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  • Digitale Medien  (9)
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  • Digitale Medien  (9)
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  • 1
    Digitale Medien
    Digitale Medien
    Thermal redistribution of localized excitons and its effect on the luminescence band in InGaN ternary alloys (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 1810-1812 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Temperature-dependent photoluminescence measurements have been carried out in zinc-blende InGaN epilayers grown on GaAs substrates by metalorganic vapor-phase epitaxy. An anomalous temperature dependence of the peak position of the luminescence band was observed. Considering thermal activation and the transfer of excitons localized at different potential minima, we employed a model to explain the observed behavior. A good agreement between the theory and the experiment is achieved. At high temperatures, the model can be approximated to the band-tail-state emission model proposed by Eliseev et al. [Appl. Phys. Lett. 71, 569 (1997)]. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1403655
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  • 2
    Digitale Medien
    Digitale Medien
    Reduction of threading defects in GaN grown on vicinal SiC(0001) by molecular-beam epitaxy (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 1105-1107 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We observe a significant reduction of threading dislocations in GaN grown on vicinal substrates of SiC(0001). Using scanning tunneling microscopy, we find films grown on vicinal substrates maintain the surface misorientation of the substrate and display terraces with straight edges. On top of the terraces there is no spiral mound, which is the main feature found for films grown on singular substrates. Transmission electron microscopy studies confirm that threading screw dislocations are reduced by two orders of magnitude while edge dislocations are reduced by one order. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1289266
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  • 3
    Digitale Medien
    Digitale Medien
    X-ray diffraction and optical characterization of interdiffusion in self-assembled InAs/GaAs quantum-dot superlattices (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2130-2132 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We report on the characterization of thermally induced interdiffusion in InAs/GaAs quantum-dot superlattices with high-resolution x-ray diffraction and photoluminescence techniques. The dynamical theory is employed to simulate the measured x-ray diffraction rocking curves of the InAs/GaAs quantum-dot superlattices annealed at different temperatures. Excellent agreement between the experimental curves and the simulations is achieved when the composition, thickness, and stress variations caused by interdiffusion are taken in account. It is found that the significant In–Ga intermixing occurs even in the as-grown InAs/GaAs quantum dots. The diffusion coefficients at different temperatures are estimated. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1314298
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  • 4
    Digitale Medien
    Digitale Medien
    Transient growth rate change during gas source molecular beam epitaxy of Si1−xGex alloys (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 2042-2044 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Reflection high-energy electron diffraction intensity oscillations during gas source molecular beam epitaxy growth of Si1−xGex using disilane and germane are reported. Transient changes of the oscillation period and hence the growth rate are observed during the growth. Their origin is discussed on the basis of hydrogen desorption kinetics on the alloy surface and attributed to Ge surface segregation effects at the growth interface. This observation provides a unique opportunity for in situ investigations with monolayer-scale resolution, of Ge segregation effects in Si/Si1−xGex heterostructures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.109473
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  • 5
    Digitale Medien
    Digitale Medien
    Reflection high-energy electron diffraction intensity oscillations of germanium growth on Si(100) using gas source molecular beam epitaxy (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 3066-3068 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Reflection high-energy electron diffraction intensity oscillations during Ge heteroepitaxy on Si(100) have been observed using a gas source molecular beam epitaxy system. Intensity oscillations can be observed over 6 ML (monolayers) of growth in the temperature range 400–650 °C. The oscillation frequency, however, varies from the first to subsequent layers and this variation is interpreted primarily as a change in the limiting growth kinetics as the surface composition changes from Si to Ge. Growth temperature and GeH4 flux dependence data indicate that the surface Ge concentration increases gradually, not abruptly, over the first several layers of deposition. Surface roughening effects which are attributed to Stranski–Krastanov type growth, are also found to contribute to the nonuniform oscillation frequency. © 1994 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.112508
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  • 6
    Digitale Medien
    Digitale Medien
    In situ observation of growth rate enhancement during gas source molecular beam epitaxy of Si1−xGex alloys on Si(100) surfaces (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 2548-2550 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Using reflection-high-energy-electron-diffraction intensity oscillations the growth rate of Si1−xGex alloys at various compositions and different growth temperatures has been studied in situ. It was found that the growth rate shows a strong dependence on GeH4 flux at low temperatures (T〈600 °C), while at high temperatures (T(approximately-greater-than)600 °C) the growth rate is nearly independent of the GeH4 flux but proportional to the incident Si2H6 beam flux. In addition to the enhanced growth rate, a lower activation energy is observed in the low temperature region when compared to Si homoepitaxy from Si2H6. This suggests that surface germanium atoms act as good sites for hydrogen removal which is known to inhibit Si growth from hydride sources at low temperatures. Above 600 °C, however, surface hydrogen is desorbed thermally and the addition of GeH4 has little effect on the growth rate.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.108122
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  • 7
    Digitale Medien
    Digitale Medien
    Two dimensional electron gases in SiGe/Si heterostructures grown by gas source molecular beam epitaxy (1995)
    Springer
    Journal of materials science 6 (1995), S. 330-335 
    Details
    ISSN: 1573-482X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Maschinenbau
    Notizen: We have realized two dimensional electron gases (2DEGs) in tensile strained silicon (Si) channels between strain relaxed silicon germanium (Si0.70Ge0.30) barriers grown on Si(100) substrates by Gas Source Molecular Beam Epitaxy (GSMBE). Disilane (Si2H6), germane (GeH4), and arsine (AsH3) are used as the source gases. Compositionally graded buffer layers with a linear gradient of 30%; Ge/1 Μm relax the strain of the Si0.70Ge0.30 barrier layers by an amount greater than 95%; as determined from X-ray diffraction (XRD) rocking curves. Dislocation densities in the vicinity of the active strained Si channels are below 107 cm−2 as determined from transmission electron microscopy (TEM) measurements. These structures have low n-type background impurity concentrations ( 〈 1016 cm−3) and the Si0.70Ge0.30 barriers can be successfully doped with a unity activation ratio in the 1017 to 1020 cm−3 range. At present, we obtain 300 K (0.4 K) electron mobilities and sheet densities in our 2DEGs of 103 (5.3 × 104) cm2/Vs and 3 × 1012 (5.2 × 1011) cm−2, respectively. A discussion of the requirements for growing these structures by GSMBE and the modifications needed to improve the transport properties of the 2DEGs is presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00125888
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  • 8
    Digitale Medien
    Digitale Medien
    Epitaxial growth mode and silicon/silicon-germanium heterointerfaces (1996)
    Springer
    Journal of materials science 7 (1996), S. 321-325 
    Details
    ISSN: 1573-482X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Maschinenbau
    Notizen: Abstract Silicon-germanium/silicon (Si1 − x Ge x /Si, x 〈 0.50) multiple quantum wells (MQWs) have been grown on (001) Si substrates by gas source molecular beam epitaxy (GSMBE) using disilane (Si2H6) and germane (GeH4) as source gases. Their structural properties have been evaluated by X-ray diffraction (XRD), rocking curve techniques and transmission electron microscopy (TEM). For the substrate temperatures used in this work (450
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00185925
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  • 9
    Digitale Medien
    Digitale Medien
    In situ studies of epitaxial silicon growth by gas source molecular beam epitaxy (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 7 (1997), S. 215-224 
    Details
    ISSN: 1057-9257
    Schlagwort(e): silicon ; epitaxy ; kinetics ; dynamics ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: The value of in situ monitoring to study growth dynamics and surface reaction kinetics in a gas source molecular beam epitaxy process is illustrated with reference to the growth of Si films on Si(001) substrates using a beam of disilane (Si2H6). By using a combination of reflection high-energy electron diffraction (RHEED) and reflection anisotropy spectroscopy (RAS), we show first how morphological (long-range order) and local electronic structure effects can be separated in the evaluation of growth dynamics. This involves the measurement of step density changes by RHEED concomitantly with the variation in domain coverage on the Si(001) (2×1)+(1×2) reconstructed surface by RAS. This approach is then extended to investigate the kinetics of hydrogen desorption, which is the rate-limiting step in Si growth from Si2H6. It is shown that over a significant temperature range, zeroth-order kinetics are obeyed and this is explained on the basis of a step-mediated desorption process. Finally we show how this influences the growth rate on substrates of differing degrees of vicinality. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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