APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

16 May 2011

Volume 98, Issue 20, Articles (20xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 98, 201101 (2011); http://dx.doi.org/10.1063/1.3590716 (3 pages)

Martynas Beresna, Mindaugas Gecevičius, Peter G. Kazansky, and Titas Gertus
Enlarge Image | Read More
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
back to top
RSS Feeds

Combined electron beam imaging and ab initio modeling of T1 precipitates in Al–Li–Cu alloys

C. Dwyer, M. Weyland, L. Y. Chang, and B. C. Muddle

Appl. Phys. Lett. 98, 201909 (2011); http://dx.doi.org/10.1063/1.3590171 (3 pages) | Cited 1 time

Online Publication Date: 19 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Among the many considerable challenges faced in developing a rational basis for advanced alloy design, establishing accurate atomistic models is one of the most fundamental. Here we demonstrate how advanced imaging techniques in a double-aberration-corrected transmission electron microscope, combined with ab initio modeling, have been used to determine the atomic structure of embedded 1 nm thick T1 precipitates in precipitation-hardened Al–Li–Cu aerospace alloys. The results provide an accurate determination of the controversial T1 structure, and demonstrate how next-generation techniques permit the characterization of embedded nanostructures in alloys and other nanostructured materials.
Show PACS
61.66.Dk Alloys
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
81.40.Cd Solid solution hardening, precipitation hardening, and dispersion hardening; aging
61.80.Fe Electron and positron radiation effects
71.20.Lp Intermetallic compounds

Influence of secondary phase CuxSe on the optoelectronic quality of chalcopyrite thin films

Jes K. Larsen, Levent Gütay, and Susanne Siebentritt

Appl. Phys. Lett. 98, 201910 (2011); http://dx.doi.org/10.1063/1.3592735 (3 pages) | Cited 1 time

Online Publication Date: 20 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effect of secondary phase CuxSe on the absorber quality of epitaxial CuGaSe2 films is studied by spatially resolved photoluminescence combined with scanning electron microscopy. We show that the presence of CuxSe crystals on the absorber during growth under Cu excess results in a locally increased crystal quality in the vicinity of the CuxSe crystallites, affecting the defect structure of the absorber. This effect remains after removal of CuxSe and induces a local reduction in the recombination centers, resulting in locally higher excess carrier concentrations and larger splitting of quasi-Fermi levels.
Show PACS
81.05.Gc Amorphous semiconductors
78.66.Jg Amorphous semiconductors; glasses
78.55.Qr Amorphous materials; glasses and other disordered solids
73.61.Jc Amorphous semiconductors; glasses
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
71.23.Cq Amorphous semiconductors, metallic glasses, glasses

Improved luminescence and thermal stability of semipolar (11-22) InGaN quantum dots

A. Das, G. P. Dimitrakopulos, Y. Kotsar, A. Lotsari, Th. Kehagias, Ph. Komninou, and E. Monroy

Appl. Phys. Lett. 98, 201911 (2011); http://dx.doi.org/10.1063/1.3588335 (3 pages) | Cited 1 time

Online Publication Date: 20 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Semipolar (11-22)-oriented InGaN/GaN quantum dots (QDs) emitting in the 380–620 nm spectral range were synthesized by plasma-assisted molecular-beam epitaxy. The influence of the growth temperature on the properties of InGaN QDs has been investigated by photoluminescence and transmission electron microscopy. Growth temperatures low enough to prevent indium desorption provide a favorable environment to semipolar plane (11-22) to enhance the internal quantum efficiency of InGaN/GaN nanostructures.
Show PACS
81.07.Ta Quantum dots
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
81.05.Ea III-V semiconductors
78.67.Hc Quantum dots
back to top
RSS Feeds

Strain in Si doped GaN and the Fermi level effect

Jinqiao Xie, Seiji Mita, Anthony Rice, James Tweedie, Lindsay Hussey, Ramón Collazo, and Zlatko Sitar

Appl. Phys. Lett. 98, 202101 (2011); http://dx.doi.org/10.1063/1.3589978 (3 pages) | Cited 5 times

Online Publication Date: 16 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using high resolution x-ray diffraction and Hall effect measurements, we found that the tensile strain caused by dislocation inclination in Si doped GaN became immeasurable when carbon codoping was used to compensate the free carriers. This result suggested that the tensile strain is related to free carrier concentration instead of Si concentration. Such an effect could be explained by the Fermi level effect on the surface-mediated dislocation climb governed by Ga vacancies, whose concentration is strongly influenced by the Fermi level position. This phenomenon is possibly similar to the well-known Fermi level effect in GaAs and GaP systems.
Show PACS
71.20.Nr Semiconductor compounds
72.20.My Galvanomagnetic and other magnetotransport effects
61.72.uj III-V and II-VI semiconductors
81.05.Ea III-V semiconductors
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
61.72.jd Vacancies

Solution processed Ni-doped TiO2 p-type channel in field effect transistor assembly with <10 nm thin Ba0.5Sr0.5TiO3 dielectric layer

Soumen Das, Jin-Hwan Kim, Yong-Kyu Park, and Yoon-Bong Hahn

Appl. Phys. Lett. 98, 202102 (2011); http://dx.doi.org/10.1063/1.3592736 (3 pages) | Cited 1 time

Online Publication Date: 18 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Solution processed field effect transistor structures were fabricated by inserting a Ba0.5Sr0.5TiO3 layer to form Ag/ZnO/Ba0.5Sr0.5TiO3/Ni2+:TiO2/n-Si assembly. Such assembly registered an on-to-off current ratio as large as 103 with very low off-state current ∼ 10−12 A. The low leakage current is attributed to the appreciably higher values of valence/conduction band off-set of Ba0.5Sr0.5TiO3/semiconductor heterojunction. The device response was studied as a function of temperature in the range of 25–175 °C. The hole diffusion coefficient and mobility of p-TiO2 was calculated ∼ 10−3 cm2/s and ∼ 0.13–0.15 cm−2 V−1 s−1, respectively.
Show PACS
85.30.Tv Field effect devices

Sub-Poissonian shot noise in CoFeB/MgO/CoFeB-based magnetic tunneling junctions

Tomonori Arakawa, Koji Sekiguchi, Shuji Nakamura, Kensaku Chida, Yoshitaka Nishihara, Daichi Chiba, Kensuke Kobayashi, Akio Fukushima, Shinji Yuasa, and Teruo Ono

Appl. Phys. Lett. 98, 202103 (2011); http://dx.doi.org/10.1063/1.3590921 (3 pages)

Online Publication Date: 18 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We measured the shot noise in the CoFeB/MgO/CoFeB-based magnetic tunneling junctions with a high tunneling magnetoresistance ratio (over 200% at 3 K). Although the Fano factor in the antiparallel configuration is close to unity, it is observed to be typically 0.91±0.01 in the parallel configuration. It indicates the sub-Poissonian process of the electron tunneling in the parallel configuration due to the relevance of the spin-dependent coherent transport in the low bias regime.
Show PACS
72.70.+m Noise processes and phenomena
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
72.25.-b Spin polarized transport
79.60.Jv Interfaces; heterostructures; nanostructures

Fast electrical switching of spin injection in nonlocal spin transport devices

A. Fuhrer, S. F. Alvarado, G. Salis, and R. Allenspach

Appl. Phys. Lett. 98, 202104 (2011); http://dx.doi.org/10.1063/1.3590726 (3 pages) | Cited 2 times

Online Publication Date: 19 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present spin-injection experiments in a nonlocal spin transport device where spin is injected from a ferromagnetic FeCo electrode into a GaAs epilayer. The magnetization of the injection contact is switched by Oersted fields generated by alternating current pulses. This enables fast and offset-free measurements of nonlocal spin signals. Due to a negligible time-averaged electron spin polarization, dynamic nuclear polarization effects are small and Hanle curves measured down to T = 3 K can be fit very accurately by drift-diffusion theory if a small constant Overhauser field BN = 0.4 mT is accounted for.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
72.25.-b Spin polarized transport

Diffusion-limited nonradiative recombination at extended defects in hydride vapor phase epitaxy GaN layers

Patrik Ščajev, Alexander Usikov, Vitali Soukhoveev, Ramūnas Aleksiejūnas, and Kęstutis Jarašiūnas

Appl. Phys. Lett. 98, 202105 (2011); http://dx.doi.org/10.1063/1.3591173 (3 pages) | Cited 3 times

Online Publication Date: 19 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Time-resolved free-carrier absorption and transient grating techniques were applied to determine carrier lifetimes and diffusion coefficients in a set of hydride vapor phase epitaxy GaN layers of various thickness (from 10 to 145 μm). A linear increase in nonradiative carrier lifetime in 80–800 K range found to be in a correlation with decrease of the bipolar carrier diffusion coefficient. This correlation confirmed that recombination rate is governed by carrier diffusive flow to the grain boundaries of columnar defects. A model of diffusion-governed nonradiative lifetime was proposed for fitting the measured lifetime values in the layers of different thickness as well as lifetime dependence on temperature or threading dislocation density.
Show PACS
61.72.Nn Stacking faults and other planar or extended defects
66.30.-h Diffusion in solids
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
78.47.D- Time resolved spectroscopy (>1 psec)
73.61.Ey III-V semiconductors

Charge transport in solution processable polycrystalline dual-gate organic field effect transistors

A. K. Tripathi, E. C. P. Smits, M. Loth, J. E. Anthony, and G. H. Gelinck

Appl. Phys. Lett. 98, 202106 (2011); http://dx.doi.org/10.1063/1.3591969 (3 pages)

Online Publication Date: 19 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Dual gate organic thin film transistors based on solution processable fluorinated 5,11 bis(triethylsilylethynyl) anthradithiophene semiconductor were fabricated. Top (Teflon™, εr = 2.1) and bottom (SiO2, εr = 3.9) gate dielectrics with different dielectric constants were chosen. Top gate mobilities >1 cm2/Vs and bottom gate mobilities >0.1 cm2/V s were achieved. Temperature dependent mobility measurements show thermally activated charge transport and a comparative analysis is performed in the framework of two models representing polaron hopping as well as hopping in Gaussian density of states (DOS), respectively.
Show PACS
85.30.Tv Field effect devices

Band gap of InxGa1−xN: A first principles analysis

Mathieu César, Youqi Ke, Wei Ji, Hong Guo, and Zetian Mi

Appl. Phys. Lett. 98, 202107 (2011); http://dx.doi.org/10.1063/1.3592573 (3 pages) | Cited 1 time

Online Publication Date: 19 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report first principles analysis of the band gap Eg of ternary group-III nitride InxGa1−xN in both the wurtzite and zincblende form, within the linear muffin-tin orbital (LMTO) density functional theory method. We have implemented the semilocal modified Becke–Johnson (MBJ) exchange potential to accurately determine the band gap. The doping of In atoms into the GaN crystal is handled by the InxGa1−xN alloy model within the coherent potential approximation (CPA). The LMTO-CPA-MBJ approach allows us to predict Eg as a function of arbitrary In concentration x. Quantitative comparison to the experimental data is made.
Show PACS
71.20.Nr Semiconductor compounds
61.72.uj III-V and II-VI semiconductors
71.55.Eq III-V semiconductors
81.05.Ea III-V semiconductors
71.15.Mb Density functional theory, local density approximation, gradient and other corrections

Discerning passivation mechanisms at a-Si:H/c-Si interfaces by means of photoconductance measurements

C. Leendertz, N. Mingirulli, T. F. Schulze, J. P. Kleider, B. Rech, and L. Korte

Appl. Phys. Lett. 98, 202108 (2011); http://dx.doi.org/10.1063/1.3590254 (3 pages) | Cited 7 times

Online Publication Date: 20 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The photoconductance decay (PCD) measurement is a fast and simple method to characterize amorphous/crystalline (a-Si:H/c-Si) silicon interfaces for high-efficiency solar cells. However, PCD only yields information concerning the overall recombination rate in the structure. To overcome this limitation, we have developed and validated a computer-aided PCD (CA-PCD) analysis method to determine the defect density of recombination-active dangling bonds at the interface and the potential drop in the crystalline absorber adjacent to the interface. As a practical example, we investigate a-Si:H(p)/a-Si:H(i)/c-Si(n) layer stacks and show that the CA-PCD method is capable of discerning the influence of field-effect and defect passivation.
Show PACS
81.65.Rv Passivation
71.55.Cn Elemental semiconductors
88.40.H- Solar cells (photovoltaics)
68.35.Ct Interface structure and roughness
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.40.+w Photoconduction and photovoltaic effects

Anisotropic thermopower and magnetothermopower in a misfit-layered calcium cobaltite

G. D. Tang, H. H. Guo, T. Yang, D. W. Zhang, X. N. Xu, L. Y. Wang, Z. H. Wang, H. H. Wen, Z. D. Zhang, and Y. W. Du

Appl. Phys. Lett. 98, 202109 (2011); http://dx.doi.org/10.1063/1.3592831 (3 pages)

Online Publication Date: 20 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An unusual anisotropy of thermopower and magnetothermopower has been observed in the powerful thermoelectric Ca3Co4O9+δ single crystal. The in-plane thermopower is about twice as big as the out-of-plane thermopower. Combining ab initio band structure calculation with semiclassical model analysis, we understand this anisotropy with band structure effects and especially with anisotropic Fermi surface. We find that a strong anisotropy in the topology of Fermi surface leads to the anisotropy of (magneto)thermopower. This study may also shed light on anisotropic properties of other layered cobalt oxides.
Show PACS
72.20.Pa Thermoelectric and thermomagnetic effects
71.15.-m Methods of electronic structure calculations
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor
71.20.Ps Other inorganic compounds

Structural and vibrational properties of amorphous GeO2 from first-principles

E. Scalise, M. Houssa, G. Pourtois, V. V. Afanas’ev, and A. Stesmans

Appl. Phys. Lett. 98, 202110 (2011); http://dx.doi.org/10.1063/1.3593036 (3 pages) | Cited 1 time

Online Publication Date: 20 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The structural and vibrational properties of amorphous germanium oxide (a-GeO2) are investigated using first-principles calculations based on density functional theory. We first generate an a-GeO2 structure by first-principles molecular dynamics and analyze its structural properties. The vibrational spectra is then calculated within a density-functional approach. Both static and dynamic properties are in good agreement with experimental data. We next generate defects in our structure (oxygen vacancies with several density and charge states) and consider the most stable atomic configurations, focusing on the vibrational features of threefold coordinated O and divalent Ge centers.
Show PACS
63.50.Lm Glasses and amorphous solids
71.15.Pd Molecular dynamics calculations (Car-Parrinello) and other numerical simulations
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
71.23.-k Electronic structure of disordered solids
61.43.Bn Structural modeling: serial-addition models, computer simulation
back to top
RSS Feeds

Field- and current-induced domain-wall motion in permalloy nanowires with magnetic soft spots

Andreas Vogel, Sebastian Wintz, Theo Gerhardt, Lars Bocklage, Thomas Strache, Mi-Young Im, Peter Fischer, Jürgen Fassbender, Jeffrey McCord, and Guido Meier

Appl. Phys. Lett. 98, 202501 (2011); http://dx.doi.org/10.1063/1.3590267 (3 pages) | Cited 1 time

Online Publication Date: 16 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study field- and current-induced domain-wall motion in permalloy nanowires containing a square-shaped magnetically softened region. Implantation of chromium ions is used to induce pinning sites via a local reduction in the saturation magnetization. Micromagnetic simulations, magnetic transmission soft x-ray microscopy, and electrical measurements are employed to characterize the pinning potential which significantly differs for transverse and vortex walls. Reliable domain-wall depinning from a so-called magnetic soft spot by single current pulses is observed. This demonstrates the suitability of these pinning sites for applications.
Show PACS
75.75.-c Magnetic properties of nanostructures
73.63.-b Electronic transport in nanoscale materials and structures
72.15.Gd Galvanomagnetic and other magnetotransport effects
61.72.up Other materials
75.60.Ch Domain walls and domain structure
75.47.Np Metals and alloys

Electronic tuning of magnetic permeability in Co2Z hexaferrite toward high frequency electromagnetic device miniaturization

Yajie Chen, Andrew Daigle, Trifon Fitchorov, Bolin Hu, Michael Geiler, Anton Geiler, C. Vittoria, and V. G. Harris

Appl. Phys. Lett. 98, 202502 (2011); http://dx.doi.org/10.1063/1.3590771 (3 pages)

Online Publication Date: 17 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The magnetic and magnetostriction properties of Z-type cobalt-doped barium hexaferrite with perpendicular c-axis crystallographic texture are presented. The hexaferrite was utilized as a component in Co2Z/lead magnesium niobate-lead titanate multiferroic heterostructures whose tunability of permeability with electric field in terms of ferromagnetic resonance shift was supported by experiments and theoretical calculation. A permeability change of 16% was measured by an induced magnetic field of 38 Oe under the application of 6 kV/cm of electric field. These findings lay the foundation for the application of Z-type hexaferrites in tunable rf and microwave devices valued for sending, receiving, and manipulating electromagnetic signals.
Show PACS
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
75.80.+q Magnetomechanical effects, magnetostriction
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
77.80.-e Ferroelectricity and antiferroelectricity
75.50.Gg Ferrimagnetics

Superconducting quantum interference device as a near-quantum-limited amplifier for the axion dark-matter experiment

D. Kinion and John Clarke

Appl. Phys. Lett. 98, 202503 (2011); http://dx.doi.org/10.1063/1.3583380 (3 pages) | Cited 2 times

Online Publication Date: 17 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We characterized a microstrip superconducting quantum interference device amplifier (MSA) as a function of frequency and temperature. At 40 mK, with optimal current and flux biases, the maximum gain of 20.4 dB was at 620 MHz; the bandwidth was 21 MHz. The minimum noise temperature TN = 48±5 mK occurred at 612 MHz, slightly below the frequency of maximum gain. This value of TN is within a factor of 1.6 of the quantum limit TQ = hf/kB (f is frequency) for a linear, phase-preserving amplifier. Incorporating the MSA into the axion detector at the University of Washington will increase the scan rate by two to three orders of magnitude.
Show PACS
85.25.Dq Superconducting quantum interference devices (SQUIDs)
84.30.Le Amplifiers

Quantum well thickness dependence of Rashba spin–orbit coupling in the InAs/InGaAs heterostructure

Tae Young Lee, Joonyeon Chang, Mark C. Hickey, Hyun Cheol Koo, Hyung-jun Kim, Suk Hee Han, and Jagadeesh S. Moodera

Appl. Phys. Lett. 98, 202504 (2011); http://dx.doi.org/10.1063/1.3589812 (3 pages)

Online Publication Date: 18 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the quantum well thickness dependence of spin–orbit coupling in InAs/InGaAs heterostructures. The beat patterns of the oscillatory magnetoresistance were measured to determine the magnitude of the parameter of an inverted type InAs quantum well structures with the thicknesses ranging from 2 to 7 nm. The band energies, electronic charge distribution, and Rashba spin–orbit coupling parameter of the structure were calculated using a self-consistent field method and a k⋅P perturbation scheme. The magnitude of the parameter increases with decreasing the InAs quantum well thickness. Comparison with the calculated data revealed that the increase in the spin–orbit interaction parameter is due to the stronger penetration of the wave function envelope into the barriers where more pronounced band bending and barrier asymmetry occur in both the conduction and valence bands.
Show PACS
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
73.21.Fg Quantum wells
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
72.20.My Galvanomagnetic and other magnetotransport effects

Magnetic order near 270 K in mineral and synthetic Mn2FeSbO6 ilmenite

R. Mathieu, S. A. Ivanov, G. V. Bazuev, M. Hudl, P. Lazor, I. V. Solovyev, and P. Nordblad

Appl. Phys. Lett. 98, 202505 (2011); http://dx.doi.org/10.1063/1.3593194 (3 pages)

Online Publication Date: 19 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The structural and magnetic properties of Mn2FeSbO6 single-crystalline mineral and ceramic samples synthesized under thermobaric treatment have been investigated, and compared to theoretical predictions based on first-principles electronic structure calculations. This ilmenite system displays a sharp magnetic transition just below the room temperature related to a ferrimagnetic ordering of the Mn2+ and Fe3+ cations, which makes Mn2FeSbO6 a promising candidate for designing functional magnetic materials.
Show PACS
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
71.15.Dx Computational methodology (Brillouin zone sampling, iterative diagonalization, pseudopotential construction)
71.20.Ps Other inorganic compounds
61.66.Fn Inorganic compounds
75.50.Gg Ferrimagnetics
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)

Tunability of the critical-current density in superconductor-ferromagnet hybrids

Nuria Del-Valle, Carles Navau, Alvaro Sanchez, and Du-Xing Chen

Appl. Phys. Lett. 98, 202506 (2011); http://dx.doi.org/10.1063/1.3591971 (3 pages) | Cited 1 time

Online Publication Date: 19 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Important modifications on the magnetization loops of the superconductor have been observed in superconductor-ferromagnet hybrids due to the effects of the ferromagnetic components, which can be used for tuning the superconductor critical-current density Jc to desirable values. Here, a model based on an energy minimization procedure is presented to analyze the complex interaction between the superconductor and the ferromagnets. We show how the geometry and orientation of the ferromagnets can be chosen for shifting the position of the peaks appearing in the magnetization to positive or negative applied fields, and, consequently, to tune Jc in superconductor-ferromagnet hybrids.
Show PACS
74.25.Sv Critical currents
74.25.Ha Magnetic properties including vortex structures and related phenomena
back to top
RSS Feeds

Resonant excitation of coherent Cerenkov radiation in dielectric lined waveguides

G. Andonian, O. Williams, X. Wei, P. Niknejadi, E. Hemsing, J. B. Rosenzweig, P. Muggli, M. Babzien, M. Fedurin, K. Kusche, R. Malone, and V. Yakimenko

Appl. Phys. Lett. 98, 202901 (2011); http://dx.doi.org/10.1063/1.3592579 (3 pages) | Cited 2 times

Online Publication Date: 18 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the observation of coherent Cerenkov radiation in the terahertz regime emitted by a relativistic electron pulse train passing through a dielectric lined cylindrical waveguide. We describe the beam manipulations and measurements involved in repetitive pulse train creation including comb collimation and nonlinear optics corrections. With this technique, modes beyond the fundamental are selectively excited by use of the appropriate frequency train. The spectral characterization of the structure shows preferential excitation of the fundamental and of a higher longitudinal mode.
Show PACS
42.65.Wi Nonlinear waveguides
41.60.Bq Cherenkov radiation
42.79.Gn Optical waveguides and couplers
42.79.Ag Apertures, collimators

Photovoltaic properties of Bi2FeCrO6 epitaxial thin films

R. Nechache, C. Harnagea, S. Licoccia, E. Traversa, A. Ruediger, A. Pignolet, and F. Rosei

Appl. Phys. Lett. 98, 202902 (2011); http://dx.doi.org/10.1063/1.3590270 (3 pages) | Cited 5 times

Online Publication Date: 19 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report a large photovoltaic (PV) effect in multiferroic Bi2FeCrO6 (BFCO) films under monochromatic illumination at 635 nm with an intensity of 1.5 mW cm−2. These multiferroic films exhibit a large photocurrent at zero bias voltage and an open-circuit voltage of about 0.6 V. A high PV power conversion efficiency of about 6% for red light is achieved and attributed to a high degree of B-site cationic ordering between Fe and Cr sublattices, the tuning of which is likely to play a key role in further improvements of the PV properties in BFCO.
Show PACS
73.50.Pz Photoconduction and photovoltaic effects
75.85.+t Magnetoelectric effects, multiferroics
77.55.Nv Multiferroic/magnetoelectric films

Real-space mapping of dynamic phenomena during hysteresis loop measurements: Dynamic switching spectroscopy piezoresponse force microscopy

A. Kumar, O. S. Ovchinnikov, H. Funakubo, S. Jesse, and S. V. Kalinin

Appl. Phys. Lett. 98, 202903 (2011); http://dx.doi.org/10.1063/1.3590919 (3 pages) | Cited 2 times

Online Publication Date: 20 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Dynamic switching spectroscopy piezoresponse force microscopy is developed to separate thermodynamic and kinetic effects in local bias-induced phase transitions. The approaches for visualization and analysis of five-dimensional data are discussed. The spatial and voltage variability of relaxation behavior of the a-c domain lead zirconate-titanate surface suggest the interpretation in terms of surface charge dynamics. This approach is applicable to local studies of dynamic behavior in any system with reversible bias-induced phase transitions ranging from ferroelectrics and multiferroics to ionic systems such as batteries, fuel cells, and electroresistive materials.
Show PACS
77.80.Dj Domain structure; hysteresis
77.65.-j Piezoelectricity and electromechanical effects
77.84.Cg PZT ceramics and other titanates

Low temperature phenomena in ferroic BiMO3–PbTiO3 (M: Mn and Sc)

M. Algueró, R. Jiménez, H. Amorín, E. Vila, and A. Castro

Appl. Phys. Lett. 98, 202904 (2011); http://dx.doi.org/10.1063/1.3591176 (3 pages)

Online Publication Date: 20 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Low temperature, reversible mechanical effects in BiMnO3–PbTiO3 are shown to be analogous to those reported in multiferroic BiFeO3. The same stiffening (on cooling) has been found in ferroelectric BiScO3–PbTiO3 that shows negligible conduction. This has allowed permittivity and polarization studies, not possible in BiMnO3–PbTiO3, to be accomplished. Results indicate mechanical effects to be associated with a phase transition, most probably governed by an order parameter other than electric polarization, but to which it is coupled. The possibility of a common origin for the effects in the three Bi-containing perovskites is discussed, along with implications on the multiferroicity of BiMnO3–PbTiO3.
Show PACS
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.de Elastic moduli
77.22.Ch Permittivity (dielectric function)
77.80.B- Phase transitions and Curie point
77.84.Cg PZT ceramics and other titanates
77.22.Ej Polarization and depolarization
back to top
RSS Feeds

Molecular monolayers for conformal, nanoscale doping of InP nanopillar photovoltaics

Kee Cho, Daniel J. Ruebusch, Min Hyung Lee, Jae Hyun Moon, Alexandra C. Ford, Rehan Kapadia, Kuniharu Takei, Onur Ergen, and Ali Javey

Appl. Phys. Lett. 98, 203101 (2011); http://dx.doi.org/10.1063/1.3585138 (3 pages)

Online Publication Date: 17 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Semiconductor nanopillar arrays with radially doped junctions have been widely proposed as an attractive device architecture for cost effective and high efficiency solar cells. A challenge in the fabrication of three-dimensional nanopillar devices is the need for highly abrupt and conformal junctions along the radial axes. Here, a sulfur monolayer doping scheme is implemented to achieve conformal ultrashallow junctions with sub-10 nm depths and a high electrically active dopant concentration of 1019–1020 cm−3 in arrays of InP nanopillars. The enabled solar cells exhibit a respectable conversion efficiency of 8.1% and a short circuit current density of 25 mA/cm3. The work demonstrates the utility of well-established surface chemistry for fabrication of nonplanar junctions for complex devices.
Show PACS
88.40.jm Thin film III-V and II-VI based solar cells
61.72.uj III-V and II-VI semiconductors

Band gap formation in graphene by in-situ doping

Jeongho Park, W. C. Mitchel, Gail J. Brown, Said Elhamri, Lawrence Grazulis, Howard E. Smith, Shanee D. Pacley, John J. Boeckl, Kurt G. Eyink, Shin Mou, David H. Tomich, and John E. Hoelscher

Appl. Phys. Lett. 98, 203102 (2011); http://dx.doi.org/10.1063/1.3589364 (3 pages) | Cited 1 time

Online Publication Date: 17 May 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the formation of band gaps in as-grown stacks of epitaxial graphene with opposite doping. Control of in-situ doping during carbon source molecular beam epitaxy growth on SiC was achieved by using different carbon sources. Doping heterostructures were grown by stacking n-type material from a C60 source on p-type material from a graphite filament source. Activation energies for the resistivity and carrier concentration indicated band gaps up to 200 meV. A photoconductivity threshold was observed in the range of the electrical activation energies. Band gap formation is attributed to electric fields induced by spatially separated ionized dopants of opposite charge.
Show PACS
73.22.Pr Electronic structure of graphene
72.80.Vp Electronic transport in graphene
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
61.72.up Other materials
72.40.+w Photoconduction and photovoltaic effects
73.50.Pz Photoconduction and photovoltaic effects
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close