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1 Nov 1998

Volume 84, Issue 9, pp. 4649-5372

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Comparison of fluorescence-based temperature sensor schemes: Theoretical analysis and experimental validation

S. F. Collins, G. W. Baxter, S. A. Wade, T. Sun, K. T. V. Grattan, Z. Y. Zhang, and A. W. Palmer

J. Appl. Phys. 84, 4649 (1998); http://dx.doi.org/10.1063/1.368705 (6 pages) | Cited 72 times

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The performance of the two most promising fluorescence-based temperature sensing techniques, namely the fluorescence intensity ratio (FIR) and fluorescence lifetime (FL) schemes, have been compared. Theoretical calibration graphs for the two methods illustrate the useful monotonic change of the response with temperature variation. Comparison of the responses and the sensitivities of the two schemes show that at very low temperatures the FIR method exhibits a significant variation with temperature, while the response of the FL method becomes constant with its sensitivity approaching zero. With increasing temperature, the FIR and the FL methods (with short relaxation times and shorter intrinsic lifetimes of the upper energy levels) share a similar sensitivity over a wide temperature range. The presence of a long relaxation time or a longer intrinsic lifetime of the upper level in the use of the FL method gives a less satisfactory response. Experimental data obtained for a range of dopant ions in various host materials are found to be consistent with the theoretical expectation, with each material having a specific energy gap difference. The sensitivities of each material are compared graphically which would allow the most appropriate sensor for an intended application to be selected. © 1998 American Institute of Physics.
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07.20.Dt Thermometers
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing

Tip-sample distance regulation for near-field scanning optical microscopy using the bending angle of the tapered fiber probe

P. K. Wei and W. S. Fann

J. Appl. Phys. 84, 4655 (1998); http://dx.doi.org/10.1063/1.368706 (6 pages) | Cited 5 times

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A method to directly measure the bending angle of a vibrating tapered optical fiber probe is demonstrated. This modified optical beam deflection method allows the vibrational amplitude and angle to be measured independently. The results show that there is a bending in the tip shaft. The merits of using this vibrational angle for distance regulation in near-field scanning optical microscopy are discussed. © 1998 American Institute of Physics.
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07.79.Fc Near-field scanning optical microscopes
07.60.Vg Fiber-optic instruments
42.81.Pa Sensors, gyros

Characterization and optimization of the detection sensitivity of an atomic force microscope for small cantilevers

Tilman E. Schäffer and Paul K. Hansma

J. Appl. Phys. 84, 4661 (1998); http://dx.doi.org/10.1063/1.368707 (6 pages) | Cited 30 times

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The detection sensitivity of an atomic force microscope with optical beam deflection for small cantilevers is characterized experimentally and theoretically. An adjustable aperture is used to optimize the detection sensitivity for cantilevers of different length. With the aperture, the signal-to-noise ratio of cantilever deflection measurements is increased by a factor of 1.5 to nearly 3. A theoretical model is set up that generally describes the optical beam deflection detection in an atomic force microscope. This model is based on diffraction theory and includes the particular functional shape of the cantilever. © 1998 American Institute of Physics.
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07.79.Lh Atomic force microscopes
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy
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Some effects of conduction band nonparabolicity on electron reflection spectrum of multiquantum barriers

Michinori Irikawa, Takuya Ishikawa, Yoshitaka Sasaki, Katsumi Iwasawa, Ikuo Suemune, and Kenichi Iga

J. Appl. Phys. 84, 4667 (1998); http://dx.doi.org/10.1063/1.368708 (6 pages) | Cited 3 times

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The effect of nonparabolicity of conduction band on the electron reflection spectrum of multiquantum barriers (MQB) has been examined. Drastic reduction in the effective barrier height is expected by adopting the nonparabolic model on the MQB which had been designed using the parabolic model for 1.5 μm semiconductor lasers (LDs). The predicted enhancement in barrier height by the MQB is over 600 meV under parabolic model. However, it decreases to 40 meV under nonparabolic model with the same structure. On the other hand, the experimental enhancement in barrier height by the MQB is estimated to be around 30 meV on 1.5 μm LDs, close to the value calculated by nonparabolic model. Those results suggest that a much higher effective barrier height can be realized by optimizing the MQB design taking the nonparabolicity into account. The conduction band nonparabolicity was incorporated by the k⋅p perturbation method. © 1998 American Institute of Physics.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.23.-b Electronic transport in mesoscopic systems
42.55.Px Semiconductor lasers; laser diodes

Comparison between the Monte Carlo method and the drift-diffusion approximation in quantum-well laser simulation

A. D. Güçlü, R. Maciejko, A. Champagne, M. Abou-Khalil, and T. Makino

J. Appl. Phys. 84, 4673 (1998); http://dx.doi.org/10.1063/1.368709 (4 pages) | Cited 1 time

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The most widespread approaches to semiconductor device simulation are the drift-diffusion equations, momentum/energy balance equations, and the Monte Carlo method. In this article, the first comparison between results of a Monte Carlo simulation of a multiple-quantum-well structure and those obtained using a classical drift-diffusion simulator is presented. The outcome of the two methods is found to be similar. Still, the Monte Carlo approach offers much more insight into several issues such as the effects of the light holes and the carrier–carrier interactions. The limits and advantages of both methods are discussed. © 1998 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
85.30.De Semiconductor-device characterization, design, and modeling
02.70.Rr General statistical methods
42.25.Fx Diffraction and scattering
05.60.-k Transport processes

Giant sonic stop bands in two-dimensional periodic system of fluids

M. S. Kushwaha and B. Djafari-Rouhani

J. Appl. Phys. 84, 4677 (1998); http://dx.doi.org/10.1063/1.368710 (7 pages) | Cited 37 times

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Periodic binary systems can give rise to genuine acoustic stop bands within which sound and vibrations remain forbidden. We compute extensive band structures for two-dimensional (2D) periodic arrays of air cylinders in water. Complete, multiple, huge stop bands are found for both square and hexagonal lattices. The lowest stop bands are largest for a range of filling fraction 10% ⩽ f ⩽ 55%, with a gap/midgap ratio of 1.8. The most interesting finding of the present investigation is that the low-frequency, flat passbands for a perfectly periodic system correspond to the discrete modes of a single airy cylinder. This is attributed to the low filling fraction and huge density contrast in air and water. We stress that such a simple inhomogeneous system as made up of air and water exhibits the largest stop bands ever reported for 2D or 3D elastic as well as dielectric composites. © 1998 American Institute of Physics.
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62.60.+v Acoustical properties of liquids

Laser-induced evolution of hypocycloidal formation of vortex filaments from nonlinear Rayleigh–Taylor instability in a thin layer of molten metal

S. Lugomer and A. Maksimović

J. Appl. Phys. 84, 4684 (1998); http://dx.doi.org/10.1063/1.368711 (9 pages) | Cited 1 time

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A tiny vortex filament, the self-organization of which follows the contour of the nonlinear Rayleigh–Taylor (RT) instability was generated by the Gaussian laser pulse on a ns time scale. Vortex filament self-organization on the nonplanar target surface follows the asymmetric RT evolution consisting of the compressed half of the hypocycloide whose cusps have evolved into spikes, and of the other half whose cusps have evolved into loops. Since the loops cannot be formed, the filaments break into short sets of parallel rolls, oriented in radial direction. The asymmetric contour of the filament self-organization was reproduced by the two-dimensional multimode model that gives the analytical solution, based on the model of Ott. The asymmetry in the vortex filament self-organization is generated by the random wave number mode values, and by the specific phase relations between the modes. © 1998 American Institute of Physics.
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47.20.Ky Nonlinearity, bifurcation, and symmetry breaking
68.15.+e Liquid thin films
47.32.C- Vortex dynamics
79.20.Ds Laser-beam impact phenomena

Statistical–mechanical calculations of thermal properties of diatomic gases

Francisco J. Gordillo-Vázquez and Joseph A. Kunc

J. Appl. Phys. 84, 4693 (1998); http://dx.doi.org/10.1063/1.368712 (11 pages) | Cited 1 time

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The impact of rotational–vibrational dynamics of molecules on the molecular partition functions, law of mass action and thermodynamic functions of partially dissociated diatomic gases is discussed. A group of 11 gases, expected to have their partition functions the most sensitive to the molecular rotational–vibrational properties, is selected for rigorous and detailed studies, and the partition functions, dissociation degrees and free energies of the gases are calculated (using various models of molecular rotational–vibrational dynamics) and compared in a broad range of temperature and particle density. © 1998 American Institute of Physics.
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51.30.+i Thermodynamic properties, equations of state
05.20.-y Classical statistical mechanics
34.50.Ez Rotational and vibrational energy transfer
05.70.Ce Thermodynamic functions and equations of state

Modeling and three-dimensional simulation of the neutral dynamics in an air discharge confined in a microcavity. I. Formation and free expansion of the pressure waves

O. Eichwald, M. Yousfi, P. Bayle, and M. Jugroot

J. Appl. Phys. 84, 4704 (1998); http://dx.doi.org/10.1063/1.368713 (12 pages) | Cited 9 times

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A three-dimensional numerical analysis of the neutral dynamics is performed in the case of a short-gap (0.5 mm) spark discharge in air confined in microcavities at atmospheric pressure (760 Torr) and ambient temperature (293 K). This work is undertaken in the framework of silicon microsystems bearing a micropump actuated by pressure waves which result from a discharge. The short-gap discharge characteristics are taken from experimental results namely 470 ns for the duration and 13.5 W for the maximum injected power. The neutral gas evolution is described by the classical transport equations and solved by a powerful numerical monotonic upstream-centered scheme for conversion laws. The gas–solid interaction occurring in thermal and hydrodynamic boundary layers is taken into account assuming that the microcavity temperature remains invariant (293 K). This article (part I) is devoted to the first evolution phase of the neutral dynamics whose the duration corresponds to the discharge time. Our results clearly show that the first phase can again be split into a neutral inertia phase (during which the thermal energy transferred is stored in the ionized channel) followed by a free expansion one where this thermal energy is dissipated in the microcavity volume. The latter phase is analyzed before the neutral heterogeneities reach the microcavity’s walls. We also discuss the specific gas behaviors of the gas nearby the electrode surfaces, following heat exchanges and viscous stress. © 1998 American Institute of Physics.
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52.80.Mg Arcs; sparks; lightning; atmospheric electricity
47.45.-n Rarefied gas dynamics
47.11.-j Computational methods in fluid dynamics
47.27.T- Turbulent transport processes

Modeling and three dimensional simulation of the neutral dynamics in an air discharge confined in a microcavity. II. Analysis of the wall and geometry effects

O. Eichwald, P. Bayle, Y. Yousfi, and M. Jugroot

J. Appl. Phys. 84, 4716 (1998); http://dx.doi.org/10.1063/1.368714 (11 pages) | Cited 5 times

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This article is devoted to the analysis of the confinement effects of the neutral dynamics generated by a short-gap (0.5 mm) discharge inside three different microcavity geometries (cylinder, cube, and bricklike) filled with air at atmospheric pressure (760 Torr) and ambient temperature (293 K). The discharge is modelled by two mathematical functions representing the Joule heating and the momentum transfer between charged and neutral particles. Their spatio-temporal evolution are taken from experimental results with 470 ns for the duration and 13.5 W for the maximum injected power. The neutral gas evolution is described by the classical transport equations and solved by a powerful numerical monotonic upstream-centered scheme for conversion laws. Because of the microcavity dimensions considered, particular care has been used in the analysis of the thermal and hydrodynamics boundary layers which condition the gas–solid interaction in terms of viscous slip effects and thermal exchanges. The results presented show the microcavity geometry effects on the distribution of the initial cylindrical pressure wave as soon as it reaches the lateral walls. They show the specificity of the cube and bricklike microcavities due to the delayed reflections on the corners leading to a more heterogeneous gas behavior than in the case of the cylindrical microcavity. We also discuss the specific gas behaviors near the wall resulting from heat exchange and viscous stress. © 1998 American Institute of Physics.
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52.80.Mg Arcs; sparks; lightning; atmospheric electricity
47.11.-j Computational methods in fluid dynamics
47.45.-n Rarefied gas dynamics
47.27.T- Turbulent transport processes
47.40.-x Compressible flows; shock waves

Reactions in the afterglow of time modulated inductive discharges of Xe and I2 mixtures

Paul N. Barnes and Mark J. Kushner

J. Appl. Phys. 84, 4727 (1998); http://dx.doi.org/10.1063/1.368799 (4 pages) | Cited 1 time

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An investigation was conducted using absorption and emission spectroscopy of the afterglow from rf inductive discharges in Xe/I2 mixtures. RF power at 11.5 MHz was supplied to coils surrounding a cylindrical discharge cell. Total pressures were between 0.8 and 5.3 Torr. Measurements were made as a function of radius and time following the termination of the discharge. Results presented here indicate that in the afterglow the XeI∗ excimer is formed by highly excited I2 and ground state Xe. Evidence is also presented that ion–ion neutralization is a major precursor reaction for the formation of other excited species in the afterglow. © 1998 American Institute of Physics.
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52.80.Pi High-frequency and RF discharges
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)
52.80.Hc Glow; corona
52.70.Kz Optical (ultraviolet, visible, infrared) measurements

Information from probe characteristics in negative ion containing plasma

M. Vucelić and S. Mijović

J. Appl. Phys. 84, 4731 (1998); http://dx.doi.org/10.1063/1.368715 (5 pages) | Cited 8 times

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The effect of negative ions on the probe characteristic is studied theoretically. The reliability of results obtained from probe characteristics is analyzed. The methods of determining the energy distribution functions of charged particles is analyzed as an inverse ill-posed problem. A Tikhonov’s regularization procedure for detection of negative ions from a probe characteristic is described. This method parallels the Dryvestein method with the key difference stemming from the fact that experimental determination of the second derivative of the probe characteristic is avoided. For a small ratio of negative ion to electron densities and quite plasma, the energy distribution, temperature and density for the electrons and negative ions can be estimated only from the probe characteristic and the errors in the experimental data. The model functions, simulating experimental energy distribution for the electrons and negative ions, are introduced to test applicability limitations of the method. In addition, the comparative advantages of the method are presented as well. © 1998 American Institute of Physics.
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52.70.Ds Electric and magnetic measurements
52.25.-b Plasma properties
52.27.Jt Nonneutral plasmas

Surface interactions of CF2 radicals during deposition of amorphous fluorocarbon films from CHF3 plasmas

Nathan E. Capps, Neil M. Mackie, and Ellen R. Fisher

J. Appl. Phys. 84, 4736 (1998); http://dx.doi.org/10.1063/1.368716 (8 pages) | Cited 42 times

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Surface reactivities for CF2 radicals formed in a CHF3 plasma molecular beam are measured during film deposition on a variety of substrates. The imaging of radicals interacting with surfaces (IRIS) technique was used to collect spatially resolved laser-induced fluorescence (LIF) images of CF2 radicals interacting with SiO2, Si3N4, Si, 304 stainless steel, and system 8 photoresist substrates. Films deposited during IRIS experiments were characterized using x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy and were found to be nearly identical in composition on all substrates. Simulation of LIF cross-sectional data shows high scattering coefficients for CF2 radicals on all substrates. These extremely large scattering coefficients (>1.0) indicate that CF2 molecules are generated through plasma interactions with the substrate. Possible CF2 surface generation mechanisms are discussed, with consideration of CF and ion bombardment contributions to the generation of CF2. © 1998 American Institute of Physics.
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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.30.Cf Atom and radical reactions; chain reactions; molecule-molecule reactions
33.50.Dq Fluorescence and phosphorescence spectra
33.60.+q Photoelectron spectra
79.60.Fr Polymers; organic compounds
68.55.-a Thin film structure and morphology

Electromagnetic surface wave modes in nonrelativistic electron–positron plasmas

Sang-Hoon Cho and Hee J. Lee

J. Appl. Phys. 84, 4744 (1998); http://dx.doi.org/10.1063/1.368717 (5 pages) | Cited 9 times

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Electromagnetic surface waves propagating on the plane interface (x = 0) between the electron–positron plasma and vacuum are investigated by the specular reflection procedure. The transverse electromagnetic modes are studied in terms of dispersion relation both in the presence and absence of an applied magnetic field. The analytic modes for some limiting cases are derived and discussed with the aid of some numerical analysis. In the presence of an applied magnetic field (B0 = B0ŷ) directed perpendicular both to the interface normal and the wave vector, the cold electromagnetic surface wave dispersion relation shows that possible modes appear only when the frequency (ω) and the wave vector (k) satisfy the condition Ω2<ω2<Ω2+ωp2 and c2k2>Ω2 (Ω is cyclotron frequency). © 1998 American Institute of Physics.
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52.35.Hr Electromagnetic waves (e.g., electron-cyclotron, Whistler, Bernstein, upper hybrid, lower hybrid)
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Electrical signatures and thermal stability of interstitial clusters in ion implanted Si

J. L. Benton, K. Halliburton, S. Libertino, D. J. Eaglesham, and S. Coffa

J. Appl. Phys. 84, 4749 (1998); http://dx.doi.org/10.1063/1.368800 (8 pages) | Cited 47 times

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Deep level transient spectroscopy (DLTS) investigations have been used to characterize the electrical properties of interstitial clusters in ion-implanted Si. Both n- and p-type samples were implanted with 145 keV–1.2 MeV Si ions to doses of 1×1010–5×1013 cm−2 and annealed at 450–750 °C. On samples annealed at temperatures above 550 °C, the residual damage is dominated by two hole traps (B lines) in p-type and five electron traps (K lines) in n-type samples. Analyses of the spectra and defect depth profiles reveal that these signatures are related to Si self-interstitial clusters, and experiments confirm that these clusters do not embody large numbers of impurities such as C, O, B, or P. Four deep level signatures exhibit similar annealing behavior, suggesting that they arise from the same defect structure. On the other hand, the remaining signatures exhibit different annealing behaviors and are tentatively associated with different cluster configurations. We have found that the thermal stability of the clusters is enhanced by either increasing the Si dose or by reducing the impurity content of the substrate. The explanation of these effects proposes that bigger and more stable clusters are formed when the concentration of free interstitials available for clustering is increased and the competing interstitial trapping at impurities is inhibited. Finally, in samples implanted at doses of ≥ 1×1013 cm−2, most of the DLTS signals exhibit a complex and nonmonotonic annealing behavior providing evidence that the clusters can transform between electronic configurations. © 1998 American Institute of Physics.
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71.55.Cn Elemental semiconductors
61.72.uf Ge and Si
61.80.Jh Ion radiation effects
61.72.J- Point defects and defect clusters
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments
61.82.Fk Semiconductors

Electrical isolation of n-type GaAs layers by proton bombardment: Effects of the irradiation temperature

J. P. de Souza, I. Danilov, and H. Boudinov

J. Appl. Phys. 84, 4757 (1998); http://dx.doi.org/10.1063/1.368817 (4 pages) | Cited 7 times

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The electrical isolation in n-type GaAs layers produced by proton irradiation at temperatures from −100 to 300 °C was investigated. The threshold dose for the isolation (Dth) was found almost identical for irradiation at temperatures from −100 to 220 °C. At 300 °C, a dose of ≅1.3 times higher is required for the isolation threshold. In samples irradiated to a dose of Dth at −100 °C or nominal room temperature, the isolation is maintained up to a temperature of ≈ 250 °C. In those samples irradiated at 300 °C it persists up to ≈ 350 °C. For doses of 3Dth or above, the stability of the isolation is limited to temperatures of 450–650 °C, irrespective of the irradiation temperature (Ti). For practical applications where doses in excess to 5Dth are usually employed, the irradiation temperature (from −100 to 300 °C) has only a minor effect on the formation and thermal stability of the electrical isolation. © 1998 American Institute of Physics.
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61.80.Jh Ion radiation effects
68.60.Dv Thermal stability; thermal effects
85.40.Ry Impurity doping, diffusion and ion implantation technology
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.uj III-V and II-VI semiconductors

Influence of the inhomogeneous surface pretilt on zig-zag defects

S. Kralj, J. Pirš, S. Žumer, and R. Petkovšek

J. Appl. Phys. 84, 4761 (1998); http://dx.doi.org/10.1063/1.368718 (8 pages) | Cited 6 times

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The influence of the inhomogeneous surface pretilt (slope) on chevron structures and on zig-zag defects in a SmC liquid-crystal cell is studied. The experimentally observed effect of the confining substrate with controlled variation of the surface slope on the formation of zig-zag defects is qualitatively explained with the Landau–Ginzburg-type free-energy expanded in terms of the nematic director field and the smectic complex order parameter. Transitions in the C1 and C2 chevron structures are studied as functions of the surface pretilt angle θt. The threshold conditions are calculated. The width of the straight element of the domain wall (running parallel to the smectic layers) and the costs for its formation are estimated. © 1998 American Institute of Physics.  
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61.30.Jf Defects in liquid crystals
42.79.Kr Display devices, liquid-crystal devices
65.20.-w Thermal properties of liquids
65.40.gd Entropy

Annealing and recrystallization of amorphous silicon carbide produced by ion implantation

A. Höfgen, V. Heera, F. Eichhorn, and W. Skorupa

J. Appl. Phys. 84, 4769 (1998); http://dx.doi.org/10.1063/1.368801 (6 pages) | Cited 24 times

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The annealing behavior of amorphous SiC layers produced by MeV Si implantation into 6H–SiC has been investigated systematically by means of step height measurements, x-ray diffraction, and optical microscopy. Two annealing stages are found. Each of them causes a specific densification of the amorphous layer. At temperatures between 250 and 700 °C both the rapidity and the low activation energy (184 meV) of the densification suggest that defect annealing processes are responsible for densification. Partial crystallization and changes of the amorphous network structure can be excluded as a possible reason for low temperature densification. Annealing at temperatures above 700 °C is characterized by a combination of defect annealing and recrystallization. The crystallization kinetics is analyzed in terms of the Johnson–Mehl–Avrami theory. It is shown that the crystallization mode changes with increasing temperature from nucleated growth at 800 °C to epitaxial growth at 1000 °C. The recrystallization generates stress in the layer which leads to surface cracking if the layer exceeds a critical thickness. © 1998 American Institute of Physics.
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61.72.Cc Kinetics of defect formation and annealing
61.43.Dq Amorphous semiconductors, metals, and alloys
61.80.Jh Ion radiation effects
61.72.up Other materials
68.35.B- Structure of clean surfaces (and surface reconstruction)

Influence of net strain, strain type, and temperature on the critical thickness of In(Ga)AsP-strained multi quantum wells

Matsuyuki Ogasawara, Hideo Sugiura, Manabu Mitsuhara, Mitsuo Yamamoto, and Masashi Nakao

J. Appl. Phys. 84, 4775 (1998); http://dx.doi.org/10.1063/1.368719 (6 pages) | Cited 7 times

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We examined the critical thickness of strained multi quantum wells (MQWs) consisting of InAsP/InGaAsP and InGaAsP/InGaAsP. More than 50 MQWs with different total thicknesses, well strain, and well thicknesses were prepared by metalorganic molecular beam epitaxy (MOMBE) or metalorganic vapor phase epitaxy (MOVPE) to study the influence of net strain, strain type, and temperature on critical thickness. The microscopic photoluminescence method was used mainly to observe misfit dislocations in the MQWs. Three kinds of net strain-critical thickness curves were experimentally determined, i.e., the curves for compressive as well as tensile strained MQWs grown by MOMBE and that for compressive strained MQWs grown by MOVPE. We found that the above three curves coincide with each other and differ greatly from the Matthews’ [J. W. Matthews and A. E. Blakeslee, J. Cryst. Growth 27, 118 (1974)] theoretical curve in a low-net strain range of less than 0.5%. © 1998 American Institute of Physics.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
62.20.-x Mechanical properties of solids

Simulation of clustering and transient enhanced diffusion of boron in silicon

Masashi Uematsu

J. Appl. Phys. 84, 4781 (1998); http://dx.doi.org/10.1063/1.368720 (7 pages) | Cited 16 times

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We have simulated the postimplantation clustering and transient enhanced diffusion (TED) in boron profiles with peak concentrations below the boron (B) solubility limit. First, we derive an analytical formula for B clustering in terms of the reaction between B atoms and supersaturated self-interstitials. Then, using this formula and taking into account the dissolution of B clusters to emit self-interstitials, a unified simulation is done with just three essential parameters for the B clusters and based on the self-interstitial cluster model and the B diffusion model. We have satisfactorily fitted B TED profiles not only for implanted B layers but also for initially active B layers. Moreover, a comparison with TED induced by P implantation is made in terms of the trapping and diffusivities of self-interstitials. © 1998 American Institute of Physics.
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66.30.J- Diffusion of impurities
61.72.uf Ge and Si
61.72.S- Impurities in crystals
61.72.J- Point defects and defect clusters
81.05.Cy Elemental semiconductors

Abnormal electrical behavior and phase changes in implanted p+- and n+-Si channels under high current densities

J. S. Huang, C. N. Liao, K. N. Tu, S. L. Cheng, and L. J. Chen

J. Appl. Phys. 84, 4788 (1998); http://dx.doi.org/10.1063/1.368802 (9 pages) | Cited 4 times

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The p+- and n+-Si channels were prepared by implanting a dose of 5×1015 ions/cm2 of BF2+ and As+ at 40 keV, respectively, into the n-Si and p-Si substrates, followed by a 900 °C-30 min annealing. Nickel contacts (cathode and anode) to these channels were electron-gun evaporated. Electrical current was applied gradually to 80 mA to these channels, corresponding to current densities of 106–107 A/cm2. For the p+-Si, the resistance responded by increasing to a maximum, then decreasing until a precipitous drop took place. For the n+-Si, the resistance increased by a less amount compared to the p+-Si, but also dropped abruptly. The resistance drop is permanent in the p+-Si channels, but not in the n+-Si channels. Mechanisms responsible for these resistance changes in terms of Joule heating, high field effect and junction leakage are proposed. For the precipitous drop in channel resistance of the p+-Si, scanning electron microscopy and transmission electron microscopy showed that a NiSi2 line bridging the cathode and anode contacts had been formed. No silicide line formation in the n+-Si channels was observed. © 1998 American Institute of Physics.
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73.40.Ns Metal-nonmetal contacts
73.40.Cg Contact resistance, contact potential
61.72.uf Ge and Si
72.20.Ht High-field and nonlinear effects

Laser ablation induced surface modification of NdBa2Cu3O7−δ single crystal target in pulsed laser deposition

Yijie Li, Xin Yao, and K. Tanabe

J. Appl. Phys. 84, 4797 (1998); http://dx.doi.org/10.1063/1.368721 (5 pages) | Cited 5 times

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The surface modification of both morphology and composition of a single crystal NdBa2Cu3O7−δ (NBCO) target induced by laser ablation has been studied by scanning electron microscopy with x-ray energy dispersive spectroscopy. After a long period of laser ablation, the sintered target displays a cone-shaped columnar surface morphology. However, the single crystal target exhibits a continuous and smooth undulating morphology with ridges and grooves. This cone-free surface morphology is thought to inhibit the ejection of droplets from the target surface and thus lead to NBCO films with excellent surface morphology. After a large number of laser shots per site on the single crystal target, both the surface composition and deposition rate remain unchanged. Our experimental results prove that the observed results for the sintered target are in agreement with the erosion model, while the laser ablation induced surface modification for the single crystal target is dominated by the melt–resolidification process. © 1998 American Institute of Physics.
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74.72.-h Cuprate superconductors
79.20.Ds Laser-beam impact phenomena
68.35.B- Structure of clean surfaces (and surface reconstruction)

High-dose helium-implanted single-crystal silicon: Annealing behavior

R. Tonini, F. Corni, S. Frabboni, G. Ottaviani, and G. F. Cerofolini

J. Appl. Phys. 84, 4802 (1998); http://dx.doi.org/10.1063/1.368803 (7 pages) | Cited 14 times

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The modifications induced in single-crystal silicon by implanted helium have been investigated by ion beam techniques. The damage has been detected by 2 MeV 4He+ backscattering in channeling conditions and the helium in-depth distribution by 7 and 8 MeV 15N++ elastic recoil scattering. The samples prepared by implanting 2×1016 cm−2 helium ions at 20 keV in silicon wafers held either at 77 K (LNT sample) or at 300 K (RT sample) have been heat treated for 2 h in the 100–800 °C temperature range. In the as-implanted LNT sample the damage maximum is at 130±20 nm and shifts in-depth to 180±10 nm after annealing at 200 °C, in the as-implanted RT sample, the damage maximum is already located at 180±10 nm. In the 250–500 °C temperature range, the LNT and RT samples follow the same annealing path with only slight differences in the temperature values; in both cases, the dechanneling signal increases and reaches a maximum value of nonregistered silicon atoms of 2.2–2.5×1022 at/cm3. In the same temperature range, the helium signal becomes narrower, builds up in a region centered on 220±20 nm and no appreciable loss of helium can be detected. The growth of the damage is consistent with the creation of cracks and a etherogenous distribution of bubbles filled with high pressure helium which stress the lattice; for the channeling Rutherford backscattering technique, their action is similar to silicon interstitials. At temperatures above 500 °C, helium is released from the samples; this process is associated with a decrease of the damage and the formation and increase in size of voids. At 900 °C empty voids with a diameter around 20 nm are found. © 1998 American Institute of Physics.
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61.72.uf Ge and Si
61.72.Cc Kinetics of defect formation and annealing
61.72.Qq Microscopic defects (voids, inclusions, etc.)
61.82.Fk Semiconductors
61.80.Jh Ion radiation effects
85.40.Ry Impurity doping, diffusion and ion implantation technology
61.85.+p Channeling phenomena (blocking, energy loss, etc.)

Evidence for the influence of thermal spikes on ion induced mixing in Si at energies between 3 and 300 keV

J. Cardenas, B. G. Svensson, and M. Petravic

J. Appl. Phys. 84, 4809 (1998); http://dx.doi.org/10.1063/1.368722 (6 pages) | Cited 1 time

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Broadening of Ge and B tracer profiles in Si during sputter depth profiling, using O2+, Ar+, Kr+, and Cs+ ions, has been accurately described using the diffusion approximation of ion induced atomic mixing. The model allows extraction of a parameter yielding the mixing efficiency as a function of deposited energy per unit length (FD) and ion energy. The mixing parameter exhibits a linear dependence on FD3/2 at ion energies between 3 and 300 keV, which provides strong evidence for a dominating influence of thermal spikes on the mixing process. © 1998 American Institute of Physics.
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61.82.Fk Semiconductors
68.35.Fx Diffusion; interface formation
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.80.Jh Ion radiation effects
64.75.-g Phase equilibria
66.30.Ny Chemical interdiffusion; diffusion barriers
61.72.S- Impurities in crystals
81.70.Jb Chemical composition analysis, chemical depth and dopant profiling

X-ray phase-amplitude contrast mapping of single-crystal alloys near the absorption edge of the alloy impurity

A. Yu. Nikulin, J. R. Davis, N. T. Jones, and P. Zaumseil

J. Appl. Phys. 84, 4815 (1998); http://dx.doi.org/10.1063/1.368723 (7 pages) | Cited 6 times

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An experimental–analytical method for the nondestructive structural and chemical composition mapping of single-crystal alloys is proposed, implemented, and successfully tested. The technique is based on analytical measurements of phase and amplitude changes in a narrow polychromatic region near the absorption edge of the alloy impurity. Synchrotron radiation energies of 11.096–11.105 keV were used to measure the Bragg diffraction profiles near the absorption edge of germanium at 11.103 keV in SiGe/Si crystal alloy superstructures. Physical dimensions and chemical composition of SiGe alloys were determined with a spatial resolution 8.6 Å. © 1998 American Institute of Physics.  
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61.05.cp X-ray diffraction
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods
81.70.Jb Chemical composition analysis, chemical depth and dopant profiling
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