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

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue

1 Dec 1979

Volume 50, Issue 12, pp. 7875-8265

Page 1 of 3 Pages Next Page | Jump to Page

Free‐electron lasers, boundary deformation, and the Robinson‐Liouville theorem

J. M. J. Madey, D. A. G. Deacon, and T. I. Smith

J. Appl. Phys. 50, 7875 (1979); http://dx.doi.org/10.1063/1.325977 (5 pages) | Cited 1 time

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
We consider the evolution of the electrons’ phase‐space distribution as they move through the interaction region in a free‐electron laser.
Show PACS
45.05.+x General theory of classical mechanics of discrete systems
42.60.-v Laser optical systems: design and operation
41.75.Fr Electron and positron beams

Optoacoustic measurements of diesel particulate emissions

Fred R. Faxvog and David M. Roessler

J. Appl. Phys. 50, 7880 (1979); http://dx.doi.org/10.1063/1.325978 (3 pages) | Cited 16 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
Infrared absorption by acetylene and diesel smoke particles was measured using a differential optoacoustic cell driven by a 3.4‐W CO2 laser. Real‐time particle mass concentration measurements are demonstrated. In addition we found the average particle extinction cross sections per unit mass of acetylene and diesel smoke were 0.94±0.1 m2/g and 0.83±0.2 m2/g, respectively, at the 10.6‐μm wavelength.
Show PACS
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.07.-a General equipment
07.60.-j Optical instruments and equipment
07.90.+c Other topics in instruments, apparatus, and components common to several branches of physics and astronomy (restricted to new topics in section 07)

Ge photocapacitive MIS infrared detectors

S. C. Binari, W. E. Miller, A. Sher, and Y. H. Tsuo

J. Appl. Phys. 50, 7883 (1979); http://dx.doi.org/10.1063/1.325979 (4 pages) | Cited 1 time

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
An undoped Ge photocapacitive detector is reported which has peak normalized detectivities D∗λ at wavelengh 1.4 μm and chopping frequencies 13–103 Hz of 9×1012, 1×1012, 4×109 cm Hz1/2/W, operating respectively at temperatures 77, 195, and 295 °K. The observed temperature, spectral, and frequency response of the signal and noise are explained in terms of the measured space charge and interface state properties of the device.
Show PACS
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.60.Gz Photodetectors (including infrared and CCD detectors)

Thin‐film sputtering yields for Fe, Cr, and an Fe‐Cr alloy measured by proton‐induced x rays

B. D. Sartwell

J. Appl. Phys. 50, 7887 (1979); http://dx.doi.org/10.1063/1.325980 (7 pages) | Cited 4 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
Proton‐induced x‐ray emission (PIXE) was used to measure the sputtering yields of thin films bombarded by 1.0 keV Ar+ at normal incidence. The films consisted of vacuum‐evaporated iron, chromium, and an Fe‐Cr alloy. An integral approximation to the theoretical x‐ray yield equation was developed that resulted in the determination of the thicknesses of the thin films. In general, this appoximation can be used to measure film thicknesses up to several hundred nanometers. The sputtering yields were determined by measuring the slope of the straight‐line fit to the experimental data which was obtained as film thickness versus accumulated sputtering charge. The chromium sputtering yield, measured by PIXE for a chromium film evaporated onto an electropolished iron substrate, agreed within 5% of that obtained using an energy‐dispersive x‐ray analyzer attached to an SEM. The sputtering yields measured for iron and chromium films with initial thicknesses between 5×1017 and 9×1017 atoms/cm2 deposited onto a nickel substrate were S (Fe) =1.23 atoms/ion and S (Cr) =0.93 atoms/ion. The agreement with previously published data for S (Fe) is good; no published data on S (Cr) are known. Using recently derived values for the nuclear stopping power, the measured iron and chromium sputtering yields agree well with Sigmund’s theory. The total sputtering yield obtained for an Fe‐35Cr alloy was 1.17 atoms/ion, and the elemental sputtering yields for the alloy were in the ratio of their concentrations. The advantages of using the PIXE technique over other techniques currently being used, particularly for compounds, are discussed.
Show PACS
34.50.Lf Chemical reactions
34.90.+q Other topics in atomic and molecular collision processes and interactions (restricted to new topics in section 34)

Nondestructive analysis of laser fusion microsphere targets using rotational Raman spectroscopy

Michael C. Drake, Gregory J. Rosasco, Roger Schneggenburger, and Robert L. Nolen

J. Appl. Phys. 50, 7894 (1979); http://dx.doi.org/10.1063/1.325981 (4 pages) | Cited 4 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
The use of rotational Raman scattering for nondestructive analysis of laser fusion microsphere targets is reported. Typical hollow‐glass‐microsphere sample characteristics are 100 μm in diameter, 1.0 μm in glass wall thickness, and 0.5 nl in volume, containing a mixture of hydrogen, deuterium, and tritium gases at pressures of 10–70 atm (total gas sample weights of 5 ng). Relative species mole fraction measurements for all hydrogen isotope species are determined from spectral peak height analysis of rotational Raman spectra. Accuracies of ±0.01 (mole fraction) are obtained from spectra requiring 20 min scan time. Individual species detectability limits are less than 100 picogram. Absolute partial pressure measurements (accurate to ±20%) are obtained using calibration spheres of known diameter and pressure.
Show PACS
07.77.-n Atomic, molecular, and charged-particle sources and detectors
37.20.+j Atomic and molecular beam sources and techniques
33.20.-t Molecular spectra
33.15.Ta Mass spectra

The formation of waveguides and modulators in LiNbO3 by ion implantation

G. L. Destefanis, J. P. Gailliard, E. L. Ligeon, S. Valette, B. W. Farmery, P. D. Townsend, and A. Perez

J. Appl. Phys. 50, 7898 (1979); http://dx.doi.org/10.1063/1.325982 (8 pages) | Cited 80 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
Ion implantation is an attractive method for writing optical circuits for use in integrated optics. In LiNbO3 it is shown that there are large changes produced in both refractive indices n0 and ne by the energy deposited in nuclear collisions between the implanted ions and the lattice. The process is insensitive to ion species and at 300 K a universal curve exists for the decrease of n0 as a function of deposited energy by nuclear collisions. Saturation changes of −6% occur at 300 °K, and larger values are noted for 77 K implants. The saturation condition is reached after the deposition of ∼1022 keV cm−3 from the ion beams. Because the indices are reduced, ion beams have been used to write low index boundaries to define waveguiding regions. By using energetic light ions (e.g., 2‐MeV He+) negligible change is produced in the surface layer where the energy loss is primarily electronic and thus the low index region is formed deep within the solid. The computed and measured mode characteristics are in good agreement. The guides show complex annealing characteristics but absorption losses are negligible after annealing at 200 °C. Guiding action exists after heat treatments up to some 400 °C. The surface layers retain crystallinity and electro‐optic properties; as a demonstration of this we report results from three‐dimensional modulators formed by helium‐ion implantation.
Show PACS
42.79.Gn Optical waveguides and couplers
41.75.Ak Positive-ion beams
41.75.Cn Negative-ion beams
61.72.U- Doping and impurity implantation
78.30.Hv Other nonmetallic inorganics
78.40.Ha Other nonmetallic inorganics

Phase‐matched second‐harmonic generation in vapor‐grown GaP ribbon waveguides

J. Stone, C. A. Burrus, and R. D. Standley

J. Appl. Phys. 50, 7906 (1979); http://dx.doi.org/10.1063/1.325964 (8 pages) | Cited 3 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
Phase‐matched second‐harmonic generation has been achieved in twinned as‐grown ribbon ’’whiskers’’ of GaP about 50 μm wide and of submicrometer thicknesses. These naturally occurring slab waveguides were pumped with a Nd : YAG laser at a wavelength of 1.064 μm, and the second‐harmonic output was observed as greenlight at 0.532 μm wavelength. Experiments concerning the second‐harmonic generation are described, and the results are related to those expected from the crystallography of, and the modal dispersion in, the slab‐waveguide ribbons.
Show PACS
42.65.Dr Stimulated Raman scattering; CARS
42.65.Es Stimulated Brillouin and Rayleigh scattering
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
68.70.+w Whiskers and dendrites (growth, structure, and nonelectronic properties)
42.79.Gn Optical waveguides and couplers
42.70.-a Optical materials

Strain‐enhanced luminescence degradation in GaAs/GaAlAs double‐heterostructure lasers revealed by photoluminescence

B. Wakefield

J. Appl. Phys. 50, 7914 (1979); http://dx.doi.org/10.1063/1.325965 (3 pages) | Cited 20 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
Photoluminescence degradation observed in room‐temperature‐lifetested GaAs/GaAlAs DH stripe lasers has been correlated with the strain field induced in the devices by the stripe‐defining oxide. A degradation mechanism based on strain‐ and nonradiative‐recombination‐enhanced point‐defect migration is proposed.
Show PACS
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.55.Px Semiconductor lasers; laser diodes
61.80.-x Physical radiation effects, radiation damage

Measurement of phase fluctuations in a HF chemical laser beam

C. P. Wang and R. L. Varwig

J. Appl. Phys. 50, 7917 (1979); http://dx.doi.org/10.1063/1.325966 (4 pages) | Cited 5 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
A new phase detector, which uses an acousto‐optic modulation and optical heterodyne technique, has been developed. The minimum detectable phase difference is 4 °, with a temporal response of 10 μsec and a spatial resolution of 0.14 mm. This phase detector was used to measure fluctuations in the wave front of a cw HF chemical laser beam caused by mechanical vibration, medium turbulence, and gain variation. Potential applications are laser beam quality measurement, beam steering measurement, and sensing for an active resonator.
Show PACS
42.55.Ks Chemical lasers
42.60.By Design of specific laser systems

CO2‐laser‐produced plasma‐initiated neutral‐gas recombination lasers

W. T. Silfvast, L. H. Szeto, and O. R. Wood

J. Appl. Phys. 50, 7921 (1979); http://dx.doi.org/10.1063/1.325967 (8 pages) | Cited 5 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
Plasmas produced with focused 10.6‐μm radiation from a high‐pressure pulsed CO2 laser have been used to initiate a number of neutral‐gas recombination lasers. The results have implications for the future development of high‐efficiency lasers in the near infrared.
Show PACS
42.55.Lt Gas lasers including excimer and metal-vapor lasers
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)

Measurements of absorption in the CdHg excimer system

John B. West, Hiroshi Komine, and Eddy A. Stappaerts

J. Appl. Phys. 50, 7929 (1979); http://dx.doi.org/10.1063/1.325968 (5 pages) | Cited 5 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
The CdHg excimer has received attention as a possible efficient visible laser medium. In the experiments described here, a pulsed tunable laser was used to excite the Cd(5 3P1) atomic state, which forms CdHg excimers in three‐body collisions with Hg and Ar. Gain and absorption measurements were performed by using an argon‐ion laser to probe several wavelengths within the 470‐nm excimer emission band. Net absorption was observed at all wavelengths investigated. Acoustic and thermal disturbances which might mimic absorption have been carefully considered and it is determined that these are not important. We conclude that the CdHg excimer exhibits net absorption within its 470‐nm emission band. These results cast considerable doubt on the possibility of efficient laser action in CdHg.
Show PACS
42.25.Bs Wave propagation, transmission and absorption
42.55.Lt Gas lasers including excimer and metal-vapor lasers

Operation characteristics of buried‐stripe GaInAsP/InP DH lasers made by melt‐back method

H. Kano and K. Sugiyama

J. Appl. Phys. 50, 7934 (1979); http://dx.doi.org/10.1063/1.325969 (5 pages) | Cited 3 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
A buried‐stripe configuration of GaInAsP/InP dh laser was made by using a melt‐back method combined with a chemical etching for obtaining a mesa‐stripe geometry. The wavelength of laser emission was 1.3 μm at room temperature. The lowest threshold current of cw operation at room temperature was 30 mA with the 2‐μm‐wide buried‐stripe laser. External differential quantum efficiency was 24% per facet, and the laser power increased up to 40 mW (dc current of 230 mA) without any significant kink. As the buried‐stripe laser had good thermal characteristics, cw operation was realized at 100 °C in a laboratory atmosphere. When the buried‐stripe laser was activated by a pulse current of 3 ns in width, no relaxation oscillation was observed in the pulse response of laser emission, which is considered to be preferable for high‐speed modulation of the laser power.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.82.-m Integrated optics

CO chemical laser utilizing combustor‐generated reactants

R. J. Richardson, H. Y. Ageno, H. V. Lilenfeld, T. J. Menne, J. A. Smith, and C. E. Wiswall

J. Appl. Phys. 50, 7939 (1979); http://dx.doi.org/10.1063/1.325970 (9 pages) | Cited 3 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
A CO chemical laser utilizing combustor‐generated CS and S is described. The combustor is fueled with NF3‐CH4‐H2‐CS2 and produces CS and S and the side products HF and N2. A common supersonic expansion mixing nozzle is used to extract the CS and S from the combustor and mix O2 and diluent (N2 or He) into the flow stream. A chain reaction between CS and O2 in the mixed flow stream, initiated by S atoms, produces vibrationally excited CO. The maximum power obtained from the laser was 700 W operating with He in a free expansion. Pressure and temperature measurements of the supersonic flow stream are compared with the results of a one‐dimensional fluid‐dynamics model, and the results of mass‐spectrometric sampling are presented. It is concluded that the power extraction efficiency could be greatly improved by operation of the laser with either a combustor fuel–oxidizer combination that does not produce HF or an improved supersonic mixing nozzle. Nevertheless, it has been demonstrated that the output power of this device scales with mass flowrate.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
82.33.Vx Reactions in flames, combustion, and explosions
78.60.Ps Chemiluminescence

Ultrasonic nonspecular reflectivity near longitudinal critical angle

Tran D. K. Ngoc and Walter G. Mayer

J. Appl. Phys. 50, 7948 (1979); http://dx.doi.org/10.1063/1.325971 (4 pages) | Cited 6 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
A numerical integration method is developed to determine the intensity profile of an ultrasonic beam reflected from a liquid‐solid interface near the longitudinal critical angle. The profiles are calculated for different combinations of frequencies and beam widths with the angle of incidence being varied about the longitudinal critical angle for a water‐Plexiglas interface. These calculations demonstrate the existence of nonspecular reflectivity near this particular critical angle and provide a quantitative description of its basic features. Theoretical results and experimental measurements are compared.
Show PACS
43.20.Fn Scattering of acoustic waves
43.35.Pt Surface waves in solids and liquids

Laser heating of a slab having temperature‐dependent surface absorptance

R. E. Warren and M. Sparks

J. Appl. Phys. 50, 7952 (1979); http://dx.doi.org/10.1063/1.325972 (6 pages) | Cited 12 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
The exact solution obtained here for the temperature in a laser‐heated slab with surface absorptance A=Ai+A1 T (0,t) proportional to temperature and with negligible radial heat flow, shows that the temperature is considerably greater in general than for A1=0. In the limit of long time, for negligible cooling, the surface temperature increases exponentially as TA{ exp[(I/Il)(t/τl)]−1} for I≲Il and as TA{2 exp[(I/Il)2(t/τl)]−1} for I≳Il, where TA=Ai/A1, Il=K/lA1, τl=Cl2/K, K is the thermal conductivity, C is the heat capacity per unit volume, and l is the slab thickness. The limiting temperature derived here for t≳τl/5 and that derived by Sparks and Loh for t≲τl/5 afford simple closed‐form expressions for T (z,t) for all z and t. With cooling, the temperature increases without bound (thermal runaway) for I≳Ihl, where Ihl=Il[Hs+H/(1+H)] with Hs and H normalized heat‐transfer coefficients at the front and rear surfaces of the slab. The intrinsic cw damage threshold, which is slightly less than Ihl, can be quite low—from 100 W/cm2 to 150 kW/cm2 for the examples considered. The ability to withstand a given irradiance in a small beam does not imply the ability to withstand the same irradiance in a large beam.
Show PACS
44.10.+i Heat conduction
61.80.-x Physical radiation effects, radiation damage

The evaporation rate from a single cathode spot on precious metal electrodes in vacuum arcs

Takayoshi Kubono

J. Appl. Phys. 50, 7958 (1979); http://dx.doi.org/10.1063/1.325937 (7 pages) | Cited 4 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
Utilizing the values of a cathode spot radius and its temperature, which are calculated on the basis of the cathode mechanism theory proposed recently by Kubono, the rate of metal evaporation from a single cathode spot on Ag, Au, Ir, Pd, Pt, and Rh electrodes is expressed in simple approximate formulas as a function of arc current. In the case of Ag and Au electrodes, the calculated results are found to be in agreement with experimental data by different investigators, but it is difficult to compare calculations with measurements on the other electrodes because of few experimental data. This estimating process and these approximate formulas for the radius, temperature, and evaporation rate on the cathode spot as a function of arc current are useful, because it is very laborious to measure the cathode spot radius, temperature, and the evaporation rate.
Show PACS
52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.80.Vp Discharge in vacuum
81.40.-z Treatment of materials and its effects on microstructure, nanostructure, and properties
84.32.Dd Connectors, relays, and switches

Electric discharge excitation of thallium in high‐pressure xenon

L. W. Schumann, D. W. Wildman, and A. C. Gallagher

J. Appl. Phys. 50, 7965 (1979); http://dx.doi.org/10.1063/1.325973 (6 pages) | Cited 2 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
We report data obtained in pulsed 1.5–280‐MW/l electric discharges in thallium‐doped xenon gas at thallium densities of (1.5–26) ×1015 cm−3 and xenon densities of (1–4) ×1019 cm−3. Stable steady‐state discharges were obtained without the use of preionization or sustainers. Steady‐state E/N, J/N, and Tl and Xe excited‐state populations were determined for the positive column of the discharge. These measurements indicate an electron temperature of 0.45–0.65 eV, with the gas temperature remaining at ∼0.1 eV during the several‐microsecond discharges. The thallium states lower in energy than Tl(8S1/2) generally show a higher excitation temperature than the states from Tl(8S1/2) to the thallium ionization limit, particularly at the higher current densities. The homogeneity of a 9‐cm‐long transverse discharge and the effects of this discharge on a laser beam propagating through the thallium‐xenon medium were investigated. The implications of these results for a discharge‐pumped Tl‐Xe excimer laser are discussed.
Show PACS
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.80.-s Electric discharges
42.55.Lt Gas lasers including excimer and metal-vapor lasers
42.68.Wt Remote sensing; LIDAR and adaptive systems

Enhanced arcing as a function of organic exposure and arc current for Pd and Pd/Ag electrodes

Eoin W. Gray and Julian R. Pharney

J. Appl. Phys. 50, 7971 (1979); http://dx.doi.org/10.1063/1.325974 (3 pages) | Cited 3 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
We report the existence of a region within which enhanced arcing (activation) exists for palladium and palladium/silver contacts, as a function of arc current and of exposure to organic vapors. The current range where activation exists is from ∼0.1 to ∼1.2 A, where the range of exposures (partial pressure times time) used for diethyl phthalate was from ∼10−3 to ∼10 Pa s. At very low organic exposure levels (depending upon the organic vapor and the electrode metal), arc‐duration statistics show an exponential behavior. Under moderate to high organic exposure levels, arc‐duration show a log‐normal distribution similar to that obtained under clean conditions when the arc current exceeds the minimum arc‐sustaining current. At sufficiently high currents arc‐duration statistics become independent of organic exposure. The envelope of the activated curves is predicted by the activation theory of Gray, Uhrig, and Hohnstreiter.
Show PACS
52.80.Mg Arcs; sparks; lightning; atmospheric electricity

Spectra of a glow discharge in flowing nitrogen

H. Keren, Y. Kaufman, F. Dothan, and P. Avivi

J. Appl. Phys. 50, 7974 (1979); http://dx.doi.org/10.1063/1.325975 (3 pages)

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
The visible spectrum of the positive column of a glow discharge in flowing nitrogen was investigated. There is experimental evidence that the emission spectra depend on the flow velocity and that the changes in the intensity of the first positive and second positive bands of nitrogen are quite different. The results cannot be explained by one‐step excitation of electronic levels from the ground state. On the other hand they are consistent with the assumption of stepwise excitation and of atomic recombination to electronically excited molecular levels.
Show PACS
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
51.70.+f Optical and dielectric properties
52.80.Hc Glow; corona

Precessional rotation and other nonlinear effects due to standing waves and other two‐wave resonant interactions in a magnetized plasma

Manoranjan Khan and B. Chakraborty

J. Appl. Phys. 50, 7977 (1979); http://dx.doi.org/10.1063/1.325976 (9 pages) | Cited 10 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
When two electromagnetic waves propagate along the fixed direction of an uniform and constant magnetic field in a homogeneous, cold, and collisionally damped plasma, the effects of their nonlinear interaction are large and so important in two special cases. One is the case in which the beat frequency equals the characteristic plasma frequency and moreover, one of the wave frequencies equals the gyration frequency of electrons (or ions). The other is the nonlinear evolution of the wave pattern formed by an appropriate superposition of the two waves in a manner which produces standing waves from them in the linear approximation. These two cases have been theoretically investigated in this paper. Moreover, the nonlinear evolution of the standing‐wave patterns has been discussed with a view to initiate the exploration of the application side of this effect.
Show PACS
52.40.Db Electromagnetic (nonlaser) radiation interactions with plasma
52.35.Hr Electromagnetic waves (e.g., electron-cyclotron, Whistler, Bernstein, upper hybrid, lower hybrid)
52.35.Mw Nonlinear phenomena: waves, wave propagation, and other interactions (including parametric effects, mode coupling, ponderomotive effects, etc.)

Associated incorporation of boron, lead, and oxygen vacancies in garnets

B. Andlauer and W. Tolksdorf

J. Appl. Phys. 50, 7986 (1979); http://dx.doi.org/10.1063/1.325983 (10 pages) | Cited 3 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
Local vibrational modes observed in the IR spectrum of iron garnets and noniron garnets have been identified and arise from a complex formed by a boron‐oxygen group [BO3]3−, a heavy metal ion M2+, and an oxygen vacancy. The energy of the local modes is affected by the electron population of the vacancy ranging from 0 to 2, and by the exact nature of the M2+ ion, being in most cases Pb2+. This is a first spectroscopic indication of the occurrence of oxygen vacancies in iron garnets. In iron‐containing garnets, the whole complex can act as a charge compensator of additional lattice defects, owing to the associated M2+ ion and oxygen vacancy, the latter having different states of ionization. From the boron spectrum observed in a particular yttrium iron garnet (YIG) sample, one may infer at least in a qualitative way the underlying position of the Fermi level. Measurements at different temperatures reveal that the donor level of the singly ionized oxygen vacancy in YIG should lie about 0.15 eV below the level of a silicon donor residing nearby. Formation of the boron‐oxygen complex near the M2+ ion seems to be facilitated since it tends to compensate the expansive lattice strain induced by the heavy metal ion.
Show PACS
61.72.J- Point defects and defect clusters
78.30.Hv Other nonmetallic inorganics
78.40.Ha Other nonmetallic inorganics
71.55.Ht Other nonmetals
63.20.Pw Localized modes

Kinetics of growth of the oxidation stacking faults

Bernard Leroy

J. Appl. Phys. 50, 7996 (1979); http://dx.doi.org/10.1063/1.325984 (10 pages) | Cited 57 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
A model for the growth of oxidation stacking faults (OSF) has been developed with three main hypotheses: (1) The growth of the OSF is due to the diffusion of silicon self‐interstitials from the Si‐SiO2 interface to the partial dislocation. The diffusion coefficient of the interstitials can be determined from the data of silicon self‐diffusion. (2) The concentration of interstitials at the Si‐SiO2 interface, Cs, is determined by the equilibrium between the interstitials and the atoms of oxygen free to react with the silicon atoms, Cs =4.1×1018t−0.25 PO20.25 exp(−0.5/kT)  F, where Cs is in cm−3, t is the time in seconds, PO2 is the oxygen partial pressure in atmospheres, and kT is in eV. F value is 1 for wafers of (001) orientation, and 0.7 for the (111) wafers. (3) The concentration of the interstitials in equilibrium with the partial dislocation, C0, in cm−3, is C0=12×1025 exp(−3.02/kT), with kT in eV. The majority of the experimental data can be calculated from R =1640Ft0.75 PO20.25 exp(−2.5/kT) −3.6×1010t exp(−5.02/kT), where R is one‐half of the OSF length in cm, t is in sec, PO2 is in atmospheres, and kT is in eV. The role of the vacancies in the OSF growth is also discussed, but the model favors a mechanism of silicon self‐diffusion involving a silicon interstitial, and a double mechanism for boron diffusion.
Show PACS
61.72.Nn Stacking faults and other planar or extended defects
66.30.Lw Diffusion of other defects
81.65.-b Surface treatments

Characterization of grain boundaries using deep level transient spectroscopy

Michael Spencer, Richard Stall, Lester F. Eastman, and Colin E.C. Wood

J. Appl. Phys. 50, 8006 (1979); http://dx.doi.org/10.1063/1.325985 (4 pages) | Cited 17 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
Using the rectifying characteristics of grain boundaries, modified deep‐level transient spectroscopy (DLTS) and optical deep‐level transient spectroscopy (ODLTS) sensitive techniques have been developed for identification and for quantitative estimation of electron and hole traps in the region of grain boundaries. This method has been used in conjunction with conventional surface oriented Schottky barrier DLTS and ODLTS techniques to show accumulation of native defects, enhanced segregation, and diffusion of copper from the substrate along grain boundaries during epitaxy of GaAs.
Show PACS
61.72.Mm Grain and twin boundaries

Effect of morphology on the properties of alkaline earth silicate glasses

J. E. Shelby

J. Appl. Phys. 50, 8010 (1979); http://dx.doi.org/10.1063/1.325986 (6 pages) | Cited 15 times

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
The effect of morphology on the thermal expansion behavior, helium permeability, density, and refractive index of alkaline earth silicate glasses has been determined for the calcium, strontium, and barium silicate systems. These data have been used to determine the miscibility limits and the limits of connectivity of the high silica phase for each of these systems. The miscibility limits occur at approximately 46, 42, and 40 mol% CaO, SrO, and BaO, respectively. The limit for a connected high silica phase occurs at approximately 33, 25, and 22 mol% CaO, SrO, and BaO, respectively. This paper demonstrates the use of these techniques in the determination of the morphology of simple glass‐forming systems.
Show PACS
81.05.Kf Glasses (including metallic glasses)
65.40.De Thermal expansion; thermomechanical effects
66.30.J- Diffusion of impurities
81.90.+c Other topics in materials science (restricted to new topics in section 81)

Net lateral flow during a twist‐cell cycle

Dwight W. Berreman and Alan Sussman

J. Appl. Phys. 50, 8016 (1979); http://dx.doi.org/10.1063/1.325987 (3 pages)

Online Publication Date: 29 July 2008

Full Text: | Download PDF

Show Abstract
The flow pattern that is caused by the backflow effect when a twist cell is turned on is not exactly reversed when the cell is turned off. Computer simulation of flow far from the boundary of an element shows an average lateral flow distance of up to several percent of the cell thickness in each cycle. This flow would account for observed transport and deposition of particles of debris at one edge or corner of deteriorating cells. Such flow has also been observed directly by introducing dye markers into cells.
Show PACS
61.30.-v Liquid crystals
47.15.-x Laminar flows
85.60.-q Optoelectronic devices
46.35.+z Viscoelasticity, plasticity, viscoplasticity
83.60.Bc Linear viscoelasticity
83.60.Df Nonlinear viscoelasticity
Page 1 of 3 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close