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12 Oct 2009

Volume 95, Issue 15, Articles (15xxxx)

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Appl. Phys. Lett. 95, 153101 (2009); http://dx.doi.org/10.1063/1.3244597 (3 pages)

Geunjae Kwak, Mikyung Lee, Karuppanan Senthil, and Kijung Yong
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High temperature strain glass in Ti50(Pd50−xCrx) alloy and the associated shape memory effect and superelasticity

Yumei Zhou, Dezhen Xue, Xiangdong Ding, Kazuhiro Otsuka, Jun Sun, and Xiaobing Ren

Appl. Phys. Lett. 95, 151906 (2009); http://dx.doi.org/10.1063/1.3249580 (3 pages) | Cited 8 times

Online Publication Date: 15 October 2009

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Strain glass has recently been reported in Ti50−xNi50+x (x ≥ 1.5 at %) alloys and caused by the existence of point defects. This strain glass alloy, being nonmartensitic, exhibits shape memory effect (SME) and superelasticity (SE) around the freezing temperature T0. However, the T0 of Ti50−xNi50+x (x ≥ 1.5 at %) strain glass alloy is very low ( ∼ 160 K), thus restricting its potential applications. In the present letter, we report a strain glass system, Ti50(Pd50−xCrx) (x ≥ 9 at %), which has a significantly higher freezing temperature. It is based on a high-temperature martensitic system TiPd (with Ms ∼ 810 K) and dopant Cr (as point defect). For Ti50(Pd40Cr10) strain glass, the freezing transition occurs at T0 ∼ 250 K, being close to the room temperature. Correspondingly, it exhibits SME and SE around its high T0. We further clarified that T0 of strain glass alloy is controlled by the martensitic transformation temperature Ms (i.e., martensite stability) of its corresponding host alloy without point defect. Our work provides insight into how to develop strain glass with desired T0 and the associated SME and SE for applications.
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81.30.Kf Martensitic transformations
62.20.fg Shape-memory effect; yield stress; superelasticity
81.40.Lm Deformation, plasticity, and creep
64.70.kj Glasses
81.40.Jj Elasticity and anelasticity, stress-strain relations
61.72.J- Point defects and defect clusters

Temperature dependence of the band gap of ZnSe1−xOx

R. Broesler, E. E. Haller, W. Walukiewicz, T. Muranaka, T. Matsumoto, and Y. Nabetani

Appl. Phys. Lett. 95, 151907 (2009); http://dx.doi.org/10.1063/1.3242026 (3 pages) | Cited 8 times

Online Publication Date: 15 October 2009

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We have studied the temperature dependence of the band gap of molecular-beam-epitaxy-grown ZnSe1−xOx films (x = 0–0.021) using photoluminescence spectroscopy from 15 to 280 K. The temperature dependence of the band gap decreases with increasing oxygen concentration, which can be quantitatively explained by an anticrossing interaction between the highly localized oxygen defect states and the extended states of the conduction band.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.ag Semiconductors
71.20.Nr Semiconductor compounds
78.55.Et II-VI semiconductors
78.66.Hf II-VI semiconductors
81.05.Dz II-VI semiconductors

Influence of heat treatments on electrical properties of ZnO films grown by molecular-beam epitaxy

D. C. Oh, S. H. Park, H. Goto, I. H. Im, M. N. Jung, J. H. Chang, T. Yao, J. S. Song, C. H. Bae, C. S. Han, and K. W. Koo

Appl. Phys. Lett. 95, 151908 (2009); http://dx.doi.org/10.1063/1.3247889 (3 pages) | Cited 3 times

Online Publication Date: 15 October 2009

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We report on the influence of heat treatments on the electrical properties of ZnO films grown by molecular-beam epitaxy. We note that the electrical resistance of the ZnO films is significantly changed by the heat treatments: the electrical resistance increases with the increase of ambient temperature, but above a critical temperature the resistance decreases with the increase of temperature, irrespective of ambient gases. On the other hand, it is found that the large amount of photocurrent is generated in the ZnO films, exposed to white sources: the photocurrent decreases with the increase of the obtained resistance, and the current increases with the decrease of the resistance. Also, it is shown that the x-ray diffraction linewidth of the ZnO films is significantly decreased by the heat treatments. These indicate that the increase/decrease of the electrical resistance is ascribed to the annihilation/formation of the residual donor-type defects in the ZnO films by the heat treatments. It is suggested that the increase of the electrical resistance is due to the annihilation of Zni-complex defects, while the decrease of the electrical resistance is due to the formation of VO-complex defects.
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73.61.Ga II-VI semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
72.40.+w Photoconduction and photovoltaic effects
73.50.Pz Photoconduction and photovoltaic effects
68.55.ag Semiconductors
72.80.Ey III-V and II-VI semiconductors

X-ray linear dichroism of defects in GaN:Mg using hard x-ray nanoprobe

G. Martínez-Criado, R. Tucoulou, P. Cloetens, J. A. Sans, and J. Susini

Appl. Phys. Lett. 95, 151909 (2009); http://dx.doi.org/10.1063/1.3238557 (3 pages) | Cited 1 time

Online Publication Date: 15 October 2009

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In this study, we report the application of synchrotron radiation nanoprobe techniques to the structural analysis of pyramidal defects in Mg doped GaN. A combination of fluorescence mapping with spectroscopic techniques enabled us to examine not only the elemental nature but also their crystallographic orientation on the submicron scale. Our observations provide strong evidence for the diffusion and subsequent segregation of background impurities of Fe and Cr on the sample surface, with the absence of pronounced sequential stacking compared with Ga atoms. The strong polarization-dependent x-ray absorption near-edge structure features showed the preservation of the hexagonal crystalline structure in both defect-free and hexagonal pyramids. From the spatially resolved x-ray linear dichroism, no preferential disorder was observed in the direction parallel or perpendicular to the crystal growth.
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78.20.Fm Birefringence
61.72.uj III-V and II-VI semiconductors
66.30.H- Self-diffusion and ionic conduction in nonmetals
78.70.Dm X-ray absorption spectra
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.55.Cr III-V semiconductors
61.46.-w Structure of nanoscale materials

Understanding the relation between stress and surface morphology in sputtered films: Atomistic simulations and experiments

Luis A. Zepeda-Ruiz, Eric Chason, George H. Gilmer, Yinmin Wang, Hongwei Xu, Abbas Nikroo, and Alex V. Hamza

Appl. Phys. Lett. 95, 151910 (2009); http://dx.doi.org/10.1063/1.3246791 (3 pages) | Cited 7 times

Online Publication Date: 16 October 2009

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The relation between stress evolution and surface morphology during deposition of sputtered films is examined by combining kinetic Monte Carlo simulations and stress measurements. We find that the surface morphology is susceptible to an instability, which transforms from layer-by-layer growth to the formation of pillarlike columns. The gaps between these columns prevent complete densification and can lead to a network of pores in the layer. We propose that the formation of this structure changes the stress in the growing layers from compressive to tensile.
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68.35.B- Structure of clean surfaces (and surface reconstruction)
61.43.Bn Structural modeling: serial-addition models, computer simulation
81.15.Cd Deposition by sputtering
61.72.Mm Grain and twin boundaries

Comparison of the magnetic properties of GeMn thin films through Mn L-edge x-ray absorption

S. Ahlers, P. R. Stone, N. Sircar, E. Arenholz, O. D. Dubon, and D. Bougeard

Appl. Phys. Lett. 95, 151911 (2009); http://dx.doi.org/10.1063/1.3232245 (3 pages) | Cited 4 times

Online Publication Date: 16 October 2009

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X-ray absorption spectroscopy of epitaxial GeMn thin films reveals an experimentally indistinguishable electronic configuration of Mn atoms incorporated in Ge1−xMnx nanoclusters and in precipitates of the intermetallic compound Mn5Ge3, respectively. However, the average magnetic response of thin films containing Ge1−xMnx nanoclusters is lower than the response of films containing Mn5Ge3 precipitates. This reduced magnetic response of Ge1−xMnx nanoclusters is explained in terms of a fraction of Mn atoms being magnetically inactive due to antiferromagnetic coupling or the presence of structural disorder. A determination of the role of magnetically inactive Mn atoms in the self-assembly of the thermodynamically metastable Ge1−xMnx nanoclusters seems to be an essential ingredient for an enhanced control of this promising high Curie temperature magnetic semiconductor.
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78.70.Dm X-ray absorption spectra
75.70.Ak Magnetic properties of monolayers and thin films
75.50.Ee Antiferromagnetics
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.50.Pp Magnetic semiconductors
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Tunneling anisotropic spin polarization in lateral (Ga,Mn)As/GaAs spin Esaki diode devices

A. Einwanger, M. Ciorga, U. Wurstbauer, D. Schuh, W. Wegscheider, and D. Weiss

Appl. Phys. Lett. 95, 152101 (2009); http://dx.doi.org/10.1063/1.3247187 (3 pages) | Cited 3 times

Online Publication Date: 12 October 2009

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We report here on anisotropy of spin polarization obtained in lateral all-semiconductor, all-electrical spin injection devices employing p+-(Ga,Mn)As/n+-GaAs Esaki diode structures as spin aligning contacts, resulting from the dependence of the efficiency of spin tunneling on the orientation of spins with respect to different crystallographic directions. We observed an in-plane anisotropy of 8% in the case of spins oriented either along [1math0] or [110] direction and 25% anisotropy between in-plane and perpendicular-to-plane orientations of spins.
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85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
81.05.Ea III-V semiconductors

Monte Carlo investigation of terahertz plasma oscillations in gated ultrathin channel of n-InGaAs

J.-F. Millithaler, J. Pousset, L. Reggiani, P. Ziade, H. Marinchio, L. Varani, C. Palermo, J. Mateos, T. González, S. Perez, and D. Pardo

Appl. Phys. Lett. 95, 152102 (2009); http://dx.doi.org/10.1063/1.3248096 (3 pages) | Cited 4 times

Online Publication Date: 12 October 2009

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By numerical simulations we investigate the dispersion of the plasma frequency in a gated channel of n-type InGaAs layer of thickness W and submicron length L at T = 300 K. In the presence of a source-drain voltage and for a carrier concentrations of 1018 cm−3 the spectra evidences a peaked shape with two main bumps, the former at high frequency corresponding to the three-dimensional plasma frequency and the latter at a low frequency. The frequency value of the latter peak exhibits a dispersion as the inverse of the channel length in agreement with the predictions of gradual channel approximation. At increasing drain voltages the instabilities associated with the presence of Gunn domains are responsible for a suppression of the plasma peak in favor of the onset of a peak in the subterahertz domain associated with transit time effects.
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73.50.Mx High-frequency effects; plasma effects
73.61.Ey III-V semiconductors
81.05.Ea III-V semiconductors
52.77.-j Plasma applications

In situ passivation of InP surface using H2S during metal organic vapor phase epitaxy

Hong-Liang Lu, Yuki Terada, Yukihiro Shimogaki, Yoshiaki Nakano, and Masakazu Sugiyama

Appl. Phys. Lett. 95, 152103 (2009); http://dx.doi.org/10.1063/1.3233935 (3 pages) | Cited 4 times

Online Publication Date: 13 October 2009

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An in situ surface passivation of InP(100) using H2S during metal organic vapor phase epitaxy has been characterized by x-ray photoemission spectroscopy and photoluminescence. X-ray photoelectron spectra indicate that the H2S-treated InP at 300 °C is free of P and In oxides even after exposure to air. The enhancement of photoluminescence intensity confirms that H2S passivation of an InP epilayer can reduce the surface defects. It is shown that H2S treatment results in In–S bonds, which dominate the sulfur-passivated InP surface, effectively suppressing interface oxidation during the subsequent ultrathin Al2O3 dielectric film growth.
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81.65.Rv Passivation
79.60.Bm Clean metal, semiconductor, and insulator surfaces
81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
77.55.-g Dielectric thin films
68.55.ag Semiconductors

Single spin transport spectroscopy: Current blockade and spin decay

Gerold Kiesslich, Gernot Schaller, Clive Emary, and Tobias Brandes

Appl. Phys. Lett. 95, 152104 (2009); http://dx.doi.org/10.1063/1.3243693 (3 pages) | Cited 4 times

Online Publication Date: 13 October 2009

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We present a theory of a single-electron transistor exchange-coupled to a localized spin. We show how to gain detailed quantitative knowledge about the attached spin such as spin size, exchange coupling strength, Landé g-factor, and spin decay time T1 by utilizing a robust blockade phenomenon of dc magnetotransport with accompanying noise enhancement. Our studies are of particular relevance to spin-resolved scanning single-electron transistor microscopy, electronic transport through nanomagnets, and the effect of hyperfine interaction on transport electrons by surrounding nuclear spins.
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73.23.Hk Coulomb blockade; single-electron tunneling
85.35.Gv Single electron devices
75.30.Et Exchange and superexchange interactions
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
72.25.Fe Optical creation of spin polarized carriers
73.40.Gk Tunneling
75.50.Tt Fine-particle systems; nanocrystalline materials
71.70.Jp Nuclear states and interactions

Temperature-dependent Hall and photoluminescence evidence for conduction-band edge shift induced by alloying ZnO with magnesium

X. H. Pan, W. Guo, Z. Z. Ye, B. Liu, Y. Che, W. Tian, D. G. Schlom, and X. Q. Pan

Appl. Phys. Lett. 95, 152105 (2009); http://dx.doi.org/10.1063/1.3236771 (3 pages) | Cited 3 times

Online Publication Date: 14 October 2009

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This work discusses the effect of conduction-band edge shift induced by alloying ZnO with magnesium. Temperature-dependent Hall and temperature-dependent photoluminescence measurements are used to characterize the epitaxial Zn1−xMgxO thin films grown on (111) Si using intervening epitaxial Lu2O3 buffer layers, which prove that the addition of Mg in ZnO shifts the conduction-band edge to higher energy, thus increasing the activation energy of the defect donor states and reducing the n-type background carrier concentration.
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81.05.Dz II-VI semiconductors
71.20.Nr Semiconductor compounds
72.20.My Galvanomagnetic and other magnetotransport effects
78.55.Et II-VI semiconductors
78.66.Hf II-VI semiconductors
68.55.ag Semiconductors
71.55.Gs II-VI semiconductors

Nonvolatile resistive switching in spinel ZnMn2O4 and ilmenite ZnMnO3

Haiyang Peng and Tom Wu

Appl. Phys. Lett. 95, 152106 (2009); http://dx.doi.org/10.1063/1.3249630 (3 pages) | Cited 13 times

Online Publication Date: 14 October 2009

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We report that spinel ZnMn2O4 and ilmenite ZnMnO3 show excellent unipolar resistive switching behaviors, with ON/OFF ratios larger than 104. For both oxides, retention of more than 10 h and good endurance are achieved. Conduction of the OFF state is dominated by the space-charge-limited conduction mechanism, while the Ohmic behavior dictates the ON state, which suggests a filamentary conduction mechanism. Our study introduces two promising materials candidates for nonvolatile resistive random access memory devices, and furthermore it suggests that formation and rupture of conducting filaments are universal in certain ternary oxides even though they may possess distinct crystalline structures.
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73.50.Fq High-field and nonlinear effects
73.61.Le Other inorganic semiconductors
73.40.Ns Metal-nonmetal contacts
84.30.Sk Pulse and digital circuits

Behaviors of gate induced drain leakage stress in lightly doped drain n-channel metal-oxide-semiconductor field-effect transistors

X. H. Ma, Y. R. Cao, H. X. Gao, H. F. Chen, and Y. Hao

Appl. Phys. Lett. 95, 152107 (2009); http://dx.doi.org/10.1063/1.3250435 (3 pages) | Cited 5 times

Online Publication Date: 14 October 2009

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The behaviors of the gate induced drain leakage (GIDL) stress during the single and alternating stresses were investigated. A combination of threshold voltage Vth and GIDL current Igidl has been applied to investigate n-channel metal-oxide-semiconductor field-effect transistors with different gate oxide thicknesses. The recovery and enhancement of Vth depending on the gate oxide thickness, are found to result from the GIDL stress in the two processes. This study reveals that different behaviors of GIDL stress for different gate oxide thicknesses are attributed to the rivalship between the hole-induced carrier mobility increase and the interface states-induced increase in lightly doped drain resistance.
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85.30.Tv Field effect devices

Real-time band structure changes of GaAs during continuous dynamic compression to 5 GPa

P. Grivickas, M. D. McCluskey, and Y. M. Gupta

Appl. Phys. Lett. 95, 152108 (2009); http://dx.doi.org/10.1063/1.3247886 (3 pages) | Cited 2 times

Online Publication Date: 15 October 2009

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Real time changes of the GaAs band structure were determined using time-resolved photoluminescence (PL) spectroscopy, with nanosecond resolution, in single-event continuous compression experiments. Continuous compression to 5 GPa over 150 ns was achieved by impacting fused silica buffers preceding the GaAs crystals. PL spectra and compression wave profiles were measured simultaneously for uniaxial strain compression along the [100] orientation. Below 3 GPa, PL peaks from Te donors and Zn acceptors showed a blueshift upon compression, consistent with a widening of the band gap. At 3 GPa, the PL intensity decreased abruptly, due to a direct-to-indirect transition.
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71.20.Nr Semiconductor compounds
78.55.Cr III-V semiconductors
78.47.jd Time resolved luminescence

Measurements of current-voltage-induced heating in the Al/SrTiO3−xNy/Al memristor during electroformation and resistance switching

A. Shkabko, M. H. Aguirre, I. Marozau, T. Lippert, and A. Weidenkaff

Appl. Phys. Lett. 95, 152109 (2009); http://dx.doi.org/10.1063/1.3238563 (3 pages) | Cited 5 times

Online Publication Date: 15 October 2009

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Heating of the Al/SrTiO3−xNy/Al memristor is characterized during electroformation and switching of the resistances. The electrode with the higher voltage potential is heated to higher temperatures than the electrode with the lower potential, suggesting a reversible (nonstable) displacement of the anions in a low voltage region (|V|<±3 V). Application of a threshold voltage appropriate for resistance switching (|V| ≥ ±3 V) facilitates migration of anions to the anode interface and increases the local anode temperature to a maximum of 285 °C. The hysteretic I-V curves are discussed taking into account tunnel barrier formation/break and inhomogeneous Schottky barrier modification at the anode interface.
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85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
73.30.+y Surface double layers, Schottky barriers, and work functions
85.30.Hi Surface barrier, boundary, and point contact devices
85.30.Kk Junction diodes

Chemical stability and transport properties of ultrathin La1.2Sr1.8Mn2O7 Ruddlesden–Popper films

M. Matvejeff, K. Yoshimatsu, H. Kumigashira, M. Oshima, and M. Lippmaa

Appl. Phys. Lett. 95, 152110 (2009); http://dx.doi.org/10.1063/1.3243978 (3 pages) | Cited 4 times

Online Publication Date: 15 October 2009

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Epitaxial La1.2Sr1.8Mn2O7 films with n = 2 Ruddlesden–Popper structure were grown on SrTiO3 (001) substrates. Decomposition through water intercalation led to the disappearance of the metal-insulator transition in samples exposed to ambient atmosphere. Crystal damage was limited to the surface layer only, demonstrating the anisotropic nature of the water intercalation process. By protecting films with a SrTiO3 capping layer, the metal-insulator transition persisted down to 2.5 unit cell thick films. In thinner films, we propose a mechanism related to the loss of interlayer ferromagnetic order in favor of in-plane antiferromagnetism as a reason for the loss of the metallic state.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.55.-a Thin film structure and morphology
71.30.+h Metal-insulator transitions and other electronic transitions
75.50.Ee Antiferromagnetics
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Role of copper in light induced minority-carrier lifetime degradation of silicon

H. Savin, M. Yli-Koski, and A. Haarahiltunen

Appl. Phys. Lett. 95, 152111 (2009); http://dx.doi.org/10.1063/1.3250161 (3 pages) | Cited 6 times

Online Publication Date: 16 October 2009

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We investigate the impact of copper on the light induced minority-carrier lifetime degradation in various crystalline silicon materials. We demonstrate here that the presence of neither boron nor oxygen is necessary for the degradation effect. In addition, our experiments reveal that copper contamination alone can cause the light induced minority-carrier lifetime degradation.
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72.40.+w Photoconduction and photovoltaic effects
61.72.jj Interstitials
72.80.Cw Elemental semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Characterization of electrical conductivity in a zeolitelike material

V. Soghomonian and J. J. Heremans

Appl. Phys. Lett. 95, 152112 (2009); http://dx.doi.org/10.1063/1.3251070 (3 pages) | Cited 4 times

Online Publication Date: 16 October 2009

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We present the electrical characterization of a zeolitelike oxo-vanadium arsenate framework. The experimentally obtained electronic and ionic conductivities and their interactions are discussed. Further, we investigate the potential use of electrically conducting zeolitelike materials in electrical energy storage applications, in light of the material’s structural and electronic characteristics.
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66.30.H- Self-diffusion and ionic conduction in nonmetals
71.20.Ps Other inorganic compounds
84.60.-h Direct energy conversion and storage

High-mobility enhancement-mode 4H-SiC lateral field-effect transistors utilizing atomic layer deposited Al2O3 gate dielectric

Daniel J. Lichtenwalner, Veena Misra, Sarit Dhar, Sei-Hyung Ryu, and Anant Agarwal

Appl. Phys. Lett. 95, 152113 (2009); http://dx.doi.org/10.1063/1.3251076 (3 pages) | Cited 6 times

Online Publication Date: 16 October 2009

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Lateral metal-oxide-semiconductor field-effect transistors (MOSFETs) have been fabricated on 4H-SiC utilizing deposited dielectrics and gate-last processing. The bilayer dielectric consists of thin nitrided SiO2 covered by 25 nm of Al2O3 deposited using atomic layer deposition. Field-effect mobility and threshold voltage (VT) vary with SiC nitric oxide (NO) anneal temperature. Peak mobility of 106 cm2/V⋅s was obtained with corresponding VT of 0.8 V. The peak mobility decreases to 61 cm2/V⋅s with a lower temperature NO anneal, while the VT increased to 1.4 V. Thus with proper gate engineering, high-mobility normally off MOSFET devices can be obtained, leading to higher-performance gate-controlled power devices.
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85.30.Tv Field effect devices
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
61.72.Cc Kinetics of defect formation and annealing

Ultralow-voltage transparent electric-double-layer thin-film transistors processed at room-temperature

Jie Jiang, Qing Wan, Jia Sun, and Aixia Lu

Appl. Phys. Lett. 95, 152114 (2009); http://dx.doi.org/10.1063/1.3251782 (3 pages) | Cited 13 times

Online Publication Date: 16 October 2009

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Electric-double-layer effect is observed in mesoporous SiO2 films deposited by plasma-enhanced chemical vapor deposition at room temperature. Room-temperature processed transparent InGaZnO4 thin film transistors (TFTs) gated with such mesoporous SiO2 dielectric show an ultralow operating voltage of 1.0 V due to the large electric-double-layer capacitance. The InGaZnO4 TFTs exhibit a good performance with a high field-effect mobility of 28.5 cm2/V s, a low subthreshold swing of 110 mV/decade, and a large on-off ratio of 1.1×106, respectively. Such ultralow-voltage devices are very promising for low-power transparent macroelectronics on temperature-sensitive substrates.
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85.30.Tv Field effect devices
84.32.Tt Capacitors
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Modeling spin transport with current-sensing spin detectors

Jing Li and Ian Appelbaum

Appl. Phys. Lett. 95, 152501 (2009); http://dx.doi.org/10.1063/1.3241080 (3 pages) | Cited 1 time

Online Publication Date: 12 October 2009

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By incorporating the proper boundary conditions, we analytically derive the impulse response (or “Green’s function”) of a current-sensing spin detector. We also compare this result to a Monte Carlo simulation (which automatically takes the proper boundary condition into account) and an empirical spin transit time distribution obtained from experimental spin precession measurements. In the strong drift-dominated transport regime, this spin current impulse response can be approximated by multiplying the spin density impulse response by the average drift velocity. However, in weak drift fields, large modeling errors up to a factor of 3 in most-probable spin transit time can be incurred unless the full spin current Green’s function is used.
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72.25.Pn Current-driven spin pumping
75.30.Ds Spin waves

Epitaxial-strain effect on charge/orbital order in Pr0.5Ca0.5MnO3 films

D. Okuyama, M. Nakamura, Y. Wakabayashi, H. Itoh, R. Kumai, H. Yamada, Y. Taguchi, T. Arima, M. Kawasaki, and Y. Tokura

Appl. Phys. Lett. 95, 152502 (2009); http://dx.doi.org/10.1063/1.3246158 (3 pages) | Cited 13 times

Online Publication Date: 12 October 2009

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Effect of growth orientation on charge- and orbital-ordering (CO-OO) phenomena has been studied for Pr0.5Ca0.5MnO3 epitaxial thin films fabricated on (LaAlO3)0.3–(SrAl0.5Ta0.5O3)0.7 (LSAT) substrates by means of resistivity, synchrotron x-ray diffraction, and polarized optical microscopy measurements. CO-OO transition is observed around 220 K for a film grown on an LSAT (011) substrate [(011) film], similarly to a bulk sample, while a film grown on a (001) plane of LSAT [(001) film] shows much higher transition temperature around 300 K. The domain size of OO is approximately three times as large in the (011) film as in the (001) film. These results demonstrate that various properties of CO-OO phenomena can be controlled with the growth orientation via the epitaxial strain from the substrate.
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73.61.Ng Insulators
68.55.aj Insulators

Ni–Mn–In–Co single-crystalline particles for magnetic shape memory composites

Jian Liu, Nils Scheerbaum, Sandra Weiß, and Oliver Gutfleisch

Appl. Phys. Lett. 95, 152503 (2009); http://dx.doi.org/10.1063/1.3249585 (3 pages) | Cited 6 times

Online Publication Date: 13 October 2009

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Single- and oligo-crystalline magnetic shape memory (MSM) Ni45.2Mn36.7In13Co5.1 particles were prepared by mechanical grinding the melt-spun ribbons. The influence of annealing and grinding on the crystal structure and magnetic properties of the ribbons and particles was systematically investigated. The obtained Ni45.2Mn36.7In13Co5.1 single-crystalline particles exhibit a field-induced martensitic transformation above room temperature, thus are used for MSM-polyester composites.
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81.30.Kf Martensitic transformations
81.40.Gh Other heat and thermomechanical treatments
64.70.K- Solid-solid transitions

Magnetism of single-crystalline Co nanorods

K. Soulantica, F. Wetz, J. Maynadié, A. Falqui, R. P. Tan, T. Blon, B. Chaudret, and M. Respaud

Appl. Phys. Lett. 95, 152504 (2009); http://dx.doi.org/10.1063/1.3237157 (3 pages) | Cited 8 times

Online Publication Date: 13 October 2009

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We report on the synthesis and preparation of oriented nanomaterials of single crystalline metallic Co nanorods of 6 nm in diameters and two different aspect ratios (7 and 15). They display optimized magnetic properties, with a spontaneous magnetization just below the bulk one, and large coercive fields (up to 6.5 kOe at 300 K) as a result of coherent switching (i.e., Stoner and Wohlfarth mechanism). We measured a strong effective anisotropy very close to the expected value resulting from the sum of shape and magnetocrystalline contributions.
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75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Tt Fine-particle systems; nanocrystalline materials
81.07.Bc Nanocrystalline materials

Magnetic domain wall pinning by a curved conduit

E. R. Lewis, D. Petit, L. Thevenard, A. V. Jausovec, L. O’Brien, D. E. Read, and R. P. Cowburn

Appl. Phys. Lett. 95, 152505 (2009); http://dx.doi.org/10.1063/1.3246154 (3 pages) | Cited 9 times

Online Publication Date: 13 October 2009

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The pinning of a magnetic domain wall in a curved Permalloy (NiFe) nanostrip is experimentally studied. We examine the dependence of the pinning on both the radius of curvature of the bend and the chirality of the transverse domain wall. We find that bends act as potential wells or potential barriers depending on the chirality of the domain wall; the pinning field in both cases increases with decreasing radius of curvature. Micromagnetic simulations are consistent with the experimental results and show that both exchange and demagnetizing energies play an important role.
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75.60.Ch Domain walls and domain structure
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