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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of p-dopant interdiffusion in 1.3 μm InGaAsP/InP laser structures using modulation spectroscopy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 2020-2024 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated three In1−xGaxAsyP1−y/InP p-i-n multiple quantum well (MQW) laser structures with different p-doping profiles using contactless electroreflectance (CER) and piezoreflectance (PZR). From the observed Franz–Keldysh oscillations originating in the i-InGaAsP regions, we have evaluated the electric field and hence the amount of p-dopant interdiffusion, which is in agreement with secondary ion mass spectrometry measurements. The CER/PZR spectra from the MQWs makes it possible to evaluate the parameters of these regions of the samples. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371150
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  • 2
    Electronic Resource
    Electronic Resource
    Atomic force microscopy studies of ZnSe self-organized dots fabricated on ZnS/GaP (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1340-1342 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: ZnSe self-organized dot structures on ZnS thin films were fabricated by the molecular beam epitaxy technique. In situ reflection high-energy electron diffraction studies reveal that growth interruption is required for the formation of the dot structure. Atomic force microscopy (AFM) images of the dots taken within the same day of growth reveal that the dot density increases with increasing ZnSe coverage. A density of 18 μm−2 was achieved with a coverage of 8.0 ZnSe monolayers. AFM images taken at later times (up to six months later) show ripening effects. The average dot size measured at various times after growth is consistent with the prediction of the Ostwald ripening model with a growth time constant of 4±1 days for the structure with a coverage of 8.0 ZnSe monolayers. The dot size and density in the fully ripened state are essentially independent of the initial ZnSe coverage. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122156
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  • 3
    Electronic Resource
    Electronic Resource
    Characterization of a graded index of refraction separate confinement heterostructure (GRINSCH) laser structure using contactless electroreflectance (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 2229-2235 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using contactless electroreflectance we have characterized the complete potential profile of a pseudomorphic 0.98 μm InGaAs/GaAs/GaAlAs graded index of refraction separate confinement heterostructure (GRINSCH) laser fabricated by molecular beam epitaxy. Signals were detected from all three relevant portions of the sample. Comparison of the observed transitions from the InGaAs single quantum well (SQW) section with an envelope function calculation (including the effects of strain and electric field) made it possible to evaluate the In composition and width of the SQW. These values are in good agreement with the intended parameters. The energy of 11HH, the fundamental conduction to heavy-hole level (which is closely related to the lasing frequency) can easily be determined to less than ±1 meV at 300 K. From the period of the observed Franz–Keldysh oscillations (FKOs) originating in the GaAlAs GRINSCH region it was possible to directly evaluate the built-in electric field in the structure. We also present a general expression for FKOs in the presence of both electric fields (due to charge) and the "fields" (potential gradient) due to compositional grading. The temperature dependence (20 K〈T〈320 K) of quantum transitions from the InGaAs SQW has been evaluated. Our analysis has emphasized the 11HH transition because it can provide information on the operational temperature of the laser. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368288
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  • 4
    Electronic Resource
    Electronic Resource
    On the origins of the Franz–Keldysh oscillations observed in the electromodulation spectra of graded emitter Ga1−xAlxAs/GaAs heterojunction bipolar transistor structures (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 4447-4453 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have derived expressions for the origins of the Franz–Keldysh oscillations (FKOs), observed in electromodulation, associated with the fields in the Ga1−xAlxAs emitter and GaAs collector regions of graded band gap heterojunction bipolar transistor structures. We show that while the latter FKOs are a measure of the maximum collector space charge field at the collector/base junction the former FKOs are determined by both the space-charge field and the "field" due to the grading in the emitter region. The special case of the abrupt emitter/base junction also is considered. Our expressions are general and can easily be applied to any graded (or abrupt) emitter structure. The results will be compared with experiment, including the photovoltaic effect. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367205
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  • 5
    Electronic Resource
    Electronic Resource
    Room-temperature photoluminescence, contactless electroreflectance, and x-ray characterization of a double-side delta-doped GaAlAs/InGaAs high electron mobility transistor structure (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 1851-1853 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using room-temperature photoluminescence and contactless electroreflectance we have characterized a double-side delta-doped Ga0.8Al0.2As/In0.2Ga0.8As pseudomorphic high electron mobility transistor structure fabricated by metal-organic chemical vapor deposition. Signals have been observed from every region of the sample making it possible to evaluate In and Al compositions, channel width, and two-dimensional electron gas density as well as the properties of the GaAs/GaAlAs superlattice buffer layer. The optical determination of the In composition and channel width are in good agreement with an x-ray measurement. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123690
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  • 6
    Electronic Resource
    Electronic Resource
    Contactless electroreflectance characterization of GaInP/GaAs heterojunction bipolar transistor structures (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 214-216 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have characterized two GaInP/GaAs (001) heterojunction bipolar transistor structures, fabricated by organometallic chemical vapor deposition and chemical beam epitaxy, using contactless electroreflectance, including the dependence of the signals on the polarization {[110] and [11¯0]} of the incident radiation. The ordering parameters deduced from the polarization dependence of the GaInP emitter signals are consistent with transmission electron microscope measurements. From the observed Franz–Keldysh oscillations we have evaluated the electric fields in the collector/base and emitter/base regions. In general, these fields are in good agreement with a calculation based on a comprehensive, self-consistent model, including the photovoltaic effect. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121759
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of the thermal conductivity of diamond-like nanocomposite films using a scanning thermal microscope (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1802-1804 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous "diamond-like/quartz-like" composites a-(C:H/Si:O) constitute a novel class of diamond-related materials with a number of unique bulk and surface properties. Using a thermal imaging microscope we have determined the thermal conductivity (κs) of a-(C:H/Si:O) films deposited on Si(001) substrates. We have developed a calibration procedure which makes it possible to use this method for the evaluation of not only topographical variations in κs but also absolute values. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122287
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  • 8
    Electronic Resource
    Electronic Resource
    Franz–Keldysh oscillations from combined space-charge and grading fields as observed in graded emitter GaAlAs/GaAs heterojunction bipolar transistor structures (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1215-1217 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed a systematic room-temperature photoreflectance study of Franz–Keldysh oscillations from the Ga0.77Al0.23As emitter and GaAs collector regions of a series of graded band-gap emitter GaAlAs/GaAs heterojunction bipolar transistor structures in which both the emitter grading and doping [space-charge field (SCF)] have been varied. It is found that the fields in the emitter depend on both the grading field and SCF, in agreement with the recent theory of Sun and Pollak [W. P. Sun and F. H. Pollak, J. Appl. Phys. 83, 4447 (1998)]. Good agreement for both the collector and emitter fields is found between experiment and simulation using a comprehensive, self-consistent model, including the photovoltaic effect. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122131
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  • 9
    Electronic Resource
    Electronic Resource
    Characterization of InGaAsP/InP p-i-n solar cell structures using modulation spectroscopy and secondary ion mass spectrometry (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 1921-1926 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated two In1−xGaxAsyP1−y/InP p-i-n multiple quantum well (MQW) solar cell structures (with and without gold contacts) with intrinsic (i)-InP spacers and two InP p-i-n control samples (with and without gold contacts) using electroreflectance (ER), piezoreflectance (PZR) and secondary ion mass spectrometry (SIMS). From a comparison of the rich ER/PZR spectra from the MQW regions (including the quantum confined Stark effect produced by an external bias) with an envelope function calculation (strain and electric field), we have been able to completely characterize the composition (x,y), strain and well width of the MQWs. From the electric fields originating in the i-InP region of the two InP p-i-n control samples, as determined from the observed Franz–Keldysh oscillations (FKOs), we have evaluated the amount of p-dopant interdiffusion, in agreement with the SIMS data. The FKOs from the i-InP region of the MQW samples reveal an unusual effect, i.e., a modulation-doping field (superimposed on the p-i-n field) due to a transfer of charge from the n-InP layer to the nearest InGaAsP quantum well. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369170
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  • 10
    Electronic Resource
    Electronic Resource
    Quark-Quark Correlations in the Nucleon in a Generalized Nambu-Jona-Lasinio Model (1996)
    Springer
    Few body systems 20 (1996), S. 93-127 
    Details
    ISSN: 1432-5411
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We present a relativistic model of the nucleon based upon a quark-diquark structure that emerges from a study of the Nambu-Jona-Lasinio model. Similar calculations, made by other authors, have been carried out after a Wick rotation is performed. These previous calculations have neglected confinement; therefore, the masses of the quarks and diquarks had to be adjusted so that the diquarks and the nucleon were stable, in which case the Wick rotation may be made. In our work, we include a momentum-space model of confinement developed earlier and we are therefore able to carry out the calculation in Minkowski space, after making a number of approximations. We determine the relative admixture of a scalar-isoscalar diquark and an axialvector-isovector diquark dynamically and find that an approximately equal admixture provides a reasonable fit to the nucleon magnetic moments. While the original problem (without approximation) requires the specification of eight scalar functions of two variables, our various approximations allow us to calculate several functions of a single variable. We find that only two of these functions are important. Therefore, we can exhibit a relatively simple relativistic wave function of the nucleon expressed in terms of two wave functions describing the relative motion of the quarks and diquarks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s006010050034
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