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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1587-1590 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deep levels in lattice-matched Ga0.51In0.49P/GaAs heterostructure have been investigated by thermal-electric effect spectroscopy (TEES) and temperature-dependent conductivity measurements. Four samples were grown by molecular-beam epitaxy with various phosphorus (P2) beam-equivalent pressures (BEP) of 0.125, 0.5, 2, and 4×10−4 Torr. A phosphorus vacancy (VP) -related deep level, an electron trap, was observed located at EC−0.28±0.02 eV. This trap dominated the conduction-band conduction at T(approximately-greater-than)220 K and was responsible for the variable-range hopping conduction when T〈220 K. Its concentration decreased with the increasing phosphorous BEP. Successive rapid thermal annealing showed that its concentration increased with the increasing annealing temperature. Another electron trap at EC−0.51 eV was also observed only in samples with P2 BEP less than 2×10−4 Torr. Its capture cross section was 4.5×10−15 cm2. This trap is attributed to VP-related complexes. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 28 (1995), S. 4904-4907 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2521-2523 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigate the transient thermal expansion of a scanning tunneling microscope tip after excitation with intense femtosecond laser pulses. The expansion dynamics are measured electrically by monitoring the time-resolved tunneling current and mechanically by use of an atomic force microscope. The tip expansion reaches values as high as 15 nm and exceeds the typical working distance of a scanning tunneling microscope by far. This results in a mechanical contact between tunneling tip and surface leading to surface modifications on a nanometer scale. Our findings clarify the mechanism of the recently proposed focusing of laser radiation in the near field of a tip technique [J. Jersch and K. Dickmann, Appl. Phys. Lett. 68, 868 (1996)] for nanostructuring. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 1506-1508 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We perform measurements of the differential gain of modelocked semiconductor quantum well lasers over a wide spectral range employing a modified "electrical pump-optical probe" technique. We find that the two-dimensional density of states expresses itself significantly in the spectral dependence and value of the differential gain. Contributions of the second electronic level are observed in the high-energy range with an increasing in the differential gain, whereas a slightly decreasing differential gain with decreasing wavelength is observed in spectral regimes, where only the first quantized level contributes. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 1240-1242 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the observation of ultrafast intensity oscillations in the time resolved optical emission from a semiconductor microcavity resonantly pumped with intense femtosecond pulses. The observed oscillations are pronounced, persist for several picoseconds, and have frequencies varying from 1.4 to 2.7 THz, depending upon the incidence angle of the pump beam. The angular dependence and spectra show that the oscillations result from interference between the pump and surface-normal modes of the microcavity. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 3227-3229 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on gate voltage dependent electron transport in modulation-doped In0.75Al0.25As/In0.75Ga0.25As heterostructures with strained InAs-inserted-channels grown on GaAs substrates. At temperatures of T=4.2 K we achieve mobilities of up to μ=215 000 cm2(V s)−1 and electron densities of nS=1.2×1012 cm−2 for the highest measured gate voltage of Vg=20 V. The electron effective mass m*=0.036 me is determined by temperature dependent Shubnikov–de Haas measurements. The observation of an anisotropic mobility when the first excited subband becomes populated proves interface scattering to be the limiting mechanism for the electron mobility. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 140-142 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigate optical transmission through individual nanometer-sized holes in opaque metal films using scanning near-field optical microscopy. We show unambiguously that excitation and lateral propagation of surface plasmons support the light transmission through these nanoholes. The direction of the surface plasmon propagation is given by the light polarization, thus controlled addressing of individual holes is possible. In addition, we find characteristic interference effects due to scattering of surface plasmons off holes. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2786-2788 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Beryllium (Be) diffusion into the active layers of single quantum well separate confinement heterostructure lasers grown by molecular beam epitaxy is investigated using photoluminescence absorption spectroscopy, secondary ion mass spectroscopy, capacitance–voltage profiling, and laser threshold current measurements. A significant amount of Be diffusion occurs under normal growth conditions. Large concentrations of Be in the quantum well are correlated to the lack of an exciton feature in the absorption spectrum. The amount of Be in the active region is reduced through a combination of lower Be concentration and lower growth temperature in the upper cladding region of the laser. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 14 (2000), S. 0 
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: To perform a meta-analysis to assess the effectiveness and safety of oral budesonide for inducing remission in active Crohn’s disease and for preventing relapse in Crohn’s disease with medically- or surgically-induced remission.〈section xml:id="abs1-2"〉〈title type="main"〉Methods:All randomized, double-blind controlled trials involving oral budesonide therapy in Crohn’s disease were retrieved from a Medline search, reviews articles or their bibliographies. Of 83 articles retrieved, 12 met the inclusion criteria. Data extraction was performed by three independent observers and scoring disagreements were resolved by consensus.〈section xml:id="abs1-3"〉〈title type="main"〉Results:Six trials tested budesonide in active disease and six in quiescent disease. Budesonide was less effective than conventional corticosteroids for inducing remission of active Crohn’s disease (pooled rate difference, RD –8.5%; 95% CI: –16.4 to –0.7%; P=0.02), but corticosteroid-related adverse events were reduced (RD –22.4%; 95% CI: –32 to –12.8%; P 〈 0.001). In quiescent Crohn’s disease, budesonide was as effective as placebo for preventing relapse in medically induced remission (RD –0.8%; 95% CI: –9.9 to 8.3%; P=0.42) and endoscopic recurrence in surgically induced remission (RD –3.5%; 95% CI: –16.9 to 9.8%; P=0.30). In the long term treatment, budesonide had an occurrence rate of corticosteroid-related adverse effects similar to placebo (RD 5.3%; 95% CI: –3.9 to 14.5%; P=0.30).〈section xml:id="abs1-4"〉〈title type="main"〉Conclusions:Budesonide is significantly less effective than conventional corticosteroids for inducing remission in active Crohn’s disease, but the risk of corticosteroid-related adverse effects is significantly reduced. Budesonide is not effective in preventing relapse of Crohn’s disease after medically- or surgically-induced remission.
    Type of Medium: Electronic Resource
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