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Physics Faculty Publications

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Articles 1951 - 1980 of 2178

Full-Text Articles in Physical Sciences and Mathematics

Electrochemical Capacitance-Voltage Analysis Of Delta-Doped Pseudomorphic High-Electron-Mobility Transistor Material, C. E. Stutz, B. Jogai, David C. Look, J. M. Ballingall, T. J. Rogers May 1994

Electrochemical Capacitance-Voltage Analysis Of Delta-Doped Pseudomorphic High-Electron-Mobility Transistor Material, C. E. Stutz, B. Jogai, David C. Look, J. M. Ballingall, T. J. Rogers

Physics Faculty Publications

This work shows how electrochemical capacitance‐voltage (EC‐V) measurements can be used to evaluate delta‐doped pseudomorphic high electron mobility transistor material. These EC‐V measurements are compared with magnetic‐field‐dependent Hall effect (M‐Hall) measurements and a self‐consistent Poisson/k⋅p calculation of the band structure and electron concentration. The EC‐V technique can clearly delineate the cap layer, the delta‐doped layer, and the InxGa1−xAs channel layer, whereas the M‐Hall method characterizes only the cap and InxGa1−xAs channel layers. The amount of electron charge seen by …

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Phase Diagram Of The Ising Model On Percolation Clusters, Miron Kaufman, T. Berger, P. D. Gujrati, D. Bowman Apr 1994

Phase Diagram Of The Ising Model On Percolation Clusters, Miron Kaufman, T. Berger, P. D. Gujrati, D. Bowman

Physics Faculty Publications

The annealed Ising magnet on percolation clusters is studied by means of a mapping into a Potts-Ising model and with the Migdal-Kadanoff renormalization-group method. The phase diagram is determined in the three-dimensional parameter space of the Ising coupling K, the bond-occupation probability p, and the fugacity q, which controls the number of clusters. Three phases are identified: percolating ferromagnetic, percolating paramagnetic, and nonpercolating paramagnetic. For large q the phase diagram includes a multicritical point at the intersection of the Ising critical line and the percolation critical line. In the case of random bond percolation (q = 1) the Ising critical …

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Observation Of Free And Bound Excitons Associated With The 2-Dimensional Electron-Gas In Modulation-Doped Heterostructures, D. C. Reynolds, David C. Look, B. Jogai, C. E. Stutz Apr 1994

Observation Of Free And Bound Excitons Associated With The 2-Dimensional Electron-Gas In Modulation-Doped Heterostructures, D. C. Reynolds, David C. Look, B. Jogai, C. E. Stutz

Physics Faculty Publications

Overlapping bulk and two-dimensional excitons have been observed in modulation-doped heterostructures. Their differing behavior in a magnetic field allows them to be studied separately. Both free and bound excitons, associated with the two-dimensional electron gas, have been observed in the photoluminescence spectra of these structures. These excitons show a reduced binding energy due to screening and are found in a region of the structure where band-gap renormalization occurs due to many-body interactions. The two-dimensional excitons are identified from measurements conducted in applied magnetic fields.

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Force Field And Potential Due To The Fermi-Coulomb Hole Charge For Nonspherical-Density Atoms, Marlina Slamet, Viraht Sahni, Manoj K. Harbola Feb 1994

Force Field And Potential Due To The Fermi-Coulomb Hole Charge For Nonspherical-Density Atoms, Marlina Slamet, Viraht Sahni, Manoj K. Harbola

Physics Faculty Publications

In the work formalism for the determination of electronic structure, the exchange-correlation energy and (local) potential of the electrons both arise via Coulomb’s law from the same source, viz., the quantum-mechanical Fermi-Coulomb hole charge. The potential is the work Wxc(r) done to move an electron in the field of its Fermi-Coulomb hole and the energy is the interaction energy between the electronic and hole charge densities. For nonsymmetrical electronic density systems for which the curl of the field may not vanish, a local effective exchange-correlation potential Wxceff(r) is determined from the …

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Rate Coefficient For The Reaction N + No, Jane L. Fox Jan 1994

Rate Coefficient For The Reaction N + No, Jane L. Fox

Physics Faculty Publications

Evidence has been advanced that the rate coefficient for the reaction N + NO → N2; + O has a small positive temperature dependence at the high temperatures (900-1500 K) that prevail in the terrestrial middle and upper thermosphere by Siskind and Rusch (1992), and at the low temperatures (100-200 K) of the Martian lower thermosphere by Fox (1993). Assuming that the rate coefficient recommended by the Jet Propulsion Laboratory evaluation (DeMore et al., 1992) is accurate at 300 K, we derive here the low temperature value of the activation energy for this reaction and thus the rate …

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Hopping Conduction In Molecular Beam Epitaxial Gaas Grown At Very Low Temperatures, David C. Look, Z-Q. Fang, J. W. Look, J. R. Sizelove Jan 1994

Hopping Conduction In Molecular Beam Epitaxial Gaas Grown At Very Low Temperatures, David C. Look, Z-Q. Fang, J. W. Look, J. R. Sizelove

Physics Faculty Publications

Conductivity and Hall effect measurements have been performed on 2 μm thick molecular beam epitaxial layers grown at very low substrate temperatures, 200 to 400°C. For growth temperatures below 300°C, the conduction is dominated by hopping between arsenic antisite defects of concentrations up to 1020 cm−3. Below measurement temperatures of about 130 K, the hopping conduction can be quenched by strong IR light illumination, because the antisite then becomes metastable. The antisite has a thermal activation energy of , and thus is not identical to the famous EL2. Both nearest‐neighbor and variable‐range hopping mechanisms are considered in …

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Interstellar Gas And Dust In The Young Cluster Ic 348, Theodore P. Snow, Margaret Murray Hanson, C Gregory Seab, Jon M. Saken Jan 1994

Interstellar Gas And Dust In The Young Cluster Ic 348, Theodore P. Snow, Margaret Murray Hanson, C Gregory Seab, Jon M. Saken

Physics Faculty Publications

We have completed a multiband absorption- and emission-line study of a star embedded in the young cluster IC 348, to determine the environmental effect of star formation on the interstellar medium (ISM) local to the region. The hottest and youngest star in IC 348 is BD+31°643, a B5 V star which samples the inner bright nebular region. The nearby star o Per, which lies only 8 to the north and is thought to lie beyond IC 348, samples the gas and dust which has not been processed by very recent star formation. We speculate that the ISM throughout the region …

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Molecular-Dynamics Simulations Of Some Baxf4 Compounds, John Flocken, Z. Mo, Wai-Ning Mei, John R. Hardy, Dorian Hatch Jan 1994

Molecular-Dynamics Simulations Of Some Baxf4 Compounds, John Flocken, Z. Mo, Wai-Ning Mei, John R. Hardy, Dorian Hatch

Physics Faculty Publications

We have carried out molecular-dynamics simulations on BaXF4 compounds, where X is Mg, Mn, or Zn. Ab initio potentials, with no adjustable parameters, were used to obtain short-range interactions between ion pairs. We found a polar ground-state structure which is in agreement with the A21am space group reported experimentally. We were able to reverse polarization in BaMgF4 at high temperatures, using large fields, but were unable to reverse polarization in the other compounds. The second-order phase transition in the Mn compound at 250 K was reproduced. We believe this to be the first extension of …

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The Physics Of Grain-Grain Collisions And Gas-Grain Sputtering In Interstellar Shocks, A G. Tielens, C F. Mckee, C G. Seab, D J. Hollenbach Jan 1994

The Physics Of Grain-Grain Collisions And Gas-Grain Sputtering In Interstellar Shocks, A G. Tielens, C F. Mckee, C G. Seab, D J. Hollenbach

Physics Faculty Publications

Grain-grain collisions and ion sputtering destroy dust grains in interstellar shocks. An analytical theory is developed for the propagation of shock waves in solids driven by grain-grain collisions, which compares very favorably with detailed numerical calculations. This theory is used to determine the fraction of a grain vaporized by a grain-grain collision. Our results predict much less vaporization of colliding grains in interstellar shocks than previous estimates. This theory can also be used to determine the fraction of a colliding grain that melts, shatters, or undergoes a phase transformation to a higher density phase. In particular, the latter two processes …

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Multinucleon Effects In Muon Capture On ³He At High Energy Transfer, S. E. Kuhn, W. J. Cummings, G. E. Dodge, S. S. Hanna, B. H. King, Y. M. Shin, J. G. Congleton, R. Helmer, R. B. Schubank, N. R. Stevenson, U. Wienands, Y. K. Lee, G. R. Mason, B. E. King, K. S. Chung, J. M. Lee, D. P. Rosenzweig Jan 1994

Multinucleon Effects In Muon Capture On ³He At High Energy Transfer, S. E. Kuhn, W. J. Cummings, G. E. Dodge, S. S. Hanna, B. H. King, Y. M. Shin, J. G. Congleton, R. Helmer, R. B. Schubank, N. R. Stevenson, U. Wienands, Y. K. Lee, G. R. Mason, B. E. King, K. S. Chung, J. M. Lee, D. P. Rosenzweig

Physics Faculty Publications

Energy spectra of both protons and deuterons emitted following the capture of negative muons by 3He nuclei have been measured for energies above 15 MeV. A limited number of proton-neutron pairs emitted in coincidence were also observed. A simple plane wave impulse approximation (PWIA) model calculation yields fair agreement with the measured proton energy spectra, but underpredicts the measured rate of deuteron production above our energy threshold by a large factor. A more sophisticated PWIA calculation for the two-body breakup channel, based on a realistic three-body wave function for the initial state, is closer to the deuteron data at …

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A Covariant Description Of The Deuteron, J. W. Van Orden Jan 1994

A Covariant Description Of The Deuteron, J. W. Van Orden

Physics Faculty Publications

An introduction to the use of Bethe-Salpeter and quasipotential equations in the description of electron scattering from the deuteron is provided. The basic formalism and many technical issues are introduced in the context of a simple scalar theory. Results for bound-state wave functions and scattering phases shifts for a variety of quasipotential prescriptions are presented and qualitative characteristics of these solutions are discussed. The elastic form factors for the bound state in this model are calculated using the spectator or Gross equation. The calculations are then extended to account for the complexities associated with nucleon spin and results are presented …

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Evidence For Day-To-Night Ion Transport At Low Solar Activity In The Venus Pre-Dawn Ionosphere, J. F. Brannon, Jane L. Fox, H. S. Porter Dec 1993

Evidence For Day-To-Night Ion Transport At Low Solar Activity In The Venus Pre-Dawn Ionosphere, J. F. Brannon, Jane L. Fox, H. S. Porter

Physics Faculty Publications

Periapsis of the Pioneer Venus spacecraft dropped below 180 km on August 28, 1992 near midnight, and 42 orbits of low altitude data at moderately low solar activity in the pre-dawn sector were obtained before contact was lost to the spacecraft in October, 1992. Through a combination of analysis of data from the PV orbiter ion mass spectrometer (OIMS) and modeling, we consider here what can be learned about the relative importance of plasma transport from the dayside and electron precipitation in maintaining the nightside ionosphere during the re-entry period. In particular, we examine here the atomic ion density profiles. …

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Recombination Of 2-Dimensional Electrons With Free Light And Heavy Holes In Alxga1-Xas-Gaas Single Heterojunctions In A Magnetic-Field, D. C. Reynolds, David C. Look, B. Jogai, C. E. Stutz Dec 1993

Recombination Of 2-Dimensional Electrons With Free Light And Heavy Holes In Alxga1-Xas-Gaas Single Heterojunctions In A Magnetic-Field, D. C. Reynolds, David C. Look, B. Jogai, C. E. Stutz

Physics Faculty Publications

Landau-level oscillations are observed in the photoluminescence from an AlxGa1-xAs-GaAs single heterojunction in an applied magnetic field. Extrapolating the oscillations back to zero field gives the energy of the transition from the two-dimensional (2D) electrons to the free heavy holes (hh1 and hh2) and free light holes (lh) weakly confined in the GaAs active layer. The measured energy separation between hh1 and lh is 1.8 meV, which agrees very well with the calculated value of 2.2 meV. The measured energy separation between hh1 and hh2 is 3.8 meV, in good agreement with the calculated value of …

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Mirrorless All‐Optical Bistability In Bacteriorhodopsin, D.V.G.L.N. Rao, F. J. Aranda, B. J. Wiley, J. A. Akkar, D. L. Kaplan, J. F. Roach Sep 1993

Mirrorless All‐Optical Bistability In Bacteriorhodopsin, D.V.G.L.N. Rao, F. J. Aranda, B. J. Wiley, J. A. Akkar, D. L. Kaplan, J. F. Roach

Physics Faculty Publications

We report direct observations of all‐optical mirrorless bistability associated with saturable absorption in three kinds of bacteriorhodopsin (BR) samples: wild‐type BR in water solution and dispersed in thin films of a polymer matrix as well as water solution of the genetically engineered mutant BRD96N. The experiments are carried out with picosecond pulses at 532 nm. The values measured for the saturation intensity are explained in terms of the relaxation of the excited M state population to the B state of the BR photocycle for the three kinds of samples studied.

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On The Escape Of Oxygen And Hydrogen From Mars, Jane L. Fox Sep 1993

On The Escape Of Oxygen And Hydrogen From Mars, Jane L. Fox

Physics Faculty Publications

Escape rates of oxygen atoms from dissociative recombination of O2+ above the Martian exobase are computed in light of new information from ab initio calculations of the dissociative recombination process, and our recently revised understanding of the Martian dayside ionosphere. Only about 60% of the dissociative recombinations occur in channels in which the O atoms are released with energies in excess of the escape velocity. Futhermore, we find that the computed escape fluxes for O depend greatly on the nature of the ion loss process that has been found necessary to reproduce the topside ion density profiles measured …

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Numerical Study Of A High-Order Quasiconserved Quantity In The Henon-Heiles Problem, Paul Finkler, C. Edward Jones, Glenn A. Sowell Sep 1993

Numerical Study Of A High-Order Quasiconserved Quantity In The Henon-Heiles Problem, Paul Finkler, C. Edward Jones, Glenn A. Sowell

Physics Faculty Publications

Recent efforts to derive and study a quasiconserved quantity K in the Henon-Heiles problem in terms of a single set of variables are discussed. Numerical results are given, showing how the value of such a quantity varies with time and order in a power-series expansion for K in terms of monomials of the coordinates and velocities. The lowest order in the power series for K corresponds to n =4 and the highest order to n =27, so that 24 orders are included in the series. The results are compared with an earlier study by the authors [Phys. Rev. A 42, …

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Diffraction Of A Gaussian Beam By A Spherical Obstacle, James A. Lock, Edward A. Hovenac Aug 1993

Diffraction Of A Gaussian Beam By A Spherical Obstacle, James A. Lock, Edward A. Hovenac

Physics Faculty Publications

The Kirchhoff integral for diffraction in the near-forward direction is derived from the exact solution of the electromagnetic boundary value problem of a focused Gaussian laser beam incident on a spherical particle. The diffracted intensity in the vicinity of the particle is computed and the way in which the features of the diffraction pattern depend on the width of the Gaussian beam is commented on.

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Semi-Insulating Nature Of Gas Source Molecular Beam Epitaxial Ingap Grown At Very Low Temperatures, David C. Look, Y. He, J. Ramdani, N. Elmasry, S. M. Bedair Aug 1993

Semi-Insulating Nature Of Gas Source Molecular Beam Epitaxial Ingap Grown At Very Low Temperatures, David C. Look, Y. He, J. Ramdani, N. Elmasry, S. M. Bedair

Physics Faculty Publications

InxGa1−xP lattice matched to GaAs (x≂0.51) has proven to be useful in many device applications. Here we show that undoped, semi‐insulating InGaP is possible by growing with gas source molecular beam epitaxy at very low temperatures, 150–250 °C. The material grown at about 200 °C is n‐type with a 296‐K resistivity of 9×105 Ω cm, a mobility of 120 cm2/V s, and a donor activity energy of 0.48 eV. When annealed at 600 °C for 1 h, the resistivity increases to greater than 109 Ω cm and the …

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Electron-Drift Velocities In Argon-Boron Trichloride Gas-Mixtures, Donald L. Mosteller Jr., Merrill L. Andrews, Jerry D. Clark, A. Garscadden Aug 1993

Electron-Drift Velocities In Argon-Boron Trichloride Gas-Mixtures, Donald L. Mosteller Jr., Merrill L. Andrews, Jerry D. Clark, A. Garscadden

Physics Faculty Publications

Electron drift velocities were measured for argon gas mixtures containing 25 ppm to 0.5% boron trichloride additive using a pulsed-Townsend drift tube. These results show a marked sensitivity to mixture ratio and the gas mixtures also show negative differential conductivity and strong attachment at low electric field/gas number density.

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Electron-Beam Modification Of Gaas Surface-Potential - Measurement Of Richardson Constant, S. M. Lindsay, Joseph W. Hemsky, David C. Look Aug 1993

Electron-Beam Modification Of Gaas Surface-Potential - Measurement Of Richardson Constant, S. M. Lindsay, Joseph W. Hemsky, David C. Look

Physics Faculty Publications

The surface potential of GaAs is strongly modified in the presence of a high‐energy electron beam due to the creation of electron‐hole pairs in the depletion region and the subsequent drift of the holes to the surface where they neutralize surface states. This effect is modeled in terms of a parameter K=A∗T2/Ib(dE/dz)η, where Ib is the beam current density, A∗ is the effective Richardson constant, dE/dz is the beam energy loss per unit length, and η−1 is the average energy required to …

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Interpretation Of Electron Correlation In Local-Density Approximation For Exchange, Viraht Sahni, Marlina Slamet Jul 1993

Interpretation Of Electron Correlation In Local-Density Approximation For Exchange, Viraht Sahni, Marlina Slamet

Physics Faculty Publications

We provide a new interpretation of how electron correlations are represented within the local-density approximation for exchange by deducing via Harbola-Sahni theory the corresponding pair-correlation density. The expression differs from that in the literature and contains, in addition to the uniform electron-gas result, a term proportional to the gradient of the density. Thus, the nonuniformity of the electron density is explicitly incorporated in the approximation, and constitutes thereby the reason underlying its success.

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Upper Limits To The Nightside Ionosphere Of Mars, Jane L. Fox Jul 1993

Upper Limits To The Nightside Ionosphere Of Mars, Jane L. Fox

Physics Faculty Publications

The nightside ionosphere of Mars could be produced by electron precipitation or by plasma transport from the dayside, by analogy to the Venus, but few measurements are available. We report here model calculations of upper limits to the nightside ion densities on Mars that would be produced by both mechanisms. For the auroral model, we have adopted the downward traveling portions of the electron spectra measured by the HARP instrument on the Soviet Phobos spacecraft in the Martian plasma sheet and in the magnetotail lobes. For the plasma transport case, we have imposed on a model of the nightside thermosphere, …

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High-Voltage Mosfet Bipolar Square-Wave Generator, T. D. Usher, Grant A. Mcauley Jul 1993

High-Voltage Mosfet Bipolar Square-Wave Generator, T. D. Usher, Grant A. Mcauley

Physics Faculty Publications

he construction of a high‐voltage (up to 1000 V) bipolar metal‐oxide‐semiconductor field‐effect transistor square‐wave generator is described. This generator is capable of producing both positive and negative going square waves with variable amplitude, repetition rate, and width. The circuit was designed for ferroelectrics research, however other applications are possible. The rise time of the prototype was 200 ns which was quite satisfactory for the present ferroelectric research project however the rise time can be decreased to 50 ns if necessary. The reader with a modest knowledge of electronics should be able to construct the circuit. Possible pitfalls and critical points …

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Prominent Thermally Stimulated Current Trap In Low-Temperature-Grown Molecular-Beam Epitaxial Gaas, Z-Q. Fang, David C. Look Jul 1993

Prominent Thermally Stimulated Current Trap In Low-Temperature-Grown Molecular-Beam Epitaxial Gaas, Z-Q. Fang, David C. Look

Physics Faculty Publications

By far, the largest thermally stimulated current trap in molecular beam epitaxial GaAs grown at 200–250 °C is T5, with an activation energy of 0.27 eV and most likely related to VGa. After an anneal at 300–350 °C, another trap T6☒ appears, with an activation energy of 0.14 eV and closely identified with VAs or the complex, VAs‐AsGa. Proposed defect reactions in this As‐rich material include VGa+AsAs→VAs‐AsGa, and VGa+AsGa→VGa‐AsGa.

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Annealing Dynamics Of Molecular-Beam Epitaxial Gaas Grown At 200°C, David C. Look, D. C. Walters, G. D. Robinson, J. R. Sizelove, M. G. Mier, C. E. Stutz Jul 1993

Annealing Dynamics Of Molecular-Beam Epitaxial Gaas Grown At 200°C, David C. Look, D. C. Walters, G. D. Robinson, J. R. Sizelove, M. G. Mier, C. E. Stutz

Physics Faculty Publications

By separating a 2‐μm‐thick molecular‐beam‐epitaxial GaAs layer grown at 200 °C from its 650‐μm‐thick substrate, we have been able to obtain accurate Hall‐effect and conductivity data as functions of annealing temperature from 300 to 600 °C. At a measurement temperature of 300 K, analysis confirms that hopping conduction is much stronger than band conduction for all annealing temperatures. However, at higher measurement temperatures (up to 500 K), the band conduction becomes comparable, and a detailed analysis yields the donor and acceptor concentrations and the donor activation energy. Also, an independent absorption study yields the total and charged AsGa concentrations. …

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Analytical Two-Layer Hall Analysis - Application To Modulation-Doped Field-Effect Transistors, David C. Look, C. E. Stutz, Christopher A. Bozada Jul 1993

Analytical Two-Layer Hall Analysis - Application To Modulation-Doped Field-Effect Transistors, David C. Look, C. E. Stutz, Christopher A. Bozada

Physics Faculty Publications

The classical magnetic‐field‐dependent Hall coefficient and conductivity equations are inverted to give the mobilities μ1 and μ2 and carrier concentrations n1 (or p1) and n2 (or p2) in two degenerate bands. The two‐band solution holds for arbitrary magnetic‐field strength as long as quantum effects can be ignored (i.e., kT≳ℏeB/m∗), and it is argued that the analysis can also be applied to two separate layers up to reasonable field strengths. The results are used to determine the two‐dimensional electron gas mobility and carrier concentration in a modulation‐doped field‐effect …

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Thermally Activated Escape Over Fluctuating Barriers, Ulrich Zürcher, Charles R. Doering Jun 1993

Thermally Activated Escape Over Fluctuating Barriers, Ulrich Zürcher, Charles R. Doering

Physics Faculty Publications

We investigate the thermally activated escape of a Brownian particle over a potential barrier whose height fluctuates with a rate α between the values E+ and E−. We are mainly interested in the low-temperature behavior where E+/T≫E−/T. We calculate the mean exit time as a function of the rate of the barrier fluctuations for the piecewise linear and the piecewise constant barrier, τ=τ(α). For the piecewise constant potential we find three different regimes: τ∼τ+ for α<τ−1+=exp(-E+/T), τ∼2τ− for α>τ−1−=exp(-E−/T), and τ∼α−1 for τ−1+<α<τ−1−. The mean exit time for the piecewise linear potential has a different behavior for fast barrier fluctuations, α>τ−1−; τ(α) is a monotonously increasing function that approaches the asymptotic value τ∼ √τ+τ− for α→∞. We show that …

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Donor And Acceptor Concentrations In Molecular-Beam Epitaxial Gaas Grown At 300-Degrees-C And 400-Degrees-C, David C. Look, G. D. Robinson, J. R. Sizelove, C. E. Stutz Jun 1993

Donor And Acceptor Concentrations In Molecular-Beam Epitaxial Gaas Grown At 300-Degrees-C And 400-Degrees-C, David C. Look, G. D. Robinson, J. R. Sizelove, C. E. Stutz

Physics Faculty Publications

The first Hall‐effect measurements on molecular beam epitaxial GaAs layers grown at the low temperatures of 300 and 400 °C are reported. Two independent methods were used to determine donor ND and acceptor NA concentrations and activation energy ED0, with the following combined results: ND≂3±1×1018, NA≂1.5±1×1017 cm−3, and ED0=0.645±0.009 eV for the 300 °C layer; ND≂2±1×1017, NA≂7±3×1016 cm−3, and ED0=0.648±0.003 eV for the 400 °C layer. Thus, the deep donor is …

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Photoquenching And Thermal Recovery Of A Thermally Stimulated Current Peak In Semi-Insulating Gaas, Z-Q. Fang, David C. Look May 1993

Photoquenching And Thermal Recovery Of A Thermally Stimulated Current Peak In Semi-Insulating Gaas, Z-Q. Fang, David C. Look

Physics Faculty Publications

A prominent thermally stimulated current peak T5 appearing in semi‐insulating GaAs is shown to photoquench under infrared illumination, and then thermally recover at a rate r=2.0×108 exp(−0.26 eV/kT) s−1, exactly the same as that observed for EL2, within experimental error. Two possible explanations exist: (1) T5 and EL2 are microscopically very similar, probably each with an AsGa core; or (2) T5 is an electron trap that only appears to quench and recover with EL2 because EL2 controls the electron lifetime. Several other traps show similar quenching and recovery behavior.

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Contribution Of High-Order Rainbows To The Scattering Of A Gaussian Laser Beam By A Spherical Particle, James A. Lock Apr 1993

Contribution Of High-Order Rainbows To The Scattering Of A Gaussian Laser Beam By A Spherical Particle, James A. Lock

Physics Faculty Publications

I review the theory of the scattering of a Gaussian laser beam by a dielectric spherical particle and give the details for constructing a computer program to implement the theory. Computational results indicate that if the width of the laser beam is much less than the diameter of the particle and if the axis of the beam is incident near the edge of the particle, the fifth-, sixth-, and ninth-order rainbows should be evident in the far-field scattered intensity. I performed an experiment that yielded tentative evidence for the presence of the sixth-order rainbow.

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