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

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue

15 Dec 1995

Volume 78, Issue 12, pp. 6885-7427

Page 1 of 4 Pages Next Page | Jump to Page

Local and global ordering in rodlike polymer monolayers at the air–water interface

Yang‐Ming Zhu and Yu Wei

J. Appl. Phys. 78, 6885 (1995); http://dx.doi.org/10.1063/1.360454 (3 pages)

Full Text: | Download PDF

Show Abstract
The compressed monolayers of a rodlike polymer at the air–water interface were transferred onto solid substrates by a horizontal lifting method and studied by the liquid crystal alignment technique. It has been found that the rodlike polymer monolayers have a well ordered orientation on a local region while on a larger scale they consist of disordered domains within which the polymers are uniformly oriented. © 1995 American Institute of Physics.
Show PACS
61.41.+e Polymers, elastomers, and plastics
68.18.-g Langmuir-Blodgett films on liquids

Stochastic scattering in charged particle projection systems: A nearest neighbor approach

M. M. Mkrtchyan, J. A. Liddle, S. D. Berger, L. R. Harriott, J. M. Gibson, and A. M. Schwartz

J. Appl. Phys. 78, 6888 (1995); http://dx.doi.org/10.1063/1.360455 (15 pages) | Cited 22 times

Full Text: | Download PDF

Show Abstract
Image blurring as a result of stochastic particle–particle interactions has been investigated for projection electron‐ and ion‐beam lithography systems. A comparative analysis of the currently available analytical theories is presented. The results from these theories are also compared with Monte Carlo simulation results and experimental data. Large variations in results and serious disagreements between the different theoretical approaches are found. We have formulated a new theory on the basis of a simple, analytical approach that overcomes most of the difficulties experienced by earlier theories with two key concepts: consideration of nearest‐neighbor interactions only, and a randomization length, over which the interactions are correlated. Our model displays satisfactory functional and numerical agreement with Monte Carlo simulation results over a large range of beam currents, as well as with the only available experimental data. The physical basis of our model also enables us to understand the origins of the discrepancies arising from earlier theories. © 1995 American Institute of Physics.
Show PACS
41.75.Fr Electron and positron beams
85.40.Hp Lithography, masks and pattern transfer

Photorefractive composites with high‐band‐gap second‐order nonlinear optical chromophores

Ryszard Burzynski, Yue Zhang, Saswati Ghosal, and Martin K. Casstevens

J. Appl. Phys. 78, 6903 (1995); http://dx.doi.org/10.1063/1.360456 (5 pages) | Cited 11 times

Full Text: | Download PDF

Show Abstract
A series of photorefractive composite materials has been developed in which an inert polymer has been doped with second‐order nonlinear optical chromophores, charge transporting agents, and photocharge generation sensitizers. The composites show high photoconductivity, large photorefractive responses, and optical transparency at many wavelengths. Photorefractivity has been demonstrated at wavelengths of 633, 514.5, and 488 nm, with net two‐beam coupling gains. © 1995 American Institute of Physics.
Show PACS
42.70.Jk Polymers and organics
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
78.20.Jq Electro-optical effects

Optical gain and laser emission in HgCdTe heterostructures

J. Bonnet‐Gamard, J. Bleuse, N. Magnea, and J. L. Pautrat

J. Appl. Phys. 78, 6908 (1995); http://dx.doi.org/10.1063/1.360457 (8 pages) | Cited 8 times

Full Text: | Download PDF

Show Abstract
A detailed study of stimulated emission mechanisms as well as laser emission capability has been carried out on Hg1−xCdxTe (0.44<x<0.5) separate‐confinement heterostructures grown by molecular beam epitaxy. At low temperature, spontaneous photoluminescence (PL) occurs on extrinsic levels below the gap whereas optical gain exhibits a maximum of stimulated emission shifted towards higher energy, close to the gap. As temperature increases, spontaneous PL is shifted from the extrinsic states to the band‐to‐band transition by a thermally activated detrapping of the carriers. Above 100 K, spontaneous and stimulated emission vary in a similar way with temperature. Laser emission has been observed up to room temperature for all the heterostructures. The use of quantum wells in the active layer and graded index in the barriers has allowed a significant reduction of the excitation density threshold, as compared to a single separate‐confinement heterostructure (SCH) of same composition. However, the high‐temperature characteristic temperature T0 is found to be similar in the two structures. A SCH with a higher energy gap exhibits a more favorable behavior with temperature. These experimental results have been compared to theoretical models. The experimentally observed T0 can be well simulated by taking into account the Auger effect. From the experimental data, the Auger constant has been determined for each heterostructure. © 1995 American Institute of Physics.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
78.45.+h Stimulated emission
78.66.Hf II-VI semiconductors

Stoichiometry of Cd(S,Se) nanocrystals by anomalous small‐angle x‐ray scattering

Aline Ramos, Olivier Lyon, and Claire Levelut

J. Appl. Phys. 78, 6916 (1995); http://dx.doi.org/10.1063/1.360458 (7 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
In Cd(S,Se)‐doped glasses the optical properties are strongly dependent on the size of the nanocrystals, but can be also largely modified by changes in the crystal stoichiometry; however, the information on both stoichiometry and size is difficult to obtain in crystals smaller than 10 nm. The intensity scattered at small angles is classically used to get information about nanoparticles sizes. Moreover the variation of amplitude of this intensity with the energy of the x ray—‘‘the anomalous effect’’—near the selenium edge is related to stoichiometry. Anomalous small‐angle x‐ray scattering has been used as a tentative method to get information about stoichiometry in nanocrystals with size lower than 10 nm. Experiments have been performed on samples treated for 2 days at temperatures in the range 540–650 °C. The samples treated at temperatures above 580 °C contain crystals with size larger than 4 nm. For all these samples the anomalous effect has nearly the same amplitude, and we found the stoichiometry x=0.4 for the CdSxSe1−x nanocrystals. This agrees with the previous results obtained by scanning electron microscopy and Raman spectroscopy. The results are also confirmed by measurements of the position of the optical absorption edge and by wide‐angle x‐ray scattering experiments. For the sample treated at 560 °C, the nanocrystal size is 3 nm and the stoichiometry x=0.6 is deduced from the anomalous effect. For samples treated at lower temperatures the anomalous effect is not observable, indicating an even lower selenium content in the nanocrystals (x≳0.7). We observed differences in the Se content of nanocrystals for different heat treatments of the same initial glass. These results may be very helpful to interpret the change in the optical properties when the temperature of the treatments decreases in the range 560–590 °C. In this temperature range, compositional effects seem to be of the same order of magnitude as the effects of the quantum confinement. © 1995 American Institute of Physics.
Show PACS
42.70.Ce Glasses, quartz
61.05.cf X-ray scattering (including small-angle scattering)
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.
61.46.-w Structure of nanoscale materials

Resolution limits from charge transport in optically addressed spatial light modulators

Li Wang and Garret Moddel

J. Appl. Phys. 78, 6923 (1995); http://dx.doi.org/10.1063/1.360459 (13 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
Spatial resolution of optically addressed spatial light modulators (OASLMs) is degraded by several different transfer processes in these devices. We have developed a general transient charge transport model to calculate and simulate the resolution limits of OASLMs due to the following charge spreading mechanisms during the transfer process in which the input image is converted into a particular charge distribution in the photosensor layer. (i) The effect of charge drift in the photosensor bulk on resolution increases with the thickness of the photosensor and the light‐modulating layers. It also increases with the total amount of photogenerated charge collected at the interface. (ii) The effect of charge diffusion in the photosensor bulk on resolution is largely independent of the carrier mobility in the semiconductor photosensor. In most cases the corresponding spatial frequency f50% is proportional to √Vsc/dsc, where dsc is the photosensor thickness and Vsc is the voltage drop in that layer. To have high‐sensitivity OASLMs the transit time of charge carriers from the photosensor bulk to the interface must be much shorter than the recombination lifetime. (iii) The effects that charge drift, diffusion, and trapping at the photosensor‐light‐modulating layer interface have on resolution depend strongly on the interface properties. Decreasing the mobility or the trapping time of charge carriers at the interface can dramatically improve the resolution of OASLMs. The resolution ranges from 3 to 875 line pairs/mm for respective diffusion lengths of 10 to 0.1 μm at the interface. The combined effect on resolution from each of the charge spreading and other resolution‐degrading mechanisms is also discussed. © 1995 American Institute of Physics.
Show PACS
42.30.Lr Modulation and optical transfer functions
42.79.Hp Optical processors, correlators, and modulators
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Waveguide formation mechanism generated by double doping in ferroelectric crystals

V. V. Atuchin, C. C. Ziling, I. Savatinova, M. N. Armenise, and V. M. N. Passaro

J. Appl. Phys. 78, 6936 (1995); http://dx.doi.org/10.1063/1.360460 (4 pages) | Cited 7 times

Full Text: | Download PDF

Show Abstract
Physical mechanisms causing the refractive index increase Δn in uniaxial oxidized ferroelectric crystals subjected to double doping are discussed. The analysis shows that the index changes of the two different dopants, ΔnA and ΔnB, are additive only if the corresponding changes of the spontaneous polarization are small. Ti indiffusion and proton exchange (TIPE) waveguides in LiNbO3 are considered as an example of the case when this condition is not fulfilled. The hydrogen–lithium substitution in such waveguides leads to a strong reduction of the spontaneous polarization of the virgin crystals and the final index change Δn is not a sum of ΔnA and ΔnB. A physical model is developed to explain light waveguiding in double‐doped ferroelectric structures. Experimental data obtained for TIPE waveguides confirm the model. © 1995 American Institute of Physics.
Show PACS
42.82.Et Waveguides, couplers, and arrays
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates

Wave scattering by a two‐dimensional band‐limited fractal surface based on a perturbation of the Green’s function

P. E. McSharry, P. J. Cullen, and D. Moroney

J. Appl. Phys. 78, 6940 (1995); http://dx.doi.org/10.1063/1.360461 (9 pages) | Cited 8 times

Full Text: | Download PDF

Show Abstract
A fast approximate method is described to calculate the acoustic scattering from a one‐dimensional Dirichlet band‐limited fractal surface. The formulation is based on a perturbation of the Green’s function allowing an approximation of the propagator in the kernel of the Helmholtz integral equation, which reduces the integral equation to a convolution equation. This allows us to find a solution using Fourier transforms rather than the usual matrix inversion that is required. We have shown that in the limit of small kσ, where k is the incident wave number and σ is the rms height, it is possible to find accurate closed form expressions for the reflection coefficients Rn, the spectral components of the normal gradient of the field ψn, the scattered field psca, and the angular scattering coefficient Isca representing the scattering from a band‐limited fractal surface. For small values of kσ≪1, we have used the generalized Rayleigh method [D. L. Jaggard and X. Sun, J. Appl. Phys. 68, 5456 (1990)] to determine the theoretical linear relationship which exists between the slope of the absolute value of the reflection coefficients in dB versus the reflection mode and the fractal dimension D. This theoretical relationship has been verified by using the Green’s function perturbation method. This relationship and an analogous relationship between the scattering coefficient and the scattering angle allows the determination of the fractal dimension D and the rms height σ from the scattering pattern when kσ≤0.2. © 1995 American Institute of Physics.
Show PACS
43.20.Fn Scattering of acoustic waves
43.30.Hw Rough interface scattering

The function estimation in measuring temperature‐dependent thermal conductivity in composite material

Cheng‐Hung Huang and Jan‐Yuan Yan

J. Appl. Phys. 78, 6949 (1995); http://dx.doi.org/10.1063/1.360462 (8 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
An inverse analysis utilizing the conjugate gradient method of minimization and adjoint equation is used successfully to solve the inverse problem in estimating the temperature‐dependent thermal conductivity of a composite material. No prior information is available on the functional form of the unknown thermal conductivity in the present study, thus, it is classified as the function estimation in inverse calculation. The accuracy of the inverse analysis is examined by using the simulated exact and inexact measurements that were obtained within the medium. © 1995 American Institute of Physics.
Show PACS
05.70.Ce Thermodynamic functions and equations of state

On the formation and loss of S2 molecules in a reactive ion etching reactor operating with SF6

L. St‐Onge, N. Sadeghi, J. P. Booth, J. Margot, and C. Barbeau

J. Appl. Phys. 78, 6957 (1995); http://dx.doi.org/10.1063/1.360463 (10 pages) | Cited 8 times

Full Text: | Download PDF

Show Abstract
Laser‐induced‐fluorescence (LIF) spectroscopy was used to study, with spatial and temporal resolution, the processes by which diatomic sulfur S2 is formed and lost in SF6 plasmas. We present results concerning the relative S2 number density in steady‐state or pulsed discharges in a reactive ion etching (RIE) reactor operated at different SF6 gas pressures and RF powers, in the presence or absence of a silicon wafer. It is found that S2 is formed mainly on surfaces under conditions when the F‐atom density is high, but that volume formation can also occur when the F‐atom population is depleted (namely, when Si is present). It is also shown that loss of S2 is mainly due to diffusion out of the inter‐electrode space to the main reactor volume, excluding electron‐impact dissociation processes. It is apparent that, in a RIE reactor, the only electron process pertinent to the balance of S2 density is the formation of its precursors (probably S atoms and SF molecules) by fragmentation of the SF6 gas. The remaining reactions controlling the density of S2 are neutral‐neutral interactions in the volume and on surfaces. © 1995 American Institute of Physics.
Show PACS
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
81.65.-b Surface treatments

Two‐dimensional fluid simulation of expanding plasma sheaths

MunPyo Hong and G. A. Emmert

J. Appl. Phys. 78, 6967 (1995); http://dx.doi.org/10.1063/1.360464 (7 pages) | Cited 20 times

Full Text: | Download PDF

Show Abstract
The transient sheath expansion around square and cross‐shaped targets is simulated numerically with a two‐dimensional fluid model. The angular distribution of the ions impinging on the target surface and the nonuniformity of the incident ion dose are calculated. The incident ion dose peaks near, but not at, the convex corner and has a minimum at the concave corner. The dip of the dose profile at the convex corner is shown to be caused by the product of a decreasing normal velocity profile and an increasing ion density profile along the target surface from the center to the corner. © 1995 American Institute of Physics.
Show PACS
52.40.Hf Plasma-material interactions; boundary layer effects
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition

Properties of a vacuum ultraviolet laser created plasma sheet for a microwave reflector

W. Shen, J. E. Scharer, N. T. Lam, B. G. Porter, and K. L. Kelly

J. Appl. Phys. 78, 6974 (1995); http://dx.doi.org/10.1063/1.360773 (6 pages) | Cited 12 times

Full Text: | Download PDF

Show Abstract
A 193 nm excimer laser and a custom fabricated cylindrical lens system is used to produce a plasma sheet of 8 cm×30 cm×0.4 cm in tetrakis(dimethylamino)ethylene (TMAE), a low ionization energy organic gas. Plasma density variation due to photon absorption is studied by scanning the filling pressure of TMAE between 12 and 150 mTorr. A high density (n≥2.0×1013 cm−3), low temperature (Te≊0.8 eV) plasma sheet of 4 mm thickness is obtained with less than 50% spatial density variation over the 30 cm axial length. Charge recombination is found to be the dominant process for t≤1.2 μs with the plasma diffusion playing a perturbational role. A one‐dimensional plasma model is utilized to model the experimental plasma data by treating the diffusion as a perturbation. This study shows that the recombination coefficient is 1.8±0.1×10−7 cm3 s−1 and the diffusion coefficient is 2.8±0.4×104 cm2 s−1. The plasma sheet has attractive properties for a microwave agile mirror. © 1995 American Institute of Physics.
Show PACS
52.38.-r Laser-plasma interactions
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)

Microstructural changes in GeSbTe film during repetitious overwriting in phase‐change optical recording

N. Nobukuni, M. Takashima, T. Ohno, and M. Horie

J. Appl. Phys. 78, 6980 (1995); http://dx.doi.org/10.1063/1.360465 (9 pages) | Cited 27 times

Full Text: | Download PDF

Show Abstract
Microstructural changes that occur in a GeSbTe film during repetitious overwriting in phase‐change optical recording were investigated. The GeSbTe active layer was melted by a focused laser diode (LD) beam during each overwriting process over amorphous mark formation. The repetitious solidification and liquefaction process in such a short time as 50–200 ns resulted in microstructural changes in the active layer: a segregation, sink, and void formations. The sink was formed in the low‐density active layer due to the shrinking of the volume during the resolidification process. Sink formation could be suppressed when a high‐density active layer, having more than 80% of the bulk density, was used. Such a high‐density GeSbTe film, however, resulted in a void formation of the size of 0.1 μm. The voids were thought to be nucleated by residual vacancies and Ar precipitation, since the active layer contained a high concentration of Ar impurities, due to the atomic peening effect. The subsequent void coalescence and migration processes across the beam scanning direction could result in the formation of thermally discontinuous grooves at the edges of the written marks. The voids could also migrate along the LD beam scanning direction, accompanied by a material flow of the active layer in the opposite direction. These phenomena were also found to depend on the material used to fabricate the protective layers which sandwiched the active layer. A TaOx protective layer enhanced the void migration across the track, resulting in the removal of voids from the center of the track. Use of the ZnS:SiO2 compound protective layer confined voids to the center of the track. The ZnS:SiO2 protective layer also promoted the formation of thermally discontinuous grooves at the edges of amorphous marks. The material flow along the track resulted in a thicker active layer at the start of the consecutive LD irradiation, and also in a high void density region at the final edge of the irradiation having a length on the order of 10 μm. This tendency was found for both the ZnS:SiO2 and TaOx sandwiching media. © 1995 American Institute of Physics.
Show PACS
42.70.Ln Holographic recording materials; optical storage media
68.55.-a Thin film structure and morphology

Radiation‐induced defects in CaF2: An electron‐spin resonance and dielectric constant investigation

F. Beuneu and P. Vajda

J. Appl. Phys. 78, 6989 (1995); http://dx.doi.org/10.1063/1.360466 (5 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
CaF2 single crystals have been irradiated at T=21 K and at 0 °C with electrons of 0.5 and 1 MeV energy. The low‐temperature irradiated samples exhibit electron‐spin‐resonance (ESR) spectra with signals due to F‐centers and an unchanged real component of the dielectric constant ϵ′. The room temperature irradiated crystals, on the other hand, present ESR‐spectra due to VF‐, U‐, and, possibly, to metallic‐colloid (g=2.003) centers as well as an increased (dose dependent) ϵ′. The introduced defects and the radiation‐induced Δϵ′ are investigated in a thermal annealing treatment up to 900 °C. Their recovery behaviour is complex and can be interpreted as a competition between growth and annihilation processes of metallic clusters estimated to have initially a radius of ∼200 Å. Thus, the appearance of a new ESR‐line near g=2.000 after an anneal at 200 °C indicates the possible transformation of colloids to larger units before vanishing. The annealing spectrum of Δϵ′ and the dose dependence of its substages support the ESR findings. © 1995 American Institute of Physics.
Show PACS
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
61.80.Fe Electron and positron radiation effects
76.30.Mi Color centers and other defects

Lattice constants and thermal expansion of AlxGa1−xAs:Te

J. Bak‐Misiuk, M. Leszczynski, J. Domagala, and Z. Zytkiewicz

J. Appl. Phys. 78, 6994 (1995); http://dx.doi.org/10.1063/1.360467 (5 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
An influence of Te doping on the lattice parameter and the thermal expansion of AlxGa1−xAs epitaxial layers was examined by high‐resolution x‐ray diffractometry over a temperature range 77–673 K. For doped AlxGa1−xAs layers the thermal expansion coefficients were found to be larger relative to undoped samples of the same Al content. This phenomenon is attributed to the change of anharmonic part of lattice vibrations by free electrons and/or ionized tellurium atoms. An increase of thermal expansion caused by doping is a factor which should be taken into account in lattice constant measurements at 295 K. We propose an interpretation of the lattice expansion (examined at room temperature by other authors and by us) of GaAs caused by Te doping in terms of three factors: (i) ‘‘size’’ effect (bigger Te atoms with respect to As), (ii) free electrons via the deformation potential of the conduction‐band minimum occupied by these electrons, (iii) increase of the thermal expansion. © 1995 American Institute of Physics.
Show PACS
61.05.cf X-ray scattering (including small-angle scattering)
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.
65.40.De Thermal expansion; thermomechanical effects

Raman spectroscopy of amorphous and microcrystalline silicon films deposited by low‐pressure chemical vapor deposition

A. T. Voutsas, M. K. Hatalis, J. Boyce, and A. Chiang

J. Appl. Phys. 78, 6999 (1995); http://dx.doi.org/10.1063/1.360468 (8 pages) | Cited 67 times

Full Text: | Download PDF

Show Abstract
In this work we used Raman spectroscopy to investigate the structural characteristics of as‐deposited amorphous and micro‐crystalline silicon films. For amorphous silicon films, the order (or disorder) of the silicon network was quantified using properties of the Raman spectra that were related to key deposition conditions. We found that a strong relationship exists between the structural order of the silicon matrix and the deposition temperature and deposition rate. A quantitative model was proposed relating the intensity ratio of transverse optical phonon peak to longitudinal optical phonon peak to the surface diffusion length, a parameter that was calculated from available data. It was found that optimization of the as‐deposited silicon microstructure is possible by selecting deposition conditions yielding peak–ratio values in the vicinity of 0.53. For as‐deposited micro‐crystalline silicon films, Raman spectroscopy was used to estimate the initial crystalline fraction of the film and monitor the crystallization process during annealing. These data were used to confirm the crystallization mechanism in mixed‐phase silicon films and identify the effect of different process parameters on the crystallization time of the annealed films. © 1995 American Institute of Physics.
Show PACS
61.43.Dq Amorphous semiconductors, metals, and alloys
68.55.-a Thin film structure and morphology
78.35.+c Brillouin and Rayleigh scattering; other light scattering

The effect of focused ion‐beam implantation on the threshold voltage of short‐channel silicon metal–oxide–semiconductor field‐effect transistors

Amer Ahmed, S. Noor Mohammad, and Ronald L. Carter

J. Appl. Phys. 78, 7007 (1995); http://dx.doi.org/10.1063/1.360469 (11 pages)

Full Text: | Download PDF

Show Abstract
A theoretical modeling of the threshold voltage of short‐channel silicon metal–oxide–semiconductor field‐effect transistors (MOSFETs) taking into consideration the focused ion‐beam technology for the direct implantation of dopants into semiconductor substrates has been performed. Based on a quasitwo‐dimensional solution of Poisson’s equation, the surface potential distribution along the channel of a MOSFET has been derived. For this, implanted channel doping concentration is varied linearly along the channel and in a Gaussian‐type fashion in a direction perpendicular to the channel. The threshold voltage has been determined from a knowledge of the minimum surface potential in the channel. The effects of finite source and drain junction depths have been included by modifying the depletion capacitance beneath the gate. Short‐channel effects on the threshold voltage are thus taken into consideration. The model provides important insight of the physics controling the threshold voltage of a MOSFET. It is noted that a nonuniform doping with density lower in the drain end of the channel and higher in the source end of the channel, and a proper tailoring of the doses, straggles, and energy of implantation are keys to the improvement of the electrical characteristics of a MOSFET. © 1995 American Institute of Physics.
Show PACS
61.72.uf Ge and Si
85.30.Tv Field effect devices

Formation of β‐Si3N4 by nitrogen implantation into SiC

S. Miyagawa, S. Nakao, K. Saitoh, M. Ikeyama, H. Niwa, S. Tanemura, Y. Miyagawa, and K. Baba

J. Appl. Phys. 78, 7018 (1995); http://dx.doi.org/10.1063/1.360470 (4 pages) | Cited 13 times

Full Text: | Download PDF

Show Abstract
Polycrystalline β‐SiC samples were implanted with 50 keV 15N ions with fluences ranging from 3×1017 to 1.5×1018 ions/cm2 at elevated temperature up to 1100 °C. Nitrogen depth profiles were measured as a function of implantation temperature and annealing temperature using nuclear reaction analysis, Rutherford backscattering spectroscopy, and Auger electron spectroscopy. It was found that the maximum concentration and the width of nitrogen depth profiles implanted at 1100 °C were reduced distinctly in comparison with the profiles implanted below 930 °C or annealed at 1100 °C. The redistribution of nitrogen implanted in SiC at 1100 °C was ascribed to the formation of β‐Si3N4 crystallites in SiC, which was confirmed by x‐ray diffraction at glancing incidence. © 1995 American Institute of Physics.
Show PACS
61.72.up Other materials
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.

Laser‐generated shock waves in thin films of energetic materials

Ping Ling and Charles A. Wight

J. Appl. Phys. 78, 7022 (1995); http://dx.doi.org/10.1063/1.360471 (4 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Shock waves are generated in thin films of glycidyl azide polymer (GAP) by pulsed laser vaporization of a thin aluminum film. The rapidly expanding aluminum plasma launches a shock wave into the adjacent layer of GAP, initiating chemical reactions. The shock velocity has been measured by use of a velocity interferometer as a function of the thickness of the GAP layer and the fluence of the Nd:YAG laser pulse. Shock pressures as high as 8 GPa have been generated in this manner. Detonation of thick GAP samples has been observed, providing important information about the chemical reaction rates and the thickness of the reaction zone. © 1995 American Institute of Physics.
Show PACS
62.50.-p High-pressure effects in solids and liquids
82.40.Fp Shock wave initiated reactions, high-pressure chemistry

Nonlinear motion of crack tip atoms during dislocation emission processes

Honglai Tan and Wei Yang

J. Appl. Phys. 78, 7026 (1995); http://dx.doi.org/10.1063/1.360472 (9 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
Nonlinear features of dislocation emission processes under mode II loads are explored from an atomic scale. Crack tip atom string models coupling with the continuum mechanics analysis are devised. Dynamic analysis shows that the atom motion at the crack tip changes from periodic to chaotic, as the mode II stress intensity factor increases. The chaotic atom motion dictates the dislocation nucleation process at the crack tip. Study on the dislocation emission band reveals the phenomenon of cloudlike drifting of the dislocation core ahead of the crack tip. © 1995 American Institute of Physics.
Show PACS
61.72.Lk Linear defects: dislocations, disclinations
62.20.M- Structural failure of materials

Nonlinear effect of self‐induced electric field on diffusion‐induced stresses

Senpuu Lin and Chi‐Chuan Hwang

J. Appl. Phys. 78, 7035 (1995); http://dx.doi.org/10.1063/1.360473 (5 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
This article investigates the nonlinear effect of the self‐induced electric field on the diffusion‐induced stresses in a thin plate. We first approximate the nonlinear concentration‐dependent diffusivity as a series of third‐degree polynomials by the least‐squares curve‐fitting techniques and then calculate the distributions of concentration by the Galerkin method; afterwards and using these results, the diffusion‐induced stresses inside the slab are determined. It is found that the differences from the linear case with a constant diffusivity are apparent. Furthermore, the nonlinear effect is modest for low‐surface‐concentration diffusion but extremely pronounced for high‐surface‐concentration diffusion. © 1995 American Institute of Physics.
Show PACS
62.20.-x Mechanical properties of solids
66.30.-h Diffusion in solids

A kinetic study of the C49 to C54 TiSi2 conversion using electrical resistivity measurements on single narrow lines

K. L. Saenger, C. Cabral, L. A. Clevenger, R. A. Roy, and S. Wind

J. Appl. Phys. 78, 7040 (1995); http://dx.doi.org/10.1063/1.360407 (5 pages) | Cited 26 times

Full Text: | Download PDF

Show Abstract
We describe a simple quasi‐in situ resistivity technique and its application to the study of C49 to C54 TiSi2 conversion in narrow (0.1‐1.0 μm) lines. This technique allowed comparison of both aggregate conversion versus time at temperature behavior and individual‐line conversion versus time behavior for silicide lines of different linewidths. As linewidth decreased, the aggregate conversion versus time at temperature behavior slowed, and the conversion behaviors of individual lines having the same linewidth became more variable. Both of these observations are consistent with a nucleation‐site‐density controlled reaction under conditions of low nucleation site density. Correlations were also found between individual line behaviors and resistance to agglomeration; resistance to agglomeration (for 0.35–1.0 μm lines already in the C54 phase) was highest for lines which had ‘‘prompt’’ conversion behaviors (as measured by the sheet resistance drop during the first minute of the conversion anneal). Additional data concerning the sensitivity of the initial sheet resistances to formation anneal conditions and linewidth is also briefly discussed. © 1995 American Institute of Physics.
Show PACS
64.70.K- Solid-solid transitions
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder

Interface reactions between manganese zinc ferrite single crystals and SiO2‐PbO‐ZnO ternary systems

Hae June Je, Do Kyung Kim, Chong Hee Kim, Kug Sun Hong, Byeong Won Park, and Sung Do Jang

J. Appl. Phys. 78, 7045 (1995); http://dx.doi.org/10.1063/1.360408 (8 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Interface reactions between Mn‐Zn ferrite single crystals and SiO2‐PbO‐ZnO ternary systems were investigated using scanning electron microscope, electron probe microanalyzer, and x‐ray diffractometer. The addition of ZnO in a SiO2‐PbO glass resulted in inhibition of formation of the intermediate phase and suppression of dissolution of the ferrite. The interface morphology became a dendrite structure with increase of ZnO concentration in the glass. Appearance of the anomalous concentration profile of Zn and Mn at the ferrite adjacent to the interface was investigated in terms of the dissolved quantity of Mn and Zn ion. It was found that Zn ion has dissolved from the ferrite into the glass melt during the reaction and Mn ion in the ferrite dissolved into the glass melt more than Zn ion, resulting in changing the undissolved ferrite adjacent to the interface into a Zn‐rich Mn‐Zn ferrite, Mn0.16Zn0.85Fe2O4, after reaction with 57SiO2‐38PbO‐5ZnO (in mol %) glass. It was considered that the source of the hump of Zn concentration at the ferrite adjacent to the interface would be the undissolved, remaining Zn ions. A microscopic model was suggested. © 1995 American Institute of Physics.
Show PACS
66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Fx Diffusion; interface formation
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

High density plasma processing of diamond films on titanium: Residual stress and adhesion measurements

Shane A. Catledge and Yogesh K. Vohra

J. Appl. Phys. 78, 7053 (1995); http://dx.doi.org/10.1063/1.360409 (6 pages) | Cited 19 times

Full Text: | Download PDF

Show Abstract
High density plasma processing of diamond films on titanium was carried out by microwave plasma chemical vapor deposition. The deposited films were characterized by Raman spectroscopy and thin film x‐ray diffraction. We measure a residual compressive stress of 3.5±1.0 GPa which is lower than that obtained in previous studies. A measure of the film adherence to the titanium substrates was obtained by examining micro‐Raman spectra near Brale C indentations. Using a model for biaxially stressed polycrystalline diamond films, it is determined that as much as 7.8 GPa can be sustained in the film before delamination occurs. Our experimental results are compared to earlier adhesion data of diamond on titanium. © 1995 American Institute of Physics.
Show PACS
68.60.Bs Mechanical and acoustical properties
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Characterization of heavily B‐doped polycrystalline diamond films using Raman spectroscopy and electron spin resonance

P. Gonon, E. Gheeraert, A. Deneuville, F. Fontaine, L. Abello, and G. Lucazeau

J. Appl. Phys. 78, 7059 (1995); http://dx.doi.org/10.1063/1.360410 (4 pages) | Cited 54 times

Full Text: | Download PDF

Show Abstract
Heavily B‐doped polycrystalline diamond films ([B]≳1019 cm−3) are studied by Raman spectroscopy and electron spin resonance. The formation of an impurity band is accompanied by a Fano‐type interference for the one‐phonon scattering. Bands at 1200 and 500 cm−1 are observed in Raman spectroscopy for concentrations above 1020 cm−3. They are related to maxima in the phonon density of states, and are ascribed to disordered regions or crystalline regions of very small size. The concentration of defects associated with the paramagnetic signal observed around g=2.0030 increases drastically above 1021 B cm−3. The Mott insulator‐metal transition is accompanied by the presence of a new paramagnetic signal (g=2.0007 for 2×1020 B cm−3, g=1.9990 for 1021 B cm−3) ascribed to free holes in the impurity band. © 1995 American Institute of Physics.
Show PACS
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
76.30.Lh Other ions and impurities
78.30.Hv Other nonmetallic inorganics
Page 1 of 4 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close