Magneto-optical effects in photoluminescence of Si nanocrystals

Heckler, H.; Kovalev, D.; Polisski, G.; Zinov’ev, N. N.; Koch, F.

doi:10.1103/physrevb.60.7718

Cited by 22 publications

(19 citation statements)

References 17 publications

(20 reference statements)

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“…[40,59] Despite the fact that this treatment of the structure of the exciton ground level in Si nanocrystals is simplified, it explains all the experimental observations very well. [60] In Figure 7, the resonant PL spectrum measured very near the excitation energy is shown. The spectral gap D exch , of the order of a few millielectronvolts, between the excitation line and the onset of emission is clearly seen.…”

Section: Spin Structure Of Excitons Confined In Si Nanocrystalsmentioning

confidence: 98%

“…The first experimental evidence for the importance of this type of interaction in Si nanocrystals was provided by Calcott et al [40] and was later confirmed by a number of different groups. [58][59][60] The upper and lower exciton states are assumed to be an optically active spin singlet (S = 0) and an optically passive spin triplet (S = 1), respectively. Although spin-orbit interaction in Si is weak, it has been shown to play an important role in Si nanocrystals.…”

Section: Spin Structure Of Excitons Confined In Si Nanocrystalsmentioning

confidence: 99%

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Silicon Nanocrystals: Photosensitizers for Oxygen Molecules

2005

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Molecular oxygen plays an important role in many of the chemical reactions involved in the synthesis of biological life. In this review, we explore the interaction between O2 and silicon nanocrystals, which can be employed in the photosynthesis of singlet oxygen. We demonstrate that nanoscale Si has entirely new properties owing to morphological and quantum size effects, i.e., large accessible surface areas and excitons of variable energies and with well‐defined spin structures. These features result in new emerging functionality for nanoscale silicon: it is a very efficient spin‐flip activator of O2, and therefore, a chemically and biologically active material. This whole effect is based on energy transfer from long‐lived electronic excitations confined in Si nanocrystals to surrounding O2 via the exchange of single electrons of opposite spin, thus enabling the spin‐flip activation of O2. Further, we discuss the implications of these findings for physics, chemistry, biology, and medicine.

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Section: Spin Structure Of Excitons Confined In Si Nanocrystalsmentioning

confidence: 98%

Section: Spin Structure Of Excitons Confined In Si Nanocrystalsmentioning

confidence: 99%

Silicon Nanocrystals: Photosensitizers for Oxygen Molecules

2005

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“…At Surprisingly, the most interesting results with also a very clear interpretation have been found from studies of the PL spectral response as a function of external magnetic and electric fields. Following the initial report that an external magnetic field increases the energy gap between singlet and triplet states in Si nanocrystals, the fact that the PL lifetime increases while the intensity decreases in Si nanocrystals with increasing magnetic field was quite well understood [78][79][80]. However, our studies show that in nc-Si superlattices this PL quenching is selective and affects only PL at wavelengths longer than ~ 750 nm.…”

Section: Photoluminescencementioning

confidence: 67%

Optical properties of silicon nanocrystal superlattices

Tsybeskov

2008

J. Nanophoton

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The many interesting and unique physical properties of nanocrystallineSi/amorphous-SiO 2 superlattices stem from their vertical periodicity and nearly defect-free, atomically flat, and chemically abrupt nanocrystalline-Si/SiO 2 interfaces. By combining a less than 5% variation in the initial as-grown amorphous-Si layer thickness with control over the Si nanocrystal shape and crystallographic orientation produced via an appropriate annealing process, systems of nearly identical Si nanocrystals having remarkably different shapes (spheres, ovoids, bricks, etc.) have been produced. Such details governing the fabrication of nanocrystalline-Si/amorphous-SiO 2 superlattices have dramatic effects on their structural and optical-Raman scattering and photoluminescence-properties. The reliable fabrication of Sibased nanostructures with control over the nanocrystal size, shape, and crystallographic orientation is an important first step in their applications in Si photonics.

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“…In a silicon nanostructure with another dielectric, they arise as a result of excitation of charge carriers in the silicon nanocrystallites [17]. In an external magnetic field in silicon nanocrystallites of size 2-3 nm, substantial polarization of nuclei for the magnetic isotope of silicon is possible using such states.…”

Section: Introductionmentioning

confidence: 99%

Nuclear spin polarization in silicon nanostructures with charge carrier injection

Danilyuk

Борисенко

2006

J Appl Spectrosc

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We theoretically examine injection polarization of nuclear spins in silicon nanostructures with hyperfine interaction of nuclei with excited triplet states. We predict the possibility of the appearance of self-sustaining nuclear spin polarization, initiated by an external field. We show that if the external magnetic field is varied, we observe up to a 600-fold jump in the number of spin-polarized nuclei. A similar up to 40-fold jump also appears as the charge carrier injection rate increases.Introduction. Study of the behavior of electronic and nuclear spins in nanostructures upon excitation of their electronic subsystem is important for spintronics and quantum calculations. Due to the insufficient sensitivity of traditional rf spectroscopy methods, optical and electrical polarization and detection methods are used for these purposes [1-3]. Using electrical methods for metrology and control of spin ensembles leads to full-fledged integration of spin systems into semiconductor electronics [4]. From this standpoint, nuclear polarization (controllable by excitation of the electronic subsystem) is promising. For example, in silicon it is due to hyperfine interaction of the 29 Si nuclei with donor or triplet centers [5][6][7]. Substantial polarization of the nuclei in the first case is achieved by excitation of the electronic subsystem with circularly polarized light in compensated silicon, containing donor and acceptor centers; in the second case, by excitation with unpolarized light in a magnetic field. In this case, the degree of nuclear polarization reaches 5%-8% of the concentration of silicon nuclei as a result of hyperfine interaction with excited triplet centers of the Si-S1 type [7]. This effect is promising for development of electronic control of nuclear polarization in silicon nanostructures.The aim of this work was to model injection polarization of silicon nuclear spins in silicon nanostructures when they interact with triplet states, taking into account the magnetic field created by the nuclei.The model. Let us describe the contact interaction of the nuclei with a triplet center with spin S = 1 using the familiar Hamiltonian in [7,8] which, taking into account the field H N = h N sIt created by the nuclei at the electron, has the form:

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Magneto-optical effects in photoluminescence of Si nanocrystals

Cited by 22 publications

References 17 publications

Silicon Nanocrystals: Photosensitizers for Oxygen Molecules

Silicon Nanocrystals: Photosensitizers for Oxygen Molecules

Optical properties of silicon nanocrystal superlattices

Nuclear spin polarization in silicon nanostructures with charge carrier injection

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