Jump to Content
View Cart
Top 20 Most Read Articles
December 2012
The 20 articles with the most full-text downloads during the month, in descending order.
 |
High quality factor single-crystal diamond mechanical resonators Appl. Phys. Lett. 101, 163505 (2012); http://dx.doi.org/10.1063/1.4760274 (4 pages) Online Publication Date: 18 October 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Single-crystal diamond is a promising material for microelectromechanical systems (MEMs) because of its low mechanical loss, compatibility with extreme environments, and built-in interface to high-quality spin centers. But its use has been limited by challenges in processing and growth. We demonstrate a wafer bonding-based technique to form diamond on insulator, from which we make single-crystal diamond micromechanical resonators with mechanical quality factors as high as 338 000 at room temperature. Variable temperature measurements down to 10 K reveal a nonmonotonic dependence of quality factor on temperature. These resonators enable integration of single-crystal diamond into MEMs technology for classical and quantum applications.
|
|||
|
Show PACS
|
|||
|
|
Ultra-thin perfect absorber employing a tunable phase change material Appl. Phys. Lett. 101, 221101 (2012); http://dx.doi.org/10.1063/1.4767646 (5 pages) Online Publication Date: 26 November 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
|||||||||||||
|
Show Abstract
We show that perfect absorption can be achieved in a system comprising a single lossy dielectric layer of thickness much smaller than the incident wavelength on an opaque substrate by utilizing the nontrivial phase shifts at interfaces between lossy media. This design is implemented with an ultra-thin (∼λ/65) vanadium dioxide (VO2) layer on sapphire, temperature tuned in the vicinity of the VO2 insulator-to-metal phase transition, leading to 99.75% absorption at λ = 11.6 μm. The structural simplicity and large tuning range (from ∼80% to 0.25% in reflectivity) are promising for thermal emitters, modulators, and bolometers.
|
||||||||||||||
|
Show PACS
|
||||||||||||||
|
|
Luminescence decay in disordered low‐dimensional semiconductors Appl. Phys. Lett. 60, 2672 (1992); http://dx.doi.org/10.1063/1.106891 (3 pages)
Full Text:
|
Download PDF
|
||
|
Show Abstract
The luminescence decay of excitons in disordered low‐dimensional semiconductors with quantum confinement is shown experimentally to be characterized by a nonexponential profile and an absence of spectral diffusion. We are able to describe this luminescence as a hopping‐assisted recombination using the correlation function approach to nondispersive transport developed by H. Scher, M. F. Shlesinger, and J. T. Bendler [Phys. Today 41, 26 (1991)]. We suggest a simple derivation of analytical functions which accurately describe the anomalous luminescence decays of disordered II‐VI superlattices and of porous silicon, and show that this model includes exponential and Kohlrausch [Pogg. Ann. Phys. 119, 352 (1863)] (stretched‐exponential) relaxations as special cases. |
|||
|
Show PACS
|
|||
|
|
Polarization spectroscopy of N-polar AlGaN/GaN multi quantum wells grown on vicinal (000 Appl. Phys. Lett. 101, 182103 (2012); http://dx.doi.org/10.1063/1.4764070 (3 pages) Online Publication Date: 29 October 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Pronounced polarized light emission was observed from N-polar AlGaN/GaN multi quantum wells grown on (000
 ) GaN with a misorientation of 4° toward the m-direction grown by metal organic chemical vapor deposition. The misoriented (Al,Ga,In)N layers exhibited a high density of surface steps parallel to the 〈11 0〉 direction with step heights between 1 and 2 nm. The corrugated surfaces led to the formation of self organized quantum wire arrays in samples with 2.5 and 3.5 nm thick wells, revealed by a degree of polarization of 0.19 and 0.14, respectively, for light emission at 10 K. |
|||
|
Show PACS
|
|||
|
|
Electrical excitation and detection of magnetic dynamics with impedance matching Appl. Phys. Lett. 101, 182402 (2012); http://dx.doi.org/10.1063/1.4764519 (4 pages) Online Publication Date: 2 November 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Motivated by the prospects of increased measurement bandwidth, improved signal to noise ratio, and access to the full complex magnetic susceptibility we develop a technique to extract microwave voltages from our high resistance ( ∼ 10kΩ) (Ga,Mn)As microbars. We drive magnetization precession with microwave frequency current, using a mechanism that relies on the spin orbit interaction. A capacitively coupled λ/2 microstrip resonator is employed as an impedance matching network, enabling us to measure the microwave voltage generated during magnetisation precession.
|
|||
|
Show PACS
|
|||
|
|
Correlation between interface energetics and open circuit voltage in organic photovoltaic cells Appl. Phys. Lett. 101, 233301 (2012); http://dx.doi.org/10.1063/1.4769360 (4 pages) Online Publication Date: 4 December 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We have used ultraviolet and inverse photoemission spectroscopy to determine the transport gaps (Et) of C60 and diindenoperylene (DIP), and the photovoltaic gap (EPVG) of five prototypical donor/acceptor interfaces used in organic photovoltaic cells (OPVCs). The transport gap of C60 (2.5 ± 0.1) eV and DIP (2.55 ± 0.1) eV at the interface is the same as in pristine films. We find nearly the same energy loss of ca 0.5 eV for all material pairs when comparing the open circuit voltage measured for corresponding OPVCs and EPVG.
|
|||
|
Show PACS
|
|||
|
|
A laser-driven nanosecond proton source for radiobiological studies Appl. Phys. Lett. 101, 243701 (2012); http://dx.doi.org/10.1063/1.4769372 (4 pages) Online Publication Date: 10 December 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Ion beams are relevant for radiobiological studies and for tumor therapy. In contrast to conventional accelerators, laser-driven ion acceleration offers a potentially more compact and cost-effective means of delivering ions for radiotherapy. Here, we show that by combining advanced acceleration using nanometer thin targets and beam transport, truly nanosecond quasi-monoenergetic proton bunches can be generated with a table-top laser system, delivering single shot doses up to 7 Gy to living cells. Although in their infancy, laser-ion accelerators allow studying fast radiobiological processes as demonstrated here by measurements of the relative biological effectiveness of nanosecond proton bunches in human tumor cells.
|
|||
|
Show PACS
|
|||
|
|
Appl. Phys. Lett. 101, 213101 (2012); http://dx.doi.org/10.1063/1.4767230 (3 pages) Online Publication Date: 19 November 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
The relationship between cutting forces and lattice orientations of monolayer graphene is investigated by using an atomic force microscopy (AFM) based nanorobot. In the beginning, the atomic resolution image of the graphene lattice is obtained by using an AFM. Then, graphene cutting experiments are performed with sample rotation method, which gets rid of the tip effect completely. The experimental results show that the cutting force along the armchair orientation is larger than the force along the zigzag orientation, and the cutting forces are almost identical every 60°, which corresponds well with the 60° symmetry in graphene honeycomb lattice structure. By using Poisson analysis method, the single cutting force along zigzag orientation is 3.9 nN, and the force along armchair is 20.5 nN. This work lays the experimental foundation to build a close-loop fabrication strategy with real-time force as a feedback sensor to control the cutting direction.
|
|||
|
Show PACS
|
|||
|
|
Appl. Phys. Lett. 101, 163303 (2012); http://dx.doi.org/10.1063/1.4761947 (4 pages) Online Publication Date: 19 October 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We demonstrate improved efficiency of organic solar cells (OSCs) by employing a periodically corrugated metallic electrode in the OSCs. The improved efficiency can be attributed to the absorption enhancement resulted from the excitation of propagating surface-plasmon polariton (SPP) modes at the corrugated metal/organic interface. Through tuning the SPP resonance to the intrinsic absorption region, the short circuit current of the corrugated device with appropriate period has been increased from 4.1 mA/cm2 for planar device to 5.5 mA/cm2. The power conversion efficiency exhibits an enhancement of 35%.
|
|||
|
Show PACS
|
|||
|
|
Localizing trapped charge carriers in NO2 sensors based on organic field-effect transistors Appl. Phys. Lett. 101, 153302 (2012); http://dx.doi.org/10.1063/1.4758697 (5 pages) Online Publication Date: 8 October 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Field-effect transistors have emerged as NO2 sensors. The detection relies on trapping of accumulated electrons, leading to a shift of the threshold voltage. To determine the location of the trapped electrons we have delaminated different semiconductors from the transistors with adhesive tape and measured the surface potential of the revealed gate dielectric with scanning Kelvin probe microscopy. We unambiguously show that the trapped electrons are not located in the semiconductor but at the gate dielectric. The microscopic origin is discussed. Pinpointing the location paves the way to optimize the sensitivity of NO2 field-effect sensors.
|
|||
|
Show PACS
|
|||
|
|
Continuous diffraction patterns from circular arrays of carbon nanotubes Appl. Phys. Lett. 101, 251102 (2012); http://dx.doi.org/10.1063/1.4770503 (4 pages) Online Publication Date: 17 December 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We report the remarkable diffraction effects produced from circular patterned arrays of multiwalled carbon nanotubes (MWCNTs). Highly ordered circular arrays of multiwalled carbon nanotubes (with inter-nanotube spacings of 633 nm) display optical dispersion effects similar to compact discs. These arrays display remarkable diffraction patterns in the far field which are spatially continuous. High quality diffraction patterns were obtained experimentally which are in excellent agreement with the theoretical calculations. The achieved continuous diffraction patterns pave the way towards the utilization of engineered carbon nanotube arrays in applications like three dimensional holograms.
|
|||
|
Show PACS
|
|||
|
|
Taking whispering gallery-mode single virus detection and sizing to the limit Appl. Phys. Lett. 101, 043704 (2012); http://dx.doi.org/10.1063/1.4739473 (4 pages) Online Publication Date: 27 July 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We report the label-free detection and sizing by a microcavity of the smallest individual RNA virus, MS2, with a mass only ∼1% of InfluenzaA (6 vs. 512 ag). Although detection of such a small bio-nano-particle has been beyond the reach of a bare spherical microcavity, it was accomplished with ease (S/N = 8, Q = 4 × 105) using a single dipole stimulated plasmonic-nanoshell as a microcavity wavelength shift enhancer, providing an enhancement of ∼70×, in agreement with theory. Unique wavelength shift statistics are recorded consistent with an ultra-uniform genetically programmed substance that is drawn to the plasmonic hot spots by light-forces.
|
|||
|
Show PACS
|
|||
|
|
Enhanced charge detection of spin qubit readout via an intermediate state Appl. Phys. Lett. 101, 233101 (2012); http://dx.doi.org/10.1063/1.4749281 (3 pages) Online Publication Date: 3 December 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We employ an intermediate excited charge state of a lateral quantum dot device to increase the charge detection contrast during the qubit state readout procedure, allowing us to increase the visibility of coherent qubit oscillations. This approach amplifies the coherent oscillation magnitude but has no effect on the detector noise resulting in an increase in the signal to noise ratio. In this letter, we apply this scheme to demonstrate a significant enhancement of the fringe contrast of coherent Landau-Zener-Stückelberg oscillations between singlet S and triplet T+ two-spin states.
|
|||
|
Show PACS
|
|||
|
|
Appl. Phys. Lett. 101, 172109 (2012); http://dx.doi.org/10.1063/1.4764065 (3 pages) Online Publication Date: 23 October 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
The properties of thin-film silicon grown by plasma enhanced chemical vapor deposition were investigated with respect to the flux ratio of hydrogen radical to film precursor. The absolute density and translational temperature of H radicals in SiH4/H2 capacitively coupled plasma were measured using vacuum ultraviolet laser absorption spectroscopy. The flux of effective H radicals to the surface reactions was estimated from the results. The flux of effective film precursor for deposition was estimated from the deposition rate, so that the critical flux ratio of H radicals to film precursor to obtain suitable film properties was identified to be approximately 65–70.
|
|||
|
Show PACS
|
|||
|
|
Growth and ferromagnetic resonance properties of nanometer-thick yttrium iron garnet films Appl. Phys. Lett. 101, 152405 (2012); http://dx.doi.org/10.1063/1.4759039 (5 pages) Online Publication Date: 11 October 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Growth of nm-thick yttrium iron garnet films and ferromagnetic resonance (FMR) linewidth properties in the films are reported. The films were grown on gadolinium gallium garnet substrates by pulsed laser deposition (PLD). Films in the 5–35 nm thickness range showed a (111) orientation and a surface roughness between 0.1 and 0.3 nm. The 10 nm films showed a 10 GHz FMR linewidth of about 6 Oe and a damping constant of 3.2 × 10−4. The FMR linewidth increases with both the surface roughness and the surface Fe deficiency. Thicker films exhibit a smaller FMR linewidth and a lower damping constant.
|
|||
|
Show PACS
|
|||
|
|
Photophoretic trampoline—Interaction of single airborne absorbing droplets with light Appl. Phys. Lett. 101, 131115 (2012); http://dx.doi.org/10.1063/1.4755761 (4 pages) Online Publication Date: 28 September 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We present the light-induced manipulation of absorbing liquid droplets in air. Ink droplets from a printer cartridge are used to demonstrate that absorbing liquids—just like their solid counterparts—can interact with regions of high light intensity due to the photophoretic force. It is shown that droplets follow a quasi-ballistic trajectory after bouncing off a high intensity light sheet. We estimate the intensities necessary for this rebound of airborne droplets and change the droplet trajectories through a variation of the manipulating light field.
|
|||
|
Show PACS
|
|||
|
|
Organic electroluminescent diodes Appl. Phys. Lett. 51, 913 (1987); http://dx.doi.org/10.1063/1.98799 (3 pages)
Full Text:
|
Download PDF
|
||
|
Show Abstract
A novel electroluminescent device is constructed using organic materials as the emitting elements. The diode has a double‐layer structure of organic thin films, prepared by vapor deposition. Efficient injection of holes and electrons is provided from an indium‐tin‐oxide anode and an alloyed Mg:Ag cathode. Electron‐hole recombination and green electroluminescent emission are confined near the organic interface region. High external quantum efficiency (1% photon/electron), luminous efficiency (1.5 lm/W), and brightness (>1000 cd/m2) are achievable at a driving voltage below 10 V. |
|||
|
Show PACS
|
|||
|
|
Quantitative self-calibrating lock-in carrierographic lifetime imaging of silicon wafers Appl. Phys. Lett. 101, 242107 (2012); http://dx.doi.org/10.1063/1.4772207 (4 pages) Online Publication Date: 12 December 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Quantitative self-calibrating lock-in carrierography (LIC) imaging of crystalline silicon wafers is introduced using an InGaAs camera and a spread super-bandgap illumination laser beam. Images at several modulation frequencies and a simplified model based on photocarrier radiometric theory are used to construct the effective carrier lifetime image from the phase-frequency dependence. The phase image data at several frequencies and at selected locations on a wafer were compared to frequency scans obtained with a single-element InGaAs detector, and good agreement was found. The quantitative LIC lifetime imaging capability demonstrated in this work is self-calibrating and eliminates the requirement for calibration in conventional photoluminescence imaging.
|
|||
|
Show PACS
|
|||
|
|
A simplified GaN/AlGaN quantum cascade detector with an alloy extractor Appl. Phys. Lett. 101, 251101 (2012); http://dx.doi.org/10.1063/1.4772501 (4 pages) Online Publication Date: 17 December 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We have demonstrated a GaN/AlGaN quantum cascade detector based on a simplified design of the extractor region relying on an AlGaN thick layer. The device grown by molecular beam epitaxy exhibits both TM-polarized intersubband absorption and photocurrent at room temperature at a peak wavelength of 1.87 μm. Based on the measured absorption and responsivity, we estimate the transfer efficiency of photoelectrons to the next period to be around 62%. This simplified design is robust against thickness fluctuations in the extractor region and offers prospects for ultrafast detectors.
|
|||
|
Show PACS
|
|||
|
|
Vacuum nanoelectronics: Back to the future?—Gate insulated nanoscale vacuum channel transistor Appl. Phys. Lett. 100, 213505 (2012); http://dx.doi.org/10.1063/1.4717751 (4 pages) Online Publication Date: 23 May 2012
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
A gate-insulated vacuum channel transistor was fabricated using standard silicon semiconductor processing. Advantages of the vacuum tube and transistor are combined here by nanofabrication. A photoresist ashing technique enabled the nanogap separation of the emitter and the collector, thus allowing operation at less than 10 V. A cut-off frequency fT of 0.46 THz has been obtained. The nanoscale vacuum tubes can provide high frequency/power output while satisfying the metrics of lightness, cost, lifetime, and stability at harsh conditions, and the operation voltage can be decreased comparable to the modern semiconductor devices.
|
|||
|
Show PACS
|
|||
This Publication
Scitation
Google Scholar
PubMed