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5 May 2008

Volume 92, Issue 18, Articles (18xxxx)

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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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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

Anomalous photocurrent in self-assembled InAs/GaAs quantum dots

A. F. G. Monte, Fanyao Qu, and M. Hopkinson

Appl. Phys. Lett. 92, 182102 (2008); http://dx.doi.org/10.1063/1.2920763 (3 pages) | Cited 1 time

Online Publication Date: 5 May 2008

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Carrier dynamics in self-assembled InAs/GaAs quantum dots (QDs) is studied by photoluminescence (PL) and its complementary photocurrent (PC) spectroscopy. We found that carrier capture from the GaAs barriers, radiative recombination in InAs quantum dots, and tunneling among vertical QDs are very sensitive to applied bias voltage. An unusual behavior, by which the PL intensity presents steplike bias voltage dependence, has been observed. It is also consistently manifested in bias voltage dependent PC signals. We attribute this anomalous behavior to the interplay between the coupling of lateral QDs and tunneling among vertical ones.
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73.63.Kv Quantum dots
73.40.Gk Tunneling
78.67.Hc Quantum dots
78.55.Cr III-V semiconductors
72.40.+w Photoconduction and photovoltaic effects
81.16.Dn Self-assembly

Current-induced magnetization excitation in a pseudo-spin-valve with in-plane anisotropy

Jie Guo, Mansoor Bin Abdul Jalil, and Seng Ghee Tan

Appl. Phys. Lett. 92, 182103 (2008); http://dx.doi.org/10.1063/1.2919734 (3 pages) | Cited 2 times

Online Publication Date: 6 May 2008

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We study the magnetization dynamics of a pseudo-spin-valve structure with in-plane anisotropy, which is induced by the passage of a perpendicular-to-plane spin-polarized current. The magnetization dynamics is described by a modified Landau–Lifshitz–Gilbert (LLG) equation, which incorporates two spin torque terms. The simulation results reveal two magnetization excitation modes: (a) complete magnetization reversal and (b) persistent spin precession. The existence of these dual modes may be explained in terms of the competition between the four terms of the modified LLG equation. Our results give indications to the optimal operating conditions for current-induced magnetization dynamics for possible device applications.
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Gw Magnetic anisotropy
75.40.Mg Numerical simulation studies
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
75.47.-m Magnetotransport phenomena; materials for magnetotransport

Achievement of sensing single spin with the aid of Kondo resonance in quantum dot connected to ferromagnetic electrodes

Jiang Chen, Yibin Hu, Ke Xia, and Zhongshui Ma

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

Online Publication Date: 7 May 2008

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We theoretically propose the detection of spin states of magnetic atom or molecule in proximity to a quantum dot by the Kondo effect with ferromagnetic electrodes, which can be switched in parallel or antiparallel alignments. The relative orientation of spin to the magnetization of electrode can be evidentially tracked from the spin splitting in Kondo peak of differential conductance. The experimental realization is discussed.
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75.30.Mb Valence fluctuation, Kondo lattice, and heavy-fermion phenomena
75.50.-y Studies of specific magnetic materials
75.30.Et Exchange and superexchange interactions
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
72.25.-b Spin polarized transport
73.21.La Quantum dots

Enhanced Seebeck coefficient in EuTe/PbTe [100] short-period superlattices

Akihiro Ishida, Daoshe Cao, Sinsuke Morioka, Martin Veis, Yoku Inoue, and Takuji Kita

Appl. Phys. Lett. 92, 182105 (2008); http://dx.doi.org/10.1063/1.2917482 (3 pages) | Cited 9 times

Online Publication Date: 9 May 2008

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Theoretical and experimental studies on Seebeck effect in EuTe/PbTe superlattices were performed. Theoretical calculations, which take into account temperature dependent band gap, nonparabolicity, and anisotropy of effective masses in the PbTe conduction band, were performed in the framework of Boltzmann equation in which enhancement of Seebeck coefficient in EuTe/PbTe short-period superlattices grown in [100] direction was predicted. The EuTe/PbTe short-period superlattices with few monolayers EuTe were prepared on KCl (100) substrate and an enhanced Seebeck coefficient was observed in these superlattices as expected by theoretical calculations.
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72.20.Pa Thermoelectric and thermomagnetic effects
73.63.Hs Quantum wells
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor
73.21.Cd Superlattices

Stress-induced morphology and fine-line stability enhancement of NiSi on poly-SiGe with a buffer polycrystalline silicon interlayer

Chi-Chang Wu, Wen-Fa Wu, Fu-Hsiang Ko, Hsin-Chiang You, and Wen-Luh Yang

Appl. Phys. Lett. 92, 182106 (2008); http://dx.doi.org/10.1063/1.2920202 (3 pages)

Online Publication Date: 9 May 2008

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The thermal and morphological stability of NiSi is enhanced by inserting a polycrystalline (poly-Si) buffer layer between the Ni and poly-SiGe films. NiSi films formed on poly-Si/poly-SiGe stack layers possessed continuous, smooth structures after annealing at 500–850 °C. Moreover, nickel germanosilicide [Ni(Si, Ge)] lines formed on the poly-SiGe exhibited a fine-line effect, i.e., the sheet resistance increased upon decreasing the linewidth, whereas the sheet resistance of NiSi lines formed on the poly-Si/poly-SiGe stack layers remained less than 5 Ω/square. A model for the stress-confined grain growth and recrystallization is proposed to explain the improved properties of the poly-Si-buffered film.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
61.72.Cc Kinetics of defect formation and annealing
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization

A visible light-sensitive tungsten carbide/tungsten trioxde composite photocatalyst

Young-ho Kim, Hiroshi Irie, and Kazuhito Hashimoto

Appl. Phys. Lett. 92, 182107 (2008); http://dx.doi.org/10.1063/1.2924276 (3 pages) | Cited 10 times

Online Publication Date: 9 May 2008

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A photocatalyst composed of tungsten carbide (WC) and tungsten oxide (WO3) has been prepared by the mechanical mixing of each powder. Its photocatalytic activity was evaluated by the gaseous isopropyl alcohol decomposition process. The photocatalyst showed high visible light photocatalytic activity with a quantum efficiency of 3.2% for 400–530 nm light. The photocatalytic mechanism was explained by means of enhanced oxygen reduction reaction due to WC, which may serve as a multielectron reduction catalyst, as well as the photogeneration of holes in the valence band of WO3.
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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.50.Hp Processes caused by visible and UV light
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)

Giant carrier mobility in single crystals of FeSb2

Rongwei Hu, V. F. Mitrović, and C. Petrovic

Appl. Phys. Lett. 92, 182108 (2008); http://dx.doi.org/10.1063/1.2926662 (3 pages) | Cited 18 times

Online Publication Date: 9 May 2008

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We report the giant carrier mobility in single crystals of FeSb2. Nonlinear field dependence of Hall resistivity is well described with the two-carrier model. Maximum mobility values in high mobility band reach ∼ 105 cm2/V s at 8 K and are ∼ 102 cm2/V s at the room temperature. Our results point to a class of materials with promising potential for applications in solid state electronics.
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72.20.My Galvanomagnetic and other magnetotransport effects
72.80.Jc Other crystalline inorganic semiconductors
75.30.Cr Saturation moments and magnetic susceptibilities
75.50.Pp Magnetic semiconductors
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
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