61.72.jj Interstitials
61.80.Jh Ion radiation effects

Silicon-germanium interdiffusion in high-germanium-content epitaxial heterostructures

Nevran Ozguven and Paul C. McIntyre

Appl. Phys. Lett. 92, 181907 (2008); http://dx.doi.org/10.1063/1.2917798 (3 pages) | Cited 11 times

Online Publication Date: 9 May 2008

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We report on multilayer x-ray reflectivity measurements of the Si–Ge interdiffusivity in epitaxial SixGe1−x/SiyGe1−y superlattices that have an average Ge composition of 91 at. %. The extracted activation enthalpy (3.20±0.2 eV) is substantially smaller than that previously reported for Si-rich SiGe alloys and the interdiffusivity value at typical dopant anneal temperatures is, therefore, much larger for the Ge-rich heterostructures. The activation enthalpy for interdiffusion measured for the 〈XGe〉 = 0.91 superlattice is reasonably consistent with a linear interpolation between the recently reported value for an alloy with 〈XGe〉 ≈ 0.5 and that reported for self-diffusion in pure Ge.
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66.30.Ny Chemical interdiffusion; diffusion barriers
68.65.Cd Superlattices
65.40.G- Other thermodynamical quantities

DX centers in CdTe: A density functional study

Mao-Hua Du

Appl. Phys. Lett. 92, 181908 (2008); http://dx.doi.org/10.1063/1.2920203 (3 pages) | Cited 3 times

Online Publication Date: 9 May 2008

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DX centers induced by both group-III and group-VII donors in CdTe are studied using density functional calculations. The results show that, for group-VII donors, the DX centers with a cation-cation bond (α- and β-CCB-DX centers) are more stable than the previously proposed broken-bond DX (BB-DX) center and the β-CCB-DX center is the most stable. The stability trend found for the CCB-DX centers for different donors in CdTe is consistent with that for GaAs and GaSb, which suggests a general rule that the CCB-DX centers are favored for small donor atoms on anion site especially for semiconductors with large anion size.
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71.55.Gs II-VI semiconductors
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
61.72.Bb Theories and models of crystal defects

Resonant optical excitation of longitudinal-optical phonons and intermixing in InAs/AlAs single quantum dots

D. Sarkar, H. P. van der Meulen, J. M. Calleja, J. M. Meyer, R. J. Haug, and K. Pierz

Appl. Phys. Lett. 92, 181909 (2008); http://dx.doi.org/10.1063/1.2920441 (3 pages) | Cited 1 time

Online Publication Date: 9 May 2008

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Excitations of a single InAs/AlAs self-assembled quantum dot were investigated by photoluminescence excitation spectroscopy. Resonant absorption by longitudinal-optical (LO) phonons of the quantum dot and the barriers is observed. In particular, a resonance at 41 meV is attributed to the AlAs-like mode of InAlAs with low Al content. Our results represent a direct optical measure of the intermixing (estimated below 10%) in a single quantum dot. They also demonstrate that all LO phonons of this mixed quantum dot system couple to the exciton states.
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78.67.Hc Quantum dots
78.55.Cr III-V semiconductors
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
63.20.kk Phonon interactions with other quasiparticles
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Low thermal conductivity and high thermoelectric figure of merit in n-type BaxYbyCo4Sb12 double-filled skutterudites

X. Shi, H. Kong, C.-P. Li, C. Uher, J. Yang, J. R. Salvador, H. Wang, L. Chen, and W. Zhang

Appl. Phys. Lett. 92, 182101 (2008); http://dx.doi.org/10.1063/1.2920210 (3 pages) | Cited 111 times

Online Publication Date: 5 May 2008

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Filled skutterudites are one of the most promising thermoelectric materials for power generation applications. The choice and concentration of filler atoms are key aspects for achieving high thermoelectric figure of merit values. We report on the high temperature thermoelectric properties in the double-filled skutterudites BaxYbyCo4Sb12. The combination of Ba and Yb fillers inside the voids of the skutterudite structure provides a broad range of resonant phonon scattering and consequently a strong suppression in the lattice thermal conductivity is observed. A dimensionless thermoelectric figure of merit of 1.36 at 800 K is achievable for n-type BaxYbyCo4Sb12.
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72.20.Pa Thermoelectric and thermomagnetic effects
72.80.Jc Other crystalline inorganic semiconductors
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