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

28 Feb 2005

Volume 86, Issue 9, Articles (09xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 86, 093101 (2005); http://dx.doi.org/10.1063/1.1870108 (3 pages)

G. S. Paraoanu and A. M. Halvari
Enlarge Image | Read More
Page 1 of 4 Pages Next Page | Jump to Page
back to top
RSS Feeds

Numerical modeling of the induced grating autocorrelation for studying optical fiber nonlinearities in the picosecond regime

F. A. Oguama, A. Tchouassi, A. M. Johnson, and Hernando Garcia

Appl. Phys. Lett. 86, 091101 (2005); http://dx.doi.org/10.1063/1.1868069 (3 pages)

Online Publication Date: 23 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report a direct numerical model of the induced grating autocorrelation (IGA) based on the numerical solution of the nonlinear Schrödinger equation for an intense optical pulse that has experienced nonlinear distortion [notably, self-phase modulation (SPM) and stimulated Raman scattering (SRS)] after propagating through an optical fiber. Our numerical simulations are in good agreement with experiments. A significant advantage of the numerical approach over the well-known analytical models is its capability to predict IGA traces in the presence of pump depletion. In the light of this, IGA can now be used to study the combined effects of SPM and SRS in optical fibers in the regime where pump depletion is important, and both the nonlinear refractive index and the Raman gain coefficient of the fiber can be extracted.
Show PACS
42.81.Dp Propagation, scattering, and losses; solitons
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.65.Dr Stimulated Raman scattering; CARS
42.65.Es Stimulated Brillouin and Rayleigh scattering
42.79.Dj Gratings
42.30.Lr Modulation and optical transfer functions

Add-drop filters utilizing vertically coupled microdisk resonators in silicon

Prakash Koonath, Tejaswi Indukuri, and Bahram Jalali

Appl. Phys. Lett. 86, 091102 (2005); http://dx.doi.org/10.1063/1.1873064 (3 pages) | Cited 14 times

Online Publication Date: 23 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Add-drop filters, based on vertically coupled microdisk resonators, have been realized in silicon, using a modified separation by implantation of oxygen process. Buried rib waveguides in the bottom-layer silicon, of a two-layer structure, are coupled to microdisk resonators in the top-layer silicon through a silicon dioxide layer formed by oxygen implantation. The radii of the microdisk structures were varied suitably to obtain resonators with slightly shifted resonance wavelengths. The average adjacent channel crosstalk suppression of these filters exhibits an upper limit of 12.11 dB and a lower limit of 6.2 dB over the wavelength band under consideration.
Show PACS
42.79.Ci Filters, zone plates, and polarizers
42.79.Gn Optical waveguides and couplers
81.16.Pr Micro- and nano-oxidation

Large plasma-edge broadened magneto-optic-polar-Kerr-effect-based broadband incoherent detection of terahertz spectral frequencies

A. De and A. Puri

Appl. Phys. Lett. 86, 091103 (2005); http://dx.doi.org/10.1063/1.1865345 (3 pages) | Cited 2 times

Online Publication Date: 23 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A magneto-optic Kerr effect (MOKE)-based spectroscopic technique is proposed in the terahertz regime. This method relies on very large reflection edge splitting effects, which occur when the cyclotron frequency (CF) is of the same order of magnitude or greater than the plasma frequency. In the event of a very large reflection edge split, the Kerr rotation (KR) no longer occurs at the plasma edge, but instead occurs at Re(ε+ε−) ≈ 1, within the macroscopic framework of the Drude model. This implies that one can control the spectral occurrence of the MOKE resonance, simply by tuning the magnetic field strength. This phenomenon is unheard of for much shorter wavelengths, due to practical limitations on required magnetic field strengths and hence, can only be realized in the THz regime. A 3 T magnet can easily cover the proposed 0.5–5 THz spectral range for an InSb substrate. Our calculations show that in order to achieve good spectral resolution, the InSb substrate needs to be cooled to 77 K. The Kerr rotation obtained at 77 K for a CF of 1 THz is about 6.28°, which can be increased to about 18.35° by coating a thin low refractive index material on the InSb substrate. A well established ellipsometric technique, which uses four incoherent detectors, is proposed, for fast-simultaneous measurement of KR, Kerr ellipticity and reflectivity.
Show PACS
78.20.Ls Magneto-optical effects
78.70.Gq Microwave and radio-frequency interactions
78.66.Fd III-V semiconductors
73.61.Ey III-V semiconductors
52.77.-j Plasma applications
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
73.50.Dn Low-field transport and mobility; piezoresistance

Triplet exciton diffusion in fac-tris(2-phenylpyridine) iridium(III)-cored electroluminescent dendrimers

Ebinazar B. Namdas, Arvydas Ruseckas, Ifor D. W. Samuel, Shih-Chun Lo, and Paul L. Burn

Appl. Phys. Lett. 86, 091104 (2005); http://dx.doi.org/10.1063/1.1867571 (3 pages) | Cited 42 times

Online Publication Date: 24 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have studied triplet-triplet annihilation in neat films of electrophosphorescent fac-tris(2-phenylpyridine) iridium(III) [Ir(ppy)3]-cored dendrimers containing phenylene- and carbazole-based dendrons with 2-ethylhexyloxy surface groups using time-resolved photoluminescence. From measured annihilation rates, the limiting current densities above which annihilation would dominate in dendrimer light-emitting devices are found to be >1 A/cm2. The triplet exciton diffusion length varies in the range of 2–10 nm depending on the dendron size. The distance dependence of the nearest-neighbor hopping rate shows that energy transfer is dominated by the exchange mechanism.
Show PACS
85.60.Jb Light-emitting devices
78.55.Kz Solid organic materials
78.60.Fi Electroluminescence
71.70.Gm Exchange interactions
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
73.50.Dn Low-field transport and mobility; piezoresistance
78.66.Qn Polymers; organic compounds
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
78.47.-p Spectroscopy of solid state dynamics

Spectroscopic studies of molecular-beam epitaxially grown Cr2+-doped ZnSe thin films

A. Gallian, V. V. Fedorov, J. Kernal, J. Allman, S. B. Mirov, E. M. Dianov, A. O. Zabezhaylov, and I. P. Kazakov

Appl. Phys. Lett. 86, 091105 (2005); http://dx.doi.org/10.1063/1.1861952 (3 pages) | Cited 6 times

Online Publication Date: 24 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Cr:ZnSe thin films were grown by molecular-beam epitaxy with the long-term goal of demonstrating a route for the development of transitional-metal-doped semiconductor lasers. Photoluminescence (PL) and PL lifetime measurements of doped thin films and bulk crystals indicate that Cr is incorporated in the optically active Cr2+ state up to levels of 5×1019 cm−3. The shape of PL spectra and lifetime measurements of doped thin films compares favorably with that reported for bulk samples. A microcavity formed by film interfaces is responsible for differences in spontaneous emission observed between films and bulk crystals.
Show PACS
81.05.Dz II-VI semiconductors
78.66.Hf II-VI semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.55.Et II-VI semiconductors
68.55.A- Nucleation and growth
68.55.-a Thin film structure and morphology
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Ab initio study of the gas phase nucleation mechanism of GaN

Davide Moscatelli, Pierpaolo Caccioppoli, and Carlo Cavallotti

Appl. Phys. Lett. 86, 091106 (2005); http://dx.doi.org/10.1063/1.1870129 (3 pages) | Cited 3 times

Online Publication Date: 25 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The mechanism of formation of gas phase adducts in a Ga(CH3)3–NH3 atmosphere was investigated using density functional theory and fluid dynamic simulations. We found that the GaN gas phase chemistry is dominated by a radical chain mechanism, started by the CH3· radicals originated by the decomposition of Ga(CH3)3, and resulting in the fast formation of linear covalently bonded R(GaN)x adducts. As the number of GaN units in the adduct reaches three, the molecule cyclises. A kinetic mechanism suitable to study the formation of GaN adducts was then proposed and used to simulate the chemistry in a GaN metalorganic chemical vapor deposition reactor. It was found that GaNH2 is among the most important precursors to the film growth.
Show PACS
64.60.Q- Nucleation
82.60.Nh Thermodynamics of nucleation
81.05.Ea III-V semiconductors
81.15.Aa Theory and models of film growth

Polarization of III-nitride blue and ultraviolet light-emitting diodes

J. Shakya, K. Knabe, K. H. Kim, J. Li, J. Y. Lin, and H. X. Jiang

Appl. Phys. Lett. 86, 091107 (2005); http://dx.doi.org/10.1063/1.1875751 (3 pages) | Cited 30 times

Online Publication Date: 25 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Polarization-resolved electroluminescence studies of III-nitride blue and ultraviolet (UV) light-emitting diodes (LEDs) were performed. The LEDs were fabricated on nitride materials grown by metalorganic chemical vapor deposition on sapphire substrates (0001). Transverse electric (TE) polarization dominates in the InGaN∕GaN quantum-well (QW) blue LEDs (λ′ = 458 nm), whereas transverse magnetic (TM) polarization is dominant in the AlInGaN QW UV LEDs (λ = 333 nm). For the case of edge emission in blue LEDs, a ratio (r = I⊥/I‖) of about 1.8:1 was observed between the EL intensities with polarization E⊥c (TE mode) and E‖c (TM mode), which corresponds to a degree of polarization ∼ 0.29. The UV LEDs exhibit a ratio r of about 1:2.3, corresponding to a degree of polarization ∼ 0.4. This is due to the fact that the degree of polarization of the bandedge emission of the AlxInyGa1−x−yN active layer changes with Al concentration. The low emission efficiency of nitride UV LEDs is partly related to this polarization property. Possible consequences and ways to enhance UV emitter performances related to this unique polarization property are discussed.
Show PACS
85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.67.De Quantum wells
78.60.Fi Electroluminescence

Efficient drift dominated photodiodes using defected materials

Yanning Sun, Aristo Yulius, and Jerry M. Woodall

Appl. Phys. Lett. 86, 091108 (2005); http://dx.doi.org/10.1063/1.1875757 (2 pages)

Online Publication Date: 25 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Lattice-mismatched crystal growth can result in a high density of defects, which usually degrades the performance of optoelectronic devices. We demonstrate a drift dominated photodiode, which has high responsivity even with defected material. A drift dominated InP grown on GaP substrate photodiode, with the 8% lattice mismatch, has been developed for InP on Si application. Meanwhile, a conventional p-i-n InP on GaP photodiode was also made as a control sample. Results show that with the same defected material, the drift dominated device has much higher quantum efficiencies than those of the p-i-n device, especially at short wavelengths. The internal quantum efficiencies of the drift dominated InP on GaP photodiode are higher than 70% in UV and visible region.
Show PACS
85.60.Dw Photodiodes; phototransistors; photoresistors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.uj III-V and II-VI semiconductors
61.72.S- Impurities in crystals
78.66.Fd III-V semiconductors
78.40.Fy Semiconductors
68.55.-a Thin film structure and morphology

High-performance type-II InAs/GaSb superlattice photodiodes with cutoff wavelength around 7 μm

Y. Wei, A. Hood, H. Yau, V. Yazdanpanah, M. Razeghi, M. Z. Tidrow, and V. Nathan

Appl. Phys. Lett. 86, 091109 (2005); http://dx.doi.org/10.1063/1.1879113 (3 pages) | Cited 12 times

Online Publication Date: 25 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the most recent result in the area of type-II InAs/GaSb superlattice photodiodes that have a cutoff wavelength around 7 μm at 77 K. Superlattice with a period of 40 Å lattice matched to GaSb was realized using GaxIn1−x type interface engineering technique. Compared with significantly longer period superlattices, we have reduced the dark current density under reverse bias dramatically. For a 3 μm thick structure, using sulfide-based passivation, the dark current density reached 2.6×10−5 A/cm2 at −3 V reverse bias at 77 K. At this temperature the photodiodes have R0A of 9300 Ω cm2 and a thermally limited zero bias detectivity of 1×1012 cm Hz1/2/W. The 90%–10% cutoff energy width was only 16.5 meV. The devices did not show significant dark current change at 77 K after three months storage in the atmosphere.
Show PACS
85.60.Dw Photodiodes; phototransistors; photoresistors
72.40.+w Photoconduction and photovoltaic effects
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
81.65.Rv Passivation

Second-order optical nonlinear and luminescent properties of Ba2TiSi2O8 nanocrystallized glass

Yoshihiro Takahashi, Kenji Kitamura, Yasuhiko Benino, Takumi Fujiwara, and Takayuki Komatsu

Appl. Phys. Lett. 86, 091110 (2005); http://dx.doi.org/10.1063/1.1879114 (3 pages) | Cited 44 times

Online Publication Date: 25 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The optical properties of Ba2TiSi2O8 nanocrystals in transparent crystallized glasses were investigated. The transparent nanocrystallized glass with Ba2TiSi2O8 crystals having a particle size of ∼ 200 nm was fabricated by crystallization (at 760 °C for 1 h) of a glass with the stoichiometric composition of Ba2TiSi2O8, i.e., 40BaO∙20TiO2∙40SiO2 glass. Both visible second-harmonic generation (green light, 532 nm) and luminescence (blue light, ∼ 470 nm) could be observed in the transparent Ba2TiSi2O8 nanocrystallized glass, demonstrating the optical multifunctional nanocrystallized material. It was suggested that the blue luminescence from the transparent Ba2TiSi2O8 nanocrystallized glass originated from the oxygen-related defects of the SiO4 unit in the Ba2TiSi2O8 nanocrystals.
Show PACS
81.05.Kf Glasses (including metallic glasses)
81.07.Bc Nanocrystalline materials
42.70.Ce Glasses, quartz
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
78.55.Qr Amorphous materials; glasses and other disordered solids
81.16.-c Methods of micro- and nanofabrication and processing
64.70.D- Solid-liquid transitions
81.40.Gh Other heat and thermomechanical treatments

Optical amplification in two-dimensional photonic crystals

F. Raineri, G. Vecchi, C. Cojocaru, A. M. Yacomotti, C. Seassal, X. Letartre, P. Viktorovitch, R. Raj, and A. Levenson

Appl. Phys. Lett. 86, 091111 (2005); http://dx.doi.org/10.1063/1.1879094 (3 pages) | Cited 5 times

Online Publication Date: 25 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Optical amplification is demonstrated in a two-dimensional photonic crystal. Amplification at 1575 nm is observed in the direction normal to the plane of periodicity, by pumping the device at 810 nm. A gain up to 27 dB is measured with moderate pump fluence (50 μJ/cm2). Gain is shown to clamp as laser threshold is attained.
Show PACS
42.55.Tv Photonic crystal lasers and coherent effects
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.65.Yj Optical parametric oscillators and amplifiers
42.70.Qs Photonic bandgap materials
42.70.Hj Laser materials
42.82.Gw Other integrated-optical elements and systems

Effective plasma frequency in one-dimensional metallic-dielectric photonic crystals

Xiaochuang Xu, Yonggang Xi, Dezhuan Han, Xiaohan Liu, Jian Zi, and Ziqiang Zhu

Appl. Phys. Lett. 86, 091112 (2005); http://dx.doi.org/10.1063/1.1879101 (3 pages) | Cited 20 times

Online Publication Date: 25 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Photonic band structures of one-dimensional (1D) metallic-dielectric photonic crystals (MDPCs) are studied theoretically. We show that a 1D MDPC can be considered as an effective metallic medium with a well-defined effective plasma frequency. This effective plasma frequency is found to be inversely proportional to the optical thickness of the dielectric layer and is independent of either the constituent metal or the thickness of the metallic layer. By increasing the optical thickness of the dielectric layer, the effective plasma frequency of a 1D MDPC can be depressed into extremely low frequencies such as far infrared or even below.
Show PACS
42.70.Qs Photonic bandgap materials
77.22.Ch Permittivity (dielectric function)

Ultrafast resonant optical switching in isolated polyfluorenes chains

Tersilla Virgili, Daniele Marinotto, Guglielmo Lanzani, and Donal D.C. Bradley

Appl. Phys. Lett. 86, 091113 (2005); http://dx.doi.org/10.1063/1.1879085 (3 pages) | Cited 38 times

Online Publication Date: 25 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using ultrafast spectroscopy, we report evidence of monodimensional photophysics coming from isolated chains of poly(9,9-dioctylfluorene) dispersed in a polymethylmethacrylate matrix. We identify intrachain charge carriers dynamics, the decay taking place in about 1 ps. Using a three-pulse experiment we bring evidence for charges generation from higher lying states and we report an ultrafast optical gain switching in the stimulated emission region over a broad wavelength range (around 100 nm). Our experiments suggest that the expected maximum rate of on–off switching in such a molecular device can be as high as 300 GHz.
Show PACS
42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.70.Jk Polymers and organics
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Erbium-doped and Raman microlasers on a silicon chip fabricated by the sol–gel process

Lan Yang, Tal Carmon, Bumki Min, Sean M. Spillane, and Kerry J. Vahala

Appl. Phys. Lett. 86, 091114 (2005); http://dx.doi.org/10.1063/1.1873043 (3 pages) | Cited 30 times

Online Publication Date: 25 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report high-Q sol–gel microresonators on silicon chips, fabricated directly from a sol–gel layer deposited onto a silicon substrate. Quality factors as high as 2.5×107 at 1561 nm were obtained in toroidal microcavities formed of silica sol–gel, which allowed Raman lasing at absorbed pump powers below 1 mW. Additionally, Er3+-doped microlasers were fabricated from Er3+-doped sol–gel layers with control of the laser dynamics possible by varying the erbium concentration of the starting sol–gel material. Continuous lasing with a threshold of 660 nW for erbium-doped microlaser was also obtained.
Show PACS
42.55.Sa Microcavity and microdisk lasers
42.55.Ye Raman lasers
81.10.Dn Growth from solutions
81.10.Fq Growth from melts; zone melting and refining
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
71.55.-i Impurity and defect levels

Interference effects in electromodulation spectroscopy applied to GaAs-based structures: A comparison of photoreflectance and contactless electroreflectance

R. Kudrawiec, P. Sitarek, J. Misiewicz, S. R. Bank, H. B. Yuen, M. A. Wistey, and James S. Harris

Appl. Phys. Lett. 86, 091115 (2005); http://dx.doi.org/10.1063/1.1873052 (3 pages) | Cited 23 times

Online Publication Date: 25 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this letter, we show that the oscillation features (OFs) usually observed in photoreflectance (PR) spectra of GaAs-based structures grown on the n-type GaAs substrate below the GaAs fundamental gap could be eliminated completely by applying the contactless electroreflectance (CER) instead of PR. This finding confirms that the origin of OFs is the modulation of the refractive index in the sample due to the generation of additional carriers by the modulated pump beam. In the case of CER spectroscopy, any additional carriers are not generated during the modulation hence CER spectra are free of OFs. This advantage of CER spectroscopy is very important in investigations of all structures for which OFs are present in PR spectra. In order to illustrate this advantage of CER spectroscopy we show PR and CER spectra measured first for the GaAs epilayer and next for more complicated steplike GaInNAsSb/GaNAs/GaAs quantum well structures.
Show PACS
78.66.Fd III-V semiconductors
78.67.De Quantum wells
78.20.Jq Electro-optical effects
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
back to top
RSS Feeds

Double layer formation in the expanding region of an inductively coupled electronegative plasma

N. Plihon, C. S. Corr, and P. Chabert

Appl. Phys. Lett. 86, 091501 (2005); http://dx.doi.org/10.1063/1.1869533 (3 pages) | Cited 39 times

Online Publication Date: 24 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Double-layers (DLs) were observed in the expanding region of an inductively coupled plasma with Ar–SF6 gas mixtures. No DL was observed in pure argon or SF6 fractions below a few percent. They exist over a wide range of power and pressure although they are only stable for a small window of electronegativity (typically between 8% and 13% of SF6 at 1 mTorr), becoming unstable at higher electronegativity. They seem to be formed at the boundary between the source tube and the diffusion chamber and act as an internal boundary [the amplitude being roughly 1.5(kTe/e)] between a high electron density, high electron temperature, low electronegativity plasma upstream (in the source), and a low electron density, low electron temperature, high electronegativity plasma downstream.
Show PACS
52.40.Kh Plasma sheaths
52.25.Fi Transport properties
52.40.Hf Plasma-material interactions; boundary layer effects

Large-volume and low-frequency atmospheric glow discharges without dielectric barrier

J. J. Shi and M. G. Kong

Appl. Phys. Lett. 86, 091502 (2005); http://dx.doi.org/10.1063/1.1879095 (3 pages) | Cited 11 times

Online Publication Date: 25 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
It is widely believed that, at low frequencies of 1–100 kHz, the generation of atmospheric pressure glow discharges (APGD) requires a dielectric barrier added to at least one electrode. This letter reports the experimental observation of a uniform and stable APGD generated between two bare electrodes without a dielectric barrier over a wide frequency range from 20 kHz to 260 kHz. Below 70 kHz, it is shown that preionization in the rising phase of the applied voltage is important and plasma generation occurs in the voltage-falling phase. Mechanism of barrier-free APGD is found to be different from both atmospheric dielectric-barrier discharges and radio-frequency APGD.
Show PACS
52.80.Hc Glow; corona
52.25.Jm Ionization of plasmas
52.50.-b Plasma production and heating
52.25.Fi Transport properties
52.35.Py Macroinstabilities (hydromagnetic, e.g., kink, fire-hose, mirror, ballooning, tearing, trapped-particle, flute, Rayleigh-Taylor, etc.)
back to top
RSS Feeds

Interaction of atomic hydrogen with Zn-polar and O-polar ZnO surfaces

Maria Losurdo and Maria M. Giangregorio

Appl. Phys. Lett. 86, 091901 (2005); http://dx.doi.org/10.1063/1.1870103 (3 pages) | Cited 13 times

Online Publication Date: 23 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The interaction of Zn-polar and O-polar ZnO surfaces with atomic hydrogen produced by a remote rf plasma source is investigated in situ and in real time using spectroscopic ellipsometry. It is found that the reactivity of ZnO with atomic hydrogen depends on polarity. The interaction of O-polar surfaces with atomic hydrogen at 100 °C is suitable for producing clean surfaces, while Zn-polar surfaces strongly react with atomic hydrogen resulting in a disruption of the ZnO lattice with formation of Zn surface clusters.
Show PACS
68.43.Mn Adsorption kinetics
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Ps Atomic force microscopy (AFM)

Yellowish-white luminescence in codoped zinc oxide

Naoki Ohashi, Naoki Ebisawa, Takashi Sekiguchi, Isao Sakaguchi, Yoshiki Wada, Tadashi Takenaka, and Hajime Haneda

Appl. Phys. Lett. 86, 091902 (2005); http://dx.doi.org/10.1063/1.1871349 (3 pages) | Cited 23 times

Online Publication Date: 23 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The broad-band visible emission of codoped ZnO was studied. The codoped ZnO specimens were intentionally and simultaneously doped with IIIa elements (donors) and Li (acceptor). Broad-band emission covering nearly the whole visible range was achieved. The emission was found to be yellowish white to the naked eye. The visible band was composed of two components, i.e., a green emission having a peak at 2.2 eV and a yellow emission having a peak at 2.0 eV. The peak at 2.2 eV was distinct from the nonstructured green emission at 2.45 eV. The 2.2 and 2.0 eV peaks were attributed to donor-acceptor pair transitions involving the zinc vacancy and lithium, respectively.
Show PACS
78.55.Et II-VI semiconductors
78.60.Hk Cathodoluminescence, ionoluminescence
61.72.uj III-V and II-VI semiconductors
71.55.Gs II-VI semiconductors
61.72.S- Impurities in crystals
61.72.Yx Interaction between different crystal defects; gettering effect
61.72.J- Point defects and defect clusters

Observation of recombination enhanced defect annealing in 4H–SiC

L. Storasta, F. H. C. Carlsson, J. P. Bergman, and E. Janzén

Appl. Phys. Lett. 86, 091903 (2005); http://dx.doi.org/10.1063/1.1811381 (3 pages) | Cited 5 times

Online Publication Date: 23 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report observation of recombination enhanced defect annealing in 4H–SiC detected by capacitance transient spectroscopy and low temperature photoluminescence (PL). Intrinsic defect centers, created by 160 keV electron irradiation, reduce in concentration after illumination at temperatures much lower than previously reported annealing temperatures of 400 and 800 °C. The effect is observed after both external intense above band gap laser excitation, and with recombination in a forward biased pin diode. PL measurements show that several lines, normally detected after electron irradiation, have almost or entirely disappeared by recombination enhanced annealing at room temperature. From capacitance transient measurements, the annealing enhancement is found to be largest for the HS2 hole trap, while the EH1 and EH3 electron traps also anneal out by recombination enhanced reaction but at a lower rate.
Show PACS
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
78.55.Hx Other solid inorganic materials
61.72.Cc Kinetics of defect formation and annealing
61.80.Fe Electron and positron radiation effects

Temperature-dependent dielectric and electro-optic properties of a ZnO-BaTiO3-ZnO heterostructure grown by pulsed-laser deposition

B. N. Mbenkum, N. Ashkenov, M. Schubert, M. Lorenz, H. Hochmuth, D. Michel, M. Grundmann, and G. Wagner

Appl. Phys. Lett. 86, 091904 (2005); http://dx.doi.org/10.1063/1.1862778 (3 pages) | Cited 26 times

Online Publication Date: 24 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Temperature-dependent dielectric and electro-optic properties of a ZnO-BaTiO3-ZnO heterostructure grown by pulsed-laser deposition on (0001) sapphire are reported. The wurtzite-structure ZnO layers serve as transparent conducting electrodes. Previously observed coupling effects within the wurtzite-perovskite heterostructure by spectroscopic electro-optic ellipsometry birefringence measurements manifest themselves as a “pinning” of the ferroelectric polarization in the BaTiO3 layer by the cladding ZnO layers. Temperature-controlled electro-optic Raman measurements assign the electro-optic birefringence results to a temperature-driven phase transition resulting from the leakage current within the sample. High-temperature small-signal capacitance measurements exploiting the conductive electrode properties of the cladding layers reveal occurrence of the Curie temperature of the BaTiO3 layer at 384 K.
Show PACS
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
78.20.Jq Electro-optical effects
78.66.Nk Insulators
78.66.Hf II-VI semiconductors
68.55.-a Thin film structure and morphology
78.20.Fm Birefringence
78.30.Hv Other nonmetallic inorganics
77.80.B- Phase transitions and Curie point
77.22.Ej Polarization and depolarization

Temperature dependence of the tangential momentum accommodation coefficient for gases

Bing-Yang Cao, Min Chen, and Zeng-Yuan Guo

Appl. Phys. Lett. 86, 091905 (2005); http://dx.doi.org/10.1063/1.1871363 (3 pages) | Cited 25 times

Online Publication Date: 24 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The temperature dependence of the tangential momentum accommodation coefficient (TMAC) is investigated by examining gas flows in a submicron channel using molecular dynamics simulations. The results show that the TMAC decreases with the increasing temperature following an exponential decay law, and is more sensitive to lower temperatures than to higher ones. The molecular trapping-desorption behaviors near the channel surface are found to be responsible for this dependence.
Show PACS
47.45.Gx Slip flows and accommodation
47.60.-i Flow phenomena in quasi-one-dimensional systems
47.15.-x Laminar flows
47.10.-g General theory in fluid dynamics

Electron-lattice coupling in ZnFe2O4/TiO2 nanocomposite films

Yunxia Jin, Guanghai Li, and Lide Zhang

Appl. Phys. Lett. 86, 091906 (2005); http://dx.doi.org/10.1063/1.1866503 (3 pages) | Cited 1 time

Online Publication Date: 24 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electron-lattice (e-ph) coupling originated from the low-temperature photoluminescence in ZnFe2O4/TiO2 nanocomposite films has been studied. The purely linear character of the e-ph coupling is shown through the Huang–Rhys model within the Franck–Condon approximation. The interfacial coupling capability between the ZnFe2O4 nanoparticles and the TiO2 host lattice is characterized by the Huang–Rhys factors (S0) and the vibrational quantum energy (ℏΩ). It is found that the Huang–Rhys factors S0 increases with increasing the content of ZnFe2O4 in the TiO2 films and the vibrational energy ℏΩ is quite in agreement with that in the infrared spectra.
Show PACS
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.66.Nk Insulators
78.55.Hx Other solid inorganic materials

Ductile titanium-based glassy alloy ingots

Faqiang Guo, Hsiang-Jen Wang, S. Joseph Poon, and Gary J. Shiflet

Appl. Phys. Lett. 86, 091907 (2005); http://dx.doi.org/10.1063/1.1872214 (3 pages) | Cited 73 times

Online Publication Date: 24 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report that ductile and strong amorphous titanium metallic alloys ( ∼ twice the strength of high-strength titanium alloys) have been discovered that are in the form of glassy ingots. It is found that the suppression of a competing stable quasicrystalline phase upon solidification is particularly important in forming the current glassy ingots. While there is significant technological potential for these titanium alloys, the present findings have important implications on the design of highly processable bulk metallic glasses.
Show PACS
81.05.Bx Metals, semimetals, and alloys
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
64.70.D- Solid-liquid transitions
81.30.Fb Solidification
61.43.Fs Glasses
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.M- Structural failure of materials
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure

Photoluminescence of silicon quantum dots in silicon nitride grown by NH3 and SiH4

Baek-Hyun Kim, Chang-Hee Cho, Tae-Wook Kim, Nae-Man Park, Gun Yong Sung, and Seong-Ju Park

Appl. Phys. Lett. 86, 091908 (2005); http://dx.doi.org/10.1063/1.1872211 (3 pages) | Cited 44 times

Online Publication Date: 25 February 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The photoluminescence (PL) property of crystalline silicon quantum dots (Si QDs) in silicon nitride grown by using ammonia and silane gases is reported. The peak position of PL could be controlled in the wavelength range from 450 to 700 nm by adjusting the flow rates of ammonia and silane gases. The PL intensity of Si QDs grown by ammonia was more intense compared to that of Si QDs grown by nitrogen gas. To investigate the role of hydrogen in the PL enhancement, the Si QDs grown by nitrogen gas were postannealed under hydrogen ambient. The enhancement in PL intensity was attributed to the hydrogen passivation of dangling bonds related to silicon and/or nitrogen at the interface of Si QDs and silicon nitride.
Show PACS
81.05.Cy Elemental semiconductors
81.07.Ta Quantum dots
78.67.Hc Quantum dots
71.55.Cn Elemental semiconductors
81.65.Rv Passivation
68.55.-a Thin film structure and morphology
68.65.Hb Quantum dots (patterned in quantum wells)
61.72.Cc Kinetics of defect formation and annealing
78.55.Ap Elemental semiconductors
Page 1 of 4 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close