Exciton and phonon effects in the absorption spectra of germanium and silicon

Macfarlane, G.G.; McLean, Thomas; Quarrington, J E; Roberts, V.

doi:10.1016/0022-3697(59)90372-5

Cited by 146 publications

(47 citation statements)

References 3 publications

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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%

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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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Section: Modeling Indirect Absorptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Indirect absorption in germanium quantum wells

et al. 2011

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“…!.! [23,24]. The free excitons annihilation luminescence for Ge should therefore have the form: [25].…”

Section: Temperature Dependencementioning

confidence: 99%

Photoluminescence of bulk germanium

et al. 2012

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We have performed photoluminescence (PL) measurements on intrinsic and doped bulk Ge substrates as a function of temperature and excitation power. A weak luminescence feature at 738 meV is observed at 7 K for Ge substrates with Al and Sb dopants, but not for intrinsic and Ga doped Ge. This feature can be explained by no-phonon (NP) assisted recombination of free excitons. Besides the NP feature, we observe intense luminescence peaks at 730 meV, 710 meV and 702 meV, which can be attributed to phonon assisted exciton recombination of transverse acoustic (TA), longitudinal acoustic (LA) and transverse optical (TO) phonons in the (111) direction, respectively. Besides these features, we observe luminescence at energy below 700 meV (1.77 μm). This luminescence shows much lower intensity (about 500 times) than the LA replica. The observed luminescence can be explained as a 2-phonon assisted recombination with the previously mentioned TA, LA and TO phonons with momentum in the (111) direction (at the L point) and a TO phonon at the Γ point. The power dependence of the integrated PL shows a log-log dependence with power factor of 2.02 at 9 K. This confirms that the PL originates from recombination of excitons, which are indirectly generated by creation of electrons and holes. The low energy PL edge follows the temperature dependence of the band gap as function of temperature, whereas the high energy PL edge shows an exponential broadening as function of temperature.

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“…при hν ∼ E g Si (E g Si ∼ 1.12 эВ, 293 K -ширина за-прещенной зоны Si)) [12], значительная часть падаю-щего на фотодиод излучения поглощается в глубине структуры. Так, интенсивность излучения с hν ∼ 1.12 эВ уменьшается в e раз на расстоянии ∼ α вклад в собственную ФЧ Si вносит механизм, связанный с диффузией неосновных носителей заряда из глубины структуры к границе области пространственного за-ряда (ОПЗ) p−n-перехода и дальнейшим их дрейфом в электрическом поле перехода к соответствующему контакту [13].…”

Section: результаты и обсуждениеunclassified

Влияние импульсного гамма-нейтронного облучения на фоточувствительность фотодиодов на базе Si с наноостровками GeSi и эпитаксиальными слоями Ge

Иванова¹,

Качемцев²,

Михайлов³

et al. 2018

Физика И Техника Полупроводников

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A comparative study of the effect of pulsed γ-neutron irradiation on the photosensitivity spectra of Si p – n photodiodes with active layers based on self-assembled GeSi nanoisland arrays and Ge epitaxial layers is performed. The irradiation of photodiodes with GeSi nanoislands is found to not lead to photosensitivity degradation in the spectral region of interband optical absorption in nanoislands (wavelength range of 1.1–1.7 μm). At the same time, a steady decrease in the intrinsic photosensitivity of Si and the photosensitivity of photodiodes based on Ge epitaxial layers with an increase in irradiation dose is observed. This effect is attributed to the accumulation of radiation-induced defects in the Si matrix and deep in Ge epitaxial layers, respectively.

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Exciton and phonon effects in the absorption spectra of germanium and silicon

Cited by 146 publications

References 3 publications

Indirect absorption in germanium quantum wells

Indirect absorption in germanium quantum wells

Photoluminescence of bulk germanium

Влияние импульсного гамма-нейтронного облучения на фоточувствительность фотодиодов на базе Si с наноостровками GeSi и эпитаксиальными слоями Ge

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