Jump to Content
View Cart
Top 20 Most Read Articles
September 2009
The 20 articles with the most full-text downloads during the month, in descending order.
 |
Appl. Phys. Lett. 95, 131102 (2009); http://dx.doi.org/10.1063/1.3236776 (3 pages) Online Publication Date: 28 September 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
|||||||||||||||||||||||
|
Show Abstract
Pulsed infrared photocurrent spectroscopy is used to investigate deep levels in highly resistive metal organic chemical vapor deposition-grown, magnesium-doped aluminum gallium nitride metal-semiconductor-metal test structures in the range of aluminum fraction from x = 0.0 to x = 0.52. Some background level of photocurrent is observed at all infrared pump wavelengths between 1.35 and 4.0 μm. The photocurrent decay time is a decreasing function of aluminum fraction. A peak photocurrent energy is observed for each aluminum fraction. With increasing aluminum fraction, the peak blueshifts and narrows.
|
||||||||||||||||||||||||
|
Show PACS
|
||||||||||||||||||||||||
|
|
Nanosecond switching in GeTe phase change memory cells Appl. Phys. Lett. 95, 043108 (2009); http://dx.doi.org/10.1063/1.3191670 (3 pages) Online Publication Date: 28 July 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
|||
|
Show Abstract
The electrical switching behavior of GeTe-based phase change memory devices is characterized by time resolved experiments. SET pulses with a duration of less than 16 ns are shown to crystallize the material. Depending on the resistance of the RESET state, the minimum SET pulse duration can even be reduced down to 1 ns. This finding is attributed to the increasing impact of crystal growth upon decreasing switchable volume. Using GeTe or materials with similar crystal growth velocities, hence promises nonvolatile phase change memories with dynamic random access memorylike switching speeds.
|
||||
|
Show PACS
|
||||
|
|
Organic light-emitting diode with liquid emitting layer Appl. Phys. Lett. 95, 053304 (2009); http://dx.doi.org/10.1063/1.3200947 (3 pages) Online Publication Date: 6 August 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We demonstrate an original organic light-emitting diode (OLED) having a neat liquid host of 9-(2-ethylhexyl)carbazole (EHCz) doped with a guest emitter of 5,6,11,12-tetraphenylnapthacene (rubrene). The device structure is composed of indium tin-oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulphonate)/EHCz:rubrene/Cs2CO3/ITO. We demonstrate that the liquid organic semiconducting layer surely transports charge carriers, leading to electroluminescence from rubrene with the highest external quantum efficiency of ηext = 0.03% at a current density of 0.26 mA/cm2. Our demonstration of the liquid-OLEDs will open another possibility of organic semiconductors and light-emitting applications.
|
|||
|
Show PACS
|
|||
|
|
Appl. Phys. Lett. 95, 013107 (2009); http://dx.doi.org/10.1063/1.3167775 (3 pages) Online Publication Date: 7 July 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
A direct transfer method for fabricating flexible electronics without the assistance of an adhesive layer and stamp is reported in this paper. This rapid and simple method provides an approach for the application of vertically aligned carbon nanotubes (VA-CNTs) on plastic substrates. After transfer, the VA-CNTs maintained their initial orientation in the designed pattern and showed sufficient adhesion to the substrate under extreme bending conditions. The flexible device performed an emission on the transparent substrate and showed a low turn-on of 1.13 V/μm. This VA-CNT-based flexible device, which exhibits electrical resistance sensitive to bending, is also described herein.
|
|||
|
Show PACS
|
|||
|
|
Influence of the donor/acceptor interface on the open-circuit voltage in organic solar cells Appl. Phys. Lett. 95, 093307 (2009); http://dx.doi.org/10.1063/1.3222975 (3 pages) Online Publication Date: 4 September 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
The donor/acceptor interface in a standard CuPc/C60 organic solar cell was modified by insertion of a thin layer of molybdenum trioxide (MoO3). An ultrathin layer of MoO3 between the donor and acceptor increased the open-circuit voltage (VOC) from 0.45 to 0.85 V. The enhancement in VOC is explained by the increase in the energy level offset between the lowest unoccupied molecular orbital of the acceptor and the highest occupied molecular orbital of the donor (EDHOMO-EALUMO). The explanation is supported by the energy level analysis of the donor/acceptor interface by ultraviolet photoemission spectroscopy and x-ray photoemission spectroscopy.
|
|||
|
Show PACS
|
|||
|
|
Photonic bandgap engineering with inverse opal multistacks of different refractive index contrasts Appl. Phys. Lett. 95, 091101 (2009); http://dx.doi.org/10.1063/1.3216582 (3 pages) Online Publication Date: 31 August 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
|||||||||||
|
Show Abstract
We have self-assembled photonic crystal with a multistack structure using same size of spheres but from materials with different refractive indices. Al2O3, ZnO, and TiO2 are infiltrated into opal templates by atomic layer deposition. Stacking multiple inverse opal structures with different refractive index contrasts broadens the reflection bands dramatically. Numerical simulations with plane wave expansion method show good agreement with experimental results.
|
||||||||||||
|
Show PACS
|
||||||||||||
|
|
Experimental measurement of negative index in an all-dielectric metamaterial Appl. Phys. Lett. 95, 121101 (2009); http://dx.doi.org/10.1063/1.3232222 (3 pages) Online Publication Date: 21 September 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We designed and fabricated an all-dielectric metamaterial which exhibits negative index of refraction. This metamaterial consists of one layer made up of two sets of high permittivity resonators. We experimentally showed that this metamaterial exhibits resonant effective permeability and permittivity issued from the first two modes of Mie resonances, respectively, and that matching both these parameters results in negative effective index.
|
|||
|
Show PACS
|
|||
|
|
The effect of molybdenum oxide interlayer on organic photovoltaic cells Appl. Phys. Lett. 95, 093304 (2009); http://dx.doi.org/10.1063/1.3220064 (3 pages) Online Publication Date: 3 September 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Both small molecule and polymer photovoltaic cells were fabricated with molybdenum oxide interlayer at the indium tin oxide electrode. Enhancement in power efficiencies was observed in both small molecule and polymer cells. Specifically, the power conversion efficiencies of small molecule cells with the molybdenum oxide interlayer were enhanced by a maximum of 38% due to a significant enhancement in the fill factor. The improved fill factor is attributed to the reduction in series resistance. Our ultraviolet photoemission spectroscopy data indicate that the formation of band bending and the built-in field at the interface due to the interlayer leads to enhancement in hole extraction from the photoactive layer toward the anode.
|
|||
|
Show PACS
|
|||
|
|
Graphene on gallium arsenide: Engineering the visibility Appl. Phys. Lett. 95, 102103 (2009); http://dx.doi.org/10.1063/1.3224910 (3 pages) Online Publication Date: 9 September 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Graphene consists of single or few layers of crystalline ordered carbon atoms. Its visibility on oxidized silicon (Si/SiO2) enabled its discovery and spawned numerous studies of its unique electronic properties. The combination of graphene with the equally unique electronic material gallium arsenide (GaAs) has up to now lacked such easy visibility. Here we demonstrate that a deliberately tailored GaAs-aluminum arsenide (AlAs) multilayer structure makes graphene just as visible on GaAs as on Si/SiO2. We show that standard microscope images of exfoliated graphite on GaAs/AlAs suffice to identify mono-, bi-, and multilayers of graphene. Raman data confirm our results.
|
|||
|
Show PACS
|
|||
|
|
Combined optical trapping and microphotoluminescence of single InP nanowires Appl. Phys. Lett. 95, 101109 (2009); http://dx.doi.org/10.1063/1.3225148 (3 pages) Online Publication Date: 11 September 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
|||||||||||||||
|
Show Abstract
In this letter, we demonstrate that microphotoluminescence may be combined with optical trapping for effective optical characterization of single target InP semiconductor nanowires in suspension. Using this technique, we may investigate structural properties of optically trapped nanowires, such as crystalline polytypes and stacking faults. This arrangement may also be used to resolve structural variations along the axis of the trapped nanowire. These results show that photoluminescence measurements may be coupled with optical tweezers without degrading the performance of the optical trap and provide a powerful interrogation tool for preselection of components for nanowire photonic devices.
|
||||||||||||||||
|
Show PACS
|
||||||||||||||||
|
|
Gate-controlled current switch in graphene Appl. Phys. Lett. 95, 092104 (2009); http://dx.doi.org/10.1063/1.3216580 (3 pages) Online Publication Date: 1 September 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We numerically study cross conductances in a four-terminal all-graphene setup. We show that far away from the Dirac point, current flows along zigzag directions, giving the possibility to guide the current between terminals using a tunable pn-junction. The device operates as a gate-controlled current switch, and the electronic properties of graphene are crucial for efficient performance.
|
|||
|
Show PACS
|
|||
|
|
Internal quantum efficiency of c-plane InGaN and m-plane InGaN on Si and GaN Appl. Phys. Lett. 95, 101106 (2009); http://dx.doi.org/10.1063/1.3224192 (3 pages) Online Publication Date: 8 September 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We investigated internal quantum efficiency (IQE) of polar (0001) InGaN on c-sapphire, and (1
 00) nonpolar m-plane InGaN on both m-plane GaN and specially patterned Si. The IQE values were extracted from the resonant photoluminescence intensity versus the excitation power. Data indicate that at comparable generated carrier concentrations the efficiency of the m-plane InGaN on patterned Si is approximately a factor of 2 higher than that of the highly optimized c-plane layer. At the highest laser excitation employed ( ∼ 1.2×1018 cm−3), the IQE of m-plane InGaN double heterostructure on Si is approximately 65%. We believe that the m-plane would remain inherently advantageous, particularly at high electrical injection levels, even with respect to highly optimized c-plane varieties. The observations could be attributed to the lack of polarization induced field and the predicted increased optical matrix elements in m-plane orientation. |
|||
|
Show PACS
|
|||
|
|
Self-assembled bioinspired quantum dots: Optical properties Appl. Phys. Lett. 94, 261907 (2009); http://dx.doi.org/10.1063/1.3167354 (3 pages) Online Publication Date: 2 July 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Until now, the wide research field of quantum dots (QDs) focused on inorganic structures. In the present study, we report on quantum confinement phenomena found in peptide nanocrystalline regions formed within self-assembly peptide nanospheres. These bioinspired nanostructures exhibit the optical absorption characteristics of QDs with pronounced luminescence of excitons whose origin is at the UV region. Theoretical estimations based on experimental data show that the radius of the self assembled peptide QDs is 1.3 nm.
|
|||
|
Show PACS
|
|||
|
|
Appl. Phys. Lett. 95, 091104 (2009); http://dx.doi.org/10.1063/1.3212145 (3 pages) Online Publication Date: 3 September 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
To connect the surface plasmon polariton (SPP) based devices with the conventional dielectric devices is a significant issue for the further development of SPP and related applications. In this paper, extremely high efficient coupling (>99%) between long range SPP (LRSPP) waveguide mode and TM mode of dielectric waveguide has been demonstrated from a hybrid coupler, which composed of an Au (LRSPP) waveguide and a SiN (dielectric) waveguide. Based on this hybrid coupler, a polarization splitter with pure TM mode output from one arm and TE mode output from the other arm with high TE/TM extinction ratio has been realized.
|
|||
|
Show PACS
|
|||
|
|
A three-terminal spin-torque-driven magnetic switch Appl. Phys. Lett. 95, 083506 (2009); http://dx.doi.org/10.1063/1.3216851 (3 pages) Online Publication Date: 28 August 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
|||||||||
|
Show Abstract
A three-terminal spin-torque-driven magnetic switch is experimentally demonstrated. The device uses nonlocal spin current and spin accumulation as the main mechanism for current-driven magnetic switching. It separates the current-induced write operation from that of a magnetic tunnel junction based read. The write current only passes through metallic structures, improving device reliability. The device structure makes efficient use of lithography capabilities, important for robust process integration.
|
||||||||||
|
Show PACS
|
||||||||||
|
|
Tuning electronic and magnetic properties of graphene by surface modification Appl. Phys. Lett. 95, 103108 (2009); http://dx.doi.org/10.1063/1.3225154 (3 pages) Online Publication Date: 9 September 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We have demonstrated that the electronic and magnetic properties of graphene sheet can be delicately tuned by surface modification. Applying an external electric field to a fully hydrogenated graphene sheet can unload hydrogen atoms on one side, while keeping the hydrogen atoms on the other side, thus forming a half-hydrogenated graphene sheet, where the unpaired electrons in the unsaturated C sites give rise to magnetic moments, coupled through extended p-p interactions. Furthermore, the electronic structure of the resulting half-hydrogenated graphene sheet can be further tuned by introducing F atoms on the other side, making a nonmagnetic semiconductor with a direct band gap.
|
|||
|
Show PACS
|
|||
|
|
Direct measurement of thermal conductivity of aluminum nanowires Appl. Phys. Lett. 95, 091905 (2009); http://dx.doi.org/10.1063/1.3216035 (3 pages) Online Publication Date: 1 September 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
A nanofabricated electrothermal test structure is reported for directly measuring the thermal conductivity of aluminum nanowires near room temperature. Interdigitated nanowires perturb an otherwise symmetric heater-sensor structure analogous to an electrical bridge circuit. Nanowires studied are 100 nm thick with 75, 100, and 150 nm widths. Finite element simulation accounts for complex device geometry. Thermal conductivity and electrical resistivity vary significantly with nanowire dimensions. Electron transport equation models which adequately describe the resistivity data consistently underestimate the thermal conductivity. Incorporating a phonon contribution of ∼ 21 W/m K to the total thermal conductivity is found to accurately describe the measured values.
|
|||
|
Show PACS
|
|||
|
|
Control of electric current by graphene edge structure engineering Appl. Phys. Lett. 95, 082109 (2009); http://dx.doi.org/10.1063/1.3206915 (3 pages) Online Publication Date: 27 August 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
In graphene nanoribbon junctions, the nearly perfect transmission occurs in some junctions while the zero conductance dips due to antiresonance appear in others. We have classified the appearance of zero conductance dips for all combinations of ribbon and junction edge structures. These transport properties do not attribute to the whole junction structure but the partial corner edge structure, which indicates that one can control the electric current simply by cutting a part of nanoribbon edge. The ribbon width is expected to be narrower than 10 nm in order to observe the zero conductance dips at room temperature.
|
|||
|
Show PACS
|
|||
|
|
Self-organization of polymer nanoneedles into large-area ordered flowerlike arrays Appl. Phys. Lett. 95, 091902 (2009); http://dx.doi.org/10.1063/1.3213394 (3 pages) Online Publication Date: 31 August 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Combination of top-down and bottom-up process is crucial for fabricating ordered complex micronanostructures. Here we report a simple, rapid, and versatile approach to demonstrate this useful concept, which involves the joint use of multibeam interference patterning and capillary force self-organization. Regular hydrophobic arrays of four-peddle nanoflowers consisting of bent needles with 300 nm tip diameters are readily produced. A “domino model” based on the balance of the capillary and support forces were proposed to interpret realization of large-area homogeneity of the array. The technology, promising for preparing more complex and functional structures, may find broad utilization in nano and biological researches.
|
|||
|
Show PACS
|
|||
|
|
Characterization of terahertz emission from a dc-biased filament in air Appl. Phys. Lett. 95, 101101 (2009); http://dx.doi.org/10.1063/1.3224944 (3 pages) Online Publication Date: 8 September 2009
Full Text:
Read Online (HTML)
|
Download PDF
|
|||
|
Show Abstract
We demonstrate that the terahertz emission from a dc-biased filament can be regarded as a sum of an elliptically polarized terahertz source (generated by a filament without external electric field) and a linearly polarized terahertz source induced by the external electric field applied to the filament. The peak frequency and linewidth of the linearly polarized terahertz source are related to the average plasma density of the filament.
|
||||
|
Show PACS
|
||||
This Publication
Scitation
Google Scholar
PubMed