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  • 1
    Electronic Resource
    Electronic Resource
    A marker-coupled method for site-directed mutagenesis
    Amsterdam : Elsevier
    Gene 103 (1991), S. 73-77 
    Details
    ISSN: 0378-1119
    Keywords: Recombinant DNA ; genetic engineering ; polymerase chain reaction ; protein engineering
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0378-1119(91)90393-P
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  • 2
    Electronic Resource
    Electronic Resource
    Enhancement of modulation bandwidth in InGaAs strained-layer single quantum well lasers (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1173-1175 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown that the unique properties of strained-layer quantum well lasers can be identified by measuring the relaxation oscillation frequency as a function of optical gain. These measurements are insensitive to effects due to nonradiative recombinations and leakage currents, which can mask the beneficial effects in terms of a lower threshold current due to a reduced hole mass in strained quantum wells. The conclusion, both theoretically and experimentally, is that strained-layer quantum well lasers have a higher differential gain but saturate at a lower gain level as compared to regular quantum well lasers. As a consequence, for a strained single quantum well, slightly higher relaxation oscillation frequency results, but only for certain limited ranges of device parameters. A multiple strained-layer quantum well can in theory take better advantage of the higher differential gain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101688
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  • 3
    Electronic Resource
    Electronic Resource
    Hydrogen concentration profiles in as-deposited and annealed phosphorus-doped silicon dioxide films (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 2036-2038 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hydrogen concentration depth profiles in as-deposited and annealed phosphorus-doped silicon dioxide films were measured using the nuclear reaction profiling technique with 6.4 MeV 15N ion beam. The H2/Ar annealing of 450 °C for 60 min in furnace and the rapid thermal annealing at 1000 °C for 60 s in O2 or H2/Ar were carried out. It is found that hydrogen concentration is in the range of 1021–1022 per cm3 in as-deposited films. Annealing at high temperatures, even in a hydrogen containing medium, lowers the hydrogen concentration in all films. The hydrogen concentration gradually increased with time when the films were left in the room environment. The electrical properties of the oxide are found to be related to the presence of hydrogen. The observed correlation between the flatband voltage and the hydrogen concentration is presented and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100495
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  • 4
    Electronic Resource
    Electronic Resource
    p-type doping of GaSb by Ge and Sn grown by molecular beam epitaxy (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 3393-3395 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: p-type doping of molecular beam epitaxy grown GaSb by Ge and Sn has been demonstrated. Both impurities are well behaved with demonstrated free acceptor concentrations as high as 2×1019 cm−3 for Ge and 5×1018 cm−3 for Sn. In addition reflection high-energy electron diffraction measurements during growth indicate that Sn segregation which is common in GaAs does not occur in GaSb. The absence of Sn segregation as well as the p-type nature of Ge and Sn dopants is attributed to the large covalent bond radius of Sb. These dopants are important since they provide an excellent alternative to Be for p-type doping of Sb based materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348518
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  • 5
    Electronic Resource
    Electronic Resource
    Optically induced femtosecond electromagnetic pulses from GaSb/AlSb strained-layer superlattices (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 753-756 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The strain generated electric field in a 〈111〉 oriented misfit superlattice provides a suitable bias for generating optically induced femtosecond electromagnetic radiation. We have measured the electromagnetic radiation from GaSb/AlSb strained-layer superlattices and GaSb thin films; extremely fast electromagnetic pulses from 〈111〉 oriented superlattices have been observed. Because the quantum well structure in the superlattice samples limits the pulse duration of the transient photocurrent, it is possible to generate electromagnetic radiation having a pulse duration comparable with the photocarrier transit time across the quantum well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103411
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  • 6
    Electronic Resource
    Electronic Resource
    Quantum-confined Stark effect in ZnSe/Zn1−xCdxSe quantum wells (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 503-505 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the observation of the quantum-confined Stark effect (QCSE) in the photoluminescence (PL) of ZnSe/ZnCdSe single quantum wells grown by molecular beam epitaxy. The electric field was applied via a reverse-biased Schottky barrier contact. Red shifts of the PL peak as large as 13 meV were detected, and accompanied by a dramatic reduction in the transition intensity, consistent with the QCSE. Even moderate applied voltages (∼5 V) were sufficient to completely quench the luminescence signal. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114550
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  • 7
    Electronic Resource
    Electronic Resource
    Modulated beam epitaxial growth of high quality GaAs single quantum wells at low temperature (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 820-822 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High quality AlGaAs/GaAs quantum wells and low-threshold current density lasers (〈1 kA/cm2) have been successfully grown at low temperatures (500 °C) by a modulated beam epitaxy process in which the group III flux is held constant while the As flux is periodically shut off to produce a metal-rich surface. The improved quality of these low-temperature-grown quantum structures is attributed to both a smoothing of the growth front and a reduction of excess As during the modulated beam epitaxy process. The high growth rates and less frequent shutter operation of this technique make it more practical than migration-enhanced epitaxy or atomic layer epitaxy for low-temperature growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105273
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  • 8
    Electronic Resource
    Electronic Resource
    Formation of self-assembling CdSe quantum dots on ZnSe by molecular beam epitaxy (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 3884-3886 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the formation of self-assembling CdSe quantum dots during molecular beam epitaxial growth on ZnSe and ZnMnSe. Atomic force microscopy measurements on specimens with uncapped dots show relatively narrow dot size distributions, with typical dot diameters of 40±5 nm, and with a diameter-to-height ratio consistently very close to 4:1. Uncapped CdSe dots are unstable with time: their density was observed to drop by an order of magnitude in 10 days, with clear evidence of ripening observed for some dots. Photoluminescence from capped dots indicates exciton localization much stronger than in ZnCdSe/ZnSe quantum wells, due to the additional lateral confinement. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117558
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  • 9
    Electronic Resource
    Electronic Resource
    Resonant tunneling in polytype InAs/AlSb/GaSb heterostructures
    Amsterdam : Elsevier
    Journal of Crystal Growth 111 (1991), S. 651-658 
    Details
    ISSN: 0022-0248
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0022-0248(91)91058-I
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of highly ordered MCM-41 in an alkali-free system and its catalytic activity (1996)
    Springer
    Catalysis letters 38 (1996), S. 33-37 
    Details
    ISSN: 1572-879X
    Keywords: MCM-41 synthesis ; alkali-free gel ; n-heptane cracking ; NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract MCM-41 mesoporous molecular sieve materials are synthesised using aqueous ammonia solution to adjust the pH of the reactant gel. Highly ordered MCM-41 with Si/Al ratio as low as 14 was obtained and characterised by27A1 MAS NMR, XRD, N2-adsorption, benzene sorption, and NH3-TPD measurements. The acidity of MCM-41 materials obtained in this system was conveniently generated through straightforward calcination of the as-synthesised sample. More mild acidic sites generated could be due to the avoidance of the multiple calcination procedure and/or the trace sodium species which are the poisons to Brønsted acid. The catalytic activities forn-heptane cracking and isomerization ofm-xylene were investigated, and these were in accordance with the known properties of MCM-41.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00806896
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