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15 Jun 2000

Volume 87, Issue 12, pp. 8243-8796

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Cavity detuning effects in semiconductor microcavity light emitting diodes

A. R. Pratt, T. Takamori, and T. Kamijoh

J. Appl. Phys. 87, 8243 (2000); http://dx.doi.org/10.1063/1.373534 (8 pages) | Cited 3 times

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Light output power versus current, emission spectroscopy and far-field emission patterns have been used to characterize microcavity light emitting diodes (MC-LEDs). Evidence that microcavity effects lead to enhanced emission properties is provided by changes in the total emitted light output power, as well as the electroluminescence spectra of the MC-LEDs. Compared to a conventional noncavity type LED structure, enhanced efficiency and narrow spectral linewidths have been observed for the MC-LEDs over a wide range of cavity detunings and cavity Q values. Evidence that control of the cavity detuning leads to temperature insensitive output characteristics is provided by changes in the temperature dependence of the slope efficiencies extracted from the light output versus current characteristics. Variations in the emitted radiation patterns as a function of current injection are also reported demonstrating the important role of the cavity detuning on the emission properties of MC-LEDs. © 2000 American Institute of Physics.
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85.60.Jb Light-emitting devices

Controlling spontaneous generation of optical beam spots in a liquid crystal device

Yoshiki Iino and Peter Davis

J. Appl. Phys. 87, 8251 (2000); http://dx.doi.org/10.1063/1.373533 (8 pages) | Cited 7 times

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An analysis is made of spot patterns generated in a liquid crystal spatial light modulator with optical feedback from the point of view of controlling generation of spots. The conditions for forming solitary spots were analyzed using a theoretical model which fits the experimental device well. Phenomena observed in experiments such as spontaneous birth, motion, and merging of spots is reproduced in numerical simulation with the model. It is shown how parameters characterizing nonlinearity, diffraction, and diffusion can be designed for stable spots and stable spot motion. © 2000 American Institute of Physics.
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42.79.Hp Optical processors, correlators, and modulators

Electro-optic characteristics of 4-domain vertical alignment nematic liquid crystal display with interdigital electrode

S. H. Hong, Y. H. Jeong, H. Y. Kim, H. M. Cho, W. G. Lee, and S. H. Lee

J. Appl. Phys. 87, 8259 (2000); http://dx.doi.org/10.1063/1.373535 (5 pages) | Cited 24 times

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We have fabricated a vertically aligned 4-domain nematic liquid crystal display cell with thin film transistor. Unlike the conventional method constructing 4-domain, i.e., protrusion and surrounding electrode which needs additional processes, in this study the pixel design forming 4-domain with interdigital electrodes is suggested. In the device, one pixel is divided into two parts. One part has a horizontal electric field in the vertical direction and the other part has a horizontal one in the horizontal direction. Such fields in the horizontal and vertical direction drive the liquid crystal director to tilt down in four directions. In this article, the electro-optic characteristics of cells with 2 and 4 domain have been studied. The device with 4 domain shows faster response time than normal twisted-nematic and in-plane switching cells, wide viewing angle with optical compensation film, and more stable color characteristics than 2-domain vertical alignment cell with similar structure. © 2000 American Institute of Physics.
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42.70.Df Liquid crystals
42.79.Kr Display devices, liquid-crystal devices
85.60.Pg Display systems

Looping mechanism in Er-doped fluoroindogallate glasses

M. J. V. Bell, D. F. de Sousa, and L. A. O. Nunes

J. Appl. Phys. 87, 8264 (2000); http://dx.doi.org/10.1063/1.373536 (4 pages) | Cited 2 times

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In this work we report a room temperature green upconversion in Er-doped fluoroindogallate glasses, pumped at 833 nm. The rise time and stationary intensity of the 4S3/2+2H11/2→4I15/2 Er3+ transition as a function of laser intensity were monitored. Some possible pumping mechanisms are discussed in detail, and it is concluded that the main pumping route may be described in terms of the looping mechanism. It is also shown that cross relaxation among neighboring pairs of Er3+ ions is near the threshold value to achieve the photon avalanche region. © 2000 American Institute of Physics.
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61.43.Fs Glasses
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.Ce Glasses, quartz

A nonorthogonal finite-difference time-domain method for computing the band structure of a two-dimensional photonic crystal with dielectric and metallic inclusions

Min Qiu and Sailing He

J. Appl. Phys. 87, 8268 (2000); http://dx.doi.org/10.1063/1.373537 (8 pages) | Cited 46 times

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A finite-difference time-domain scheme in a nonorthogonal coordinate system is presented to calculate the band structure of a two-dimensional photonic crystal consisting of a skew lattice. The method can be used for a photonic crystal of complicated configuration, such as a photonic crystal with both dielectric and metallic inclusions. The method is verified by comparing with the results obtained by other methods for some special cases. The band structure of a photonic crystal with a dielectric layer coated on a metallic cylinder as an inclusion is studied. For such a case, it is noticed that both the dielectric and metallic characteristics of the band structure are inherited. © 2000 American Institute of Physics.
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42.50.-p Quantum optics
02.70.Bf Finite-difference methods
42.70.Qs Photonic bandgap materials
78.20.-e Optical properties of bulk materials and thin films

Mathematical modeling of thermal runaway in semiconductor laser operation

W. R. Smith

J. Appl. Phys. 87, 8276 (2000); http://dx.doi.org/10.1063/1.373538 (10 pages) | Cited 10 times

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A mathematical model describing the coupling of electrical, optical and thermal effects in semiconductor lasers is introduced. Through a systematic asymptotic expansion, the governing system of differential equations is reduced to a single second-order boundary value problem. This highly nonlinear equation describes the time-independent maximum temperature in the boundary layer adjacent to the mirror facet. The solution of the problem is a multi-valued function of current. The graph of the maximum steady-state temperature as a function of current gives a fold-shaped response curve, which indicates that no bounded steady state exists beyond a critical value of current. For certain device parameters and initial conditions, thermal runaway occurs. A mechanism for the sudden mode of semiconductor laser failure is described in terms of thermal runaway. © 2000 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
02.30.Hq Ordinary differential equations
85.30.De Semiconductor-device characterization, design, and modeling

Modeling of the spectral response of AlxGa1−xN Schottky ultraviolet photodetectors

A. Bouhdada, M. Hanzaz, P. Gibart, F. Omnès, E. Monroy, and E. Muñoz

J. Appl. Phys. 87, 8286 (2000); http://dx.doi.org/10.1063/1.373539 (5 pages) | Cited 6 times

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Schottky AlxGa1−xN photodetectors were developed for solar ultraviolet A and B detection. Modeling is performed by developing programs of simulation leading to the most suitable device structure such as doping density, semiconductor thickness, etc. Simulations allow us to determine the most appropriate parameters © 2000 American Institute of Physics.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
42.79.Pw Imaging detectors and sensors
85.60.Dw Photodiodes; phototransistors; photoresistors
85.30.Kk Junction diodes
85.30.De Semiconductor-device characterization, design, and modeling

Thermally based light modulation through free-standing porous silicon film

Z. Gaburro and D. Babić

J. Appl. Phys. 87, 8291 (2000); http://dx.doi.org/10.1063/1.373540 (4 pages) | Cited 1 time

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A large laser induced increase of light absorption has been observed in free-standing porous silicon films, in the wavelength range 500–700 nm. Thermal origin of the observed modulation is suggested by two hitherto unreported observations: the spectral dependence and the comparison between the time decay of modulation with photoluminescence. A simple thermal model, taking into account the porosity of the porous silicon film, provides a good fit over the probed spectrum. © 2000 American Institute of Physics.
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78.66.Db Elemental semiconductors and insulators
78.20.N- Thermo-optic effects
78.20.nb Photothermal effects
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.55.Ap Elemental semiconductors
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Characterization of wire x pinches driven by a microsecond-long capacitive discharge

C. Christou, A. E. Dangor, and D. A. Hammer

J. Appl. Phys. 87, 8295 (2000); http://dx.doi.org/10.1063/1.373541 (9 pages) | Cited 16 times

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The use of a simple capacitive discharge as a driver for an x-pinch soft x-ray source is demonstrated. The 30 kV, 4 kJ capacitive discharge had a quarter period of 1.2 μs, peak current of 320 kA, and current rise of 2.5×1011 A s−1. X-pinch x-ray emission was characterized by pinhole photography and solid-state detectors. Soft x-ray emission (800 eV–4 keV) was observed in both single and multiple bursts, with yields from 180 mJ for aluminum to 1.5 J for tungsten wire x pinches. X-ray emission from x pinches was higher than z-pinch emission from the same materials using the same power source. Hard x-ray emission (>8 eV) from the x pinch was lower with the long pulse capacitive discharge than with a 360 kV pulsed power driver delivering 100 kA peak with a rate of current rise of 2.2×1012 A s−1. Visible photography and laser-based schlieren photography showed that the x pinch was asymmetric about the crossing point of the wires. This asymmetry is due to the influence of electron beam generation at this point. © 2000 American Institute of Physics.
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52.55.Ez Theta pinch
52.80.-s Electric discharges
07.85.-m X- and γ-ray instruments
52.70.Kz Optical (ultraviolet, visible, infrared) measurements

Behavior of excited argon atoms in inductively driven plasmas

G. A. Hebner and P. A. Miller

J. Appl. Phys. 87, 8304 (2000); http://dx.doi.org/10.1063/1.373542 (12 pages) | Cited 25 times

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Laser induced fluorescence has been used to measure the spatial distribution of the two lowest energy argon excited states, 1s5 and 1s4, in inductively driven plasmas containing argon, chlorine and boron trichloride. The behavior of the two energy levels with plasma conditions was significantly different, probably because the 1s5 level is metastable and the 1s4 level is radiatively coupled to the ground state but is radiation trapped. The argon data are compared with a global model to identify the relative importance of processes such as electron collisional mixing and radiation trapping. The trends in the data suggest that both processes play a major role in determining the excited state density. At lower rf power and pressure, excited state spatial distributions in pure argon were peaked in the center of the discharge, with an approximately Gaussian profile. However, for the highest rf powers and pressures investigated, the spatial distributions tended to flatten in the center of the discharge while the density at the edge of the discharge was unaffected. The spatially resolved excited state density measurements were combined with previous line integrated measurements in the same discharge geometry to derive spatially resolved, absolute densities of the 1s5 and 1s4 argon excited states and gas temperature spatial distributions. Fluorescence lifetime was a strong function of the rf power, pressure, argon fraction and spatial location. Increasing the power or pressure resulted in a factor of 2 decrease in the fluorescence lifetime while adding Cl2 or BCl3 increased the fluorescence lifetime. Excited state quenching rates are derived from the data. When Cl2 or BCl3 was added to the plasma, the maximum argon metastable density depended on the gas and ratio. When chlorine was added to the argon plasma, the spatial density profiles were independent of chlorine fraction. While it is energetically possible for argon excited states to dissociate some of the molecular species present in this discharge, it does not appear to be a significant source of dissociation. The major source of interaction between the argon and the molecular species BCl3 and Cl2 appears to be through modification of the electron density. © 2000 American Institute of Physics.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.20.Fs Electron collisions
31.50.Df Potential energy surfaces for excited electronic states
32.50.+d Fluorescence, phosphorescence (including quenching)
31.15.vj Electron correlation calculations for atoms and ions: excited states

Structure of plasmas generated by the interaction between metallic ions and neutral gas particles in a low-pressure arc

H. Kelly, A. Lepone, and F. Minotti

J. Appl. Phys. 87, 8316 (2000); http://dx.doi.org/10.1063/1.373543 (7 pages) | Cited 6 times

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A numerical solution for the metallic-plasma-neutral-gas structure generated in a low-pressure arc is presented. The equations correspond to a spherically symmetric fluid-like steady model, valid for the outer region of the arc, and describe the ion slowing down by elastic scattering with the neutral particles. Technically, the obtention of the profiles of different magnitudes is complicated due to the existence of a critical point in the steady-state system of equations. The proposed approach to overcome this difficulty is to solve instead a pseudotransient system of equations which rapidly and efficiently relax to the stationary state. By employing this numerical method of second-order accuracy in space, the plasma and neutral gas density, the electron and ion drift velocities, the electron and neutral temperatures, and the electrostatic potential profiles are obtained from the border of the arc channel up to the discharge chamber wall. It is found that the value of the neutral gas filling pressure strongly influences the plasma density and plasma potential distributions. An important result is that metallic ions emitted from the arc channel deliver their kinetic energy to the filling gas in a gradual manner, up to a pressure-dependent point beyond which they move to the walls sustained against collisions with the gas by a self-consistent electric field. Near the mentioned point, the metallic ion density presents a peculiar behavior, showing an increase that is more pronounced at high pressures; a pattern also evident in the electrostatic potential. © 2000 American Institute of Physics.
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52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.50.Dg Plasma sources
52.20.Hv Atomic, molecular, ion, and heavy-particle collisions

Effect of metastable oxygen molecules in high density power-modulated oxygen discharges

Siddhartha Panda, Demetre J. Economou, and M. Meyyappan

J. Appl. Phys. 87, 8323 (2000); http://dx.doi.org/10.1063/1.373544 (11 pages) | Cited 41 times

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A spatially averaged (well mixed) reactor model was used to simulate a power-modulated (pulsed) high density oxygen discharge. Chemistry involving the high energy oxygen metastable molecules O2M(A 3Σu++C 3Δu+c 1Σu−) was included in the simulation. This chemistry was necessary to capture the experimentally observed increase in the O− negative ion density in the afterglow of the pulsed discharge. As the electron temperature drops in the afterglow, the rate coefficient of electron attachment with O2M increases several fold. The wall recombination probability of oxygen atoms affected the O− density drastically. For the conditions studied, the maximum O− density in the afterglow increased with pressure, decreased with power, and showed a maximum with pulse period. The time in the afterglow at which the peak O− density occurred decreased with pressure and power, and was independent of the pulse period. Knowing the temporal evolution of O− in the afterglow may be important for applications requiring extraction of negative ions out of the discharge. © 2000 American Institute of Physics.
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52.65.-y Plasma simulation
52.80.Hc Glow; corona
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)
34.80.Lx Recombination, attachment, and positronium formation
52.40.Hf Plasma-material interactions; boundary layer effects
52.25.-b Plasma properties

Calculation of gas heating in direct current argon glow discharges

Annemie Bogaerts, Renaat Gijbels, and Vladimir V. Serikov

J. Appl. Phys. 87, 8334 (2000); http://dx.doi.org/10.1063/1.373545 (11 pages) | Cited 38 times

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A model is developed for self-consistently calculating the gas temperature in a direct current argon glow discharge, used for analytical spectroscopy. The power input into the argon gas due to elastic (i.e., kinetic energy transfer) collisions of Ar+ ions, and fast Ar atoms, sputtered Cu atoms and electrons with the argon gas atoms is calculated with Monte Carlo models. This power input is used in a heat transfer model to calculate the gas temperature. The amount of power input, the contributions of the various input sources, and the resulting gas temperature are calculated for a wide range of voltages, pressures, and currents, typically applied in analytical spectroscopy. It is found that the temperature can increase significantly at high voltages, pressures, and currents (up to a factor of 3 compared to absolute room temperature). © 2000 American Institute of Physics.
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52.80.Hc Glow; corona
52.25.Kn Thermodynamics of plasmas
52.50.Gj Plasma heating by particle beams
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)

Effect of multiple current spikes on the enhancement of ion charge states of vacuum arc plasmas

George Yu. Yushkov, Efim M. Oks, André Anders, and Ian G. Brown

J. Appl. Phys. 87, 8345 (2000); http://dx.doi.org/10.1063/1.373546 (6 pages) | Cited 12 times

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Ion charge state distributions of vacuum arc ion sources are correlated to the arc operating voltage. Recent research has shown that an enhancement of ion charges via an increase of the arc voltage can be achieved utilizing the transient processes that accompany an arc current spike. The idea investigated is to further enhance the ion charge states by multiple current pulses. It is shown that although the ion charge states are enhanced compared to quasi-dc operation, the application of a sequence of pulses does not lead to the desired additional increase in charge states. This can be attributed to the additional plasma production that is caused by higher arc currents: The additional power supplied to the plasma is distributed over a larger number of plasma particles. One can expect that in the limiting case of many current spikes, the ion charges state distribution approaches the one known for arc plasmas at higher discharge current. © 2000 American Institute of Physics.
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52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.80.Vp Discharge in vacuum
52.50.Dg Plasma sources

Composition of trench sidewalls and bottoms for SiO2-masked Si(100) etched in Cl2 plasmas

K. H. A. Bogart and V. M. Donnelly

J. Appl. Phys. 87, 8351 (2000); http://dx.doi.org/10.1063/1.373547 (10 pages) | Cited 11 times

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We have investigated the possible role of redeposition of silicon–chloride etching products on profile evolution by studying the influence of etching product partial pressure on the surface layer formed during chlorine plasma etching of SiO2-masked p-type Si(100). Samples were etched with high and low etching product (SiCly)-to-etchant (Cl, Cl2) concentration ratios by changing the Cl2 flow rate (1.4 or 10.0 sccm, respectively) at a constant pressure of 4 mTorr. Compositional analysis was performed using angle-resolved x-ray photoelectron spectroscopy (XPS). Electron shadowing and differential charging of the insulating SiO2 regions were exploited to spatially resolve the composition of the trench sidewalls and bottoms (2.0, 1.0, 0.5, 0.3, and 0.22 μm wide). Chlorine content and stoichiometry of the etched surfaces were determined by quantifying the XPS intensities of both the Cl(2p) peak and the silicon chloride containing tail of the Si(2p) peak. Comparisons of chlorine content and stoichiometry were also made to unmasked Si areas etched on the same samples. For trenches etched with 10 sccm Cl2, the chlorine coverage (2.6×1015 Cl/cm2, equivalent to ∼3 monolayers) and the silicon chloride stoichiometry (SiCl:SiCl2:SiCl3=1:0.45:0.33) were identical for the unmasked Si areas and the bottoms of the trenches. The trench sidewalls, however, contained roughly 50% less Cl than the unmasked areas, all in the form of SiCl. Virtually identical results were obtained for trenches etched with 1.4 sccm Cl2, indicating that increased SiCly etching product concentrations do not result in the formation of a thick, passivating sidewall layer on trench sidewalls during Cl2 plasma etching of Si masked with SiO2. © 2000 American Institute of Physics.
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81.05.Cy Elemental semiconductors
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
81.65.Cf Surface cleaning, etching, patterning
68.35.Dv Composition, segregation; defects and impurities
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Annealing behavior of hydrogen-defect complexes in carbon-doped Si quenched in hydrogen atmosphere

Naoki Fukata and Masashi Suezawa

J. Appl. Phys. 87, 8361 (2000); http://dx.doi.org/10.1063/1.373548 (7 pages) | Cited 7 times

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Optical absorption spectra and the annealing behavior of hydrogen (H)-point defect complexes in carbon (C)-doped Si after hydrogenation were investigated. Specimens of C-doped Si (C concentration: 1.7×1017 cm−3) were sealed in quartz capsules together with H2 gas and were annealed at a high temperature for 1 h followed by quenching in water. We measured the optical absorption spectra at about 7 K with a Fourier-transform infrared spectrometer. The VH4 (V: monovacancy) defect was almost annealed out at 600 °C. The formation energy of the VH4 defect in C-doped Si was estimated to be about 3.2 eV from the quenching temperature dependence of the 2223 cm−1 peak. The observed 2192 and 2203 cm−1 peaks are probably due to the VH3 defect, which captures one H atom during annealing and become the VH4 defect. After annealing at 700 °C, we observed two absorption peaks at 2093 and 2086 cm−1, which are probably due to Si–H stretching vibration of H on internal surfaces of voids. From these assignments, it was found that V is introduced into C-doped Si at high temperatures, although it is known that C introduces I into Si at high temperatures. © 2000 American Institute of Physics.
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71.55.Cn Elemental semiconductors
61.72.Cc Kinetics of defect formation and annealing
61.72.Yx Interaction between different crystal defects; gettering effect
78.30.Am Elemental semiconductors and insulators
78.40.Fy Semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Defect identification in GaAs grown at low temperatures by positron annihilation

J. Gebauer, F. Börner, R. Krause-Rehberg, T. E. M. Staab, W. Bauer-Kugelmann, G. Kögel, W. Triftshäuser, P. Specht, R. C. Lutz, E. R. Weber, and M. Luysberg

J. Appl. Phys. 87, 8368 (2000); http://dx.doi.org/10.1063/1.373549 (12 pages) | Cited 17 times

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We use positron annihilation to study vacancy defects in GaAs grown at low temperatures (LT–GaAs). The vacancies in as-grown LT–GaAs can be identified to be Ga monovacancies, VGa, according to their positron lifetime and annihilation momentum distribution. The charge state of the vacancies is neutral. This is ascribed to the presence of positively charged AsGa+ antisite defects in vicinity to the vacancies. Theoretical calculations of the annihilation parameters show that this assignment is consistent with the data. The density of VGa is related to the growth stoichiometry in LT–GaAs, i.e., it increases with the As/Ga beam equivalent pressure (BEP) and saturates at 2×1018 cm−3 for a BEP⩾20 and a low growth temperature of 200 °C. Annealing at 600 °C removes VGa. Instead, larger vacancy agglomerates with a size of approximately four vacancies are found. It will be shown that these vacancy clusters are associated with the As precipitates formed during annealing. © 2000 American Institute of Physics.
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61.72.J- Point defects and defect clusters
78.70.Bj Positron annihilation
71.55.Eq III-V semiconductors
81.05.Ea III-V semiconductors

Investigation of the interaction between silicon interstitials and dislocation loops using the wafer bonding technique

D. Tsoukalas, D. Skarlatos, and J. Stoemenos

J. Appl. Phys. 87, 8380 (2000); http://dx.doi.org/10.1063/1.373550 (5 pages) | Cited 1 time

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In this work, we investigate (i) the interaction of silicon interstitial atoms during thermal oxidation of silicon with a dislocation loop layer positioned at different distances from the surface as well as (ii) the interaction between two loop layers positioned at different depth distances. In both experiments, interstitials are injected by surface oxidation. The results show a linear dependence of the injection flux of interstitials with the inverse of the distance of the loop layer from the surface and a small leakage (16%) of the injected interstitials escaping from the upper and becoming bounded to the deeper loop layer. The experiments are performed using the wafer bonding technique that allows versatility on their design. © 2000 American Institute of Physics.
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61.72.J- Point defects and defect clusters
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
81.65.Mq Oxidation
81.05.Cy Elemental semiconductors

Damage accumulation in Si crystal during ion implantation at elevated temperatures: Evidence of chemical effects

J. P. de Souza, Yu. Suprun-Belevich, H. Boudinov, and C. A. Cima

J. Appl. Phys. 87, 8385 (2000); http://dx.doi.org/10.1063/1.373551 (4 pages) | Cited 10 times

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Damage in Si induced by irradiation with various light/medium mass ions at elevated temperatures and high doses (⩾3×1016 cm−2) was studied using Rutherford backscattering spectroscopy, cross-section transmission electron microscopy, and high resolution x-ray diffraction. The results obtained have shown that there is a marked variation in the damage accumulation for different ion species. For O+ and N+ ions a distinct layer with a low level of damage presenting negative strain is formed at the surface. It has been found that the magnitude of the strain does not correlate with the energy deposited in the collision cascades. In the cases of Ne+ and Mg+ implantation, a low damage accumulation occurs near the surface but no negative strain is formed. In contrast to the N+ and O+ cases, with the increase of the Ne+ or Mg+ dose (>1×1017 cm−2) the damage profile stretches almost to the crystal surface. It is proposed that in addition to the mechanism of spatial separation of Frenkel pairs taking place in the collision cascades, the ability of the implanted ions to form precipitates and complexes with Si atoms noticeably influences the damage formation during implantation at elevated temperatures. © 2000 American Institute of Physics.
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61.72.uf Ge and Si
61.80.Jh Ion radiation effects
81.05.Cy Elemental semiconductors
61.82.Fk Semiconductors
85.40.Ry Impurity doping, diffusion and ion implantation technology
61.85.+p Channeling phenomena (blocking, energy loss, etc.)
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis
64.75.-g Phase equilibria

Influence of the dopant species on radiation-induced defects in Si single crystals

Aurangzeb Khan, Masafumi Yamaguchi, Minoru Kaneiwa, Tatsue Saga, Takao Abe, Osamu Annzawa, and Sumio Matsuda

J. Appl. Phys. 87, 8389 (2000); http://dx.doi.org/10.1063/1.373552 (4 pages) | Cited 7 times

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Observations on deep levels introduced in silicon by 1 MeV electron irradiation are reported using boron- or gallium-doped Czochralski (CZ) grown Si space solar cells with different doping concentrations, deep level transient spectroscopy analysis has been carried out to detect the radiation-induced deep levels. Present results provide evidence for new defect states in addition to those previously reported in gallium- and boron-doped Si. The combined boron and gallium data provide enough information to gain valuable insight into the role of the dopants on radiation induced defects in Si. The dominant donor-like electron level at EC−0.18 eV in boron-doped Si has not been observed in gallium-doped CZ-grown Si. A noticeable suppressing generation of the radiation-induced defects in gallium-doped Si is also observed, especially hole level EV+0.36 eV, which is thought to acts as a recombination center. © 2000 American Institute of Physics.
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71.55.Cn Elemental semiconductors
84.60.Jt Photoelectric conversion
61.80.Fe Electron and positron radiation effects
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
81.05.Cy Elemental semiconductors
61.82.Fk Semiconductors
61.72.S- Impurities in crystals

Phase fields of nickel silicides obtained by mechanical alloying in the nanocrystalline state

M. K. Datta, S. K. Pabi, and B. S. Murty

J. Appl. Phys. 87, 8393 (2000); http://dx.doi.org/10.1063/1.373553 (8 pages) | Cited 17 times

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Solid state reactions induced by mechanical alloying (MA) of elemental blends of Ni and Si have been studied over the entire composition range of the Ni–Si system. A monotonous increase of the lattice parameter of the Ni rich solid solution, Ni(Si), is observed with refinement of crystallite size. Nanocrystalline phase/phase mixtures of Ni(Si), Ni(Si)+Ni31Si12, Ni31Si12+Ni2Si, Ni2Si+NiSi and NiSi+Si, have been obtained during MA, over the composition ranges of 0–10, 10–28, 28–33, 33–50, and >50 at. % Si, respectively. The results clearly suggest that only congruent melting phases, Ni31Si12, Ni2Si, and NiSi form, while the formation of noncongruent melting phases, Ni3Si, Ni3Si2, and NiSi2, is bypassed in the nanocrystalline state. The phase formation during MA has been discussed based on thermodynamic arguments. The predicted phase fields obtained from effective free energy calculations are quite consistent with those obtained during MA. © 2000 American Institute of Physics.
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81.30.Dz Phase diagrams of other materials
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
64.75.-g Phase equilibria
61.46.-w Structure of nanoscale materials
65.20.-w Thermal properties of liquids
65.40.gd Entropy
61.66.Fn Inorganic compounds
81.07.-b Nanoscale materials and structures: fabrication and characterization

Formation of voids in Ti-salicided BF2+-doped submicron polysilicon lines

H. N. Chua, K. L. Pey, W. H. Lai, and S. Y. Siah

J. Appl. Phys. 87, 8401 (2000); http://dx.doi.org/10.1063/1.373554 (6 pages) | Cited 4 times

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The physical characteristics and distribution of voids in TiSi2/p+-Si system as a function of polycrystalline silicon (polySi) linewidths were investigated in detail using scanning electron microscopy, cross-sectional transmission electron microscopy, and the focused ion beam technique. Surface and subsurface voids were found in Ti-salicided BF2+-implanted polycrystalline silicon (polySi) lines that were annealed at temperatures ranging from 650 to 850 °C. Most of the subsurface voids were found in the TiSi2 film as well as at the TiSi2/polySi interface. The void density, shape irregularity, and void size increase with decreasing polySi linewidth, especially when it is smaller than 0.24 μm, indicating that stress associated with narrow polySi lines may play an important role in the voiding phenomenon. It was also shown that the TiN film overlying the TiSi2 film and the etch-back process could not be responsible for the void formation process. Instead the absence of voids in B+-implanted polySi and the segregation of fluorine into the TiSi2/polySi and TiN/TiSi2 interfaces from BF2+-implanted polySi after the first salicidation rapid thermal annealing suggest a fluorine-assisted voiding mechanism. © 2000 American Institute of Physics.
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61.72.Qq Microscopic defects (voids, inclusions, etc.)
81.05.Cy Elemental semiconductors
73.61.Cw Elemental semiconductors
73.40.Ns Metal-nonmetal contacts
61.72.Cc Kinetics of defect formation and annealing
68.35.Ct Interface structure and roughness

Thermal properties of Ti4AlN3

M. W. Barsoum, C. J. Rawn, T. El-Raghy, A. T. Procopio, W. D. Porter, H. Wang, and C. R. Hubbard

J. Appl. Phys. 87, 8407 (2000); http://dx.doi.org/10.1063/1.373555 (8 pages) | Cited 24 times

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In this article we report on the atomic displacement parameters, lattice expansions, heat capacity, and thermal conductivity of samples of Ti4AlN3 in the 298–1370 K temperature range. Rietveld refinement of high temperature neutron diffraction data shows that the nitrogen is substoichiometric and the formula is Ti4AlN2.9. In this structure, the atomic displacement parameters of the Al atoms are higher than those of either the Ti or N atoms. The Ti–N bonds adjacent to the Al planes are about 2.5% shorter than the Ti–N bonds in the inner layers. The thermal expansion coefficients along the a and c axes are, respectively, (9.6±0.1)×10−6 and (8.8±0.1)×10−6 K−1. The unit cell expansivity, (9.4±0.1)×10−6 K−1, is in agreement with the dilatometric bulk thermal expansivity (9.7±0.2)×10−6 K−1. The heat capacity, cp, is 150 J/mol K at ambient temperatures and extrapolates to ≈220 J/mol K at 1300 K. At all temperatures cp equals four times the molar heat capacity of TiN. The room temperature thermal conductivity is 12 W/m K and increases linearly to ≈20 W/m K at 1300 K. © 2000 American Institute of Physics.
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65.40.De Thermal expansion; thermomechanical effects
65.40.-b Thermal properties of crystalline solids
65.60.+a Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.
65.80.-g Thermal properties of small particles, nanocrystals, nanotubes, and other related systems
66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
61.66.Fn Inorganic compounds
61.50.Lt Crystal binding; cohesive energy

Kinetic aspects of the growth of hydrogen induced platelets in SiC

J. Grisolia, F. Cristiano, B. De Mauduit, G. Ben Assayag, F. Letertre, B. Aspar, L. Di Cioccio, and A. Claverie

J. Appl. Phys. 87, 8415 (2000); http://dx.doi.org/10.1063/1.373556 (5 pages) | Cited 5 times

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Annealing of heavily hydrogen-implanted silicon carbide (SiC) leads to the formation of one specific type of defect: hydrogen induced platelets. These defects may be regarded as two-dimensional precipitates of H atoms stored in a stable configuration. In this article, we have studied the growth kinetics of these platelets upon annealing in the 800–1000 °C range by transmission electron microscopy. We show that the growth of these defects proceeds through the exchange of H atoms with the result that larger ones grow at the expense of the smaller ones during annealing. This process can be described in terms of a conservative Ostwald ripening mechanism. The activation energy for this growth is found to be about 3.4 eV, a value similar to that observed for the “effective” diffusion of H in heavily H-implanted SiC. © 2000 American Institute of Physics.
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61.72.Cc Kinetics of defect formation and annealing
61.72.up Other materials
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
64.75.-g Phase equilibria
81.30.Mh Solid-phase precipitation

Formation energies and relative stability of perfect and faulted dislocation loops in silicon

F. Cristiano, J. Grisolia, B. Colombeau, M. Omri, B. de Mauduit, A. Claverie, L. F. Giles, and N. E. B. Cowern

J. Appl. Phys. 87, 8420 (2000); http://dx.doi.org/10.1063/1.373557 (9 pages) | Cited 38 times

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A study of the relative thermal stability of perfect and faulted dislocation loops formed during annealing of preamorphized silicon wafers has been carried out. A series of transmission electron microscopy experiments has been designed to study the influence of the ion dose, the annealing ambient and the proximity of a free surface on the evolution of both types of loops. Samples were implanted with either 150 keV Ge+ or 50 keV Si+ ions to a dose of 2×1015 cm−2 and annealed at 900 °C in N2, N2O, and O2. The calculations of formation energy of both types of dislocation loops show that, for defects of the same size, faulted dislocation loops (FDLs) are more energetically stable than perfect dislocation loops (PDLs) if their diameter is smaller than 80 nm and vice versa. The experimental results have been analyzed within the framework of the Ostwald ripening of two existing populations of interstitial defects. It is found that the defect ripening is nonconservative if the surface is close to the end of range defect layer or if the sample is oxidized during annealing. In both cases, the knowledge of the formation energy of both types of dislocation loops allows a realistic estimate of the interstitial flux towards and from the surface, respectively, during annealing, in agreement with the experimental results. During a conservative ripening process, a direct correspondence exists between the formation energy of the two defect families and the number of atoms bound to them. In this case, the relative stability of FDLs and PDLs depends on the initial supersaturation of Si interstitial atoms created during implantation. © 2000 American Institute of Physics.
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61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.82.Fk Semiconductors
61.80.Jh Ion radiation effects
61.72.Lk Linear defects: dislocations, disclinations
61.72.Cc Kinetics of defect formation and annealing
61.72.J- Point defects and defect clusters
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