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1 Feb 1990

Volume 67, Issue 3, pp. R1-1621

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Deep donor levels (DX centers) in III‐V semiconductors

P. M. Mooney

J. Appl. Phys. 67, R1 (1990); http://dx.doi.org/10.1063/1.345628 (26 pages) | Cited 520 times

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DX centers, deep levels associated with donors in III‐V semiconductors, have been extensively studied, not only because of their peculiar and interesting properties, but also because an understanding of the physics of these deep levels is necessary in order to determine the usefulness of III‐V semiconductors for heterojunction device structures. Much progress has been made in our understanding of the electrical and optical characteristics of DX centers as well as their effects on the behavior of various device structures through systematic studies in alloys of various composition and with applied hydrostatic pressure. It is now generally believed that the DX level is a state of the isolated substitutional donor atom. The variation of the transport properties and capture and emission kinetics of the DX level with the conduction‐band structure is now well understood. It has been found that the properties of the deep level when it is resonant with the conduction band, and is thus a metastable state, are similar to its characteristics when it is the stable state of the donor. And it has been consistently found that there is a large energy difference between the optical and thermal ionization energies, implying that this deep state is strongly coupled to the crystal lattice. The shifts in the emission kinetics due to the variation in the local environment of the donor atom suggest that the lattice relaxation involves the motion of an atom (the donor or a neighboring atom) from the group‐III lattice site toward the interstitial site. Total energy calculations show that such a configuration is stable provided that the donor traps two electrons, i.e., has negative U. Verification of the charge state of the occupied DX level is needed as well as direct evidence for its microscopic structure.
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61.72.jn Color centers
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.80.Ey III-V and II-VI semiconductors
71.20.Nr Semiconductor compounds
71.20.Ps Other inorganic compounds

Conductivity tensor of anisotropic composite media from the microstructure

S. Torquato and Asok K. Sen

J. Appl. Phys. 67, 1145 (1990); http://dx.doi.org/10.1063/1.345711 (11 pages) | Cited 26 times

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Perturbation expansions and rigorous bounds on the effective conductivity tensor σe of d‐dimensional anisotropic two‐phase composite media of arbitrary topology have recently been shown by the authors to depend upon the set of n‐point probability functions S(i)1,..., S(i)n. S(i)n gives the probability of simultaneously finding n points in phase i (i=1,2). Here we describe a means of representing these statistical quantities for distributions of identical, oriented inclusions of arbitrary shape. Our results are applied by computing second‐order perturbation expansions and bounds for a certain distribution of oriented cylinders with a finite aspect ratio. We examine both cases of conducting cylindrical inclusions in an insulating matrix and of insulating cracks or voids in a conducting matrix.
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72.10.Bg General formulation of transport theory
72.90.+y Other topics in electronic transport in condensed matter (restricted to new topics in section 72)
03.50.De Classical electromagnetism, Maxwell equations

Scanning tunneling microscopy on rough surfaces: Tip‐shape‐limited resolution

G. Reiss, J. Vancea, H. Wittmann, J. Zweck, and H. Hoffmann

J. Appl. Phys. 67, 1156 (1990); http://dx.doi.org/10.1063/1.345712 (4 pages) | Cited 44 times

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This paper discusses the reliability of scanning tunneling microscopy (STM) images of mesoscopically rough surfaces. The specific structure of these images represents a convolution between the real surface topography and the shape of the tip. In order to interpret these images quantitatively, the line scans of steep and high steps can be used to obtain an image of the tip itself. This image shows tip radii ranging typically from 5 to 15 nm and cone angles of about 30° over a length of 80 nm, and can in turn be used to recognize the limits of STM resolution on a rough surface: High‐resolution transmission electron microscopy cross‐section images of Au island films on a Au‐Nb double layer are convoluted with the experimentally observed tip shape; the resulting line scans correspond very well with STM graphs of the same samples. Finally an overall criterion for the resolution of the STM on such surfaces is proposed.
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07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination
68.35.B- Structure of clean surfaces (and surface reconstruction)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.90.+g Other topics in structure, and nonelectronic properties of surfaces and interfaces; thin films and low-dimensional structures (restricted to new topics in section 68)

Analytic solutions to the electrostatic problems of two dielectric spheres

Weigan Lin and Hang Jin

J. Appl. Phys. 67, 1160 (1990); http://dx.doi.org/10.1063/1.345713 (7 pages)

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The electrostatic problems of the configurations of two dielectric spheres are solved with the aid of the inversion transformation. The potentials due to a unit point charge located on the symmetry axis or that excited by a uniform external field are obtained. In the case of conducting spheres, our results are in agreement with the previous results obtained by the method of images.
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41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems

The phase angle method for electrical resistivity applied to the hollow circular cylinder geometry

Maria José Ramos, Renato Figueiredo Jardim, and Bernardo Laks

J. Appl. Phys. 67, 1167 (1990); http://dx.doi.org/10.1063/1.345714 (3 pages) | Cited 1 time

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The phase‐angle method to measure electrical resistivity in nonmagnetic metals is calculated for samples presenting the hollow circular geometry. The phase angle versus the operating frequency for a general hollow circular cylinder geometry shows a similar qualitative behavior when compared with the massive cylinder geometry. A discussion of a procedure for a desirable experimental condition related to the geometrical parameters and exciting signal is presented. UFaipxr
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41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems

Fresnel diffraction theory for steady‐state thermal lens measurements in thin films

Shaole Wu and Norman J. Dovichi

J. Appl. Phys. 67, 1170 (1990); http://dx.doi.org/10.1063/1.346057 (13 pages) | Cited 29 times

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Fresnel diffraction theory is combined with a three‐dimensional temperature model to predict accurately the beam intensity profile produced by a steady‐state thermal lens in 250‐μm liquid films. In the comparison of theory and data, the optical parameters of the thermal lens instrument and the thermo‐optical properties of the sample were introduced into the model; it was not necessary to adjust any parameter in the theory to produce good agreement between the predicted and observed beam profile. Because no parameters are adjusted to match theory to data, the thermal lens measurement provides an absolute measurement of sample absorbance. The model is used to predict the behavior of the thermal lens in thin films with respect to sample absorbance, sample thickness, laser power, and optical alignment. The new model is compared with several models from the literature; it is necessary to utilize the three‐dimensional heat‐flow analysis and Fresnel diffraction theory to obtain an accurate description of the behavior of the thermal lens in measurements of thin films.
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78.20.N- Thermo-optic effects
78.20.nb Photothermal effects
44.30.+v Heat flow in porous media
42.25.Dd Wave propagation in random media

Recrystallization and refractive index profiles of titanium‐implanted optical waveguides in LiNbO3

T. Bremer, W. Heiland, Ch. Buchal, R. Irmscher, and B. Stritzker

J. Appl. Phys. 67, 1183 (1990); http://dx.doi.org/10.1063/1.345715 (5 pages) | Cited 5 times

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Y‐cut LiNbO3 single crystals have been implanted with 200‐keV Ti+ at doses up to 4.0×1017 Ti/cm2. The annealing behavior has been studied with implantations performed at 77, 300, and 620 K. The amorphous surface layers have been annealed at 1273 K in a wet oxygen atmosphere for 2 to 8 h to achieve epitaxial regrowth. Channeling and mode spectroscopy have been applied to investigate the regrowth process. Refractive index profiles have been calculated with an inverse WKB algorithm. A maximum increase of 0.040 for the extraordinary and 0.019 for the ordinary refractive index was found at He‐Ne wavelength (632.8 nm). This indicates a solubility limit of 3.3×1027/m3 for Ti in LiNbO3. The annealing time to achieve perfect regrowth depends on the ion dose and irradiation temperature. Higher implantation temperatures yield dynamical annealing; thus, a shorter post‐implantation anneal is required.
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42.79.Gn Optical waveguides and couplers
61.72.up Other materials
61.85.+p Channeling phenomena (blocking, energy loss, etc.)

Nonlinear all‐optical beam scanner

Gaetano Assanto and George I. Stegeman

J. Appl. Phys. 67, 1188 (1990); http://dx.doi.org/10.1063/1.345716 (6 pages) | Cited 4 times

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An all‐optical integrated optics beam‐scanning device is analyzed. It consists of a surface relief grating used to couple both a control and a signal beam into and out of a nonlinear planar waveguide, respectively. Varying the control beam power tunes the signal beam out‐coupling angle. Both local and diffusive nonlinearities are considered, and various design parameters are discussed. The theoretical results are compared to experimental data from ZnS waveguides for the thermal diffusive case.
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42.65.-k Nonlinear optics
42.79.Gn Optical waveguides and couplers
42.82.-m Integrated optics

Photorefractive intermode space‐charge fields in volume holographic interconnections

Woon Sik Baek and Hyuk Lee

J. Appl. Phys. 67, 1194 (1990); http://dx.doi.org/10.1063/1.345717 (9 pages) | Cited 4 times

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Steady‐state space‐charge fields generated by a pair of light interference patterns, each of them formed by a pair of optical plane waves, are studied. Analytic solutions of the steady‐state space‐charge fields in photorefractive crystals are derived for small laser intensity at large modulation depth. Numerical solutions for the photorefractive crystal Bi12SiO20(BSO) are also obtained by utilizing Powell’s method without the assumption of small laser intensity, and they are compared with the analytic solutions in both cases of stationary light interference patterns and moving light interference patterns. The intermode space‐charge fields, which may cause the second‐order cross‐talk problem in volume holographic interconnections, are described. The data regions are obtained in which the effect of intermode space‐charge fields are suppressed and the criteria for optimal implementation of volume holographic interconnections are satisfied.
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42.79.Vb Optical storage systems, optical disks
42.30.-d Imaging and optical processing

Triplet extinction coefficients of some laser dyes. II

Theodore G. Pavlopoulos and Daniel J. Golich

J. Appl. Phys. 67, 1203 (1990); http://dx.doi.org/10.1063/1.345718 (7 pages) | Cited 11 times

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We measured the triplet extinction coefficients ϵT over the laser action spectral region of DODC, DMC, Sulforhodamine B, Rhodamine 575, Coumarin 523, Coumarin 521, Coumarin 504, Coumarin 498, Coumarin 490, LD466, bis‐MSB, and BBO. We employed the different lines from an argon‐ and a krypton‐ion cw laser for excitation. McClure’s method [J. Chem. Phys. 19, 670 (1951)] was again employed to measure the triplet extinction coefficients. We provide a simplified derivation of McClure’s equation. The triplet extinction coefficient of Rhodamine 575 was also measured by using the depletion method and improving it by reconstructing for true triplet‐triplet (T‐T) absorption. The ϵT value obtained is in good agreement with the one obtained by McClure’s method.
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42.55.Mv Dye lasers

Wave reflection at a mixed interface between two solid half‐spaces

F. Léomy, M. de Billy, G. Quentin, I Molinero, and D. Lecuru

J. Appl. Phys. 67, 1210 (1990); http://dx.doi.org/10.1063/1.345719 (9 pages) | Cited 2 times

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The reflectivity of incident longitudinal and transversal waves at the interface between two solid half‐spaces is studied for different degrees of bonding. Numerical calculations based on Murty’s assumptions [G. S. Murty, Geophys. J. R. Astron. Soc. 44, 388 (1976)] are compared with experimental measurements. The agreement between theory and experiments is reasonably good for RHHTT and RLL coefficients. The plots obtained for RVVTT reveal the existence of an interface wave, the theoretical angular position of which coincides with the critical angle calculated by assuming that this interface wave is a type of Rayleigh wave or interface wave, depending on the acoustical parameters.
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41.20.Jb Electromagnetic wave propagation; radiowave propagation
68.35.Gy Mechanical properties; surface strains

A semiempirical model for the laser‐induced molten zone in the laser recrystallization process. II

G. J. Willems and H. E. Maes

J. Appl. Phys. 67, 1219 (1990); http://dx.doi.org/10.1063/1.345720 (10 pages) | Cited 3 times

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An extension to large laser power values of the semiempirical model for the laser‐induced molten zone is given. The influence of the wafer preheating temperature and the thickness of thin capping layers on the molten zone is discussed. The variation of the size of the molten zone as caused by a change of the laser spot size is studied. An optimal laser power is determined to minimize the variation of the size of the molten zone as a result of a variation of the laser spot size. The difference between the laser power required to reach melt temperature in a silicon on insulator wafer and the laser power required to obtain complete melting is determined. A method to calculate the power required to reach the onset of complete melting in the case of a circular pseudostationary laser spot is proposed. The influence of the absorptances in liquid and in solid silicon, the thickness of the insulating layer, the thickness of the silicon overlayer, and the preheating temperature on the difference between the two threshold powers is treated.
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79.20.Ds Laser-beam impact phenomena
81.10.Fq Growth from melts; zone melting and refining
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
44.10.+i Heat conduction

Measurement of ion energy distributions at the powered rf electrode in a variable magnetic field

A. D. Kuypers and H. J. Hopman

J. Appl. Phys. 67, 1229 (1990); http://dx.doi.org/10.1063/1.345721 (12 pages) | Cited 55 times

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High‐resolution energy distributions of ions, accelerated by the sheath at the powered electrode of a low‐pressure 13.56‐MHz gas discharge, have been measured. The observed spectra are compared to existing models. Excellent agreement between measured and calculated spectra is obtained. Detailed information on rf sheath behavior is derived from the observed energy profiles and from the measured total ion current densities towards the electrode surface. Analogous to the case of dc discharges, a decrease of sheath thickness is observed when a homogeneous variable magnetic field (0≤B≤315 G) is applied. However, the product of magnetic‐field strength B and sheath thickness d is found to be independent of sheath voltage. This leads to the conclusion that in rf discharges, sheath contraction under influence of a magnetic field proceeds by a different mechanism than in dc discharges. It is suggested that the value of the product Bd is determined by the (virtually constant) temperature of the plasma electrons, rather than by the energy of secondary electrons that have been liberated from the electrode surface by ion bombardment. The decrease of sheath thickness d with magnetic‐field strength B leads to a changing capacitive‐voltage division of the applied generator voltage over the discharge. When the magnetic‐field strength is sufficiently high, this may result in a sign reversal of the electrode self‐bias voltage.
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52.70.Gw Radio-frequency and microwave measurements
52.40.Hf Plasma-material interactions; boundary layer effects
52.58.-c Other confinement methods
52.80.Sm Magnetoactive discharges (e.g., Penning discharges)

Model of plasma source ion implantation in planar, cylindrical, and spherical geometries

J. T. Scheuer, M. Shamim, and J. R. Conrad

J. Appl. Phys. 67, 1241 (1990); http://dx.doi.org/10.1063/1.345722 (5 pages) | Cited 99 times

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A model has been developed that describes the propagation of the transient sheath during a pulse of high negative voltage applied to a conductor immersed in a plasma such as that present in plasma source ion implantation. This model assumes that the transient sheath obeys the Child–Langmuir law for space‐charge‐limited emission at each instant during the propagation of the sheath. Expressions are obtained for the sheath‐edge position as a function of time. The model predicts the final sheath extent and average ion current to the target during each pulse for planar, cylindrical, and spherical geometries.
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52.40.Hf Plasma-material interactions; boundary layer effects
61.72.up Other materials

Modulation of the plasma flow in plasma wake experiments

Jin Tao, Jamie Cooney, Wee Beng Lim, Mohammad S. Ghaemi, and Karl E. Lonngren

J. Appl. Phys. 67, 1246 (1990); http://dx.doi.org/10.1063/1.345723 (3 pages)

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Experiments demonstrate that it is possible to determine the characteristics of a plasma flowing past an object by locally modulating the plasma and measuring the resulting equiphase contours of the perturbation downstream. The technique is employed in studies of the wake region behind the object.
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52.30.-q Plasma dynamics and flow
52.35.Mw Nonlinear phenomena: waves, wave propagation, and other interactions (including parametric effects, mode coupling, ponderomotive effects, etc.)

Observation of nanosecond‐pulse breakdown of gas‐insulated gaps by image converter camera

Yukimitsu Kawada and Tatsuzo Hosokawa

J. Appl. Phys. 67, 1249 (1990); http://dx.doi.org/10.1063/1.345724 (4 pages)

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Breakdown phenomena of gas‐insulated gaps with nanosecond pulses were examined by using an image converter camera. The physical appearance, i.e., luminosity of a gap, was investigated on streak photographs taken by the image converter camera. These investigations show that the breakdown mechanism of gas‐insulated gaps with nanosecond pulses can basically be explained by a conventional avalanche‐to‐streamer development theory.
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52.75.Kq Plasma switches (e.g., spark gaps)
52.80.Mg Arcs; sparks; lightning; atmospheric electricity

The bistability of the surface‐stabilized ferroelectric liquid‐crystal effect in electrically reoriented chevron structures

W. J. A. M. Hartmann and A. M. M. Luyckx‐Smolders

J. Appl. Phys. 67, 1253 (1990); http://dx.doi.org/10.1063/1.345700 (9 pages) | Cited 28 times

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Low‐frequency electric field treatment irreversibly changes the chevron structure of a surface‐stabilized ferroelectric liquid‐crystal sample: the angle between the smectic layers and the surface normal decreases. As a result different textures appear, and a pronounced effect on the switching behavior is observed. The switching angle and the necessary pulse amplitudes at constant pulse width in order to obtain switching between both stable states have increased. The required reorientation voltages decrease with rising spontaneous polarization. This reorientation process is strongly influenced by the rubbing treatment of the alignment layer. The anchoring properties of the alignment layer seem to be directly responsible for the appearance of defects, for the initial switching angle, for the electric field strength necessary to reorient the chevron structure, and for the pulse amplitudes required to switch between both stable states.
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61.30.Gd Orientational order of liquid crystals; electric and magnetic field effects on order

Atomic profiles and electrical characteristics of very high energy (8–20 MeV) Si implants in GaAs

Phillip E. Thompson, Harry B. Dietrich, and James M. Eridon

J. Appl. Phys. 67, 1262 (1990); http://dx.doi.org/10.1063/1.345701 (4 pages) | Cited 5 times

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High‐energy Si implantation into GaAs is of interest for the fabrication of fully implanted, monolithic microwave integrated circuits. Atomic concentration profiles of 8, 12, 16, and 20 MeV Si have been measured using secondary ion mass spectroscopy (SIMS). The range and shape parameters have been determined for each energy. The theoretical atomic concentration profile for 12 MeV Si calculated using TRIM‐88 corresponded to the SIMS experimental profile. No redistribution of the Si was observed for either furnace anneal, 825 °C, 15 min, or rapid thermal anneal, 1000 °C, 10 s. The activation of the Si improved when coimplanted with S. The coimplanted carrier concentration profiles did not show dopant diffusion. Peak carrier concentration of 2×1018/cm3 was obtained with a Si and S dose of 1.5×1014/cm2 each.
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61.72.U- Doping and impurity implantation
73.61.Ey III-V semiconductors
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Deep level transient spectroscopy analysis of fast ion tracks in silicon

A. Hallén, B. U. R. Sundqvist, Z. Paska, B. G. Svensson, M. Rosling, and J. Tirén

J. Appl. Phys. 67, 1266 (1990); http://dx.doi.org/10.1063/1.345702 (6 pages) | Cited 35 times

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Deep level transient spectroscopy measurements of electron traps in MeV proton‐ and alpha‐irradiated n‐type silicon have been performed. Six deep levels are found in proton‐irradiated samples, while only three appear after alpha irradiation. The influence of the irradiation dose on the defect production is investigated together with the depth concentration profiles. The profiles scale with the nuclear energy deposition, but in the case of the doubly negative charged state of the divacancy at EC −0.24 eV, the peak concentration at the end of the track is less pronounced relative to the tail region towards the surface. It is proposed that the singly negative charged state at EC −0.42 is more probable in a highly distorted lattice and it is shown that the formation of the singly negative charged state of the divacancy dominates the defect production for higher doses.
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61.80.Jh Ion radiation effects
61.72.jd Vacancies
61.72.jj Interstitials
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Local oxidation of GaP wafers heated by Nd:YAG laser beam

Tsutomu Kawamura

J. Appl. Phys. 67, 1272 (1990); http://dx.doi.org/10.1063/1.345703 (7 pages) | Cited 7 times

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GaP wafer optical properties, such as absorption coefficient and reflectance, were investigated around 1.06 μm wavelength. Next the wafers were locally heated by Nd:YAG laser beam (1.06 μm) between 600 and 1470 °C (melting point). A steep temperature gradient and the consequent explosive disordering played an important role in violent exothermic reaction on oxidation for differently surface‐treated GaP wafers, resulting in the formation of GaPO4 polycrystals. However, there was a marked difference in initial oxidation rates between a wafer, which had been mirror‐polished on only one surface, and a wafer mirror‐polished on both surfaces. The reason for this phenomena is discussed in detail.
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61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
78.20.-e Optical properties of bulk materials and thin films
81.40.Tv Optical and dielectric properties related to treatment conditions
65.20.-w Thermal properties of liquids
65.40.gd Entropy

Correlated transmission electron microscopy and photoluminescence studies of the Se+‐ion implantation of a GaAs/(Al,Ga)As multiple quantum well

E. G. Bithell, W. M. Stobbs, C. Phillips, R. Eccleston, and R. Gwilliam

J. Appl. Phys. 67, 1279 (1990); http://dx.doi.org/10.1063/1.345677 (9 pages) | Cited 5 times

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We report a study of the Se+‐ion implantation and subsequent annealing of a GaAs/(Al,Ga)As multiple quantum well, characterizing the process using transmission electron microscopy, photoluminescence spectroscopy, and Monte Carlo simulation techniques. We conclude that enhanced layer interdiffusion occurs at depths several times the projected range for the Se+ implant, and that there is evidence of residual stress at similar depths.
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61.72.U- Doping and impurity implantation
78.55.Cr III-V semiconductors
66.30.J- Diffusion of impurities
81.40.-z Treatment of materials and its effects on microstructure, nanostructure, and properties

Low‐temperature ion mixing of yttrium and silicon

T. L. Alford, P. Børgesen, J. W. Mayer, and D. A. Lilienfeld

J. Appl. Phys. 67, 1288 (1990); http://dx.doi.org/10.1063/1.345678 (5 pages) | Cited 6 times

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Ion mixing of yttrium and amorphous silicon bilayers was measured as a function of fluence and temperature using 600‐keV Xe++ ions between 80 and 498 K. At 80 K the mixing rate was in excellent agreement with a theoretical model based on thermal spike mixing. For temperatures up to ≊372 K, the temperature‐dependent contributions accounted for less than 50% of the overall mixing rate. For mixing at or above 400 K, our results revealed the formation of an ion‐beam‐induced orthorhombic Y‐Si phase, which is not normally formed during thermal anneals of such bilayers.
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61.80.Jh Ion radiation effects

Effect of flexoelectric coupling on helix distortions in cholesteric liquid crystals

Sin‐Doo Lee, J. S. Patel, and Robert B. Meyer

J. Appl. Phys. 67, 1293 (1990); http://dx.doi.org/10.1063/1.345679 (5 pages) | Cited 15 times

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The static and dynamic properties of the flexoelectric effect in cholesteric liquid crystals are presented. The application of an external electric field, below the critical strength for helix unwinding, perpendicular to the cholesteric helix, results in a linear electro‐optic effect. The experimental results are in good agreement with theoretical predictions made under the assumption of the uniform distortion of the helix due to the flexoelectric coupling with the field. The temperature dependence of the dynamic response to the field is found to be the Arrhenius type. It is suggested that the surface boundary conditions play a role in the properties of the flexoelectric effect.
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61.30.Gd Orientational order of liquid crystals; electric and magnetic field effects on order
78.20.Jq Electro-optical effects
78.66.Qn Polymers; organic compounds
64.70.-p Specific phase transitions

Monolayer resolution by means of x‐ray interference in semiconductor heterostructures

L. Tapfer, M. Ospelt, and H. von Känel

J. Appl. Phys. 67, 1298 (1990); http://dx.doi.org/10.1063/1.345680 (4 pages) | Cited 48 times

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We show that the interference of x‐ray wave fields in semiconductor heterostructures can be used to detect ultrathin layers having 1 monolayer thickness. A detailed theoretical and experimental investigation on Si/Six Ge1−x heterostructures is presented. The interference effect is studied experimentally by using a high‐resolution double‐crystal x‐ray diffractometer. The diffraction patterns are recorded in symmetrical as well as asymmetrical Bragg geometries and are analyzed by using the dynamical x‐ray diffraction theory for distorted crystals.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
68.55.-a Thin film structure and morphology
61.05.cc Theories of x-ray diffraction and scattering

Spatial distribution of defects in high‐purity silica glasses

Ryoichi Tohmon, Akihiro Ikeda, Yasushi Shimogaichi, Shuji Munekuni, Yoshimichi Ohki, Kaya Nagasawa, and Yoshimasa Hama

J. Appl. Phys. 67, 1302 (1990); http://dx.doi.org/10.1063/1.345681 (5 pages) | Cited 6 times

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The spatial distribution of defects and impurities in a variety of high‐purity silica glass manufactured by different methods are studied. The defects investigated include those found in the as‐manufactured glass (oxygen vacancy and peroxy linkage), as well as those induced by ionizing radiation or ultraviolet light (E′ center and oxygen hole centers). A significant difference is observed in the distribution between silica manufactured by different methods. Furthermore, the defects induced by ionizing radiation or ultraviolet light have a spatial distribution relative to the geometry of the as‐manufactured boule, suggesting that these defects arise primarily from the activation of preexisting precursors.
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78.30.Hv Other nonmetallic inorganics
78.40.Ha Other nonmetallic inorganics
76.30.Mi Color centers and other defects
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients
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