Intrinsic Optical Absorption in Germanium-Silicon Alloys

Braunstein, R.; Moore, A. R.; Herman, Frank

doi:10.1103/physrev.109.695

Cited by 659 publications

(216 citation statements)

References 24 publications

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“…The dotted lines in Fig. 6͑c͒ show the temperature variation of the band gap for bulk Ge x Si 1Ϫx for two Ge concentrations ͑from Braunstein et al 28 ͒. Comparing the experimental redshift of the electroluminescence of islands with the temperature variation of the band gap one can conclude that the redshift of EL is roughly due to the band gap shrinkage with temperature.…”

Section: Electroluminescence Of 3d Islandsmentioning

confidence: 74%

Size distribution and electroluminescence of self-assembled Ge dots

Vescan

Stoïca

Chretien

et al. 2000

Journal of Applied Physics

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In this article we study the electroluminescence of p-i-n diode structures with Ge dots consisting of coherent three-dimensional small ͑pyramids͒ and larger ͑dome͒ islands. The Ge dots are formed through strain-induced islanding. The diode structures, including one layer with Ge dots, were deposited on Si mesas with variable areas in order to study the influence of limited area deposition on self-assembling. It was observed that the reduction of deposited area improves island uniformity. The combined analysis of island distribution and electroluminescence spectra has lead to the conclusion that domes in small diodes have a smaller Si content or are less relaxed than domes in larger diodes. The diodes are found to emit up to room temperature near the optical communication wavelength of 1.3 microns.

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Section: Electroluminescence Of 3d Islandsmentioning

confidence: 74%

Size distribution and electroluminescence of self-assembled Ge dots

Vescan

Stoïca

Chretien

et al. 2000

Journal of Applied Physics

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“…There are three main models that have been effectively used to approximate the indirect absorption spectra in Ge and Si bulk materials: a one-phonon model, 14,17,35,36 a multiple-phonon model 15,16,18,20,37 and an electric-field dependent model. 19 The one-phonon model (Eq.…”

Section: Modeling Indirect Absorptionmentioning

confidence: 99%

“…This additional loss is largely due to indirect absorption and it is important to fully understand this mechanism in detail to optimize future modulator designs in Ge or GeSi. While bulk Ge and Si have been extensively studied with respect to their indirect absorption, [14][15][16][17][18][19][20] how this absorption changes in a quantum well (QW) heterostructures (for QCSE devices ) has not yet been similarly investigated. Only one published paper shows the presence of the longitudinal acoustic (LA) phonon in Ge/SiGe quantum wells with the same energy as that of the bulk material.…”

Section: Introductionmentioning

confidence: 99%

Indirect absorption in germanium quantum wells

et al. 2011

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Germanium has become a promising material for creating CMOS-compatible optoelectronic devices, such as modulators and detectors employing the Franz-Keldysh effect (FKE) or the quantum-confined Stark effect (QCSE), which meet strict energy and density requirements for future interconnects. To improve Ge-based modulator design, it is important to understand the contributions to the insertion loss (IL). With indirect absorption being the primary component of IL, we have experimentally determined the strength of this loss and compared it with theoretical models. For the first time, we have used the more sensitive photocurrent measurements for determining the effective absorption coefficient in our Ge/SiGe quantum well material employing QCSE. This measurement technique enables measurement of the absorption coefficient over four orders of magnitude. We find good agreement between our thin Ge quantum wells and the bulk material parameters and theoretical models. Similar to bulk Ge, we find that the 27.7 meV LA phonon is dominant in these quantum confined structures and that the electroabsorption profile can be predicted using the model presented by Frova, Phys. Rev., 145 (1966)

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“…For x<0.85 the conduction band structure resembles that of silicon and the conduction band minimum lies in the (100) direction or X-valleys [26]. Thus we make use of the silicon band structure for Monte Carlo simulations and as explained in [25], the conduction band splits and we consider only the lower 4 valleys for the sake of our simulation…”

Section: Modelmentioning

confidence: 99%

Spin dephasing in silicon germanium (Si_1−xGe_x) nanowires

Kumar

Akram

Dinda

et al. 2011

Journal of Applied Physics

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-We study spin polarized transport in silicon germanium nanowires using a semiclassical monte carlo approach. Spin depolarization in the channel is caused due to D'yakonov-Perel (DP) relaxation associated with Rashba spin orbit coupling and due to ElliottYafet (EY) relaxation. We investigate the dependence of spin dephasing on germanium mole fraction in silicon germanium nanowires. The spin dephasing lengths decrease with an increase in the germanium mole fraction. We also find that the temperature has a strong influence on the dephasing rate and spin relaxation lengths increase with decrease in temperature. The ensemble averaged spin components and the steady state distribution of spin components vary with initial polarization.

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Intrinsic Optical Absorption in Germanium-Silicon Alloys

Cited by 659 publications

References 24 publications

Size distribution and electroluminescence of self-assembled Ge dots

Size distribution and electroluminescence of self-assembled Ge dots

Indirect absorption in germanium quantum wells

Spin dephasing in silicon germanium (Si_1−xGe_x) nanowires

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Intrinsic Optical Absorption in Germanium-Silicon Alloys

Cited by 659 publications

References 24 publications

Size distribution and electroluminescence of self-assembled Ge dots

Size distribution and electroluminescence of self-assembled Ge dots

Indirect absorption in germanium quantum wells

Spin dephasing in silicon germanium (Si1−xGex) nanowires

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Spin dephasing in silicon germanium (Si_1−xGe_x) nanowires