jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

15 Jan 2010

Volume 107, Issue 2, Articles (02xxxx)

Page 1 of 6 Pages Next Page | Jump to Page
back to top
RSS Feeds
back to top Lasers, Optics, and Optoelectronics

Optical waveguide simulations for the optimization of InGaN-based green laser diodes

Chia-Yen Huang, You-Da Lin, Anurag Tyagi, Arpan Chakraborty, Hiroaki Ohta, James S. Speck, Steven P. DenBaars, and Shuji Nakamura

J. Appl. Phys. 107, 023101 (2010); http://dx.doi.org/10.1063/1.3275325 (7 pages) | Cited 6 times

Online Publication Date: 22 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Two-dimensional optical waveguide mode simulations have been employed to investigate the optimized device structures for ridge-waveguide (Al, In, Ga) N-based green (520 nm) laser diodes (LDs). The effects of thicknesses, alloy compositions, and doping densities of each epitaxially grown layers as well as ridge geometries on optical confinement factors (Γ) and waveguide absorption (α) were comprehensively surveyed. InyGa1−yN (y = 0.07–0.1) guiding layers (GLs) with thickness more than 50 nm were effective for realizing high Γ and low α. To minimize the absorption by the anode metal, p-cladding layer (p-CL) was required to be more than 500 nm. At the same time, low index insulator such as SiO2 was preferable for the narrow ridge, where the thickness at the sidewall had to be more than 60 nm. We also found that InGaN barriers layers between the quantum wells (QWs) were superior to GaN barriers to increase Γ and reduce α. Moreover, a thicker last barrier between the topmost QW and the electron blocking layer was also effective to reduce α. Regarding the effect of Mg doping concentration on the absorption, the reduction in Mg in the p-CL and the p-GL was significant to reduce α. Generally, it was confirmed the design for typical 405 nm LDs can be applied for 520 nm LD with the inclusion of InGaN GLs and barriers for the QWs.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.79.Gn Optical waveguides and couplers
61.72.U- Doping and impurity implantation

Infrared luminescence of Tm3+/Yb3+ codoped lanthanum aluminum germanate glasses

Qiang Zhang, Guorong Chen, Guang Zhang, Jianrong Qiu, and Danping Chen

J. Appl. Phys. 107, 023102 (2010); http://dx.doi.org/10.1063/1.3289589 (6 pages) | Cited 9 times

Online Publication Date: 22 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Tm3+ doped and Tm3+/Yb3+ codoped lanthanum aluminum germanate (LAG) glasses are prepared by melt-quenching method and characterized optically. Based on the measurement of absorption spectrum, Judd–Ofelt intensity parameters (Ω2,Ω4,Ω6) are calculated. The radiation emission rates, branching ratios, and lifetimes of Tm3+ are calculated to evaluate the spectroscopic properties of Tm3+ in LAG glass. The infrared emission properties of the samples are investigated and the results show that the 1.8 μm emission can be greatly enhanced by adding proper amount of Yb3+ under the excitation of 980 nm. The energy transfer processes of Yb3+–Yb3+ and Yb3+–Tm3+ are analyzed, and the results show that Yb3+ ions can transfer their energy to Tm3+ ions with high efficiency and large energy transfer coefficient.
Show PACS
78.35.+c Brillouin and Rayleigh scattering; other light scattering
78.55.Qr Amorphous materials; glasses and other disordered solids
81.05.Kf Glasses (including metallic glasses)
61.72.up Other materials

Near-infrared electroluminescence and stimulated emission from semiconducting nonconjugated polymer thin films

Takeyuki Kobayashi, Martin Djiango, and Werner J. Blau

J. Appl. Phys. 107, 023103 (2010); http://dx.doi.org/10.1063/1.3284085 (5 pages) | Cited 3 times

Online Publication Date: 25 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present the results of a study on near-infrared electroluminescence and optical amplification in semiconductor thin films based on a nonconjugated polymer doped with luminescent and electron-transport molecules. A single-layer light-emitting diode is fabricated on an indium tin oxide-coated glass substrate with poly(9-vinylcarbazole) containing an electron-transport material, 2-(4-Biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole and a near-infrared-emitting compound, 2-(6-(p-dimethylaminophenyl)-2,4-neopentylene-1,3,5-hexatrienyl)-3-ethylbenzothiazolium perchlorate. The single-layer structure shows near-infrared electroluminescence with a turn-on voltage of 13 V. The same structure is characterized under transversal pulsed photopumping with a frequency-doubled Nd: yttrium aluminum garnet laser. With increasing pump fluence, the edge emission at 0.82 μm shows both significant gain narrowing and superlinear intensity increase, which indicate the existence of optical gain by stimulated emission. Our results provide impetus for the development of near-infrared polymer lasers and optical amplifiers.
Show PACS
78.60.Fi Electroluminescence
78.45.+h Stimulated emission
42.55.Rz Doped-insulator lasers and other solid state lasers
85.60.Jb Light-emitting devices
78.66.Qn Polymers; organic compounds

An analysis of coupling between a whispering gallery mode laser in an elliptical microring and the dominant mode in the coaxially oriented elliptical optical fiber

Reyhan Baktur, L. Wilson Pearson, and John Ballato

J. Appl. Phys. 107, 023104 (2010); http://dx.doi.org/10.1063/1.3284947 (9 pages) | Cited 1 time

Online Publication Date: 25 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The problem of coupling a whispering gallery mode laser into an optical fiber is considered. The whispering gallery mode laser is generated in a polymer microring formed coaxially on the optical fiber. The focus of this paper is to determine factors that influence the coupling between the laser and the fiber around which it is formed. The coupling mechanism is analyzed and it is found that when the microring and the fiber are of elliptical cross section, there exists controllable coupling between the laser and propagation mode in the fiber. The coupling between laser mode and fiber mode is due to characteristics of Mathieu functions that describe the fields in elliptical waveguides. It is shown that the coupling between the laser and the dominant mode in the fiber can be optimized by the designing the dimension of microring, the eccentricity of the elliptical cross section, and the material contrast between fiber and microring.
Show PACS
42.55.Sa Microcavity and microdisk lasers
42.70.Jk Polymers and organics
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.By Design of specific laser systems
42.55.Rz Doped-insulator lasers and other solid state lasers
42.81.Qb Fiber waveguides, couplers, and arrays

Parametric study of laser-induced surface damage density measurements: Toward reproducibility

L. Lamaignère, M. Balas, R. Courchinoux, T. Donval, J. C. Poncetta, S. Reyné, B. Bertussi, and H. Bercegol

J. Appl. Phys. 107, 023105 (2010); http://dx.doi.org/10.1063/1.3282704 (8 pages) | Cited 5 times

Online Publication Date: 26 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In the range of nanosecond pulse lengths, the mechanisms of surface laser damage to dielectric materials are still unclear. A large amount of experimental and theoretical work has been performed over recent years. In order to test theoretical predictions and compare experimental results, reproducibility is essential whatever the beam parameters and experimental conditions. The rasterscan procedure, previously developed to test large components, is an efficient method that allows measuring extremely low surface damage site density (until 0.01 site/cm2 for large optics). In this paper, we show that by suitable data reduction, error bar calculation, and attention paid to beam analysis, laser-induced surface damage density of fused silica optics can be measured with high accuracy and repeatability in the range of pulse durations from 2 to 16 ns. This procedure provides a straightforward means of comparing the experimental results obtained from several facilities using different lasers.
Show PACS
42.82.-m Integrated optics
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.62.-b Laser applications

Influence of the salinity on the characteristics of acoustic signal in salt water generated by pulsed CO2 laser

Haihong Zhu, Qingming Chen, Zuhai Cheng, and Huiqun Tang

J. Appl. Phys. 107, 023106 (2010); http://dx.doi.org/10.1063/1.3284073 (5 pages)

Online Publication Date: 27 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The experimental study on the laser acoustic signal in salt water with different salinities using high power pulsed CO2 laser has been carried out. By using a hydrophone to receive the sound signal and further analyzing in time domain, the effects of the salinity and pulse energy on the characteristics of the sound signals were disclosed. The results show that the salinity has significant effect on the characteristics of the laser acoustic signal. As the salinity increases, the amplitude of the sound signal decreases. The profile of the sound signal also changes with the salinity. As the salinity decreases, the changes in the signal waveform show the loss of its originally bimodal shape. This phenomenon is also found in the laser energy which decreases when the salinity is kept constant.
Show PACS
62.60.+v Acoustical properties of liquids
43.35.Ud Thermoacoustics, high temperature acoustics, photoacoustic effect
43.58.Fm Sound level meters, level recorders, sound pressure, particle velocity, and sound intensity measurements, meters, and controllers
43.30.Bp Normal mode propagation of sound in water

Photopolymerization kinetics and volume holographic recording in ZrO2 nanoparticle-polymer composites at 404 nm

Koji Omura and Yasuo Tomita

J. Appl. Phys. 107, 023107 (2010); http://dx.doi.org/10.1063/1.3289729 (6 pages) | Cited 9 times

Online Publication Date: 27 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigate volume holographic recording in a ZrO2 nanoparticle-polymer composite film at a wavelength of 404 nm. Dependences of the polymerization kinetics on concentrations of an initiator and ZrO2 nanoparticles doped in acrylate monomer are examined by using a photodifferential scanning calorimeter. It is found that there exists the optimum concentration of ZrO2 nanoparticles to maximize the polymerization rate. The diffraction and scattering properties of transmission volume gratings are also investigated. It is found that the refractive index modulation and the material recording sensitivity are as high as 8×10−3 and 9000 cm/J, respectively, at the optimum ZrO2 nanoparticle concentration of 35 vol % and at a recording intensity of 5 mW/cm2. These material parameters are larger than typical minimum ones of 5×10−3 and 500 cm/J, respectively, for optimized performance in holographic data storage.
Show PACS
42.40.Eq Holographic optical elements; holographic gratings
42.70.Ln Holographic recording materials; optical storage media
82.20.-w Chemical kinetics and dynamics
82.35.Np Nanoparticles in polymers
42.79.Vb Optical storage systems, optical disks
42.40.Ht Hologram recording and readout methods

Nonlinear characterization of GeS2–Sb2S3–CsI glass system

K. Fedus, G. Boudebs, Q. Coulombier, J. Troles, and X. H. Zhang

J. Appl. Phys. 107, 023108 (2010); http://dx.doi.org/10.1063/1.3289607 (5 pages) | Cited 5 times

Online Publication Date: 28 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present the results of Z-scan measurements (1064 nm, 17 ps) of nonlinear refractive indices and nonlinear absorption coefficients for different compositions of chalcogenide glasses in GeS2–Sb2S3–CsI system. We show that the simple well known Boling, Glass, and Owyoung model based on the theory of the semiclassical harmonic oscillator can be a useful tool for theoretical predictions of the nonlinear refractive index in these infrared glasses. A quasi-linear behavior is observed relating the nonlinear index and the linear one. Some of the compositions reveal properties potentially useful for all optical switching applications.
Show PACS
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.65.-k Nonlinear optics
61.43.Fs Glasses
78.35.+c Brillouin and Rayleigh scattering; other light scattering

Directional emissions achieved with anomalous reflection phases of metamaterials

Kun Ding, Tao Jiang, Jiaming Hao, Lixin Ran, and Lei Zhou

J. Appl. Phys. 107, 023109 (2010); http://dx.doi.org/10.1063/1.3289720 (6 pages)

Online Publication Date: 28 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
For a small antenna placed on a metamaterial ground plane vertically or horizontally, we analyzed the conditions under which the antenna emissions are highly directional. We found through finite-difference time-domain (FDTD) simulations that a previously discovered directional emission phenomenon can be explained by our theory for the horizontal antenna case. For the vertical antenna case, we employed FDTD simulations to design a realistic metamaterial ground plane with desired reflection phase properties, and performed microwave experiments to verify its ability to support directional emissions.
Show PACS
42.70.-a Optical materials
42.25.Gy Edge and boundary effects; reflection and refraction

Modified spontaneous emission rate in three-dimensional layer-by-layer photonic crystals with planar defects

Ji-Feng Chen, Rong-Tai Hong, and Jaw-Yen Yang

J. Appl. Phys. 107, 023110 (2010); http://dx.doi.org/10.1063/1.3279659 (9 pages) | Cited 2 times

Online Publication Date: 28 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A finite three-dimensional layer-by-layer photonic crystal with planar defects in a layer is shown to drastically modify the spontaneous emission rate of an embedded dipole. Finite-difference time-domain calculations with one quarter symmetric boundary condition and perfectly matched layer demonstrate the strong enhancement effects induced by the cavity resonance of defect modes and band-edge resonant modes. Simulation shows that the emission spectra are quite different when the position or polarization of the dipole is changed. Moreover, the extraction efficiency is calculated to observe the percentage of light leakage through a substrate.
Show PACS
42.70.Qs Photonic bandgap materials
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
02.70.Bf Finite-difference methods

Comparison of electrical, optical, structural, and interface properties of IZO-Ag-IZO and IZO-Au-IZO multilayer electrodes for organic photovoltaics

Jin-A Jeong, Yong-Seok Park, and Han-Ki Kim

J. Appl. Phys. 107, 023111 (2010); http://dx.doi.org/10.1063/1.3294605 (8 pages) | Cited 15 times

Online Publication Date: 29 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We compared the electrical, optical, structural, and interface properties of indium zinc oxide (IZO)-Ag-IZO and IZO-Au-IZO multilayer electrodes, as well as the dependence of their electrical and optical properties on the thicknesses of the Ag and Au layers when used for organic solar cells (OSCs). Even though all deposition processes were carried out at room temperature, the IZO-Ag (14 nm)-IZO and IZO-Au (12 nm)-IZO multilayer electrodes exhibited extremely low sheet resistances of 4.15 and 5.49 Ω/sq, and resistivities of 3.9×10−5 and 5.5×10−5 Ω cm, respectively. In spite of its similar electrical properties, the optical transmittance of the IZO-Ag-IZO electrode is much higher than that of the IZO-Au-IZO electrode, due to the more effective antireflection effect of Ag than Au in the visible region. In addition, synchrotron x-ray scattering and scanning electron microscopy examinations showed that the structure and morphology of the Ag and Au layers critically depend on their thicknesses. Moreover, the bulk heterojunction OSC fabricated on the IZO-Ag (14 nm)-IZO multilayer electrode exhibited a higher power conversion efficiency than that fabricated on the IZO-Au-IZO layer, due to its higher transmittance in the 300–600 nm wavelength region corresponding to the absorption wavelength region of the organic active layer.
Show PACS
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
68.65.Ac Multilayers
78.70.Ck X-ray scattering
88.40.H- Solar cells (photovoltaics)

Simplified procedure for interferometric determination of electro-optic properties of low-Tg photorefractive polymer

Takashi Fujihara, Takafumi Sassa, Takashi Kawada, Jun-ichi Mamiya, Tsuyoshi Muto, and Shinsuke Umegaki

J. Appl. Phys. 107, 023112 (2010); http://dx.doi.org/10.1063/1.3284951 (5 pages) | Cited 1 time

Online Publication Date: 29 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A simplified procedure is proposed for the interferometric determination of optical dispersions of refractive-index changes in a low-Tg photorefractive (PR) polymer. A two-level model for the optical dispersions is used in order to separately evaluate the index changes occurring due to molecular birefringence and first-order electronic electro-optic effects. This evaluation is done by estimating the contributions of the two effects in the low-frequency limit of a modulating voltage. The evaluated results are compared with those determined by a PR two-beam coupling experiment.
Show PACS
78.20.Jq Electro-optical effects
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.20.Fm Birefringence
78.20.Mg Photorefractive effects
82.70.-y Disperse systems; complex fluids
61.41.+e Polymers, elastomers, and plastics

Controllable far-infrared electromagnetic radiation from plasmas applied by dc or ac bias electric fields

Wei-Min Wang, Zheng-Ming Sheng, X.-G. Dong, H.-W. Du, Y.-T. Li, and J. Zhang

J. Appl. Phys. 107, 023113 (2010); http://dx.doi.org/10.1063/1.3296126 (7 pages) | Cited 3 times

Online Publication Date: 29 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
It is shown theoretically and numerically that a dc/ac bias field applied over tenuous plasma can be converted efficiently into electromagnetic (EM) waves at the plasma frequency ωp, with the amplitude and polarization determined by the bias. The initial phase of the EM waves can be controlled by the triggering time of the bias and therefore circularly/elliptically polarized EM waves can be obtained by applying two bias fields perpendicular to each other. When the bias frequency is near ωp, the resonance appears and the EM waves are generated with the intensity enhanced considerably as compared with the dc-bias case. This approach provides a potential way to produce tunable far-infrared EM waves such as terahertz waves. Limits of this approach by available parameters of plasmas and bias are also discussed.
Show PACS
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
41.20.Jb Electromagnetic wave propagation; radiowave propagation
52.40.-w Plasma interactions (nonlaser)

Controlling blue-violet electroluminescence of Ge-rich Er-doped SiO2 layers by millisecond annealing using flash lamps

A. Kanjilal, L. Rebohle, M. Voelskow, M. Helm, and W. Skorupa

J. Appl. Phys. 107, 023114 (2010); http://dx.doi.org/10.1063/1.3296252 (5 pages) | Cited 1 time

Online Publication Date: 29 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Systematic evolution of the 400 nm electroluminescence (EL) with increasing flash lamp annealing (FLA) temperature from 800 to 1100 °C in an Er-doped Ge-rich metal-oxide semiconductor structure is presented. No significant change in the 1535 nm Er EL is observed with increasing FLA temperature. Enhancement of the 400 nm EL decay time with rising FLA temperature is found to be associated with recrystallization of the damaged Ge clusters in the absence of Ge outdiffusion. The 400 nm EL quenching with continuous charge injection process is also discussed within the device operation time.
Show PACS
78.60.Fi Electroluminescence
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
61.72.Cc Kinetics of defect formation and annealing
61.72.U- Doping and impurity implantation
back to top Plasmas and Electrical Discharges

Toward quantitative deuterium analysis with laser-induced breakdown spectroscopy using atmospheric-pressure helium gas

Rinda Hedwig, Zener Sukra Lie, Koo Hendrik Kurniawan, Alexander Nikitich Chumakov, Kiichiro Kagawa, and May On Tjia

J. Appl. Phys. 107, 023301 (2010); http://dx.doi.org/10.1063/1.3282801 (5 pages) | Cited 1 time

Online Publication Date: 21 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An experimental study has been carried out for the development of quantitative deuterium analysis using the neodymium doped yttrium aluminum garnet laser-induced breakdown spectroscopy (LIBS) with atmospheric pressure surrounding He gas by exploring the appropriate experimental condition and special sample cleaning technique. The result demonstrates the achievement of a full resolution between the D and H emission lines from zircaloy-4 samples, which is prerequisite for the desired quantitative analysis. Further, a linear calibration line with zero intercept was obtained for the emission intensity of deuterium from a number of zircaloy samples doped with predetermined concentrations of deuterium. The result is obtained by setting a +4 mm defocusing position for the laser beam, 6 μs detection gating time, and 7 mm imaging position of the plasma for the detection, which is combined with a special procedure of repeated laser cleaning of the samples. This study has thus provided the basis for the development of practical quantitative deuterium analysis by LIBS.
Show PACS
82.80.Dx Analytical methods involving electronic spectroscopy
61.72.sd Impurity concentration
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
42.62.-b Laser applications
78.55.Hx Other solid inorganic materials

Powder formation in SiH4–H2 discharge in large area capacitively coupled reactors: A study of the combined effect of interelectrode distance and pressure

B. Strahm and Ch. Hollenstein

J. Appl. Phys. 107, 023302 (2010); http://dx.doi.org/10.1063/1.3282802 (7 pages) | Cited 4 times

Online Publication Date: 25 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
One of the main challenges for silicon thin film deposition for solar cell applications is to achieve high rate deposition in order to reduce the manufacturing costs. However, when silane and hydrogen are used as precursor gas in parallel plate plasma-enhanced chemical vapor deposition, high rate deposition is generally synonymous of powdery discharge. In this work, time- and space-resolved light scattering experiments are presented. These were performed in an industrial-type large area reactor with a variable interelectrode distance. Results show that with a standard 25 mm interelectrode distance, the fraction of silane transformed into powder can be as high as 50% and that reducing the interelectrode distance shifts to higher pressure the appearance of powder in the discharge. From a standard 25 mm interelectrode distance to a 10 mm narrow gap reactor, the threshold pressure was increased from 2 to 7 mbars. More generally, it is proposed that the onset of powder formation depends mainly on the product of the interelectrode distance and the gas residence time in the discharge.
Show PACS
68.55.ag Semiconductors
62.50.-p High-pressure effects in solids and liquids
52.80.-s Electric discharges
52.77.Dq Plasma-based ion implantation and deposition
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.35.+c Brillouin and Rayleigh scattering; other light scattering

In situ method for real time measurement of dielectric film thickness in plasmas

Sung-Ho Jang (장성호), Gun-Ho Kim (김건호), and Chin-Wook Chung (정진욱)

J. Appl. Phys. 107, 023303 (2010); http://dx.doi.org/10.1063/1.3267307 (5 pages) | Cited 4 times

Online Publication Date: 25 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An in situ thickness measurement method of dielectric films (dual frequency method) was developed, and the thicknesses were measured in an inductively coupled plasma. This method uses a small ac bias voltage with two frequencies for thickness measurement. The dielectric thickness is obtained from measuring the amplitudes of the two frequency ac currents through a sensor, as well as using an equivalent circuit model describing impedance of the dielectric film and the plasma sheath. In the experiment, the thicknesses of Al2O3 film could be accurately measured in real time. To check the measurement reliability, the dual frequency method was compared with reflection spectrophotometry as a technique for optical thickness diagnostics. It was found that the dual frequency method agrees closely with reflection spectrophotometry at various rf powers and pressures. In addition, this method is very simple and can be installed anywhere in plasma reactors, in contrast with optical methods; therefore, it is expected to be applied to in situ surface diagnostics for various processing plasmas.
Show PACS
77.55.-g Dielectric thin films
77.84.-s Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials
52.40.Kh Plasma sheaths
52.70.-m Plasma diagnostic techniques and instrumentation
52.50.Gj Plasma heating by particle beams
52.77.-j Plasma applications

Schlieren technique applied to the arc temperature measurement in a high energy density cutting torch

L. Prevosto, G. Artana, B. Mancinelli, and H. Kelly

J. Appl. Phys. 107, 023304 (2010); http://dx.doi.org/10.1063/1.3291099 (5 pages) | Cited 5 times

Online Publication Date: 25 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Plasma temperature and radial density profiles of the plasma species in a high energy density cutting arc have been obtained by using a quantitative schlieren technique. A Z-type two-mirror schlieren system was used in this research. Due to its great sensibility such technique allows measuring plasma composition and temperature from the arc axis to the surrounding medium by processing the gray-level contrast values of digital schlieren images recorded at the observation plane for a given position of a transverse knife located at the exit focal plane of the system. The technique has provided a good visualization of the plasma flow emerging from the nozzle and its interactions with the surrounding medium and the anode. The obtained temperature values are in good agreement with those values previously obtained by the authors on the same torch using Langmuir probes.
Show PACS
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
07.20.Dt Thermometers
42.79.Mt Schlieren devices
52.77.Fv High-pressure, high-current plasmas (plasma spray, arc welding, etc.)
52.75.Hn Plasma torches

Analysis of transient electron energy in a micro dielectric barrier discharge for a high performance plasma display panel

Giichiro Uchida, Satoshi Uchida, Hiroshi Kajiyama, and Tsutae Shinoda

J. Appl. Phys. 107, 023305 (2010); http://dx.doi.org/10.1063/1.3291123 (6 pages) | Cited 5 times

Online Publication Date: 25 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present here analysis of electron energy of a micro dielectric barrier discharge (micro-DBD) for alternating-current plasma display panel (ac-PDP) with Ne/Xe gas mixture by using the optical emission spectroscopy (OES). The OES method is quite useful to evaluate a variety of electron energy in a high pressure DBD ignited in a PDP small cell. Experiment shows that the ratio of Ne emission intensity (INe) relative to Xe emission intensity (IXe) drastically decreases with time. This temporal profile is well consistent with dynamic behavior of electron temperature in a micro-DBD, calculated in one-dimensional fluid model. INe/IXe also decreases with an increase in Xe gas pressure and a decrease in applied voltage especially in the initial stage of discharge, and these reflect the basic features of electron temperature in a micro-DBD. The influences of plasma parameters such as electron temperature on luminous efficacy are also theoretically analyzed using one-dimensional fluid model. The low electron temperature, which is attained at high Xe gas pressure, realizes the efficient Xe excitation for vacuum ultraviolet radiation. The high Xe-pressure condition also induces the rapid growth of discharge and consequent high plasma density, resulting in high electron heating efficiency.
Show PACS
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.75.-d Plasma devices
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.80.-s Electric discharges

Optical properties of AlxGa1−xN alloy

Katsuki Takeuchi, Sadao Adachi, and Kohji Ohtsuka

J. Appl. Phys. 107, 023306 (2010); http://dx.doi.org/10.1063/1.3284956 (11 pages) | Cited 5 times

Online Publication Date: 28 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The optical response of the AlxGa1−xN alloy has been analyzed using a simplified model of interband transitions (E ≤ 10 eV). The present model reveals distinct structures at energies of the E0, E1, F1, and E0′ critical points. The Cauchy−Lorentz expression popularly used for the modeling of the three-dimensional M0 and saddle-point excitonic transitions does not satisfy the Kramers−Krönig requirements but does so if its form is properly modified. As a result, excellent agreement is achieved between the experimental and calculated ε(E) spectra over the entire range of photon energies. Dielectric-related optical constants, such as the complex refractive index, absorption coefficient, and normal-incidence reflectivity, of the AlxGa1−xN alloy are also presented. The high-frequency and static dielectric constants of the AlxGa1−xN alloy are determined to be ε∞(x) = 5.27−1.07x and εs(x) = 9.28−1.45x, respectively.
Show PACS
78.66.Fd III-V semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
71.35.-y Excitons and related phenomena

Quantum effect on modulational instability of laser radiation in a semiconductor plasma

M. R. Amin

J. Appl. Phys. 107, 023307 (2010); http://dx.doi.org/10.1063/1.3295917 (7 pages)

Online Publication Date: 29 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Modulational instability of a high power laser radiation in a homogeneous unmagnetized piezoelectric semiconductor plasma has been investigated analytically. The fluid equations of quantum hydrodynamics coupled with the Maxwell’s equations have been employed to find the nonlinear response of electrons in the piezoelectric semiconductor. The analysis is carried out through the derivation of the nonlinear dispersion relation for the four-wave modulational instability. An expression for the growth rate of the instability including the quantum effect due to Bohm potential has been obtained from the nonlinear dispersion relation. The quantum effect is observed to play a vital role in the four-wave scattering process. For a particular set of parameters, the quantum effect enhances the growth rate of the modulational instability by 37% compared to the growth rate predicted by the classical theory.
Show PACS
52.38.Hb Self-focussing, channeling, and filamentation in plasmas
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.60.Mi Dynamical laser instabilities; noisy laser behavior
42.60.Fc Modulation, tuning, and mode locking
52.20.-j Elementary processes in plasmas
52.35.Mw Nonlinear phenomena: waves, wave propagation, and other interactions (including parametric effects, mode coupling, ponderomotive effects, etc.)

High energy electron fluxes in dc-augmented capacitively coupled plasmas I. Fundamental characteristics

Mingmei Wang and Mark J. Kushner

J. Appl. Phys. 107, 023308 (2010); http://dx.doi.org/10.1063/1.3290870 (10 pages) | Cited 10 times

Online Publication Date: 29 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Power deposition from electrons in capacitively coupled plasmas (CCPs) has components from stochastic heating, Joule heating, and from the acceleration of secondary electrons through sheaths produced by ion, electron, or photon bombardment of electrodes. The sheath accelerated electrons can produce high energy beams which, in addition to producing excitation and ionization in the gas can penetrate through the plasma and be incident on the opposite electrode. In the use of CCPs for microelectronics fabrication, there may be an advantage to having these high energy electrons interact with the wafer. To control the energy and increase the flux of the high energy electrons, a dc bias can be externally imposed on the electrode opposite the wafer, thereby producing a dc-augmented CCP (dc-CCP). In this paper, the characteristics of dc-CCPs will be discussed using results from a computational study. We found that for a given rf bias power, beams of high energy electrons having a narrow angular spread (<1°) can be produced incident on the wafer. The maximum energy in the high energy electron flux scales as εmax = −Vdc+Vrf+Vrf0, for a voltage on the dc electrode of Vdc, rf voltage of Vrf, and dc bias on the rf electrode of Vrf0. The dc current from the biased electrode must return to ground through surfaces other than the rf electrode and so seeks out a ground plane, typically the side walls. If the side wall is coated with a poorly conducting polymer, the surface will charge to drive the dc current through.
Show PACS
52.77.Dq Plasma-based ion implantation and deposition
81.15.Jj Ion and electron beam-assisted deposition; ion plating
52.40.Kh Plasma sheaths
52.50.-b Plasma production and heating

High energy electron fluxes in dc-augmented capacitively coupled plasmas. II. Effects on twisting in high aspect ratio etching of dielectrics

Mingmei Wang and Mark J. Kushner

J. Appl. Phys. 107, 023309 (2010); http://dx.doi.org/10.1063/1.3290873 (11 pages) | Cited 5 times

Online Publication Date: 29 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In high aspect ratio (HAR) plasma etching of holes and trenches in dielectrics, sporadic twisting is often observed. Twisting is the randomly occurring divergence of a hole or trench from the vertical. Many causes have been proposed for twisting, one of which is stochastic charging. As feature sizes shrink, the fluxes of plasma particles, and ions in particular, into the feature become statistical. Randomly deposited charge by ions on the inside of a feature may be sufficient to produce lateral electric fields which divert incoming ions and initiate nonvertical etching or twisting. This is particularly problematic when etching with fluorocarbon gas mixtures where deposition of polymer in the feature may trap charge. dc-augmented capacitively coupled plasmas (dc-CCPs) have been investigated as a remedy for twisting. In these devices, high energy electron (HEE) beams having narrow angular spreads can be generated. HEEs incident onto the wafer which penetrate into HAR features can neutralize the positive charge and so reduce the incidence of twisting. In this paper, we report on results from a computational investigation of plasma etching of SiO2 in a dc-CCP using Ar/C4F8/O2 gas mixtures. We found that HEE beams incident onto the wafer are capable of penetrating into features and partially neutralizing positive charge buildup due to sporadic ion charging, thereby reducing the incidence of twisting. Increasing the rf bias power increases the HEE beam energy and flux with some indication of improvement of twisting, but there are also changes in the ion energy and fluxes, so this is not an unambiguous improvement. Increasing the dc bias voltage while keeping the rf bias voltage constant increases the maximum energy of the HEE and its flux while the ion characteristics remain nearly constant. For these conditions, the occurrence of twisting decreases with increasing HEE energy and flux.
Show PACS
81.65.Cf Surface cleaning, etching, patterning
52.77.-j Plasma applications
back to top Structural, Mechanical, Thermodynamic, and Optical Properties of Condensed Matter

Temperature behavior of electron-acceptor transitions and oxygen vacancy recombinations in ZnO thin films

Xiangdong Meng, Zhiming Shi, Xiaobing Chen, Xianghua Zeng, and Zhuxi Fu

J. Appl. Phys. 107, 023501 (2010); http://dx.doi.org/10.1063/1.3284101 (4 pages) | Cited 9 times

Online Publication Date: 19 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The present study focuses on the photoluminescence (PL) properties of ZnO films prepared by the reaction of water and zinc. Temperature-dependent PL characteristics of the ZnO films have been investigated in the range from 15 to 260 K. The PL spectrum at 15 K is dominated by neutral donor-bound exciton (D0X) emissions. The emission line at about 3.304 eV can be due to the transition of free electrons to neutral acceptor states (eA0). It is suggested that the ultraviolet emission at room temperature can be attributed to the incorporation of eA0 and free exciton (FX) transitions, rather than sole FX. According to the temperature behavior of green band, it is further confirmed that the green emission is mainly related to the singly ionized oxygen vacancies.
Show PACS
78.55.Et II-VI semiconductors
78.66.Hf II-VI semiconductors
71.35.-y Excitons and related phenomena
68.55.ag Semiconductors
61.72.jd Vacancies

Spectroscopic ellipsometry study of hydrogenated amorphous silicon carbon alloy films deposited by plasma enhanced chemical vapor deposition

D. K. Basa, G. Abbate, G. Ambrosone, U. Coscia, and A. Marino

J. Appl. Phys. 107, 023502 (2010); http://dx.doi.org/10.1063/1.3277016 (6 pages) | Cited 6 times

Online Publication Date: 19 January 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The optical properties of the hydrogenated amorphous silicon carbon alloy films, prepared by plasma enhanced chemical vapor deposition technique from silane and methane gas mixture diluted in helium, have been investigated using variable angle spectroscopic ellipsometry in the photon energy range from 0.73 to 4.59 eV. Tauc–Lorentz model has been employed for the analysis of the optical spectra and it has been demonstrated that the model parameters are correlated with the carbon content as well as to the structural properties of the studied films.
Show PACS
78.66.Jg Amorphous semiconductors; glasses
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.ag Semiconductors
81.05.Gc Amorphous semiconductors
52.77.Dq Plasma-based ion implantation and deposition
Page 1 of 6 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close