Structurally induced optical transitions in Ge-Si superlattices

Pearsall, T. P.; Bevk, J.; Feldman, L. C.; Bonar, J. M.; Mannáerts, J. P.; Ourmazd, A.

doi:10.1103/physrevlett.58.729

Cited by 345 publications

(55 citation statements)

References 12 publications

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“…A (Ge 4 Si 4 ) 5 monolayer strained-layer superlattice grown on Si(001) substrate shows strong optical transitions at 0.75, 1.25, and 2.31 eV unique to the superlattice period, found neither in constituent crystals nor in the Ge 0.5 Si 0.5 alloy [62]. Using grazing-incidence fluorescence EXAFS, Wei and colleagues [63] studied the local structure of (Ge 4 Si 4 ) 5 strained-layer superlattice.…”

Section: Semiconductor Quantum Structuresmentioning

confidence: 99%

X-ray absorption fine structure spectroscopy in nanomaterials

et al. 2015

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X-ray absorption fine structure (XAFS) spectroscopy has been widely used for decades in a wide range of scientific fields, including physics, chemistry, biology, materials sciences, environmental sciences, etc. This review article is devoted to the applications of XAFS in nanomaterials. The basic principles of XAFS are briefly described from the view point of practical application, including its theory, data analysis and experiments. Using selected examples from recent literatures, the power of XAFS in determination of local atomic/electronic structures is illustrated for various nanomaterials, covering metal and semiconductor nanoparticles, catalysts, core/shell structures, ultrathin nanosheets, and so on. The utilization of time-resolved XAFS technique is also briefly introduced, for in-situ probing the nucleation/growth processes of nanomaterials and identifying reaction intermediates of nanostructured catalysts under operando conditions.

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Section: Semiconductor Quantum Structuresmentioning

confidence: 99%

X-ray absorption fine structure spectroscopy in nanomaterials

et al. 2015

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“…[2][3][4] Intentionally ordered Si/Ge alloys, with individual layers of unit-cell thickness, displays a different electronic spectrum relative to a random alloy as evidenced by the production of a different phase as a consequence of the ordered atomic structure. 5 In this paper we report the fabrication of short-period Bi/Sb superlattices of atomic scale along with evidence of a changing band structure as a function of the superlattice modulation period thickness. It will be seen that even when the individual layers are р1 monolayer thick, the artificial ordering is preserved and the electronic structure remains distinct from that of a Bi 1Ϫx Sb x random alloy with the same average Sb composition x av .…”

Section: Introductionmentioning

confidence: 96%

Artificially ordered Bi/Sb superlattice alloys: Fabrication and transport properties

et al. 2001

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We have fabricated Bi/Sb superlattice alloys that are artificially ordered on the atomic scale using molecularbeam epitaxy. We observe that by changing the superlattice period thickness, the electronic structure can be ''tuned'' from a semimetal, through zero gap, to a narrow-gap semiconductor. These unique properties, which are distinct from those in random alloys, are believed to be a consequence of ordered atomic configurations.

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“…However, the local atomic arrangements have been shown to deviate from the simply averaged lattice positions and the dilute impurities provide opportunities to study the lattice distortion of host atoms. 8 It is well known that the strain caused by latticemismatch strongly affects the optical properties 10 and surface morphology 11 of epitaxially grown thin film semiconductors. Recently, it was revealed that the Si 1Ϫx Ge x thin films on Ge͑001͒ substrates indicate the photoluminescence spectrum due to a direct transition, where much attention has been focused on the effect of strain on the conduction band minimum.…”

Section: Introductionmentioning

confidence: 99%

Local structures of isovalent and heterovalent dilute impurities in Si crystal probed by fluorescence x-ray absorption fine structure

Wei¹,

Ōyanagi²,

Kawanami³

et al. 1997

Journal of Applied Physics

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Local structures of dilute isovalent and heterovalent impurity atoms in Si crystal ͑Si:X, XϭGa, Ge, As͒ have been studied by fluorescence x-ray absorption fine structure. The distortion of local lattice around the impurity atoms was evaluated from the Si-X bond length determined by extended x-ray absorption fine structure. The results demonstrate that the local lattice deformation is strongly dependent on the electronic configuration of impurity atoms, i.e., we find an anomalous expansion (0.09Ϯ0.01 Å) along the ͓111͔ direction for donor ͑As͒ atoms but much smaller magnitude (0.03Ϯ0.01 Å) for isovalent ͑Ge͒ atoms and acceptor ͑Ga͒ atoms. The results suggest that the local lattice distortions are strongly affected by the Coulomb interactions between the localized charge, which piles up to screen the ion core and the bond charge, and the ion-core repulsion. Absence of anomaly in case of negatively charged Ga atoms suggests that the former mechanism is a dominant factor for anomalous lattice expansion.

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Structurally induced optical transitions in Ge-Si superlattices

Cited by 345 publications

References 12 publications

X-ray absorption fine structure spectroscopy in nanomaterials

X-ray absorption fine structure spectroscopy in nanomaterials

Artificially ordered Bi/Sb superlattice alloys: Fabrication and transport properties

Local structures of isovalent and heterovalent dilute impurities in Si crystal probed by fluorescence x-ray absorption fine structure

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