Fine Structure in the Absorption-Edge Spectrum of Si

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

doi:10.1103/physrev.111.1245

Cited by 561 publications

(186 citation statements)

References 18 publications

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“…At 4.2 K, silicon possesses two thresholds for indirect band-gap transitions, with the higher at 1.2135 eV [31]. As a consequence, the types of carriers excited under each illumination varies widely.…”

Section: B Optical Selection Of Spin-pair Speciesmentioning

confidence: 99%

“…While most EDMR experiments have used white light sources for the optical excitation [17,18,26,[28][29][30], light emitting diodes [8,27] and laser excitation [16] have also been used. At cryogenic temperatures the optical penetration depth of light into silicon is known to be strongly wavelength dependent [31]. Thus both the kinetic energy and the spatial distribution of the photoexcited carriers changes with wavelength.…”

Section: Introductionmentioning

confidence: 99%

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Optical Dependence of Electrically Detected Magnetic Resonance in Lightly Doped Si:P Devices

et al. 2017

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Electrically-detected magnetic resonance (EDMR) provides a highly sensitive method for reading out the state of donor spins in silicon. The technique relies on a spin-dependent recombination (SDR) process involving dopant spins that are coupled to interfacial defect spins near the Si/SiO2 interface. To prevent ionization of the donors, the experiments are performed at cryogenic temperatures and the mobile charge carriers needed are generated via optical excitation. The influence of this optical excitation on the SDR process and the resulting EDMR signal is still not well understood. Here, we use EDMR to characterize changes to both phosphorus and defect spin readout as a function of optical excitation using: a 980 nm laser with energy just above the silicon band edge at cryogenic temperatures; a 405 nm laser to generate hot surface-carriers; and a broadband white light source. EDMR signals are observed from the phosphorus donor and two distinct defect species in all the experiments. With near-infrared excitation, we find that the EDMR signal primarily arises from donor-defect pairs, while at higher photon energies there are significant additional contributions from defect-defect pairs. The optical penetration depth into silicon is also known to be strongly wavelength dependent at cryogenic temperatures. The energy of the optical excitation is observed to strongly modulate the kinetics of the SDR process. Careful tuning of the optical photon energy could therefore be used to control both the subset of spin pairs contributing to the EDMR signal as well as the dynamics of the SDR process.

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Section: B Optical Selection Of Spin-pair Speciesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optical Dependence of Electrically Detected Magnetic Resonance in Lightly Doped Si:P Devices

et al. 2017

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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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“…No-phonon transitions can be found in indirect material at only very low temperature. This optical process can be explained by using Macfarlane's model [17]. This formula can be fitted to experimental data by the plot of the square root of I ph · hm versus udetected photon energy.…”

Section: Resultsmentioning

confidence: 99%

Si/SiGe near-infrared photodetectors grown using low pressure chemical vapour deposition

Iamraksa

Lloyd²,

Bagnall

2007

J Mater Sci: Mater Electron

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Near-infrared photodetectors have been fabricated using standard CMOS processes in conjunction with the multilayer growth of Si/SiGe 0.06 using low-pressure chemical vapor deposition (LPCVD). Cross-section scanning electron microscopy (SEM) indicates the existence of quantum dot like corrugations in devices with particularly thick SiGe 0.06 quantum wells. With an accumulation of germanium atoms at the crest of such features and commensurate high germanium concentration we see a considerable enhancement of the long wavelength detection sensitivity of photodetectors in the range 1100-1300 nm. By fitting experimental data the minimum energy gap of the structure is found to be 0.88 eV corresponding to a germanium concentration of around 15%.

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Fine Structure in the Absorption-Edge Spectrum of Si

Cited by 561 publications

References 18 publications

Optical Dependence of Electrically Detected Magnetic Resonance in Lightly Doped Si:P Devices

Optical Dependence of Electrically Detected Magnetic Resonance in Lightly Doped Si:P Devices

Indirect absorption in germanium quantum wells

Si/SiGe near-infrared photodetectors grown using low pressure chemical vapour deposition

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