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 Apr 2012

Volume 100, Issue 16, Articles (16xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 100, 164101 (2012); http://dx.doi.org/10.1063/1.3702579 (4 pages)

Cheol-Ho Yun, Leslie Y. Yeo, James R. Friend, and Bernard Yan
Enlarge Image | Read More
Page 1 of 4 Pages Next Page | Jump to Page
back to top
RSS Feeds

Effect of quantum well cap layer thickness on the microstructure and performance of InGaN/GaN solar cells

Yan-Ling Hu, Robert M. Farrell, Carl J. Neufeld, Michael Iza, Samantha C. Cruz, Nathan Pfaff, Dobri Simeonov, Stacia Keller, Shuji Nakamura, Steven P. DenBaars, Umesh K. Mishra, and James S. Speck

Appl. Phys. Lett. 100, 161101 (2012); http://dx.doi.org/10.1063/1.4704189 (4 pages) | Cited 2 times

Online Publication Date: 16 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A two-step GaN barrier growth methodology was developed for InxGa1−xN/GaN multiple quantum well solar cells in which a lower temperature GaN cap layer was grown on top of the quantum wells (QWs) and then followed by a higher temperature GaN barrier layer. The performance of the solar cells improved markedly by increasing the low temperature GaN cap layer thickness from 1.5 to 3.0 nm. High-angle annular dark field scanning transmission electron microscopy and atom probe tomography measurements showed that increasing the GaN cap layer thickness improved the uniformity and increased the average indium content of the QWs.
Show PACS
88.40.hj Efficiency and performance of solar cells
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Mid-wave infrared HgCdTe nBn photodetector

Anne M. Itsuno, Jamie D. Phillips, and Silviu Velicu

Appl. Phys. Lett. 100, 161102 (2012); http://dx.doi.org/10.1063/1.4704359 (3 pages)

Online Publication Date: 17 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A unipolar, barrier-integrated HgCdTe nBn photodetector with all n-type doping and a type-I band lineup is experimentally demonstrated. Planar mid-wave infrared (MWIR) nBn devices exhibit current-voltage (I-V) characteristics that are consistent with band inversion in reverse bias, indicating a barrier-influenced behavior. Dark current saturation is observed beyond a reverse bias of approximately −0.8 V. Bias-dependent photoresponse is observed in the mid-wave infrared with a cut-off wavelength around 5.7 μm. Numerical modeling based on experimental results predicts an internal peak quantum efficiency of approximately 66%.
Show PACS
85.60.Gz Photodetectors (including infrared and CCD detectors)
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors

Control of absorption with hyperbolic metamaterials

T. U. Tumkur, Lei Gu, J. K. Kitur, E. E. Narimanov, and M. A. Noginov

Appl. Phys. Lett. 100, 161103 (2012); http://dx.doi.org/10.1063/1.4703931 (3 pages) | Cited 3 times

Online Publication Date: 17 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We show that absorption of thin dye-doped polymeric films can be tuned and enhanced (nearly threefold) by metallic and lamellar metal-dielectric hyperbolic metamaterial substrates. The effect can be controlled by a combination of the substrate’s geometry and composition. As the enhancement of absorption is sustained over large range of incidence angles, the demonstrated phenomenon can lead to a variety of important applications, including solar cell technology.
Show PACS
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
68.35.bm Polymers, organics
77.22.Ch Permittivity (dielectric function)
68.55.A- Nucleation and growth
78.66.Qn Polymers; organic compounds
42.70.Jk Polymers and organics

Strong coupling in monolithic microcavities with ZnSe quantum wells

K. Sebald, M. Seyfried, S. Klembt, S. Bley, A. Rosenauer, D. Hommel, and C. Kruse

Appl. Phys. Lett. 100, 161104 (2012); http://dx.doi.org/10.1063/1.4704188 (4 pages) | Cited 2 times

Online Publication Date: 18 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Strong light-matter coupling is demonstrated in monolithic microcavities with only three ZnSe quantum wells embedded. Basis for this observation is the excellent structural quality of the sample as confirmed by scanning transmission electron microscopy measurements. A comparative large energy splitting between the upper and lower polariton (LP) of about 19 meV is observed by reflectivity measurements in real and k-space. Efficient polariton relaxation is shown by photoluminescence measurements at low temperatures in k-space. These beneficial properties of the sample result in a nonlinear increase of the lower polariton population in excitation density dependent measurements before the photonic cavity emission becomes dominant.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.55.Sa Microcavity and microdisk lasers

Spectroscopic ellipsometry of split ring resonators at infrared frequencies

M. M. Jakovljević, G. Isić, B. Vasić, T. W. H. Oates, K. Hinrichs, I. Bergmair, K. Hingerl, and R. Gajić

Appl. Phys. Lett. 100, 161105 (2012); http://dx.doi.org/10.1063/1.4703936 (4 pages) | Cited 1 time

Online Publication Date: 18 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using spectroscopic ellipsometry, we have determined the plasmonic resonances of split-ring resonator arrays. The features in the ellipsometric spectra were explained by the analysis of calculated polarized complex reflection spectra. The calculated near-field and current distribution revealed the nature of the resonances. The positions of Rayleigh’s anomalies are calculated and marked in the spectra. We have also shown that oblique incidence enables excitation of plasmonic modes that are not possible to excite at normal incidence.
Show PACS
42.79.-e Optical elements, devices, and systems
42.87.-d Optical testing techniques

Analytic model for the efficiency droop in semiconductors with asymmetric carrier-transport properties based on drift-induced reduction of injection efficiency

Guan-Bo Lin, David Meyaard, Jaehee Cho, E. Fred Schubert, Hyunwook Shim, and Cheolsoo Sone

Appl. Phys. Lett. 100, 161106 (2012); http://dx.doi.org/10.1063/1.4704366 (4 pages) | Cited 8 times

Online Publication Date: 19 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An analytic model is developed for the droop in the efficiency-versus-current curve for light-emitting diodes (LEDs) made from semiconductors having strong asymmetry in carrier concentration and mobility. For pn-junction diodes made of such semiconductors, the high-injection condition is generalized to include mobilities. Under high-injection conditions, electron drift in the p-type layer causes a reduction in injection efficiency. The drift-induced leakage term is shown to have a 3rd and 4th power dependence on the carrier concentration in the active region; the values of the 3rd- and 4th-order coefficients are derived. The model is suited to explain experimental efficiency-versus-current curves of LEDs.
Show PACS
85.60.Jb Light-emitting devices
85.30.Kk Junction diodes

384 nm laser diode grown on a (20math1) semipolar relaxed AlGaN buffer layer

Daniel A. Haeger, Erin C. Young, Roy B. Chung, Feng Wu, Nathan A. Pfaff, Min Tsai, Kenji Fujito, Steven P. DenBaars, James S. Speck, Shuji Nakamura, and Daniel A. Cohen

Appl. Phys. Lett. 100, 161107 (2012); http://dx.doi.org/10.1063/1.4704560 (4 pages) | Cited 3 times

Online Publication Date: 19 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate an electrically injected semipolar (20math1) laser diode grown on a partially relaxed AlGaN buffer layer. The coherency stresses are relaxed by misfit dislocations at the GaN/AlGaN heterointerface which form by glide of preexisting threading dislocations along the (0001) basal plane. The defects are confined to the heterointerface which allows the growth of high aluminum composition films with threading dislocation densities of less than 108 cm−2. The lasing wavelength was 384 nm with a threshold current density of 15.7 kA/cm−2. UV lasers grown on semipolar relaxed AlGaN buffers provide an alternative to devices grown on AlN or sapphire.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.82.Cr Fabrication techniques; lithography, pattern transfer
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.40.Jj Elasticity and anelasticity, stress-strain relations

Switchable hyperbolic metamaterials with magnetic control

Wei Li, Zheng Liu, Xiaogang Zhang, and Xunya Jiang

Appl. Phys. Lett. 100, 161108 (2012); http://dx.doi.org/10.1063/1.4705084 (4 pages) | Cited 2 times

Online Publication Date: 19 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A switchable hyperbolic material (SHM) is investigated, with which one can turn on or off the hyperbolic dispersion of the material via magnetic control. The SHM has simple structure, with a one-dimensional periodic stacking of dielectric layer and gyromagnetic layer. The hyperbolic dispersion of SHM is due to the negative effective permeability of gyromagnetic layers, and it can be transformed into a regular circular dispersion when the d.c. magnetic field is switched off. This switchable dispersion transition is reversible, which may have great potential applications in many fields.
Show PACS
42.70.-a Optical materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Passive harmonic mode-locking in Er-doped fiber laser based on graphene saturable absorber with repetition rates scalable to 2.22 GHz

Grzegorz Sobon, Jaroslaw Sotor, and Krzysztof M. Abramski

Appl. Phys. Lett. 100, 161109 (2012); http://dx.doi.org/10.1063/1.4704913 (4 pages) | Cited 4 times

Online Publication Date: 20 April 2012

Full Text: Read Online (HTML) | Download PDF

multimedia

Show Abstract
Passive harmonic-mode locking of erbium-doped fiber laser with atomic multilayer graphene is presented. The laser could operate at several harmonics (from 2nd to 21st) of the fundamental repetition frequency of the ring resonator (106 MHz). The highest achieved repetition rate was 2.22 GHz (which corresponds to the 21st harmonic) with sub-picosecond pulse durations and over 40 dB of the supermode noise suppression. The saturable absorber was formed by multilayer graphene, mechanically exfoliated from pure graphite block through Scotch-tape and deposited on the fiber ferrule.
Show PACS
42.60.Fc Modulation, tuning, and mode locking
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.55.Wd Fiber lasers

Terahertz phase microscopy in the sub-wavelength regime

Minwoo Yi, Kanghee Lee, Jin-Dong Song, and Jaewook Ahn

Appl. Phys. Lett. 100, 161110 (2012); http://dx.doi.org/10.1063/1.4705294 (3 pages) | Cited 2 times

Online Publication Date: 20 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Gouy phase shift is a well-known behavior that occurs when a propagating light is focused, but its behavior in the sub-wavelength confinement is not yet known. Here, we report the theoretical and experimental study of the aperture-size dependency of the Gouy phase shift in the sub-wavelength diffraction regime. In experiments carried out with laser-induced terahertz (THz) wave emission from various semiconductor apertures, we demonstrate the use of Guoy phase shit for sub-wavelength THz microscopy.
Show PACS
81.05.Ea III-V semiconductors
78.70.Gq Microwave and radio-frequency interactions
back to top
RSS Feeds

Seebeck coefficient of a quantum confined, high-electron-density electron gas in SrTiO3

Tyler A. Cain, SungBin Lee, Pouya Moetakef, Leon Balents, Susanne Stemmer, and S. James Allen

Appl. Phys. Lett. 100, 161601 (2012); http://dx.doi.org/10.1063/1.4704363 (3 pages) | Cited 3 times

Online Publication Date: 16 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the Seebeck coefficient of quantum confined electron gases in GdTiO3/SrTiO3 heterostructures. These structures contain two-dimensional electron gases with very high sheet-carrier concentrations on the SrTiO3-side of the interface due to intrinsic interface doping. While the sheet carrier concentrations are independent of the thickness of the SrTiO3 layer, the Seebeck coefficient initially increases with SrTiO3 thickness before saturating at a value of ∼300 μK/V. A model of the Seebeck coefficient, based on thermally populated, self-consistent, tight binding subbands, captures in a semi-quantitative manner the observed thickness dependence.
Show PACS
72.20.Pa Thermoelectric and thermomagnetic effects
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Magnetoexcitons and optical absorption of bilayer-structured topological insulators

Zhigang Wang, Zhen-Guo Fu, and Ping Zhang

Appl. Phys. Lett. 100, 161602 (2012); http://dx.doi.org/10.1063/1.4704657 (4 pages) | Cited 1 time

Online Publication Date: 17 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The optical absorption properties of magnetoexcitons in topological insulator bilayers under a strong magnetic field are theoretically studied. A general analytical formula of optical absorption selection rule is obtained in the noninteracting as well as Coulomb intra-Landau-level (LL) interacting cases, which remarkably helps to interpret the resonant peaks in absorption spectroscopy and the corresponding formation of Dirac-type magnetoexcitons. We also discuss the optical absorption spectroscopy of magnetoexcitons in the presence of inter-Landau-level Coulomb interaction, which becomes more complex. We hope our results can be detected in the future magneto-optical experiments.
Show PACS
71.35.-y Excitons and related phenomena
73.20.At Surface states, band structure, electron density of states

Substrate effect on the electronic structures of CuPc/graphene interfaces

Qi-Hui Wu, Guo Hong, T. W. Ng, and S. T. Lee

Appl. Phys. Lett. 100, 161603 (2012); http://dx.doi.org/10.1063/1.3703766 (4 pages) | Cited 5 times

Online Publication Date: 18 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The interfacial electronic structures of copper phthalocyanine (CuPc) deposited on a single-layer graphene (SLG) film prepared on Cu and SiO2 substrates (SLG/Cu and SLG/SiO2) were investigated using ultraviolet photoelectron spectroscopy. The ionization energy of CuPc on SLG/Cu and SLG/SiO2 substrate is, respectively, 5.62 eV and 4.97 eV. The energy level alignments at the two interfaces were estimated. The results revealed that the height of the electron (hole) injection barriers are 1.20 (1.10) and 1.38 (0.92) eV at CuPc/SLG/Cu and CuPc/SLG/SiO2 interfaces, respectively.
Show PACS
73.20.At Surface states, band structure, electron density of states
68.35.Ct Interface structure and roughness
79.60.Jv Interfaces; heterostructures; nanostructures
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
71.20.-b Electron density of states and band structure of crystalline solids
back to top
RSS Feeds

Quadratic electro-optic effect in GaN-based materials

P. Chen, D. G. Zhao, Y. H. Zuo, D. S. Jiang, Z. S. Liu, and Q. M. Wang

Appl. Phys. Lett. 100, 161901 (2012); http://dx.doi.org/10.1063/1.3703759 (4 pages)

Online Publication Date: 16 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The mechanism and influence of quadratic electro-optic effect in GaN-based materials is investigated. It is found that the peaks appearing in the measured electro-optic signal strongly depend on the modulation frequency of external electric field, which is attributed to the vibration frequency resonance effect. The intrinsic vibration frequency of the investigated samples is estimated to be around 21.95 kHz and is assigned to be the base frequency of the resonance.
Show PACS
78.20.Jq Electro-optical effects
63.20.D- Phonon states and bands, normal modes, and phonon dispersion

Strong second-harmonic generation in silicon nitride films

Tingyin Ning, Henna Pietarinen, Outi Hyvärinen, Janne Simonen, Goëry Genty, and Martti Kauranen

Appl. Phys. Lett. 100, 161902 (2012); http://dx.doi.org/10.1063/1.4704159 (4 pages) | Cited 7 times

Online Publication Date: 17 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We observe strong second-harmonic generation from silicon nitride films prepared on fused silica substrates by plasma enhanced chemical vapor deposition. The components of the second-order nonlinear optical susceptibility tensor of the films are calibrated against quartz crystal. The dominant component has the magnitude of 2.5 pm/V, almost two orders of magnitude larger than reported for Si3N4, and about three times larger than for the traditional nonlinear crystal of potassium dihydrogen phosphate. The results indicate that silicon nitride has great potential for second-order nonlinear optical devices, especially in on-chip nanophotonics.
Show PACS
78.66.Nk Insulators
68.55.aj Insulators
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Opto-electric particle manipulation on a bismuth silicon oxide crystal

Michael Esseling, Stefan Glasener, Federico Volonteri, and Cornelia Denz

Appl. Phys. Lett. 100, 161903 (2012); http://dx.doi.org/10.1063/1.4704361 (4 pages) | Cited 3 times

Online Publication Date: 17 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High-throughput manipulation of microparticles can be efficiently accomplished using electrokinetic effects. In this contribution, we demonstrate the two-dimensional investigation of internal space-charge fields inside a bismuth silicon oxide (BSO) crystal and their use for optically mediated particle trapping. The magnitude of the internal fields as well as the time constant for its build-up are measured by Zernike phase contrast and digital holography. The fast response time of a BSO crystal at very low light powers enables real-time generation of high electric field gradients. We demonstrate that this photoconductive material facilitates both electrophoretic and dielectrophoretic trapping of particles on an accessible surface.
Show PACS
78.20.Jq Electro-optical effects
77.22.Jp Dielectric breakdown and space-charge effects
82.45.-h Electrochemistry and electrophoresis
78.56.-a Photoconduction and photovoltaic effects
72.40.+w Photoconduction and photovoltaic effects

Diffraction resonance with strong optical-field enhancement from gain-assisted hybrid plasmonic structure

Haixi Zhang, Haifei Lu, Ho-Pui Ho, Yanyan Zhou, Xia Yu, and Feng Luan

Appl. Phys. Lett. 100, 161904 (2012); http://dx.doi.org/10.1063/1.4704360 (4 pages)

Online Publication Date: 18 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We propose and analyze the diffraction coupling of localized plasmon resonances (LPRs) through gain-assisted propagation surface plasmons (PSPs). The coupling process involves localization of incident light by LPR and LPR-PSP interaction. We demonstrate a significantly strong enhancement of electromagnetic power for LPRs in the event of diffraction resonance through incorporation of experimentally feasible optical gain to the PSP. Based on such phenomenon, we propose a hybrid plasmonic structure, which would potentially give rise to device realization of the nano-lasers. In addition, it is also a promising platform for applications such as surface enhanced Raman scattering, nonlinear optics, plasmonic trapping, etc.
Show PACS
73.22.Lp Collective excitations

Phase and thickness dependent modulus of Ge2Sb2Te5 films down to 25 nm thickness

Yoonjin Won, Jaeho Lee, Mehdi Asheghi, Thomas W. Kenny, and Kenneth E. Goodson

Appl. Phys. Lett. 100, 161905 (2012); http://dx.doi.org/10.1063/1.3699227 (4 pages) | Cited 2 times

Online Publication Date: 18 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The mechanical properties of phase-change materials including Ge2Sb2Te5 (GST) are strongly influenced by the complex interaction of phase and imperfection distributions, especially at film thicknesses relevant for phase-change memory devices. This work uses a micromechanical resonator as a substrate to study the phase dependent modulus of GST films with thicknesses from 25 nm to 350 nm. The moduli of amorphous GST and crystalline GST films increase with decreasing thickness to 10 GPa and up to 60 GPa, respectively. The phase purity is studied using X-ray diffraction and energy dissipation data, which provide qualitative information about inelastic absorption.
Show PACS
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.de Elastic moduli
68.55.jd Thickness
61.43.Er Other amorphous solids

Origin of preferential grain orientation in excimer laser-induced crystallization of silicon thin films

M. Weizman, C. Klimm, N. H. Nickel, and B. Rech

Appl. Phys. Lett. 100, 161906 (2012); http://dx.doi.org/10.1063/1.4704559 (3 pages) | Cited 1 time

Online Publication Date: 19 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The origin of the formation of {100} and {111} grain textures in polycrystalline silicon thin films prepared with multiple excimer laser shots at the super-lateral-growth crystallization regime is investigated in this study. Our results demonstrate that the type of texture formed is determined solely by the thickness of the silicon layer. At a critical value of 40 nm, a transition from {100} to {111} texture is observed with increasing layer thickness. It is therefore proposed that below this critical value, the texture formation is governed by surface energy anisotropy whereas above it, the kinetics of the solidification process predominate.
Show PACS
61.72.-y Defects and impurities in crystals; microstructure
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.Fk Semiconductors
68.35.Md Surface thermodynamics, surface energies
64.70.dg Crystallization of specific substances
68.55.jm Texture

Resistive switching phenomenon driven by antiferromagnetic phase separation in an antiperovskite nitride Mn3ZnN

Y. S. Sun, Y. F. Guo, X. X. Wang, Y. Tsujimoto, Y. Matsushita, Y. G. Shi, C. Wang, A. A. Belik, and K. Yamaura

Appl. Phys. Lett. 100, 161907 (2012); http://dx.doi.org/10.1063/1.4704664 (4 pages) | Cited 4 times

Online Publication Date: 19 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A resistive-switching phenomenon driven by antiferromagnetic phase separation is observed for a manganese nitride Mn3ZnN, which crystallizes in the antiperovskite structure. Measurements of the lattice parameters, magnetic susceptibility, electrical resistivity, and specific heat from 2 K to 300 K reveal antiferromagnetic phase separation that appears below a temperature of approximately 190 K. The mechanism of the phase separation is highly complicated; nevertheless the accompanying resistive-switching phenomenon is useful for non-volatile memory applications.
Show PACS
72.60.+g Mixed conductivity and conductivity transitions
75.30.Cr Saturation moments and magnetic susceptibilities
75.40.Cx Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)
75.50.Ee Antiferromagnetics
61.66.Fn Inorganic compounds
65.40.Ba Heat capacity
FREE

Photo-origami—Bending and folding polymers with light

Jennie Ryu, Matteo D’Amato, Xiaodong Cui, Kevin N. Long, H. Jerry Qi, and Martin L. Dunn

Appl. Phys. Lett. 100, 161908 (2012); http://dx.doi.org/10.1063/1.3700719 (5 pages) | Cited 10 times

Online Publication Date: 20 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Photo-origami uses the dynamic control of the molecular architecture of a polymer by a combination of mechanical and non-contact optical stimuli to design and program spatially and temporally variable mechanical and optical fields into a material. The fields are essentially actuators, embedded in the material at molecular resolution, designed to enable controllable, sequenced, macroscopic bending and folding to create three-dimensional material structures. Here, we demonstrate, through a combination of theory, simulation-based design, synthesis, and experiment, the operative phenomena and capabilities of photo-origami that highlight its potential as a powerful, and potentially manufacturable, approach to create three-dimensional material structures.
Show PACS
81.40.Lm Deformation, plasticity, and creep
61.41.+e Polymers, elastomers, and plastics
62.20.fg Shape-memory effect; yield stress; superelasticity
back to top
RSS Feeds

Metal–semiconductor transition in ultrathin cobalt-phthalocyanine films grown on SrTiO3 single crystal substrates

S. Samanta, Arvind Kumar, A. Singh, A. K. Debnath, P. Veerender, S. Basu, R. Prasad, D. K. Aswal, and S. K. Gupta

Appl. Phys. Lett. 100, 162101 (2012); http://dx.doi.org/10.1063/1.4704141 (4 pages)

Online Publication Date: 17 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the low temperature charge transport properties of ultrathin cobalt-phthalocyanine films grown on (100) SrTiO3 single crystal substrates. The temperature dependence of resistivity shows an anomalous behavior, i.e., a transition from semiconducting to metallic behavior at around 110 K. We demonstrated that metallic behavior in these films is triggered by compressive strains of the SrTiO3 substrate due to its cubic to tetragonal structural phase transition at 110 K.
Show PACS
71.30.+h Metal-insulator transitions and other electronic transitions
72.60.+g Mixed conductivity and conductivity transitions
81.30.-t Phase diagrams and microstructures developed by solidification and solid-solid phase transformations

Two-dimensional electron gas mobility limited by barrier and quantum well thickness fluctuations scattering in AlxGa1−xN/GaN multi-quantum wells

Guipeng Liu, Ju Wu, Yanwu Lu, Guijuan Zhao, Chengyan Gu, Changbo Liu, Ling Sang, Shaoyan Yang, Xianglin Liu, Qinsheng Zhu, and Zhanguo Wang

Appl. Phys. Lett. 100, 162102 (2012); http://dx.doi.org/10.1063/1.4704142 (4 pages) | Cited 1 time

Online Publication Date: 17 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We calculate the electron mobility limited by the AlxGa1−xN barrier and the GaN well thickness fluctuations scattering of the two-dimensional electron gas (2DEG) at AlxGa1−xN/GaN multi-quantum wells (MQWs) with a triangle potential well. For this potential well, the ground subband energy is governed by the spontaneous and piezoelectric polarization fields and the fields are determined by the barrier and well thicknesses in undoped AlxGa1−xN/GaN MQWs. Thus, the thickness fluctuations of AlxGa1−xN barrier and GaN well will cause a local fluctuation of the ground subband energy, which will reduce the 2DEG mobility.
Show PACS
73.63.Hs Quantum wells
73.21.Fg Quantum wells
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.20.Fr Low-field transport and mobility; piezoresistance
77.22.Ej Polarization and depolarization

Red-green luminescence in indium gallium nitride alloys investigated by high pressure optical spectroscopy

Marius Millot, Zachary M. Geballe, Kin M. Yu, Wladek Walukiewicz, and Raymond Jeanloz

Appl. Phys. Lett. 100, 162103 (2012); http://dx.doi.org/10.1063/1.4704367 (4 pages) | Cited 2 times

Online Publication Date: 17 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We performed optical absorption and photoluminescence experiments under high pressure up to 10 GPa on two good quality InGaN epilayers with ∼ 40% indium. The pressure coefficient of about 30 meV/GPa for the absorption edge is close to the bandgap pressure coefficients of InN and GaN, indicating similar pressure dependence of the fundamental band gap in the whole composition range. In contrast, the pressure coefficient of the photoluminescence peak energy shows much weaker pressure dependence which we attribute to an increasing role of highly localized defects when the conduction band approaches the Fermi level stabilization energy at higher indium contents.
Show PACS
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
62.50.-p High-pressure effects in solids and liquids
71.20.Nr Semiconductor compounds
61.72.J- Point defects and defect clusters

Unusual photoresponse of indium doped ZnO/organic thin film heterojunction

Sesha Vempati, Saraswathi Chirakkara, J. Mitra, Paul Dawson, Karuna Kar Nanda, and S. B. Krupanidhi

Appl. Phys. Lett. 100, 162104 (2012); http://dx.doi.org/10.1063/1.4704655 (4 pages) | Cited 3 times

Online Publication Date: 17 April 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Photoresponse of n-type indium-doped ZnO and a p-type polymer (PEDOT:PSS) heterojunction devices are studied, juxtaposed with the photoluminescence of the In-ZnO samples. In addition to the expected photoresponse in the ultraviolet, the heterojunctions exhibit significant photoresponse to the visible (532 nm). However, neither the doped ZnO nor PEDOT:PSS individually show any photoresponse to visible light. The sub-bandgap photoresponse of the heterojunction originates from visible photon mediated e-h generation between the In-ZnO valence band and localized states lying within the band gap. Though increased doping of In-ZnO has limited effect on the photoluminescence, it significantly diminishes the photoresponse. The study indicates that optimally doped devices are promising for the detection of wavelengths in selected windows in the visible.
Show PACS
85.60.Gz Photodetectors (including infrared and CCD detectors)
Page 1 of 4 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close