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12 May 2008

Volume 92, Issue 19, Articles (19xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 92, 193301 (2008); http://dx.doi.org/10.1063/1.2920199 (3 pages)

Wei Chen, Hong Liang Zhang, Han Huang, Lan Chen, and Andrew Thye Shen Wee
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Construction of an optical wire imprinted in potassium lithium tantalate niobate by He+ implantation

Har’el Ilan, Alexander Gumennik, Galina Perepelitsa, Abraham Israel, and Aharon J. Agranat

Appl. Phys. Lett. 92, 191101 (2008); http://dx.doi.org/10.1063/1.2927483 (3 pages) | Cited 11 times

Online Publication Date: 12 May 2008

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A channel waveguide constructed in potassium lithium tantalate niobate (KLTN) substrate by the implantation of He+ ions at 1.65 MeV is presented. The waveguide has a trapezoidal profile with a crystalline KLTN core surrounded by amorphized KLTN created by the implantation. The implantation was done through a 2 μm thick gold stopping mask with a trapezoidal groove. During the implantation, the contour of the groove was replicated beneath the surface of the substrate forming the trapezoidal cladding of the channel waveguide. The channel waveguide is designed as the interconnecting element in electro-optical integrated circuits.
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42.79.Gn Optical waveguides and couplers

Wide-view and single cell gap transflective liquid crystal display using slit-induced multidomain structures

Ruibo Lu, Zhibing Ge, and Shin-Tson Wu

Appl. Phys. Lett. 92, 191102 (2008); http://dx.doi.org/10.1063/1.2926669 (3 pages) | Cited 10 times

Online Publication Date: 13 May 2008

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A wide-view transflective liquid crystal display (TR-LCD) using a single cell gap multidomain vertical alignment (MVA) cell is proposed. Unlike a conventional MVA which uses physical protrusions to form multidomain structures, our TR-LCD uses slit-induced longitudinal and fringe electric fields to generate multidomains. As a result, wide-view, high contrast ratio, and high transmittance are obtained. By varying the slit density in the transmissive and reflective regions, the optical path-length disparity between these regions can be balanced. Potential application of this TR-LCD for mobile displays is emphasized.
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42.79.Kr Display devices, liquid-crystal devices

Carrier relaxation dynamics in InAs/InP quantum dots

P. Miska, J. Even, O. Dehaese, and X. Marie

Appl. Phys. Lett. 92, 191103 (2008); http://dx.doi.org/10.1063/1.2909536 (3 pages) | Cited 5 times

Online Publication Date: 13 May 2008

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The electronic properties of InAs/InP(113)B double-cap quantum dots (QDs) emitting around 1.55 μm are investigated. The carrier dynamics in QDs is studied by nonresonant time-resolved photoluminescence experiments. This analysis reveals the electronic structure of the QDs and the transient filling of the confined levels. Under low excitation densities, the spontaneous exciton lifetime is estimated and compared to time-resolved experiments. Under high excitation density, a direct Auger recombination effect is identified. The temperature analysis enables us to distinguish Auger and phonon-assisted relaxation processes.
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73.61.Ey III-V semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
79.20.Fv Electron impact: Auger emission

Spectral tuning of liquid microdroplets standing on a superhydrophobic surface using electrowetting

A. Kiraz, Y. Karadağ, and A. F. Coskun

Appl. Phys. Lett. 92, 191104 (2008); http://dx.doi.org/10.1063/1.2927373 (3 pages) | Cited 11 times

Online Publication Date: 13 May 2008

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Using electrowetting, we demonstrate reversible spectral tuning of the whispering gallery modes of glycerol/water microdroplets standing on a superhydrophobic surface by up to 4.7 nm at 400 V. Our results can inspire electrically tunable optical switches and filters based on microdroplets on a superhydrophobic surface. The sensitivity of the observed spectral drift to the contact angle can also be used to measure the contact angles of microdroplets on a superhydrophobic surface.
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42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
42.79.Ci Filters, zone plates, and polarizers
68.08.Bc Wetting
68.03.Cd Surface tension and related phenomena
42.70.-a Optical materials

Tuning the polarization state of enhanced transmission in gratings

David Crouse, Alastair P. Hibbins, and Matthew J. Lockyear

Appl. Phys. Lett. 92, 191105 (2008); http://dx.doi.org/10.1063/1.2924317 (3 pages) | Cited 9 times

Online Publication Date: 14 May 2008

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The polarization characteristics of enhanced transmission of lamellar gratings with structural dimensions on the subwavelength scale were studied and experimental results were compared to numerical models. The ability to tune the polarization state of the transmitted beam by varying the grating’s structural parameters is discussed. Gratings were fabricated and tested in the microwave spectral region, and the results were compared to theoretically modeled results. Enhanced transmission produced by cavity modes was experimentally verified for both s-polarized and p-polarized incident beams of light. Applications of these results to photonic devices in the visible, infrared, and microwave spectral regions are discussed.
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42.79.Dj Gratings
42.25.Ja Polarization
42.25.Gy Edge and boundary effects; reflection and refraction
84.40.-x Radiowave and microwave (including millimeter wave) technology

Understanding of transmission in the range of high-order photonic bands in thin opal film

S. G. Romanov, M. Bardosova, I. M. Povey, M. E. Pemble, and C. M. Sotomayor Torres

Appl. Phys. Lett. 92, 191106 (2008); http://dx.doi.org/10.1063/1.2920443 (3 pages) | Cited 8 times

Online Publication Date: 14 May 2008

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Diffraction in the face centered cubic lattice cannot explain some minima observed in the transmission spectra of self-assembled opal films. Here, we compared them with minima observed in the transmission spectra of a hexagonal close packed monolayer of spheres of the same diameter. The identity of the sphere packing on the surface of the opal film and in the sphere monolayer was demonstrated by the light diffraction at the sample surfaces. It was shown that excitation of surface propagating modes in the opal film is responsible for the formation of additional minima in opal film transmission.
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68.47.Pe Langmuir-Blodgett films on solids; polymers on surfaces; biological molecules on surfaces
68.55.A- Nucleation and growth
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.66.-w Optical properties of specific thin films
82.70.Dd Colloids

Carrier multiplication in a PbSe nanocrystal and P3HT/PCBM tandem cell

Sung Jin Kim, Won Jin Kim, Alexander N. Cartwright, and Paras N. Prasad

Appl. Phys. Lett. 92, 191107 (2008); http://dx.doi.org/10.1063/1.2920477 (3 pages) | Cited 12 times

Online Publication Date: 14 May 2008

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Photoactivation of multiple carrier charge extraction in a tandem cell configuration is demonstrated. An all-solution-processed tandem photovoltaic structure, consisting of a hydrazine treated PbSe nanocrystal film and a P3HT/PCBM bulk-heterojunction solar cell, was fabricated. The PbSe nanocrystal film was used as the top cell to predominantly absorb short wavelength light (UV/blue). The lower P3HT/PCBM cell absorbed the remaining solar energy and supplied photocurrent as well as an electric field that extracts the photogenerated charge from the PbSe layer. Carrier multiplication from excitation of the PbSe film with high energy photons was quantified by selective light bias activation measurements.
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84.60.Jt Photoelectric conversion
73.50.Pz Photoconduction and photovoltaic effects
73.61.Le Other inorganic semiconductors
85.35.-p Nanoelectronic devices

Collisionless phenomena in heteronuclear clusters

J. Jha and M. Krishnamurthy

Appl. Phys. Lett. 92, 191108 (2008); http://dx.doi.org/10.1063/1.2929378 (3 pages)

Online Publication Date: 15 May 2008

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Argon K-shell x-ray yields and electron fluxes are measured for water doped Ar clusters as a function of laser pulse width. The high energy electron and x-ray yields are significantly enhanced in doped clusters. We show that doping of the clusters can be used to enhance collisionless absorption.
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61.46.Bc Structure of clusters (e.g., metcars; not fragments of crystals; free or loosely aggregated or loosely attached to a substrate)
78.70.En X-ray emission spectra and fluorescence

Temperature insensitive linewidth enhancement factor of p-type doped InAs/GaAs quantum-dot lasers emitting at 1.3 μm

D.-Y. Cong, A. Martinez, K. Merghem, A. Ramdane, J.-G. Provost, M. Fischer, I. Krestnikov, and A. Kovsh

Appl. Phys. Lett. 92, 191109 (2008); http://dx.doi.org/10.1063/1.2929384 (3 pages) | Cited 4 times

Online Publication Date: 15 May 2008

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The temperature dependence of microwave properties—relaxation frequency and Henry factor—of undoped and p-type doped ten InAs/GaAs quantum-dot layer lasers is reported in the 20–80 °C range. It is shown that the linewidth enhancement factor of the p-type doped devices is temperature insensitive while that of the undoped lasers shows a strong dependence for temperatures above 40 °C.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Interband cascade laser emitting at λ = 3.75 μm in continuous wave above room temperature

M. Kim, C. L. Canedy, W. W. Bewley, C. S. Kim, J. R. Lindle, J. Abell, I. Vurgaftman, and J. R. Meyer

Appl. Phys. Lett. 92, 191110 (2008); http://dx.doi.org/10.1063/1.2930685 (3 pages) | Cited 16 times

Online Publication Date: 15 May 2008

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We report a five-stage interband cascade laser that operates at λ = 3.75 μm in cw mode up to a maximum temperature of 319 K. With gold electroplating, epitaxial-side-up mounting, and one facet coated for high reflectivity, a 3 mm×9.2 μm ridge emits over 10 mW of cw power at 300 K.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Spectral dependence of the excited-state absorption of erbium in silica fiber within the 1.48–1.59 μm range

A. D. Guzman-Chavez, Yu. O. Barmenkov, and A. V. Kir’yanov

Appl. Phys. Lett. 92, 191111 (2008); http://dx.doi.org/10.1063/1.2926671 (3 pages) | Cited 8 times

Online Publication Date: 15 May 2008

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We report the study of the excited-state absorption (ESA) spectrum of Er3+ in erbium-doped silica fiber (EF) within the telecom band, 1.48–1.59 μm. Two experimental techniques, the detection of up-conversion emission following the ESA process and the measurement of the EF nonlinear transmission coefficient, both supplied with a theoretical background, allow obtaining a mutually consistent spectral behavior of the ESA parameter, which is the ratio of ESA to ground-state absorption cross section, at 1.48–1.59 μm excitation.
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78.30.Hv Other nonmetallic inorganics
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

A tunable all-fiber filter based on microfiber loop resonator

Wu Yu, Zeng Xu, Hou Changlun, Bai Jian, and Yang Guoguang

Appl. Phys. Lett. 92, 191112 (2008); http://dx.doi.org/10.1063/1.2926672 (2 pages) | Cited 8 times

Online Publication Date: 15 May 2008

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In this paper, a tunable high finesse microfilter is described, which is based on microfiber loop resonator (MLR). The length of microfiber loop could be controlled by a small cylindrical piezoelectric ceramic. As we calculated, this resonator has the maximum Q factor of 2400 and the finesse of 4.3. MLR filter was demonstrated that the maximum extinction ratio is about 10 dB, and the free spectral range variation range could be more than 100 GHz. This device could also be integrated into a smaller size due to the bigger radius of curvature of the microfiber.
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85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
42.81.Wg Other fiber-optical devices

Nanoscale three dimensional pattern formation in light emitting porous silicon

Ik Su Chun, Edmond K. Chow, and Xiuling Li

Appl. Phys. Lett. 92, 191113 (2008); http://dx.doi.org/10.1063/1.2924311 (3 pages) | Cited 5 times

Online Publication Date: 16 May 2008

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A simple and efficient method for generating light emitting three-dimensional (3D) nanoscale pattern in silicon is presented. The method is based on differential chemical etching on and in-between patterned metal features. Effective transfer of various two-dimensional nanoscale (10–100 nm) metal patterns on bulk silicon to 3D porous silicon network is demonstrated. The capability and limitations of this method are discussed.
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81.07.Bc Nanocrystalline materials
81.65.Cf Surface cleaning, etching, patterning
81.16.Rf Micro- and nanoscale pattern formation

Carrier-envelope phase stabilization by controlling compressor grating separation

Chengquan Li, Hiroki Mashiko, He Wang, Eric Moon, Steve Gilbertson, and Zenghu Chang

Appl. Phys. Lett. 92, 191114 (2008); http://dx.doi.org/10.1063/1.2929743 (3 pages) | Cited 8 times

Online Publication Date: 16 May 2008

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Previously, we demonstrated the stabilization of the carrier-envelope (CE) phase of the laser pulses from a chirped pulse amplifier by controlling the effective grating separation in the stretcher. In this work, we show that the CE phase can also be stabilized to ∼ 230 mrad by controlling the grating separation in a compressor. The cutoff frequency of the piezoelectric transducer mounted grating for the phase stabilization system was found to be higher than 60 Hz.
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42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.79.Dj Gratings
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Spectroscopic measurement of electric field in dielectric barrier discharge in helium

B. M. Obradović, S. S. Ivković, and M. M. Kuraica

Appl. Phys. Lett. 92, 191501 (2008); http://dx.doi.org/10.1063/1.2927477 (3 pages) | Cited 6 times

Online Publication Date: 13 May 2008

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Spatial distribution of electric field strength in dielectric barrier discharge in helium is determined from the Stark splitting and shifting of two visible helium lines and their forbidden components. Electric field is calculated by using spectral distance between forbidden and allowed components and results are compared to those obtained by using forbidden/allowed intensity ratio. Distributions of electric field, obtained for 200 and 800 mbar pressures, are typical for the glow mode of the discharge.
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52.80.Hc Glow; corona
52.70.Kz Optical (ultraviolet, visible, infrared) measurements

Ion beam acceleration in a divergent magnetic field

Ioana A. Biloiu, Earl E. Scime, and Costel Biloiu

Appl. Phys. Lett. 92, 191502 (2008); http://dx.doi.org/10.1063/1.2927478 (3 pages) | Cited 14 times

Online Publication Date: 13 May 2008

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Two-dimensional argon ion velocity distribution functions (IVDFs) in the expansion region of a helicon plasma source have been measured by laser-induced-fluorescence tomography. Below a threshold value of the magnetic field in the expansion region, the IVDFs show a bimodal structure comprised of a supersonic ion population axially moving away from the source and an isotropic, slow, background, ion population. Increasing the magnetic field divergence leads to an increase in the axial speed of the supersonic component. A maximum axial speed of ∼ 2.9cs was obtained for a source/expansion magnetic field ratio of 43.
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52.40.Mj Particle beam interactions in plasmas
52.50.Dg Plasma sources

Experimental study of space-charge-limited flows in a nanogap

Sudeep Bhattacharjee, Adish Vartak, and Victor Mukherjee

Appl. Phys. Lett. 92, 191503 (2008); http://dx.doi.org/10.1063/1.2928232 (3 pages) | Cited 7 times

Online Publication Date: 14 May 2008

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An experimental investigation of space-charge-limited flow of current in a nanogap is presented. Electrodes with gap size d ∼ 70–110 nm corresponding to d/λ0 ∼ (1−5)×103, where λ0 is the de Broglie wavelength of the space-charge electrons are experimented. Unlike classical Child–Langmuir’s (CL) law, the current density varies as square root of applied voltage (V1/2), when d becomes comparable to λ0. Additionally, a transition regime has been found for the 90 nm gap size where the CL law appears at voltages >45 V. At d = 110 nm, the system is found to exhibit purely classical behavior.
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73.40.-c Electronic transport in interface structures
73.63.-b Electronic transport in nanoscale materials and structures

Experimental demonstration of relativistic magnetron with modified output configuration

M. Daimon, K. Itoh, G. Imada, and W. Jiang

Appl. Phys. Lett. 92, 191504 (2008); http://dx.doi.org/10.1063/1.2930684 (3 pages) | Cited 10 times

Online Publication Date: 15 May 2008

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A modified configuration of relativistic magnetron with diffraction output has been investigated experimentally by using repetitive pulsed power generator “ETIGO-IV” (400 kV, 13 kA, 120 ns, 1 Hz). The purpose is to verify the improved microwave conversion efficiency predicted by numerical simulations [ M. Daimon and W. Jiang, Appl. Phys. Lett. 91, 191503 (2007) ]. The experiments have concentrated on comparison between the output microwave powers obtained by using the modified and the conventional configurations of relativistic magnetron. The results have been in general agreement with that obtained by the simulations.
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84.40.Fe Microwave tubes (e.g., klystrons, magnetrons, traveling-wave, backward-wave tubes, etc.)
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Twisting of nanowires induced by anisotropic surface stresses

Jian-Shan Wang, Xi-Qiao Feng, Gang-Feng Wang, and Shou-Wen Yu

Appl. Phys. Lett. 92, 191901 (2008); http://dx.doi.org/10.1063/1.2928221 (3 pages) | Cited 11 times

Online Publication Date: 12 May 2008

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Many natural and synthetic quasi-one-dimensional materials are of helical or twisting shape and understanding the physical mechanisms underlying the asymmetric shape is of both theoretical and technological significances. In this letter, we pointed out that anisotropic surface stresses present as a possible reason for the formation of some micro-/nanohelices. Using Gurtin’s theory of surface elasticity, we quantitatively investigated the twisting deformation of nanowires due to anisotropic surface stresses. The present model can also elucidate the formation of some other helical materials at micro- and nanoscales, e.g., twisting lamellae in polymer spherulites, spiraled bacteria, and flagella.
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61.46.Km Structure of nanowires and nanorods (long, free or loosely attached, quantum wires and quantum rods, but not gate-isolated embedded quantum wires)
68.35.Gy Mechanical properties; surface strains
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Enhanced mechanical strength and ductility of metal-repaired defective carbon nanotubes: A density functional study

G. P. Zheng and H. L. Zhuang

Appl. Phys. Lett. 92, 191902 (2008); http://dx.doi.org/10.1063/1.2924275 (3 pages)

Online Publication Date: 12 May 2008

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Metal atoms are filled into the defective sites of single-walled carbon nanotube (SWCN) containing vacancy defects, resulting in a stable repaired SWCN. The tensile deformation of the repaired SWCN is investigated by spin-polarized density functional theory. Compared to the defective SWCN, the repaired CN shows significant enhancements in mechanical strength and ductility that are close to those of pristine CN. The underlying physics of these behaviors are analyzed by the structural transformation, electronic structures, and spin and charge distributions during the tensile tests. A strong magnetomechanical coupling effect is found to be responsible for the enhanced mechanical behaviors of metal-CN hybrid structures.
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81.07.De Nanotubes
62.25.-g Mechanical properties of nanoscale systems
73.22.-f Electronic structure of nanoscale materials and related systems
61.48.De Structure of carbon nanotubes, boron nanotubes, and other related systems
81.40.Lm Deformation, plasticity, and creep
75.80.+q Magnetomechanical effects, magnetostriction

{110}-facets formation by hydrogen thermal etching on sidewalls of Si and strained-Si fin structures

Tsutomu Tezuka, Norio Hirashita, Yoshihiko Moriyama, Naoharu Sugiyama, Koji Usuda, Eiji Toyoda, Ken Murayama, and Shin-ichi Takagi

Appl. Phys. Lett. 92, 191903 (2008); http://dx.doi.org/10.1063/1.2924281 (3 pages) | Cited 2 times

Online Publication Date: 12 May 2008

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Si-fin structures for multigate metal-oxide-semiconductor field effect transistors (MOSFETs) with smooth and vertical sidewalls composed of {110} facets were obtained by an anisotropic gas etching in atmospheric hydrogen ambient at 925–1000 °C on strained and unstrained (001) Si-on-insulator (SOI) substrates. {110} facets emerged due to higher etching rate for higher-order crystalline plane adjacent to {110} planes. The facet formation effectively eliminated the fin-width variation originating from the lithography process. The uniaxial stress along the fins on the strained SOI substrate was found to be preserved during the process, indicating the availability of this technique for fabrication of multigate MOSFETs with strained-fin channels.
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85.30.Tv Field effect devices
81.65.Cf Surface cleaning, etching, patterning
85.40.Hp Lithography, masks and pattern transfer

One-step preparation of Ca-α-SiAlON:Eu2+ fine powder phosphors for white light-emitting diodes

Takayuki Suehiro, Naoto Hirosaki, Rong-Jun Xie, Ken Sakuma, Mamoru Mitomo, Masahiro Ibukiyama, and Suzuya Yamada

Appl. Phys. Lett. 92, 191904 (2008); http://dx.doi.org/10.1063/1.2920209 (3 pages) | Cited 6 times

Online Publication Date: 12 May 2008

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A simple methodology for producing yellow-emitting Ca-α-SiAlON:Eu2+ phosphors for white light-emitting diodes has been developed, which consists of postsynthesis activation of fine α-SiAlON powders prepared by the gas-reduction-nitridation method. Phase-pure, fine Ca-α-SiAlON:Eu2+ phosphors possessing the particle size ranging ∼ 0.9–2.8 μm and high quantum efficiencies of ∼ 44%–55% under near-UV to blue light excitation are obtained as the process developed. The chromaticity coordinate of the synthesized Ca-α-SiAlON:Eu2+ can be tailored by simply controlling the activator concentration, enabling the creation of a broad range of warm-white light with the correlated color temperatures of ∼ 3500–2600 K.
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85.60.Jb Light-emitting devices

Radiative recombination dynamics in tetrapod-shaped CdTe nanocrystals: Evidence for a photoinduced screening of the internal electric field

Giovanni Morello, Davide Tarì, Luigi Carbone, Liberato Manna, Roberto Cingolani, and Milena De Giorgi

Appl. Phys. Lett. 92, 191905 (2008); http://dx.doi.org/10.1063/1.2924306 (3 pages) | Cited 1 time

Online Publication Date: 13 May 2008

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We study the radiative recombination processes in CdTe tetrapod nanocrystals at 10 K. Two intrinsic emission bands, namely the ground state (GS) and the excited state (EX), decay with three time constants, due to a power dependent Auger-like recombination process (tens of picoseconds), to the intrinsic emission of the two states (hundreds of picoseconds) and to emission from defect states (a few nanoseconds). The existence of an internal electric field originating from the e-h separation induced by the peculiar symmetry of the GS is demonstrated by a dynamical shift of the GS emission energy that is correlated to the EX population.
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72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
71.55.Gs II-VI semiconductors
78.55.Et II-VI semiconductors
73.61.Ga II-VI semiconductors
78.66.Hf II-VI semiconductors

Intersubband transitions in ZnO multiple quantum wells

M. Belmoubarik, K. Ohtani, and H. Ohno

Appl. Phys. Lett. 92, 191906 (2008); http://dx.doi.org/10.1063/1.2926673 (3 pages) | Cited 6 times

Online Publication Date: 13 May 2008

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Intersubband transitions in ZnO/MgZnO multiple quantum wells (MQWs) are investigated by a photocurrent spectroscopy. Photocurrent peaks are observed in the energy range from 300 to 400 meV and shifted to higher energy by reducing the ZnO well thickness. Polarization-resolved photocurrent spectra show that these peaks are observed when the polarization of incident lights is TM mode, following the intersubband selection rule. Calculation indicates that the photocurrent peaks are the intersubband transition from the first to the third subband in ZnO/MgZnO MQWs.
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73.63.Hs Quantum wells
72.40.+w Photoconduction and photovoltaic effects
73.21.Fg Quantum wells

Energy bandgap bowing of InAlN alloys studied by spectroscopic ellipsometry

E. Iliopoulos, A. Adikimenakis, C. Giesen, M. Heuken, and A. Georgakilas

Appl. Phys. Lett. 92, 191907 (2008); http://dx.doi.org/10.1063/1.2921783 (3 pages) | Cited 22 times

Online Publication Date: 14 May 2008

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InxAl1−xN films were heteroepitaxially grown on AlN/Al2O3 (0001) templates by molecular beam epitaxy. The compositions studied spanned the whole ternary range. The complex dielectric function of the films was investigated by variable angle spectroscopic ellipsometry in the energy range from 0.55 to 6 eV. The energy bandgap bowing parameter was found to strongly depend on composition, monotonically increasing with decreasing InN mole fraction. This behavior is in agreement with theoretical predictions of large charge transfer contributions to bandgap bowing.
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71.20.Nr Semiconductor compounds
68.55.ag Semiconductors
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
78.66.Fd III-V semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
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