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15 Jun 1987

Volume 61, Issue 12, pp. 5219-5489

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Beam end erosion

A. Faltens, E. P. Lee, and S. S. Rosenblum

J. Appl. Phys. 61, 5219 (1987); http://dx.doi.org/10.1063/1.338306 (3 pages) | Cited 13 times

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The time evolution of the line charge density and energy at the ends of an initially rectangular ion bunch due to the space charge of the bunch are measured and found to be in good agreement with a one‐dimensional dynamical theory. The ends erode at the space‐charge wave speed into the bunch, and the end particles move at twice that speed away from the bunch.
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41.75.Ak Positive-ion beams
41.75.Cn Negative-ion beams
52.35.Fp Electrostatic waves and oscillations (e.g., ion-acoustic waves)
52.58.-c Other confinement methods

Energy losses in magnetically insulated transmission lines due to microparticles

Eoin W. Gray and Regan W. Stinnett

J. Appl. Phys. 61, 5222 (1987); http://dx.doi.org/10.1063/1.338307 (15 pages)

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We discuss the effects of high‐velocity and hypervelocity microparticles in the magnetically insulated transmission lines of multiterawatt accelerators used for particle beam fusion and radiation effects simulation. These microparticles may be a possible source for plasma production near the anode and cathode in early stages of the voltage pulse, and current carriers during and after the power pulse, resulting in power flow losses. Losses in the current pulse, due to microparticles, are estimated to be approximately 12 mA/cm2 (0.3 kA) as a lower limit, and ∼0.3 A/cm2 (7.2 kA) for microparticle initiated, anode plasma positive ion transport. We have calculated the velocities reached by these microparticles and the effects on them of Van der Waals forces. Field emission from the particles and their effects on cathode and anode plasma formation have been examined. Particle collision with the electrodes is also examined in terms of plasma production, as in the electron deposition in the particles in transit across the anode‐cathode gap. Blistering of the electrode surface, thought to be due to H− bombardment was also observed and appears to be consistent with losses due to negative ions previously reported by J. P. VanDevender, R. W. Stinnett, and R. J. Anderson [App. Phys. Lett. 38, 229 (1981)].
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84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
52.75.Di Ion and plasma propulsion
52.25.Fi Transport properties
52.50.Dg Plasma sources

Eddy current decay method applied to a new geometry

R. F. Jardim, B. Laks, and C. Santos

J. Appl. Phys. 61, 5237 (1987); http://dx.doi.org/10.1063/1.338308 (6 pages) | Cited 2 times

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The eddy current decay method for determination of metallic samples resistivities is presented for the case of a hollow circular cylindrical geometry. The theory is developed for two kinds of experimental arrangements: the primary coil is driven by a voltage source or by a current source. The measurements made for several metals (Al, Cu, Nb, brass, and bronze) at room temperature and at the temperature of liquid nitrogen analyzed by the theory give accurate results compared with the four terminal method.
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72.10.Bg General formulation of transport theory
72.15.Eb Electrical and thermal conduction in crystalline metals and alloys
07.50.-e Electrical and electronic instruments and components
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems

Observation of soft x‐ray amplification in neonlike molybdenum

B. J. MacGowan, M. D. Rosen, M. J. Eckart, P. L. Hagelstein, D. L. Matthews, D. G. Nilson, T. W. Phillips, J. H. Scofield, G. Shimkaveg, J. E. Trebes, R. S. Walling, B. L. Whitten, and J. G. Woodworth

J. Appl. Phys. 61, 5243 (1987); http://dx.doi.org/10.1063/1.338309 (6 pages) | Cited 53 times

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Thin molybdenum coated foils have been irradiated in line focus geometry with from 3 to 8×1014 W cm−2 of 0.53‐μm light at the Nova laser. The resulting exploding foil plasma has demonstrated x‐ray laser gain at four wavelengths (106.4, 131.0, 132.7, and 139.4 Å), identified as 3s‐3p transitions in neonlike Mo. The J=0–1, a 3s–3p transition at 141.6 Å has been identified, but does not show evidence of significant gain in disagreement with the theory.
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42.60.By Design of specific laser systems
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
42.55.Lt Gas lasers including excimer and metal-vapor lasers

Doppler‐broadened Hα line shapes in a rf low‐pressure H2 discharge

G. Baravian, Y. Chouan, A. Ricard, and G. Sultan

J. Appl. Phys. 61, 5249 (1987); http://dx.doi.org/10.1063/1.338310 (5 pages) | Cited 50 times

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The presented results are concerned with the shapes of the Balmer‐α line emitted by a low‐pressure rf 13.56‐MHz discharge in hydrogen. Optical emission analysis has been done using a monochromator with a high spectral resolution (0.04 Å). Essentially, the lines present a central nearly Gaussian‐shape peak with a FWHM of about 0.3 Å emerging from a wide pedestal constituted by two plateaus with widths equal to 0.9 and 1.5 Å, respectively, and by large wings whose intensity quasilinearly decreases on both sides of the central wavelength. We explain these profiles by the Doppler broadening due to fast H atoms produced by the dissociative excitation and the dissociative ionization of the H2 molecules by electron impact generally followed by the excitation of the resulting atoms towards emitting states.
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52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.80.Pi High-frequency and RF discharges
32.70.Jz Line shapes, widths, and shifts

Electron swarm properties in CCl2F2 and mixtures with N2 under steady‐state conditions

M. F. Fréchette

J. Appl. Phys. 61, 5254 (1987); http://dx.doi.org/10.1063/1.338311 (9 pages) | Cited 1 time

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Spatial growth of ionization currents has been measured in CCl2F2/N2 mixtures by the steady‐state Townsend method over the range of reduced fields 80 ≤E/p20≤180 V cm−1 Torr−1. The experimental values obtained differ markedly from those published in the literature. A detailed account of the various hypotheses used in the experiment is presented in the light of correspondence with the electron transport theory and is followed by a comparison of experimental data, i.e., limit fields (E/p20)∗, ionization (α), attachment (η), and effective ionization (α) coefficients, with available theoretical values from Boltzmann‐equation analysis of electron swarms in the pure gas and its mixture with N2. Good agreement with the theoretical calculations by J. P. Novak and M. F. Fréchette [J. Appl. Phys. 57, 4368 (1985)] provides further supporting evidence for the applicability of these authors’ proposed set of electron scattering cross sections and, in particular, favors the attachment cross sections reported by E. Illenberger, H.‐U. Scheunemann, and H. Baumgärtel [Ber. Bunsenges. Phys. Chem. 82, 1154 (1978); Chem. Phys. 37, 21 (1979)].
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52.80.Dy Low-field and Townsend discharges
51.50.+v Electrical properties (ionization, breakdown, electron and ion mobility, etc.)
51.10.+y Kinetic and transport theory of gases
52.25.Fi Transport properties

Ion beam mixing of metallic and insulating layers on SiC and Si3N4

R. S. Bhattacharya, A. K. Rai, and P. P. Pronko

J. Appl. Phys. 61, 5263 (1987); http://dx.doi.org/10.1063/1.338312 (4 pages) | Cited 4 times

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Ion beam mixing of B, ZrO2, and Cr layers with sintered α‐SiC, and Y and Cr layers with hot pressed Si3N4 was measured at room temperature. The mixing ion was selected from 1‐MeV Ni+, 2‐MeV Au+, or 1‐MeV O+ ions. The amount of mixing was evaluated from Rutherford backscattering and Auger electron spectroscopies and occasionally from cross‐section transmission electron microscopy. It was found that mixing takes place in the B/SiC, Cr/SiC, and Y/Si3N4 systems. No mixing is observed in the ZrO2/SiC and Cr/Si3N4 systems even after high dose ion bombardment. The enthalpy of mixing rule, which states that metals mix with insulators if the reaction enthalpy is negative and do not mix if it is positive, has been examined and found to hold for these systems.
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61.80.Jh Ion radiation effects
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
64.75.-g Phase equilibria
82.60.Cx Enthalpies of combustion, reaction, and formation

Two‐dimensional defects in InSe

Ph. Houdy, J. L. Maurice, J. M. Besson, J. Y. Laval, A Chevy, and O. Gorochov

J. Appl. Phys. 61, 5267 (1987); http://dx.doi.org/10.1063/1.338261 (5 pages) | Cited 17 times

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Two‐dimensional precipitates associated with stacking faults in layer semiconductors have previously been put forward to explain transport properties of these crystals, especially their remarkable electrical anisotropy. High‐field cyclotron resonance behavior, among others, can be accounted for by two‐dimensional accumulation layers in the vicinity of these defects. Direct evidence for the existence of these defects has been obtained by electron microscopy and x‐ray microprobe analysis in indium selenide. Planar faults act like sinks for impurity atoms. This accounts for the unique behavior of layer compounds which exhibit intrinsic behavior (low apparent carrier concentration—high mobilities) even with high (100 ppm) initial doping levels. Optical, transport, and magnetotransport properties at low temperature can be explained along this model. As regards the applications of indium selenide to the photovoltaic conversion of solar energy, the existence of these defects explains most features of this semiconductor in this respect: (i) Its comparatively low effective diffusion length parallel to the c axis. (ii) p‐ to n‐type switching under thermal annealing which allows fabrication of p‐n junctions. (iii) Low apparent carrier density which precludes abrupt profiles for p‐n structures.
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61.72.Nn Stacking faults and other planar or extended defects
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.40.+w Photoconduction and photovoltaic effects
72.80.Jc Other crystalline inorganic semiconductors

Rapid thermal annealing of Be+‐implanted In0.52Al0.48As

Wai Lee and Clifton G. Fonstad

J. Appl. Phys. 61, 5272 (1987); http://dx.doi.org/10.1063/1.338262 (7 pages) | Cited 3 times

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A capless rapid thermal annealing method has been used to activate Be atoms implanted into n‐In0.52Al0.48As. The dependence of electrical activation upon various annealing conditions has been investigated. Annealing at 800–850 °C for 2–3 s yields high electrical activation. Activation efficiencies of 76% and 49% are achieved on InAlAs layers with implant doses of 2×1013 and 2×1014 cm−2, respectively. The lowest sheet resistivity obtained was 2.2 kΩ/☒ at an implant dose of 1.5×1014 cm−2. Electrical characteristics of Be‐implanted p+‐n InAlAs diodes are also presented. The forward diode currents were dominated by recombination current components at room temperature. The reverse leakage currents increase with increasing implant doses. Diodes annealed at 800 °C for 2–3 s have the lowest reverse leakage currents.
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61.72.U- Doping and impurity implantation
81.40.Rs Electrical and magnetic properties related to treatment conditions
72.80.Ey III-V and II-VI semiconductors
61.72.Bb Theories and models of crystal defects

X‐ray diffraction studies of microstructural transformations in single‐crystal silicon during current filamentation

Ashok Pimpale, S. M. Choudhari, and V. G. Bhide

J. Appl. Phys. 61, 5279 (1987); http://dx.doi.org/10.1063/1.338263 (7 pages)

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The (111) Bragg peak of p‐ and n‐Si single crystals is studied when a large dc current (average current density 10 A/cm2) is passing through the specimen. The integrated intensity of the peak changed drastically with time after current filamentation, showing existence of microstructural transformations. The fresh samples (type A) showed a decrease in integrated intensity by a factor of about 50, 15 min after current filamentation, with a limiting current of 330 mA passing through the sample. The intensity partially recovered when the current was switched off, and, after cooling to room temperature, the specimen behaved differently when the electric field was again applied. The specimen (type B) then showed an increase in integrated intensity a couple of minutes after current filamentation so that the diffracted intensity became comparable to the type A specimen. Thereafter, with continued high current passing through the specimen, it behaved like a fresh silicon sample. The results are interpreted by considering formation of current filaments and consequent local heating.
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77.22.Jp Dielectric breakdown and space-charge effects
61.05.cp X-ray diffraction
61.66.Bi Elemental solids
65.90.+i Other topics in thermal properties of condensed matter (restricted to new topics in section 65)

Gettering of gold in silicon: A tool for understanding the properties of silicon interstitials

Gary B. Bronner and James D. Plummer

J. Appl. Phys. 61, 5286 (1987); http://dx.doi.org/10.1063/1.338264 (13 pages) | Cited 102 times

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The movement of gold in silicon is controlled by the reaction of gold with silicon interstitials, not by the intrinsic diffusion coefficient of gold. This fact is used to understand the role silicon interstitials play during gettering in silicon. An analysis of gold profiles after gettering reveals that high concentration phosphorus diffusion, argon‐ion implantation, and mechanical damage of a silicon surface all act as sources of silicon interstitials. This finding is experimentally confirmed by studying the effect of an argon implanted surface layer on the diffusion of both phosphorus and antimony buried layers; only the phosphorus layer shows an enhancement, which is consistent with the injection of silicon interstitials. Studying the enhancement of the phosphorus diffusion versus temperature reveals that the phosphorus‐interstitial pair has a migration energy of 1.3 eV. Under the assumption of local equilibrium between silicon interstitials and phosphorus atoms, estimates of the diffusion coefficient and equilibrium concentration of the silicon interstitial are made based on this enhanced diffusion data and the gold gettering profiles. These numbers are compared with other estimates in the literature.
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61.72.jd Vacancies
61.72.jj Interstitials
66.30.Lw Diffusion of other defects
66.30.J- Diffusion of impurities
61.72.uf Ge and Si

Fe reactions with β‐SiC

K. M. Geib, C. W. Wilmsen, J. E. Mahan, and M. C. Bost

J. Appl. Phys. 61, 5299 (1987); http://dx.doi.org/10.1063/1.338932 (4 pages) | Cited 16 times

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The reaction between β‐SiC and a layer of sputter deposited Fe has been investigated by Auger profiling. The samples were vacuum annealed in the analysis chamber up to 800 °C. After a 610 °C anneal an interfacial layer of iron carbide appeared, probably the result of a reaction between the Fe and an adsorbed layer of hydrocarbons. This interfacial layer appears to prevent a reaction with the substrate until the temperature is raised to 800 °C. At this temperature a rapid and violent reaction occurs.
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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
68.35.Fx Diffusion; interface formation

The effects of the nonabrupt depletion edge on deep‐trap profiles determined by deep‐level transient spectroscopy

Jian H. Zhao, Jyh‐Chwen Lee, Z. Q. Fang, T. E. Schlesinger, and A. G. Milnes

J. Appl. Phys. 61, 5303 (1987); http://dx.doi.org/10.1063/1.338265 (5 pages) | Cited 9 times

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The effects of the nonabrupt depletion edge (the Debye tail) on the trap concentrations obtained by deep‐level transient spectroscopy are discussed. In depth profiling of traps it is shown that a dramatic drop in the apparent deep‐trap concentration is obtained near the edge of the total depth probed. This is an artifact of the measurement and is a consequence of the Debye tail in the depletion edge. It is shown that experimentally one can avoid this problem by using sufficiently large reverse biases and forward filling pulses to determine the deep‐trap concentration in any particular region of the semiconductor.
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71.55.Eq III-V semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients

The role of temperature in sample‐to‐sample comparisons of the 1/f noise of metal films

D. M. Fleetwood, D. E. Beutler, J. T. Masden, and N. Giordano

J. Appl. Phys. 61, 5308 (1987); http://dx.doi.org/10.1063/1.338266 (6 pages) | Cited 4 times

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We have performed an extensive study of the 1/f noise of several different kinds of metal films fabricated in different ways. An examination of the temperature dependence of the 1/f noise of tin and indium shows that the previously reported substrate dependence of the noise magnitude generally is only present near room temperature. At other temperatures, especially lower temperatures, the substrate dependence is much smaller or negligible. The noise magnitudes of platinum and bismuth films, on the other hand, depend strikingly on the way that the sample is made, and can vary strongly from sample to sample as a function of temperature. Taken together, these results illustrate that, in contrast to common practice, the room‐temperature magnitude of the 1/f noise of metal films is often not a useful parameter on which to base comparisons of the relative noise magnitudes of different films. The implications of these results for the interpretation of some previous studies are discussed, and recommendations are made about the interpretation of future studies of the 1/f noise of metal films.
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72.70.+m Noise processes and phenomena
05.40.-a Fluctuation phenomena, random processes, noise, and Brownian motion
73.61.At Metal and metallic alloys
73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors

Conductivity of polyethylene terephthalate induced by high electron beam current densities

D. J. Johnson, S. R. Kurtz, and M. A. Sweeney

J. Appl. Phys. 61, 5314 (1987); http://dx.doi.org/10.1063/1.338267 (11 pages) | Cited 1 time

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The radiation induced conductivity (RIC) of polyethylene terephthalate (Mylar) produced by the electron beam from a pinched electron beam diode has been measured experimentally. Data were obtained for 4–10 ns duration electron beam pulses at radiation dose rates up to 4×1016 rad/s (100 kA/cm2 current density). The conductivity is roughly proportional to radiation dose rate up to about 100 Mrad and at higher doses scales approximately with radiation dose to the (3)/(2) power. The experimental data are compared to the predictions of a model of RIC using dispersive electronic transport and bimolecular recombination. The parameters used in the model were obtained from published low dose (<100 rad) time‐resolved photoconductivity measurements on Mylar. The data agreed well with the calculations before the onset of significant sample heating (10 Mrad). The highest reported RIC results are compared to the expected results for a weakly ionized plasma experiencing electron neutral collisions. In this case the experimental conductivity is significantly higher than the calculated value.
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81.40.Rs Electrical and magnetic properties related to treatment conditions
61.80.Fe Electron and positron radiation effects
72.80.Sk Insulators
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Extrinsic photoconductive characteristics of semi‐insulating GaAs crystals

Yoh Mita

J. Appl. Phys. 61, 5325 (1987); http://dx.doi.org/10.1063/1.338268 (5 pages) | Cited 16 times

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Extrinsic photoconductive characteristics of undoped, semi‐insulating GaAs have been investigated, especially the characteristic enhancement effect at low temperatures. It has been shown that two quasistable photoconductive states exist, in which photoconductivity differs by orders of magnitude and that the two states are partly interchangeable by irradiating with an appropriate wavelength light. Spectra and temperature dependencies were investigated to elucidate the enhancement mechanism. Discussions are made on the basis of metastable states in As‐rich defects.
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72.40.+w Photoconduction and photovoltaic effects
78.30.-j Infrared and Raman spectra
78.40.Fy Semiconductors
71.55.Eq III-V semiconductors

Electron‐hole interaction and high‐field transport of photoexcited electrons in GaAs

M. A. Osman and D. K. Ferry

J. Appl. Phys. 61, 5330 (1987); http://dx.doi.org/10.1063/1.338269 (7 pages) | Cited 24 times

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We use a theoretical ensemble Monte Carlo method to study the response of carriers photoexcited by a 1.55‐eV laser pulse to applied electric fields (less than 5 kV/cm) for excited carrier densities between 1017 cm−3 and 1018 cm−3. It is found that the electron‐hole interaction reduces the fraction of electrons that transfer to the upper valleys and reduces the velocity of the electrons. These effects are more significant at low electric fields and higher excitation levels. The energy of the holes rises initially due to the energy transfer from the hot electrons through the electron‐hole interaction. This is also reflected in a higher velocity for the holes during the first picosecond.
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72.30.+q High-frequency effects; plasma effects
72.20.Ht High-field and nonlinear effects
71.35.-y Excitons and related phenomena
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons

Determination of the (100) InAs/GaSb heterojunction valence‐band discontinuity by x‐ray photoemission core level spectroscopy

G. J. Gualtieri, G. P. Schwartz, R. G. Nuzzo, R. J. Malik, and J. F. Walker

J. Appl. Phys. 61, 5337 (1987); http://dx.doi.org/10.1063/1.338270 (5 pages) | Cited 32 times

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The valence‐band discontinuity ΔEv has been determined for the (100) InAs/GaSb system by x‐ray photoemission core level spectroscopy. For 20 Å of InAs on GaSb we find that ΔEv=0.53 eV. The reverse structure, consisting of a 20‐Å layer of GaSb on InAs, gave a measured value of ΔEv=0.48 eV. Since the difference in these two values lies within our experimental uncertainty, we report an average offset of 0.51±0.1 eV. The large value of the valence‐band discontinuity in this system shows the band lineup to be of the broken gap variety with the InAs conduction‐band energy lying below that of the GaSb valence band. This result is in good agreement with theoretical predictions.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.61.Ey III-V semiconductors
81.65.-b Surface treatments

Hot‐hole injection probabilities into the insulator of metal‐insulator‐silicon devices

Y. Hellouin, F. Chehade, and M. Garrigues

J. Appl. Phys. 61, 5342 (1987); http://dx.doi.org/10.1063/1.338271 (4 pages)

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The probability of hot‐hole injection has been measured both on metal nitride‐oxide silicon (MNOS) and metal‐oxide‐semiconductor (MOS) structures in the case where the silicon electric field is one dimensional and normal to the interface. The experiment uses the effect of optically induced hot carrier injection as proposed by Ning et al. [J. Appl. Phys. 48, 286 (1977)]. In the case of MNOS structures, the hot‐hole injection currents can be readily measured because the Si‐Si3N4 interface barrier is lower than the Si‐SiO2 interface barrier. Measurements on MOS structures were carried out using heavily doped silicon. The measurements have been interpreted using the lucky carrier model with some modifications: the hot‐hole mean‐free path has been found equal to 41±5 Å in the case of MOS structures. Taking into account the accuracy of the measurements, this value is compatible with the value derived in the case of MNOS structures and also with the value derived from ionization measurements.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.50.Fq High-field and nonlinear effects

Study of excitons in an arbitrarily shaped GaAs/Al0.3Ga0.7As single quantum well in the presence of static transverse electric field

Songcheol Hong and Jasprit Singh

J. Appl. Phys. 61, 5346 (1987); http://dx.doi.org/10.1063/1.338272 (7 pages) | Cited 8 times

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A method is developed to calculate exciton parameters in an arbitrarily shaped quantum well by using numerical methods in conjunction with the variational method. We solve the Schrödinger equation of the relevant system both by the Monte Carlo method and by the ordinary differential equation solving method, and find that the two approaches yield similar results. Our technique is readily applied to arbitrarily shaped GaAs/AlGaAs quantum wells, and allows us to study the variation of exciton parameters with respect to transverse electric field. We report the results for exciton binding energies, electron and hole tunneling rates, and exciton volumes, which are essential to predicting electro‐optical properties of quantum well. Results are presented for the square, graded, and asymmetric quantum wells, and the effects of the shape of the well on exciton properties are discussed. We find that there is only small dependence of the exciton binding and emission energy on the well shape, but a strong dependence of the electron and hole tunneling rates and hence of the dynamical aspects of excitonic properties on the well shape.
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73.40.Gk Tunneling
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.20.Fz Weak or Anderson localization

Characteristics of the Si‐SiO2 interface states in thin (70–230 Å) oxide structures

S. Kar and R. L. Narasimhan

J. Appl. Phys. 61, 5353 (1987); http://dx.doi.org/10.1063/1.338273 (7 pages) | Cited 14 times

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Important characteristics of the Si‐SiO2 interface states, such as the interface state density distributions and the electron and the hole capture cross section versus energy profiles, were investigated in unannealed metal/silicon dioxide/silicon (MOS) structures with the gate oxide thickness in the range of 70–230 Å, using the optical MOS admittance technique. The experimentally obtained interface state density distribution, in case of p‐Si/SiO2/Al structures, exhibited two peaked profiles, one near the valence‐band edge Ev and the other near the conduction‐band edge Ec, overlying a concave background. The state density at the peak was observed to undergo a maximum, preceded by a minimum, as the gate oxide thickness tox was increased. The peak energy versus tox and the capture cross section versus tox profiles also indicated strong features.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
85.30.Hi Surface barrier, boundary, and point contact devices
85.60.Dw Photodiodes; phototransistors; photoresistors

Induced inversion at a silicon ferroelectric copolymer interface

J.‐M. Langlois, B. Noirhomme, A. Filion, A. Rambo, and L. G. Caron

J. Appl. Phys. 61, 5360 (1987); http://dx.doi.org/10.1063/1.338274 (6 pages) | Cited 6 times

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A copolymer of vinylidene fluoride and tetrafluoroethylene is solution cast on a p‐type silicon wafer. The dipoles in the copolymer are aligned by corona charging the film or by biasing a subsequently evaporated aluminum gate. The field coupling to the semiconductor is studied by measuring the surface channel currents which flow between a metal‐insulator‐semiconductor source and drain. We show that the field coupling following corona injection is sufficient to induce a strong inversion in silicon and that this effect decays with a time constant which can vary between a few minutes to approximately one day.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.25.+i Surface conductivity and carrier phenomena
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
85.30.De Semiconductor-device characterization, design, and modeling

The determination of diffusion length and surface barrier width from surface photovoltage measurements in CdSe and amorphous Si films

A. R. Moore and Hong‐sheng Lin

J. Appl. Phys. 61, 5366 (1987); http://dx.doi.org/10.1063/1.338275 (3 pages) | Cited 4 times

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Surface photovoltage data on CdSe films measured by Storr and Haneman have been analyzed with a formula originally intended to apply to amorphous silicon. The minority‐carrier diffusion length and surface barrier width obtained are comparable to the results of Storr and Haneman using a different formula directly applicable to CdSe. It is shown also that a‐Si:H analysis is generally suitable for deriving thin‐film surface parameters.
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73.61.Ga II-VI semiconductors
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.50.Pz Photoconduction and photovoltaic effects
73.25.+i Surface conductivity and carrier phenomena

3d and 4f magnetism in Nd2Fe14−xCoxB and Y2Fe14−xCoxB compounds

F. Bolzoni, F. Leccabue, O. Moze, L. Pareti, M. Solzi, and A. Deriu

J. Appl. Phys. 61, 5369 (1987); http://dx.doi.org/10.1063/1.338276 (5 pages) | Cited 5 times

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A systematic study of the effects of Co substitution on the crystal structure and magnetic anisotropy of Y2Fe14−xCoxB and Nd2Fe14−xCoxB has been carried out in order to clarify the different roles and contributions to the anisotropy of both rare earth and transition metals. The substitution of Co leads to an enhancement of the Curie temperature in both series of compounds. The Co has been found to provide a planar anisotropy which is larger than that of the axial anisotropy of Fe. A marked site preference has been observed. Two distinct contributions of the Co to the anisotropy have been observed.
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75.30.Gw Magnetic anisotropy
75.50.Bb Fe and its alloys
61.66.Dk Alloys

Conformational and crystallographic changes occurring in polyvinylidene fluoride during the production of D‐E hysteresis loops

I. L. Guy and J. Unsworth

J. Appl. Phys. 61, 5374 (1987); http://dx.doi.org/10.1063/1.338277 (5 pages) | Cited 10 times

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When polarization hysteresis loops are produced for biaxially oriented polyvinylidene fluoride, significant changes between successive loops are found to occur. These changes are most noticeable during the first few cycles and are shown, with the aid of infrared spectroscopy, to be the result of changes in chain conformation and consequent crystal structure in the material. Movement of free charge appears to play a negligible role in the changes observed.
Show PACS
77.80.Dj Domain structure; hysteresis
78.30.Jw Organic compounds, polymers
77.22.Jp Dielectric breakdown and space-charge effects
61.41.+e Polymers, elastomers, and plastics
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