Characterization of lateral semiconductor nanostructures by means of x-ray grazing-incidence diffraction

Paschke, K.; Geue, Thomas; Barberka, T.A.; Bolm, A.; Pietsch, U.; Rösch, M.; Batke, E.; Faller, F.; Kerkel, K.; Oshinowo, J.; Forchel, A.

doi:10.1063/1.118473

Cited by 9 publications

(5 citation statements)

References 15 publications

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“…The (001) reflection was chosen for the measurements owing to the perpendicular arrangement of the net plane relative to the surface normal. The 2θ in angle was then fixed close to the measured in-plane Bragg position followed by a rotation around the surface normal (ω-scan) to detect the appropriate angular position in ω which fulfilled the Bragg condition …”

Section: Methodsmentioning

confidence: 99%

“…The 2θ in angle was then fixed close to the measured in-plane Bragg position followed by a rotation around the surface normal (ωscan) to detect the appropriate angular position in ω which fulfilled the Bragg condition. 50 The grazing incidence diffraction allows a depth resolution of the diffraction. If L i defines the length perpendicular to the surface for which the intensity is reduced by a factor of e, this can be expressed by 51 Neglecting absorption of X-rays, q z is imaginary whenever R i < R c .…”

Section: Polymer V Synthesis Of Poly[hex-5-enyl 12-di-(11-(4′-oxy-4′′...mentioning

confidence: 99%

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Self-Ordering within Thin Films of Poly(olefin sulfone)s

et al. 1998

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A study has been performed of the manner in which two structural features of poly(olefin sulfone)s, helical backbones and calamitic side chains, create order in films. For this purpose copolymers were prepared with one (polymer I) or two (polymer III) cyanobiphenyls per residue, and terpolymers were prepared with both such residues diluted to below the 5% level within an otherwise poly(eicosene sulfone) chain (respectively, polymers II and IV). The polymers all have ordered phases according to X-ray powder diffraction studies on samples cooled from the melt, a layer spacing of about 45 Å being detected in the films as in the bulk. Those polymers with mainly eicosene sulfone residues had crystalline phases with large domains, the layers deriving from the helical backbones alone, the smectic A phases of the parent poly(eicosene sulfone) being either suppressed or reduced in extent by the presence of the aromatic moieties, which were almost randomly orientated. Those with one or two cyanobiphenyls per residue were liquid crystalline. In the latter the layer spacing derives from both backbone and side chains and is reduced when the residues bear a second mesogen as a consequence of a constraining effect from the stiff backbone, as a novel model predicts. The spacers give rise to a glass transition and segregate the planes in which the stiff backbones are assembled from the regions in which the aromatic groups aggregate on account of the strong pi-pi interactions. Amorphous and optically isotropic spun cast films of these polymers became ordered on cooling from the melt or just on annealing, with the order, as determined by studies on the optical properties, being homeotropic for the aromatics and being planar for the backbones in a monodomain. For this arrangement we introduce the term homeo-planar smectic. Order parameters as high as 0.63 were measured for polymer I, from a clear film. The cyanobiphenyl chromophores formed H aggregates, with blue shifts in absorption and red shifts in fluoresence, and a little surprisingly these resulted in a circular dichroism, detectable when the films were inspected at an angle of 45 degrees to the normal.

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Section: Methodsmentioning

confidence: 99%

Section: Polymer V Synthesis Of Poly[hex-5-enyl 12-di-(11-(4′-oxy-4′′...mentioning

confidence: 99%

Self-Ordering within Thin Films of Poly(olefin sulfone)s

et al. 1998

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“…Surface sensitive x-ray scattering, performed under grazing incidence and exit angles has been shown to be a valuable tool in the study of near surface structures of crystalline samples [9,10]. Figure 1 shows the basic scattering geometry for GISAXS.…”

Section: Gisaxsmentioning

confidence: 99%

Grazing incidence x-ray scattering: an ideal tool to study the structure of quantum dots

Metzger¹,

Kegel²,

Paniago³

et al. 1999

J. Phys. D: Appl. Phys.

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We discuss the application of grazing incidence x-ray techniques to characterize nanometer sized islands, which arise in strained layer heteroepitaxy of semiconductor systems (`quantum dots'). Using x-rays from synchrotron sources, grazing incidence small angle scattering (GISAXS) is demonstrated to yield structural information on shape, size and lateral correlation. Results on self-assembled Ge islands on Si(111) substrate are shown as an example. The crystalline properties of coherent quantum dots are obtained from grazing incidence diffraction (GID). From the analysis of reciprocal space maps the interdependence of shape and elastic strain within the quantum dots is determined. We discuss results on coherent InAs quantum structures on GaAs(100).

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“…In this letter we demonstrate that X-ray grazing-incidence diffraction permits the investigation of the interdependence of shape and strain in islands. This technique yields depthsensitive structural information on very thin vertically and laterally structured semiconductor systems [12,13] such as quantum wells and superlattices or quantum wires, respectively. Refraction effects, at incidence and exit angles close to the critical angle of total external reflection reduce the scattering depth to a range between 5 nm and 1 µm, thereby emphasising the scattering from near-or on-surface structures.…”

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confidence: 99%

Interdependence of strain and shape in self-assembled coherent InAs islands on GaAs

et al. 1999

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Self-assembled coherent InAs islands on GaAs (100) have been investigated by a novel version of grazing-incidence diffraction ("iso-strain scattering"). This method permits the determination of the interdependence of strain and shape, as well as the relaxation gradient within the InAs dots. The relaxation in the islands ranges from fully strained at the bottom to completely relaxed at the top of the islands. The radius of the dots at a given height depends linearly on the local elastic lattice relaxation, with a rapidly increasing relaxation gradient when approaching the top of the islands.

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Characterization of lateral semiconductor nanostructures by means of x-ray grazing-incidence diffraction

Cited by 9 publications

References 15 publications

Self-Ordering within Thin Films of Poly(olefin sulfone)s

Self-Ordering within Thin Films of Poly(olefin sulfone)s

Grazing incidence x-ray scattering: an ideal tool to study the structure of quantum dots

Interdependence of strain and shape in self-assembled coherent InAs islands on GaAs

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