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25 Jan 2010

Volume 96, Issue 4, Articles (04xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 96, 042501 (2010); http://dx.doi.org/10.1063/1.3291942 (3 pages)

Daniel Stickler, Robert Frömter, Holger Stillrich, Christian Menk, Carsten Tieg, Simone Streit-Nierobisch, Michael Sprung, Christian Gutt, Lorenz-M. Stadler, Olaf Leupold, Gerhard Grübel, and Hans Peter Oepen
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Control of direct band gap emission of bulk germanium by mechanical tensile strain

M. El Kurdi, H. Bertin, E. Martincic, M. de Kersauson, G. Fishman, S. Sauvage, A. Bosseboeuf, and P. Boucaud

Appl. Phys. Lett. 96, 041909 (2010); http://dx.doi.org/10.1063/1.3297883 (3 pages) | Cited 21 times

Online Publication Date: 28 January 2010

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We show that the recombination energy of the direct band gap photoluminescence (PL) of germanium can be controlled by an external mechanical stress. The stress is provided by an apparatus commonly used for bulge or blister test. An energy redshift up to 60 meV is demonstrated for the room temperature PL of a thin germanium membrane (125 nm wavelength shift from 1535 to 1660 nm). This PL shift is correlated with the in-plane tensile strain generated in the film. A biaxial tensile strain larger than 0.6% is achieved by this method. This mechanical strain allows to approach the direct band gap condition for germanium which is of tremendous importance to achieve lasing with this material.
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78.55.Ap Elemental semiconductors
71.20.Mq Elemental semiconductors

Double electrical percolation phenomenon during the crystallization of an amorphous Ge2Sb2Te5 thin film under continuous heating

Yunjung Choi and Young-Kook Lee

Appl. Phys. Lett. 96, 041910 (2010); http://dx.doi.org/10.1063/1.3298357 (3 pages) | Cited 3 times

Online Publication Date: 28 January 2010

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Crystallization behaviors of an amorphous Ge2Sb2Te5 thin film were investigated by in situ measurements of electrical resistivity Rel and optical reflectivity Rop and by transmission electron microscopy during isothermal annealing and continuous heating. Rop increased first and then Rel decreased during the initial stage of crystallization for both annealing conditions due to the electrical percolation of heterogeneous crystallization at the film surface. The two-step decrease in Rel during continuous heating, unlike the monotonous decrease in Rel during isothermal annealing, was induced by the percolation phenomenon via homogeneous crystallization inside the film. The effective activation energy for homogeneous crystallization was 4.30 eV.
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64.60.ah Percolation
81.40.Gh Other heat and thermomechanical treatments
73.61.Jc Amorphous semiconductors; glasses
64.70.dg Crystallization of specific substances

Time resolved photoluminescence of In(N)As quantum dots embedded in GaIn(N)As/GaAs quantum well

M. Syperek, R. Kudrawiec, M. Baranowski, G. Sȩk, J. Misiewicz, D. Bisping, B. Marquardt, A. Forchel, and M. Fischer

Appl. Phys. Lett. 96, 041911 (2010); http://dx.doi.org/10.1063/1.3299258 (3 pages) | Cited 3 times

Online Publication Date: 29 January 2010

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Carrier dynamics in In(N)As quantum dots embedded in GaIn(N)As quantum well has been studied by time resolved photoluminescence. We have shown that incorporation of nitrogen into InAs/InGaAs system caused a redshift of the ground state emission due to the change in the energy gap and strain distribution, and simultaneously changed the size and density of dots. This has differently affected the dynamic properties at low and room temperature. Small amount of nitrogen in the InAs/InGaAs quantum dot system has appeared to enhance the quantum confinement allowing to reach 1.3 μm emission and has not deteriorated the optical material quality.
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78.55.Cr III-V semiconductors
78.67.Hc Quantum dots
73.21.La Quantum dots

Influence of random roughness on cantilever curvature sensitivity

O. Ergincan, G. Palasantzas, and B. J. Kooi

Appl. Phys. Lett. 96, 041912 (2010); http://dx.doi.org/10.1063/1.3299713 (3 pages) | Cited 6 times

Online Publication Date: 29 January 2010

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In this work we explore the influence of random surface roughness on the cantilever sensitivity to respond to curvature changes induced by changes in surface stress. The roughness is characterized by the out-of-plane roughness amplitude w, the lateral correlation length ξ, and the roughness or Hurst exponent H(0<H<1). The cantilever sensitivity is found to decrease with increasing roughness (decreasing H and/or increasing ratio w/ξ) or equivalently increasing local surface slope. Finally, analytic expressions of the cantilever sensitivity as a function of the parameters w, ξ, and H are derived in order to allow direct implementation in sensing systems.
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68.35.Ct Interface structure and roughness
68.35.Gy Mechanical properties; surface strains
07.10.Cm Micromechanical devices and systems

Anisotropy of tensile stresses and cracking in nonbasal plane AlxGa1−xN/GaN heterostructures

Erin C. Young, Alexey E. Romanov, Chad S. Gallinat, Asako Hirai, Glenn E. Beltz, and James S. Speck

Appl. Phys. Lett. 96, 041913 (2010); http://dx.doi.org/10.1063/1.3276561 (3 pages) | Cited 5 times

Online Publication Date: 29 January 2010

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AlxGa1−xN films grown on nonpolar m {1math00} and {11math2} semipolar orientations of freestanding GaN substrates were investigated over a range of stress states (x ≤ 0.17). Cracking on the (0001) plane was observed beyond a critical thickness in the {1math00} oriented films, while no cracking was observed for {11math2} films. Theoretical analysis of tensile stresses in AlxGa1−xN for the relevant planes revealed that anisotropy of in-plane biaxial stress for the nonpolar {1math00} planes results in the highest normal stresses on the c-planes, consistent with experimental observations. Shear stresses are significant in the semipolar case, suggesting that misfit dislocation formation provides an alternative mechanism for stress relief.
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68.60.Bs Mechanical and acoustical properties
68.37.Ps Atomic force microscopy (AFM)
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.jd Thickness
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
68.55.ag Semiconductors

Investigation of Jahn–Teller splitting with O 1s x-ray absorption spectroscopy in strained Nd1−xCaxMnO3 thin films

Daniel Hsu, Y. S. Chen, M. Y. Song, C. H. Chuang, Minn-Tsong Lin, W. F. Wu, and J. G. Lin

Appl. Phys. Lett. 96, 041914 (2010); http://dx.doi.org/10.1063/1.3299023 (3 pages)

Online Publication Date: 29 January 2010

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Electronic structures of strained Nd1−xCaxMnO3 (NCMO) thin films with x = 0 to 0.8 are investigated via x-ray absorption spectroscopy (XAS). The obtained O 1s spectra within the photon energy 529–535 eV can be decomposed into eg↑1, eg↑2, t2g↓, and eg↓ bands. Based on the assigned energy levels of these band states, the energies of magnetic exchange, crystal field and Jahn–Teller (JT) splitting are determined. Particularly, the JT splitting is around 0.8 eV, which is observed with O 1s XAS for the first time in NCMO thin films.
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71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
71.70.Ch Crystal and ligand fields
78.70.Dm X-ray absorption spectra
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Single-gate accumulation-mode InGaAs quantum dot with a vertically integrated charge sensor

E. T. Croke, M. G. Borselli, M. F. Gyure, S. S. Bui, I. I. Milosavljevic, R. S. Ross, A. E. Schmitz, and A. T. Hunter

Appl. Phys. Lett. 96, 042101 (2010); http://dx.doi.org/10.1063/1.3280368 (3 pages) | Cited 2 times

Online Publication Date: 25 January 2010

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We report on the fabrication and characterization of a few-electron quantum dot controlled by a single gate electrode. Our device has a double-quantum-well design, in which the doping controls the occupancy of the lower well while the upper well remains empty under the free surface. Electrons tunneling between this accumulation-mode dot and the lower well are detected using a quantum point contact, located slightly offset from the dot gate. Addition spectra starting with N = 0 were observed as a function of gate voltage. DC sensitivity to single electrons was determined to be as high as 8.6%.
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81.07.Ta Quantum dots
81.05.Ea III-V semiconductors
68.65.Hb Quantum dots (patterned in quantum wells)
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
73.40.Gk Tunneling

Polarization-engineered removal of buffer leakage for GaN transistors

Yu Cao, Tom Zimmermann, Huili Xing, and Debdeep Jena

Appl. Phys. Lett. 96, 042102 (2010); http://dx.doi.org/10.1063/1.3293454 (3 pages) | Cited 15 times

Online Publication Date: 25 January 2010

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A dopant-free epitaxial technique is developed to achieve highly insulating buffers on semi-insulating GaN templates for nitride high electron mobility transistors by using the large polarization fields. The buffer leakage current density is reduced by several orders of magnitude, exhibiting outstanding insulating and breakdown properties. The simple polarization- and heterostructure-based solution should prove highly attractive for GaN high electron mobility transistors for analog (rf), digital, and high-voltage switching applications.
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85.30.Tv Field effect devices
85.30.De Semiconductor-device characterization, design, and modeling

AlN/GaN double-barrier resonant tunneling diodes grown by metal-organic chemical vapor deposition

C. Bayram, Z. Vashaei, and M. Razeghi

Appl. Phys. Lett. 96, 042103 (2010); http://dx.doi.org/10.1063/1.3294633 (3 pages) | Cited 16 times

Online Publication Date: 25 January 2010

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AlN/GaN double-barrier resonant tunneling diodes (RTDs) were grown by metal-organic chemical vapor deposition on sapphire. RTDs were fabricated via standard processing steps. RTDs demonstrate a clear negative differential resistance (NDR) at room temperature (RT). The NDR was observed around 4.7 V with a peak current density of 59 kA/cm2 and a peak-to-valley ratio of 1.6 at RT. Dislocation-free material is shown to be the key for the performance of GaN RTDs.
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85.30.Kk Junction diodes
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Perfect spin-filter and spin-valve in carbon atomic chains

M. G. Zeng, L. Shen, Y. Q. Cai, Z. D. Sha, and Y. P. Feng

Appl. Phys. Lett. 96, 042104 (2010); http://dx.doi.org/10.1063/1.3299264 (3 pages) | Cited 27 times

Online Publication Date: 26 January 2010

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We report ab initio calculations of spin-dependent transport in single atomic carbon chains bridging two zigzag graphene nanoribbon electrodes. Our calculations show that carbon atomic chains coupled to graphene electrodes are perfect spin-filters with almost 100% spin polarization. Moreover, the carbon atomic chains show bias-dependent magnetoresistance as large as 106% which make them perfect spin-valves. These two spin-related properties are independent of the length of carbon chains. The simultaneous occurrence of spin-filter and spin-valve in a single device opens the possibilities of all-carbon composite spintronics.
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72.25.-b Spin polarized transport
73.22.Pr Electronic structure of graphene
72.20.My Galvanomagnetic and other magnetotransport effects
75.76.+j Spin transport effects
85.75.-d Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)

Temperature dependence of plasmonic terahertz absorption in grating-gate gallium-nitride transistor structures

A. V. Muravjov, D. B. Veksler, V. V. Popov, O. V. Polischuk, N. Pala, X. Hu, R. Gaska, H. Saxena, R. E. Peale, and M. S. Shur

Appl. Phys. Lett. 96, 042105 (2010); http://dx.doi.org/10.1063/1.3292019 (3 pages) | Cited 15 times

Online Publication Date: 26 January 2010

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Strong plasmon resonances have been observed in the terahertz transmission spectra (1–5 THz) of large-area slit-grating-gate AlGaN/GaN-based high-electron-mobility transistor (HEMT) structures at temperatures from 10 to 170 K. The resonance frequencies correspond to the excitation of plasmons with wave vectors equal to the reciprocal lattice vectors of the metal grating, which serves both as a gate electrode for the HEMT and a coupler between plasmons and incident terahertz radiation. Wide tunability of the resonances by the applied gate voltage demonstrates potential of these devices for terahertz applications.
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85.30.Tv Field effect devices
84.40.-x Radiowave and microwave (including millimeter wave) technology

Terahertz heterodyne detection with silicon field-effect transistors

Diana Glaab, Sebastian Boppel, Alvydas Lisauskas, Ullrich Pfeiffer, Erik Öjefors, and Hartmut G. Roskos

Appl. Phys. Lett. 96, 042106 (2010); http://dx.doi.org/10.1063/1.3292016 (3 pages) | Cited 13 times

Online Publication Date: 27 January 2010

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We report on the detection of electromagnetic radiation at 0.65 THz by silicon field-effect transistors operated in heterodyne mode. Aiming at terahertz imaging with numerous pixels in a focal-plane array, we explore the improvement of the dynamic range achieved over power detection when the local-oscillator (LO) power is distributed quasioptically onto all detectors. These consist of resonantly antenna-coupled complementary metal-oxide-semiconductor transistors with a gate length of 0.25 μm, and each has an integrated voltage amplifier. With a LO power of 2 μW per detector, the noise-equivalent power amounts to 8 fW/Hz, leading to an estimated improvement of the dynamic range by 29 dB.
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84.40.-x Radiowave and microwave (including millimeter wave) technology
85.30.Tv Field effect devices

Rectifying characteristic of Pt/TiOx/metal/Pt controlled by electronegativity

Ni Zhong (钟妮), Hisashi Shima (島久), and Hiro Akinaga (秋永広幸)

Appl. Phys. Lett. 96, 042107 (2010); http://dx.doi.org/10.1063/1.3299011 (3 pages) | Cited 8 times

Online Publication Date: 27 January 2010

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Current voltage characteristic of the TiOx/metal interface has been studied by the systematic investigation on the top electrode (TE) material dependence of the carrier transport through the TiOx/metal interface. Rather than work function of TE (ϕM), electronegativity (χM) of TE plays a dominant role on current conduction and carrier transport of Pt/TiOx/metal (TE) devices. Pt/TiOx/metal (TE) exhibits rectifying property, if χM of TE is high. On the other hands, a symmetric I-V curves were observed if χM of TE is low. Plots of Schottky barrier at TiOx/metal (TE) interface versus χM of TE provides an index of interface behavior S ≈ 0.55, suggesting partial Fermi-level pinning at TiOx/metal interface.
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73.40.Ei Rectification
73.20.At Surface states, band structure, electron density of states
73.30.+y Surface double layers, Schottky barriers, and work functions
73.40.Ns Metal-nonmetal contacts

Atomic scale characterization of Mn doped InAs/GaAs quantum dots

M. Bozkurt, V. A. Grant, J. M. Ulloa, R. P. Campion, C. T. Foxon, E. Marega, G. J. Salamo, and P. M. Koenraad

Appl. Phys. Lett. 96, 042108 (2010); http://dx.doi.org/10.1063/1.3293296 (3 pages) | Cited 3 times

Online Publication Date: 28 January 2010

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Several growth procedures for doping InAs/GaAs quantum dots (QDs) with manganese (Mn) have been investigated with cross-sectional scanning tunneling microscopy. It is found that expulsion of Mn out of the QDs and subsequent segregation makes it difficult to incorporate Mn in the QDs even at low growth temperatures of T = 320 °C and high Mn fluxes. Mn atoms in and around QDs have been observed with strain and potential confinement changing the appearance of the Mn features.
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81.07.Ta Quantum dots
61.72.uj III-V and II-VI semiconductors
64.75.Qr Phase separation and segregation in semiconductors
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
75.50.Pp Magnetic semiconductors

Gigahertz characterization of a single carbon nanotube

L. Nougaret, G. Dambrine, S. Lepilliet, H. Happy, N. Chimot, V. Derycke, and J.-P. Bourgoin

Appl. Phys. Lett. 96, 042109 (2010); http://dx.doi.org/10.1063/1.3284513 (3 pages) | Cited 9 times

Online Publication Date: 28 January 2010

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Carbon nanotubes are intrinsically high impedance objects. The high frequency (HF) characterization of these nano-objects is crucial for applications such as interconnects in future integrated circuits, but still represents a daunting challenge. This letter presents HF characterization of an individual metallic single walled carbon nanotube up to 7 GHz. The equivalent circuit values are directly extracted from these HF measurements without numerical procedure, thus proving that the intrinsic transport parameters of a single carbon nanotube can be determined up to gigahertz frequencies.
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85.35.Kt Nanotube devices

Evidence for random networks of diodes in thin films of LaVO3 on SrTiO3 substrates

F. S. Razavi, S. Jamali Gharetape, D. A. Crandles, G. Christiani, R. K. Kremer, and H.-U. Habermeier

Appl. Phys. Lett. 96, 042110 (2010); http://dx.doi.org/10.1063/1.3293439 (3 pages)

Online Publication Date: 28 January 2010

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Highly conducting interfaces of transition metal oxide heterolayers could provide a promising access to transition metal oxide based electronic devices similar to those based on semiconductor heterostructures. Recently, metallic conductivity has been reported at the LaAlO3/SrTiO3 heterointerface. Here we report the observation of diodelike behavior and the formation of a random diode network in thin films of LaVO3 deposited on as-polished SrTiO3 substrates. Depending on films annealing conditions we observed linear or nonlinear I-V characteristic below 50 K.
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85.30.Kk Junction diodes

Ultraflexible amorphous silicon transistors made with a resilient insulator

Lin Han, Katherine Song, Prashant Mandlik, and Sigurd Wagner

Appl. Phys. Lett. 96, 042111 (2010); http://dx.doi.org/10.1063/1.3298364 (3 pages) | Cited 9 times

Online Publication Date: 29 January 2010

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The conventional, brittle, silicon nitride barrier layer and gate insulator in amorphous silicon thin-film transistors (a-Si:H TFTs) on 50 μm thick polyimide foil was replaced by a resilient, homogeneous, hybrid of silicon dioxide and silicone polymer. The transistor structures can be bent down to 0.5 mm radius (5% strain) in tension and down to 1 mm radius (2.5% strain) in compression. This pronounced flexibility shifts the criterion for reversible bending away from a-Si:H TFT backplanes and toward the materials for substrate and encapsulation. It qualifies a-Si:H TFTs for pull-out display screens in handheld devices.
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85.30.Tv Field effect devices

Universal and reconfigurable logic gates in a compact three-terminal resonant tunneling diode

L. Worschech, F. Hartmann, T. Y. Kim, S. Höfling, M. Kamp, A. Forchel, J. Ahopelto, I. Neri, A. Dari, and L. Gammaitoni

Appl. Phys. Lett. 96, 042112 (2010); http://dx.doi.org/10.1063/1.3302457 (3 pages) | Cited 9 times

Online Publication Date: 29 January 2010

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Submicron-sized mesas of resonant tunneling diodes (RTDs) with split drain contacts have been realized and the current-voltage characteristics have been studied in the bistable regime at room temperature. Dynamically biased, the RTDs show noise-triggered firing of spikelike signals and can act as reconfigurable universal logic gates for small voltage changes of a few millivolt at the input branches. These observations are interpreted in terms of a stochastic nonlinear processes. The logic gate operation shows gain for the fired-signal bursts with transconductance slopes exceeding the thermal limit. The RTD junction can be easily integrated to arrays of multiple inputs and have thus the potential to mimic neurons in nanoelectronic circuits.
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84.30.Sk Pulse and digital circuits
85.30.Kk Junction diodes
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)

Microstructure, optical, and electrical properties of p-type SnO thin films

W. Guo, L. Fu, Y. Zhang, K. Zhang, L. Y. Liang, Z. M. Liu, H. T. Cao, and X. Q. Pan

Appl. Phys. Lett. 96, 042113 (2010); http://dx.doi.org/10.1063/1.3277153 (3 pages) | Cited 19 times

Online Publication Date: 29 January 2010

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SnO thin films were fabricated by electron beam evaporation on (100) Si and c- and r-plane Al2O3 substrates. The films grown at 25 °C are nanocrystalline, while the films grown at 600 °C are epitaxial on r-plane Al2O3 and (001) textured on Si and c-plane Al2O3. The SnO films have an optical band gap of 2.82–2.97 eV and p-type conductivity, according to Hall measurements, with resistivities of 0.5–110 Ω cm, hole concentrations of 1017–1019 cm−3, and Hall mobilities of 0.1–2.6 cm2/Vs. The p-type conductivity, which appears to correlate with VSn, can be enhanced via Y- and Sb-doping. Defect complexes of SbSn−2VSn are suggested to be the acceptors in Sb-(or Y-) doped SnO films.
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68.55.J- Morphology of films
78.66.Li Other semiconductors
73.61.Le Other inorganic semiconductors
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Application of negative differential conductance in Al/AlOx single-electron transistors for background charge characterization

Hubert C. George, Mathieu Pierre, Xavier Jehl, Alexei O. Orlov, Marc Sanquer, and Gregory L. Snider

Appl. Phys. Lett. 96, 042114 (2010); http://dx.doi.org/10.1063/1.3298557 (3 pages) | Cited 5 times

Online Publication Date: 29 January 2010

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Negative differential conductance (NDC) is reported in the charging diagram of a normal state metal-metal oxide single electron transistor (SET) fabricated on a quartz substrate. We discuss the physical origin and cause of the observed effect. Using a simple electrostatic model we simulated SET charging diagrams and found excellent correlation between experiment and theory. We also found that the charging pattern associated with trap charging remains the same after warming the sample to room temperature (though position in Vg coordinates changes) and suggest to use these distinct features (such as NDC) as markers to characterize background charge in SETs.
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85.35.Gv Single electron devices

Enhanced ferromagnetism in H2O2-treated p-(Zn0.93Mn0.07)O layer

Sejoon Lee, Yoon Shon, Deuk Young Kim, Tae Won Kang, and Chong S. Yoon

Appl. Phys. Lett. 96, 042115 (2010); http://dx.doi.org/10.1063/1.3294635 (3 pages) | Cited 8 times

Online Publication Date: 29 January 2010

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Enhanced ferromagnetism was observed from the H2O2-treated p-type (Zn0.93Mn0.07)O:As layer. Compared with the untreated sample, the H2O2-treated sample showed the enlarged ferromagnetic hysteresis loop with approximately two-times-increased spontaneous magnetization. And also, in comparison with the untreated sample (TC ∼ 280 K), the H2O2-treated sample exhibited to have the increased TC persisting up to above 350 K. These results were confirmed to originate from the enhanced p-d hybridization due to the decrease in negatively charged residual background carriers. This is because the increased effective g-factor resulting from the decrease in oxygen-related defects acting as native deep donors was observed from the H2O2-treated sample.
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75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor
75.50.Dd Nonmetallic ferromagnetic materials
71.55.Gs II-VI semiconductors
75.50.Pp Magnetic semiconductors

Resistivity dominated by surface scattering in sub-50 nm Cu wires

R. L. Graham, G. B. Alers, T. Mountsier, N. Shamma, S. Dhuey, S. Cabrini, R. H. Geiss, D. T. Read, and S. Peddeti

Appl. Phys. Lett. 96, 042116 (2010); http://dx.doi.org/10.1063/1.3292022 (3 pages) | Cited 8 times

Online Publication Date: 29 January 2010

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Electron scattering mechanisms in copper lines were investigated to understand the extendibility of copper interconnects when linewidth or thickness is less than the mean free path. Electron-beam lithography and a dual hard mask were used to produce interconnects with linewidths between 25 and 45 nm. Electron backscatter diffraction characterized grain structure. Temperature dependence of the line resistance determined resistivity, which was consistent with existing models for completely diffused surface scattering and line-edge roughness, with little contribution from grain boundary scattering. A simple analytical model was developed that describes resistivity from diffuse surface scattering and line-edge roughness.
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85.40.Ls Metallization, contacts, interconnects; device isolation
85.40.Hp Lithography, masks and pattern transfer
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Soft x-ray holographic microscopy

Daniel Stickler, Robert Frömter, Holger Stillrich, Christian Menk, Carsten Tieg, Simone Streit-Nierobisch, Michael Sprung, Christian Gutt, Lorenz-M. Stadler, Olaf Leupold, Gerhard Grübel, and Hans Peter Oepen

Appl. Phys. Lett. 96, 042501 (2010); http://dx.doi.org/10.1063/1.3291942 (3 pages) | Cited 9 times

Online Publication Date: 25 January 2010

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We present a new x-ray microscopy technique based on Fourier transform holography (FTH), where the sample is separate from the optics part of the setup. The sample can be shifted with respect to the holography optics, thus large-scale or randomly distributed objects become accessible. As this extends FTH into a true microscopy technique, we call it x-ray holographic microscopy (XHM). FTH allows nanoscale imaging without the need for nanometer-size beams. Simple Fourier transform yields an unambiguous image reconstruction. We demonstrate XHM by studying the magnetic domain evolution of a Co/Pt multilayer film as function of locally varied iron overlayer thickness.
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07.85.Tt X-ray microscopes
42.40.My Applications
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.60.Ch Domain walls and domain structure
75.70.Kw Domain structure (including magnetic bubbles and vortices)
42.30.Wb Image reconstruction; tomography
42.30.Kq Fourier optics
07.60.Pb Conventional optical microscopes
07.85.-m X- and γ-ray instruments

Magnetic anisotropies in Ni–Mn–Ga films on MgO(001) substrates

V. A. Chernenko, V. Golub, J. M. Barandiarán, O. Y. Salyuk, F. Albertini, L. Righi, S. Fabbrici, and M. Ohtsuka

Appl. Phys. Lett. 96, 042502 (2010); http://dx.doi.org/10.1063/1.3293455 (3 pages) | Cited 5 times

Online Publication Date: 26 January 2010

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Ferromagnetic resonance was used to study the influence of temperature and film thickness on magnetic properties of Ni–Mn–Ga films deposited on single crystal MgO(001) substrates. It has been shown that depending on the film thickness and preparation condition, three configurations of magnetic anisotropy can be realized in these films. The temperature dependence of the anisotropy field is determined.
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75.30.Gw Magnetic anisotropy
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
68.55.-a Thin film structure and morphology

Strong perpendicular magnetic anisotropy in thick CoFeB films sandwiched by Pd and MgO layers

J. H. Jung, S. H. Lim, and S. R. Lee

Appl. Phys. Lett. 96, 042503 (2010); http://dx.doi.org/10.1063/1.3299009 (3 pages) | Cited 19 times

Online Publication Date: 27 January 2010

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A strong perpendicular magnetic anisotropy is formed in unit structures containing a thick CoFeB layer (2 nm) that are suitable for an MgO-based magnetic tunnel junction. The value of the coercivity, measured under perpendicular applied magnetic fields, is as high as 1050 Oe after annealing under optimum conditions. The intermixing between the Pd and the CoFeB and a low saturation magnetization of the Co-rich CoFeB layer are considered to be responsible for the strong perpendicular magnetic anisotropy.
Show PACS
75.70.-i Magnetic properties of thin films, surfaces, and interfaces
75.30.Gw Magnetic anisotropy
75.47.Pq Other materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
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