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11 Jan 2010

Volume 96, Issue 2, Articles (02xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 96, 021101 (2010); http://dx.doi.org/10.1063/1.3290633 (3 pages)

Ahmet Ali Yanik, Min Huang, Alp Artar, Tsung-Yao Chang, and Hatice Altug
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Numerical approach for retention characteristics of double floating-gate memories

Tetsufumi Tanamoto and Kouichi Muraoka

Appl. Phys. Lett. 96, 022105 (2010); http://dx.doi.org/10.1063/1.3285170 (3 pages) | Cited 3 times

Online Publication Date: 15 January 2010

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We report on a numerical investigation in which memory characteristics of double floating-gate (DFG) structure were compared to those of the conventional single floating-gate structure, including an interference effect between two cells. We found that the advantage of the DFG structure is its longer retention time and the disadvantage is its smaller threshold voltage shift. We also provide an analytical form of charging energy including the interference effect.
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84.30.Sk Pulse and digital circuits
85.30.De Semiconductor-device characterization, design, and modeling
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Reduced domain wall pinning in ultrathin Pt/Co100−xBx/Pt with perpendicular magnetic anisotropy

R. Lavrijsen, G. Malinowski, J. H. Franken, J. T. Kohlhepp, H. J. M. Swagten, B. Koopmans, M. Czapkiewicz, and T. Stobiecki

Appl. Phys. Lett. 96, 022501 (2010); http://dx.doi.org/10.1063/1.3280373 (3 pages) | Cited 7 times

Online Publication Date: 11 January 2010

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We have studied the magnetization reversal process in perpendicularly magnetized ultrathin Pt/Co100−xBx/Pt films by means of magneto-optical magnetometry and microscopy. The addition of boron enhances the effective Barkhausen volume indicating a decrease in domain-wall pinning site density and/or strength. This potentially reduces the field and critical current-density for domain-wall depinning/motion, indicating that perpendicularly magnetized Pt/Co100−xBx/Pt could be an interesting candidate for domain-wall motion studies and applications.
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Gw Magnetic anisotropy
75.60.Jk Magnetization reversal mechanisms
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.70.Kw Domain structure (including magnetic bubbles and vortices)
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials

Suppression of spin-pumping by a MgO tunnel-barrier

O. Mosendz, J. E. Pearson, F. Y. Fradin, S. D. Bader, and A. Hoffmann

Appl. Phys. Lett. 96, 022502 (2010); http://dx.doi.org/10.1063/1.3280378 (3 pages) | Cited 7 times

Online Publication Date: 11 January 2010

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Spin-pumping generates pure spin currents in normal metals at the ferromagnet (F)/normal metal (N) interface. The efficiency of spin-pumping is given by the spin mixing conductance, which depends on N and the F/N interface. We directly study the spin-pumping through an MgO tunnel-barrier using the inverse spin Hall effect, which couples spin and charge currents and provides a direct electrical detection of spin currents in the normal metal. We find that spin-pumping is suppressed by the tunnel-barrier, which is contrary to recent studies that suggest that the spin mixing conductance can be enhanced by a tunnel-barrier inserted at the interface.
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.50.Cc Other ferromagnetic metals and alloys
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
72.25.Mk Spin transport through interfaces

Determination of the saturation magnetization of ion irradiated Py/Ta samples using polar magneto-optical Kerr effect and ferromagnetic resonance

D. Markó, T. Strache, K. Lenz, J. Fassbender, and R. Kaltofen

Appl. Phys. Lett. 96, 022503 (2010); http://dx.doi.org/10.1063/1.3291051 (3 pages) | Cited 6 times

Online Publication Date: 11 January 2010

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Based on polar magneto-optical Kerr effect and frequency dependent ferromagnetic resonance measurements, a method has been found that allows for the quantitative determination of the saturation magnetization of samples with unknown effective magnetic volume. Conventional magnetometry cannot be used for this purpose. Thin Py/Ta multilayers with an overall Py thickness of 20 nm but different number of interfaces are used as test systems. By means of Ne ion irradiation the magnetic moment and the saturation magnetization are affected due to interfacial mixing. With both increasing ion fluence and increasing number of Py/Ta interfaces, a decrease of saturation magnetization is observed.
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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.Cr Saturation moments and magnetic susceptibilities
75.50.Bb Fe and its alloys
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
78.20.Ls Magneto-optical effects
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance

Critical velocity for the vortex core reversal in perpendicular bias magnetic field

A. V. Khvalkovskiy, A. N. Slavin, J. Grollier, K. A. Zvezdin, and K. Yu. Guslienko

Appl. Phys. Lett. 96, 022504 (2010); http://dx.doi.org/10.1063/1.3291064 (3 pages) | Cited 7 times

Online Publication Date: 11 January 2010

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For a circular magnetic nanodot in a vortex ground state, we study how the critical velocity vc of the vortex core reversal depends on the magnitude H of a bias magnetic field applied perpendicularly to the dot plane. We find that, similarly to the case H = 0, the critical velocity does not depend on the size of the dot. The critical velocity is dramatically reduced when the negative (i.e., opposite to the vortex core direction) bias field approaches the value, at which a static core reversal takes place. A simple analytical model shows good agreement with our numerical result.
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73.22.-f Electronic structure of nanoscale materials and related systems
75.60.Jk Magnetization reversal mechanisms
75.30.Gw Magnetic anisotropy
75.78.Fg Dynamics of domain structures

Electrical determination of the spin relaxation time of photoexcited electrons in GaAs

H. Kurebayashi, T. Trypiniotis, K. Lee, S. Easton, A. Ionescu, I. Farrer, D. A. Ritchie, J. A. C. Bland, and C. H. W. Barnes

Appl. Phys. Lett. 96, 022505 (2010); http://dx.doi.org/10.1063/1.3291066 (3 pages) | Cited 8 times

Online Publication Date: 11 January 2010

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Spin-dependent transport for photoexcited electrons in an epitaxial Fe/GaAs interface was characterized from 5 to 300 K. The presence of spin-dependent transport was confirmed at all the measured temperatures and the spin polarization across the interface is found to increase with decreasing temperature. A time-of-flight-type model based on the Dyakonov–Perel (DP) spin relaxation mechanism was employed to explain the temperature dependence, providing that the estimated spin relaxation time in GaAs is 62 ps at 5 K. This short spin relaxation time can be explained by the stronger efficiency of the DP mechanism for hot-electrons.
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72.25.Dc Spin polarized transport in semiconductors
76.90.+d Other topics in magnetic resonances and relaxations (restricted to new topics in section 76)
72.20.Ht High-field and nonlinear effects

Voltage-induced perpendicular magnetic anisotropy change in magnetic tunnel junctions

T. Nozaki, Y. Shiota, M. Shiraishi, T. Shinjo, and Y. Suzuki

Appl. Phys. Lett. 96, 022506 (2010); http://dx.doi.org/10.1063/1.3279157 (3 pages) | Cited 25 times

Online Publication Date: 11 January 2010

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A voltage-induced perpendicular magnetic anisotropy change in an ultrathin FeCo layer was observed in an epitaxial magnetic tunnel junction (MTJ) structure. A spin-transfer induced ferromagnetic resonance measurement technique was used under various bias voltage applications to evaluate the anisotropy change. From the peak frequency shifts, we could estimate that a surface magnetic anisotropy change of 15 μJ/m2 was induced by an electric field application of 400 mV/nm in the MTJ with a 0.5 nm thick FeCo layer. The realization of voltage-induced anisotropy changes in an MTJ structure should have a large impact on the development of electric-field driven spintronic devices.
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Gw Magnetic anisotropy
75.70.Rf Surface magnetism
75.85.+t Magnetoelectric effects, multiferroics
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
75.70.Ak Magnetic properties of monolayers and thin films

Volume magnetic domain mirroring in magnetic shape memory crystals

Yiu-Wai Lai, Rudolf Schäfer, Ludwig Schultz, and Jeffrey McCord

Appl. Phys. Lett. 96, 022507 (2010); http://dx.doi.org/10.1063/1.3292205 (3 pages) | Cited 4 times

Online Publication Date: 13 January 2010

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From the magnetic domain patterns at adjacent crystal surfaces of NiMnGa shape memory crystals the internal domain configurations across a hidden twin-boundary are derived. The results proof the existence of domains extending from the sample surfaces into the nonvisible sample volume. Moreover, the structural twin boundary inside the material acts as a mirror for the basic domains. The analysis validates the relevance of surface magnetic response analysis for the understanding of the magnetoelastic behavior of magnetic shape memory alloys and is essential for the interpretation of magnetic domain images obtained from other surface-restricted observation techniques.
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75.60.Ch Domain walls and domain structure
75.70.Rf Surface magnetism
61.72.Mm Grain and twin boundaries
75.80.+q Magnetomechanical effects, magnetostriction

Thickness dependence of the critical current density in superconducting films: A geometrical approach

F. Hengstberger, M. Eisterer, and H. W. Weber

Appl. Phys. Lett. 96, 022508 (2010); http://dx.doi.org/10.1063/1.3290254 (3 pages) | Cited 6 times

Online Publication Date: 13 January 2010

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We analyze the influence of the magnetic field generated by the supercurrents (self-field) on the current density distribution by numerical simulations. The thickness of the superconducting film determines the self-field and consequently the critical current density at zero applied field. We find an equation, which derives the thickness dependence of the critical current density from its dependence on the magnetic induction. Solutions of the equation reproduce numerical simulations to great accuracy, thus enabling a quantification of the dependence of the self-field critical current density with increasing film thickness. This result is technologically relevant for the development of coated conductors with thicker superconducting layers.
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74.78.-w Superconducting films and low-dimensional structures
74.25.Sv Critical currents
74.72.-h Cuprate superconductors
74.25.Ha Magnetic properties including vortex structures and related phenomena

A way to measure electron spin-flipping at ferromagnetic/nonmagnetic interfaces and application to Co/Cu

B. Dassonneville, R. Acharyya, H. Y. T. Nguyen, R. Loloee, W. P. Pratt, and J. Bass

Appl. Phys. Lett. 96, 022509 (2010); http://dx.doi.org/10.1063/1.3292218 (3 pages) | Cited 4 times

Online Publication Date: 13 January 2010

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We describe a technique, using the current-perpendicular-to-plane (CPP) geometry, to measure the parameter δF/N, characterizing flipping of electron spins at a ferromagnetic (F)/nonmagnetic (N) metallic interface. The technique involves measuring the CPP magnetoresistance of a sample containing a ferromagnetically coupled [F/N]n multilayer embedded within the 20 nm thick central Cu layer of a symmetric Py-based, double exchange-biased spin-valve. To focus on δF/N, the F- and N-layers are made thin compared to their spin-diffusion lengths. We test the technique using F/N = Co/Cu. Analyzing with no adjustable parameters, gives inconsistency with δCo/Cu = 0, but consistency with our prior value of δCo/Cu = 0.25±0.1. Taking δCo/Cu as adjustable gives δCo/Cu = 0.33−0.08+0.03.
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.47.De Giant magnetoresistance
75.30.Et Exchange and superexchange interactions
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)

Ab initio study on pressure-induced change of effective Coulomb interaction in superconducting yttrium

Duck Young Kim and Rajeev Ahuja

Appl. Phys. Lett. 96, 022510 (2010); http://dx.doi.org/10.1063/1.3291050 (3 pages) | Cited 1 time

Online Publication Date: 13 January 2010

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Ab initio lattice dynamics based on linear response method are performed for high pressure phase of yttrium to describe electron-phonon coupling and subsequent superconducting behavior. The critical temperature Tc in fcc-Y increases monotonically with pressure up to 9.25 K at 31 GPa, which is quantitatively in excellent agreement with two quasihydrostatic experiments and is qualitatively compatible with recent experiments. The excellent agreement with experiments gives us a better understanding of the effective pseudopotential μ∗ as well as spectral function α2(ω)F(ω) in yttrium. These results demonstrate that there exists strong electron-phonon coupling in Y within the studied pressure regime, and for lower pressure electron correlation becomes stronger. Generally, it is found that superconductivity in yttrium under pressure can be described quantitatively within standard theory of phonon-mediated superconductivity.
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73.23.Hk Coulomb blockade; single-electron tunneling
74.50.+r Tunneling phenomena; Josephson effects
71.15.-m Methods of electronic structure calculations
71.38.-k Polarons and electron-phonon interactions
71.15.Dx Computational methodology (Brillouin zone sampling, iterative diagonalization, pseudopotential construction)

Impact of interfacial roughness on spin filter tunneling

Casey W. Miller and Dustin D. Belyea

Appl. Phys. Lett. 96, 022511 (2010); http://dx.doi.org/10.1063/1.3291065 (3 pages) | Cited 9 times

Online Publication Date: 13 January 2010

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The impact of interface roughness on spin filter tunneling is considered at low biases as functions of temperature and barrier parameters. Roughness reduces the maximum achievable spin polarization, which results from tunneling “hot spots” (thin regions of the barrier) having intrinsically reduced spin filtering efficiency. Surveying a range of experimentally reasonable roughness and mean barrier thickness values allows us to conclude that roughness values greater than 10% of the mean barrier thickness have an adverse impact on the spin polarization. Atomic-scale roughness may thus be critical for achieving 100% spin polarization in spin filter tunnel junctions at low biases.
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72.25.-b Spin polarized transport
73.40.Gk Tunneling

Reversal of the extraordinary Hall effect polarity in thin Co/Pd multilayers

D. Rosenblatt, M. Karpovski, and A. Gerber

Appl. Phys. Lett. 96, 022512 (2010); http://dx.doi.org/10.1063/1.3291707 (3 pages) | Cited 10 times

Online Publication Date: 13 January 2010

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Thin Co/Pd multilayers, with room temperature perpendicular anisotropy and an enhanced surface scattering, were studied for the possible use in the extraordinary Hall effect (EHE)-based magnetic memory devices. Polarity of the EHE signal was found to change from negative in thick samples to positive in thin ones. Reversal of EHE sign was also observed in thick samples with aging. The effect is argued to be related to the dominance of surface scattering having the EHE polarity opposite to that of the bulk.
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72.20.My Galvanomagnetic and other magnetotransport effects
75.30.Gw Magnetic anisotropy
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)

Surface enhanced spin-flip scattering in lateral spin valves

Mikhail Erekhinsky, Amos Sharoni, Fèlix Casanova, and Ivan K. Schuller

Appl. Phys. Lett. 96, 022513 (2010); http://dx.doi.org/10.1063/1.3291047 (3 pages) | Cited 10 times

Online Publication Date: 14 January 2010

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Nonlocal transport in Py/Cu lateral spin valves shows that the Cu spin diffusion length and the apparent Py spin polarization increase with Cu thickness. A proper quantitative analysis shows that the Cu spin diffusion length is dominated by surface spin-flip scattering and that the Py and Cu thickness dependence of spin polarization is due to strong spin-flip back-scattering at the Py/Cu interface. This solves a long-standing puzzle regarding the discrepancy in Py spin polarizations obtained from different measurements. Interestingly, the Cu surface oxidation causes enhanced spin diffusion, contrary to expectations. These surface effects substantially affect the performance of lateral spin valves.
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85.70.Kh Magnetic thin film devices: magnetic heads (magnetoresistive, inductive, etc.); domain-motion devices, etc.
85.75.-d Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
75.76.+j Spin transport effects
75.70.Rf Surface magnetism
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)

Ultrafast spin-transfer switching in spin valve nanopillars with perpendicular anisotropy

D. Bedau, H. Liu, J.-J. Bouzaglou, A. D. Kent, J. Z. Sun, J. A. Katine, E. E. Fullerton, and S. Mangin

Appl. Phys. Lett. 96, 022514 (2010); http://dx.doi.org/10.1063/1.3284515 (3 pages) | Cited 22 times

Online Publication Date: 14 January 2010

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Spin-transfer switching with short current pulses has been studied in spin-valve nanopillars with perpendicularly magnetized free and reference layers. Magnetization switching with current pulses as short as 300 ps is demonstrated. The pulse amplitude needed to reverse the magnetization is shown to be inversely proportional to the pulse duration, consistent with a macrospin spin-transfer model. However, the pulse amplitude duration switching boundary depends on the applied field much more strongly than predicted by the zero temperature macrospin model. The results also demonstrate that there is an optimal pulse length that minimizes the energy required to reverse the magnetization.
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85.75.-d Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.47.-m Magnetotransport phenomena; materials for magnetotransport
75.30.Gw Magnetic anisotropy
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Electric double layer transistor with a (Ga,Mn)As channel

M. Endo, D. Chiba, H. Shimotani, F. Matsukura, Y. Iwasa, and H. Ohno

Appl. Phys. Lett. 96, 022515 (2010); http://dx.doi.org/10.1063/1.3277146 (3 pages) | Cited 10 times

Online Publication Date: 14 January 2010

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The authors have fabricated electric double layer transistors with a (Ga,Mn)As channel to investigate the possibility of larger modulation of magnetism by the application of electric fields. The sheet conductance as well as the Curie temperature can be modulated up to a few tens of percents by application of gate voltage of a few volts, which is almost one-order of magnitude smaller than that required in conventional metal-insulator-semiconductor structures. The 14 K modulation of the Curie temperature by applying gate voltage ranging from −1 to 3 V is the highest modulation ratio reported so far in ferromagnetic semiconductors.
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85.30.Tv Field effect devices

Enhanced multiferroicity in Mg-doped Ca3Co2−xMnxO6

L. Li, W. Z. Luo, Y. J. Guo, S. Z. Li, S. J. Luo, K. F. Wang, and J.-M. Liu

Appl. Phys. Lett. 96, 022516 (2010); http://dx.doi.org/10.1063/1.3292584 (3 pages) | Cited 6 times

Online Publication Date: 15 January 2010

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Polycrystalline Ca3−xMgxCo2−yMnyO6 (y ∼ 1.0) samples are prepared in order to investigate the A-site doping effect of Ca3Co2−yMnyO6 (y ∼ 1.0). Compared with Ca3Co2−yMnyO6 (y ∼ 1.0), the ferroelectric polarization and Curie point of Ca3−xMgxCo2−yMnyO6 (y ∼ 1.0) at the maximal doping x ∼ 0.3 are significantly enhanced. The magnetic order of Ca3−xMgxCo2−yMnyO6 (x ∼ 0.3, y ∼ 1.0) and thus ferroelectric order are more robust than the undoped compound. The slight lattice shrinking as a result of Mg substitution may contribute to the enhancement of exchange striction, leading to the changes in magnetic and ferroelectric properties.
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77.80.-e Ferroelectricity and antiferroelectricity
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
75.85.+t Magnetoelectric effects, multiferroics
61.72.U- Doping and impurity implantation
77.22.Ej Polarization and depolarization
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Effects of Na nonstoichiometry in (Bi0.5Na0.5+x)TiO3 ceramics

Y. S. Sung, J. M. Kim, J. H. Cho, T. K. Song, M. H. Kim, H. H. Chong, T. G. Park, D. Do, and S. S. Kim

Appl. Phys. Lett. 96, 022901 (2010); http://dx.doi.org/10.1063/1.3275704 (3 pages) | Cited 13 times

Online Publication Date: 11 January 2010

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Effects of Na nonstoichiometry in (Bi0.5Na0.5+x)TiO3 ceramics were investigated in the range of x = (−5)−(+1) mol % of Na0.5. A rhombohedral perovskite structure was maintained at all compositions with no secondary phases. Grain size decreased with Na nonstoichiometry. Piezoelectric coefficient (d33) increased from 74 pC/N at x = 0 up to 91 pC/N at x = −3.5 then dropped with further Na deficiency. Depolarization temperature (Td), on the other hand, decreased from 190 °C at x = 0 down to 112 °C at x = −3.5 then increased. Rhombohedral lattice distortion (90−α) decreasing with Na deficiency was a key factor for the variation in d33 and Td.
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77.65.-j Piezoelectricity and electromechanical effects
77.84.Cg PZT ceramics and other titanates
61.66.Fn Inorganic compounds
77.22.Ej Polarization and depolarization

Constrained ferroelectric domain orientation in (BiFeO3)m(SrTiO3)n superlattice

R. Ranjith, R. V. K. Mangalam, Ph. Boullay, A. David, M. B. Lepetit, U. Lüders, W. Prellier, A. Da Costa, A. Ferri, R. Desfeux, Gy. Vincze, Zs. Radi, and C. Aruta

Appl. Phys. Lett. 96, 022902 (2010); http://dx.doi.org/10.1063/1.3275726 (3 pages) | Cited 4 times

Online Publication Date: 12 January 2010

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Ferroelectric domains were investigated using piezoresponse force microscopy in superlattices composed of multiferroic BiFeO3 and SrTiO3 layers. Compared to single BiFeO3 thin films, a reduction in the domains size and a suppression of the in-plane orientation of domains are observed in a superlattice of (BiFeO3)4(SrTiO3)8, suggesting a constrained ferroelectric domain orientation along the out-of-plane 〈001〉 direction. Such modification of domain size and orientation in BiFeO3-based heterostructures could play a vital role on engineering the domains and domain wall mediated functional properties necessary for device applications.
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77.80.Dj Domain structure; hysteresis
77.84.Cg PZT ceramics and other titanates
77.55.Px Epitaxial and superlattice films
77.55.Nv Multiferroic/magnetoelectric films

Direct visualization and in-depth physical study of metal filament formation in percolated high-κ dielectrics

X. Li, K. L. Pey, M. Bosman, W. H. Liu, and T. Kauerauf

Appl. Phys. Lett. 96, 022903 (2010); http://dx.doi.org/10.1063/1.3291621 (3 pages) | Cited 11 times

Online Publication Date: 12 January 2010

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The migration of Ta atoms from a transistor gate electrode into the percolated high-κ (HK) gate dielectrics is directly shown using transmission electron microscopy analysis. A nanoscale metal filament that formed under high current injection is identified to be the physical defect responsible for the ultrafast transient breakdown (BD) of the metal-gate/high-κ (MG/HK) gate stacks. This highly conductive metal filament poses reliability concerns for MG/HK gate stacks as it significantly reduces the post-BD reliability margin of a transistor.
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85.30.Tv Field effect devices
77.55.D- High-permittivity gate dielectric films

Al2O3/NbAlO/Al2O3 sandwich gate dielectric film on InP

Xinhong Cheng, Dapeng Xu, Qing-Qing Sun, Dawei He, Zhongjian Wang, Yuehui Yu, David Wei Zhang, and Qingtai Zhao

Appl. Phys. Lett. 96, 022904 (2010); http://dx.doi.org/10.1063/1.3292217 (3 pages) | Cited 4 times

Online Publication Date: 13 January 2010

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Al2O3/NbAlO/Al2O3 sandwich dielectric films were grown on InP substrate and annealed. X-ray reflectivity measurements suggested that 1.0 nm interfacial layer existed at InP interface, x-ray diffraction and high resolution transmission electron microscopy indicated the films were crystallized. X-ray photoelectron spectra indicated the oxidization of InP substrate, and the valence-band offset between the dielectric film and InP interface was calculated to be 3.1 eV. The electrical measurements indicated that the leakage current density was 40 mA/cm2 at gate bias of 1 V, and the equivalent oxide thickness and the dielectric constant were 1.7 and 20 nm, respectively.
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77.55.-g Dielectric thin films
77.22.Ch Permittivity (dielectric function)
81.65.Mq Oxidation
73.21.Ac Multilayers
73.20.At Surface states, band structure, electron density of states
84.32.Tt Capacitors

Improved performance and reliability for metal-oxide-semiconductor field-effect-transistor with fluorinated silicate glass passivation layer

Chih-Ren Hsieh, Yung-Yu Chen, and Jen-Chung Lou

Appl. Phys. Lett. 96, 022905 (2010); http://dx.doi.org/10.1063/1.3279140 (3 pages)

Online Publication Date: 13 January 2010

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The superior characteristics of the fluorinated HfO2/SiON gate dielectric are investigated comprehensively. Fluorine is incorporated into the gate dielectric through fluorinated silicate glass (FSG) passivation layer to form fluorinated HfO2/SiON dielectric. Fluorine incorporation has been proved to eliminate both bulk and interface trap densities due to Hf–F and Si–F bonds formation, which can strongly reduce trap generation as well as trap-assisted tunneling during subsequently constant voltage stress, and results in improved electrical characteristics and dielectric reliabilities. The results clearly indicate that the fluorinated HfO2/SiON gate dielectric using FSG passivation layer becomes a feasible technology for future ultrathin gate dielectric applications.
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85.30.Tv Field effect devices
85.30.De Semiconductor-device characterization, design, and modeling
81.65.Rv Passivation
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Memory effect of a single-walled carbon nanotube on nitride-oxide structure under various bias conditions

Hongsik Park, Hyunjung Shin, Jin Ho Kim, Seungbum Hong, and Jimmy Xu

Appl. Phys. Lett. 96, 023101 (2010); http://dx.doi.org/10.1063/1.3291054 (3 pages) | Cited 1 time

Online Publication Date: 11 January 2010

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We report on the memory effect of single-walled carbon nanotubes (SWNTs) placed on a nitride-oxide layer structure designed as a charge storage medium. The conductance of the SWNT was modulated by the injected charge in the nitride-oxide interface and the polarities of injected charges were then detected. A large on/off-state current ratio (>104) was obtained at a small program/erase voltage range (<3 V). We also studied the effect of a half-selected cell on the conductance of the SWNTs to identify the issues with cross-point memory architecture.
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71.20.Tx Fullerenes and related materials; intercalation compounds
73.22.-f Electronic structure of nanoscale materials and related systems
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
61.46.Fg Nanotubes

Processing and properties of centimeter-long, in-fiber, crystalline-selenium filaments

D. S. Deng, N. D. Orf, S. Danto, A. F. Abouraddy, J. D. Joannopoulos, and Y. Fink

Appl. Phys. Lett. 96, 023102 (2010); http://dx.doi.org/10.1063/1.3275751 (3 pages) | Cited 15 times

Online Publication Date: 11 January 2010

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We report on the fabrication and characterization of globally ordered crystalline selenium filaments with diameters about 200 nm and aspect ratios upwards of 105. Amorphous Se filaments are fabricated by a recently developed approach in which a thin film evolves into an ordered array of filaments in fiber. Single-crystal and polycrystalline filaments are attained with a postdrawing annealing procedure. Arrays of two-cm-long crystalline nanowires, electrically contacted to external circuitry through the fiber end facets, exhibit a two-orders-of-magnitude change in conductivity between dark and illuminated states. These results hold promise for the fabrication of filament-detector arrays that may be integrated with large-area electronics.
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68.55.ag Semiconductors
73.61.Cw Elemental semiconductors
73.63.Nm Quantum wires
73.21.Hb Quantum wires
73.40.-c Electronic transport in interface structures
72.80.Cw Elemental semiconductors

Fully inverted single-digit nanometer domains in ferroelectric films

Noureddine Tayebi, Yoshie Narui, Nathan Franklin, C. Patrick Collier, Konstantinos P. Giapis, Yoshio Nishi, and Yuegang Zhang

Appl. Phys. Lett. 96, 023103 (2010); http://dx.doi.org/10.1063/1.3280371 (3 pages) | Cited 4 times

Online Publication Date: 12 January 2010

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Show Abstract
Achieving stable single-digit nanometer inverted domains in ferroelectric thin films is a fundamental issue that has remained a bottleneck for the development of ultrahigh density (>1 Tbit/in.2) probe-based memory devices using ferroelectric media. Here, we demonstrate that such domains remain stable only if they are fully inverted through the entire ferroelectric film thickness, which is dependent on a critical ratio of electrode size to the film thickness. This understanding enables the formation of stable domains as small as 4 nm in diameter, corresponding to 10 unit cells in size. Such domain size corresponds to 40 Tbit/in.2 data storage densities.
Show PACS
77.80.Dj Domain structure; hysteresis
77.84.Cg PZT ceramics and other titanates
77.55.fg Pb(Zr,Ti)O3-based films
85.35.Kt Nanotube devices
85.50.Gk Non-volatile ferroelectric memories
84.30.Sk Pulse and digital circuits
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