Henry M. van Driel

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NATURE | VOL 405 | 25 MAY 2000 | www.nature.com 437 13. Flemings, M. C. Solidi®cation Processing (McGraw Hill, New York, 1974). 14. Swei, G. S., Lando, J. B., Reichert, S. E. & Mauritz, K. A. Encyclopedia of Polymer Science and Engineering Vol. 6, p. 209 (Wiley, New York, 1986). 15. Wittmann, J. C. & Lotz, B. Epitaxial crystallization of polymers on organic(More)
In an earlier publication, preliminary observations of the generation of electrical currents were reported in GaAs and low-temperature-grown GaAs (LT-GaAs) at 295 K using quantum interference control of singleand two-photon band–band absorption of 1.55and 0.775m ultrashort optical pulses. Timeintegrated currents were measured via charge collection in a(More)
We show that, when fundamental optical beams are present in a noncentrosymmetric medium simultaneously with their sum-frequency beam, quantum interference between singleand two-photon transitions modifies the net absorption, if the sum frequency corresponds to an energy greater than the band gap. At a macroscopic level this effect can be related to the(More)
Hot electrons are generated in Si(001) at 295 K via linear absorption of .4.3 eV photons or by threephoton processes using 270 fs, 800 nm (1.55 eV) optical pulses. Electron trapping in oxide films is observed via time-dependent optical second harmonic generation induced by the electric field associated with charge transfer. For anodically oxidized samples(More)
Eric J. Loren, Brian A. Ruzicka, Lalani K. Werake, Hui Zhao, Henry M. van Driel, and Arthur L. Smirl Laboratory for Photonics and Quantum Electronics, 138 IATL, University of Iowa, Iowa City, Iowa 52242,USA Department of Physics and Astronomy, The University of Kansas, Lawrence, Kansas 66045, USA Department of Physics and Institute for Optical Sciences,(More)
The dynamics of charge currents ballistically injected in GaAs bulk and quantum wells are spatially and temporally resolved. The electrons and holes are injected with oppositely directed velocities without the use of accelerating fields by quantum interference between two photon absorption of a 200 fs, 1430 nm fundamental pulse and one photon absorption of(More)
We report an experimental and theoretical study of the birefringence of two-dimensional photonic crystals in the spectral region below the first photonic band gap. Transmission spectroscopy is used to measure the birefringence of a sample composed of a triangular lattice of air cylinders in silicon, with a cylinder radius of 0.644 mm and a lattice pitch of(More)
Transient trapping/detrapping of electrons at the Si~100!/SiO2 outer surface is studied studied in vacuum or with an O2 ambient ~between 10 23 and 30 Torr! following internal electron photoemission from Si. Photoemission-current ~produced by a 150 fs, 800 nm laser source! and contact-potential-difference techniques were used to investigate a wide variety of(More)
Photon-induced gas-assisted charging ~PIGAC! of 1.5 nm thick SiO2 overlayers by photoemission from the Si substrate is demonstrated to be a universal feature for all gases. In our case ~multi!photoemission is induced by high-intensity 800 nm, 150 fs pulses in samples at 295 K. O2 is more effective than other gases, probably due to the accumulation of(More)
Femtosecond time-resolved reflectivity was measured near the 1.55 mm absorption edge of several GaAsxSb12x /AlSb quantum well samples. On the basis of differences in the reflectivity recovery kinetics and plateau values, we deduce that G – L intervalley scattering can be effectively suppressed for x>0.19. This is consistent with calculations incorporating(More)