Plenarvorträge - DPG-Tagungen

Halbleiterphysik Montag
up a so called colloidal crystal. These crystals are also known as opals.
Mankind has developed further methods to invert opals by filling up the
space around the spheres with another material and expunge the spheres.
HL 7 Hauptvortrag Stangl
By means of new research results on fireopals, we will show first principles
of tuneable photonic crystals and we will also extend these to inverted
opals which are made of titanium dioxide.
Zeit: Montag 14:30–15:15 Raum: H15
Hauptvortrag HL 7.1 Mo 14:30 H15
Structural properties of semiconductor nanostructures from
x-ray scattering — •Julian Stangl 1 , Anke Hesse 1 , Vaclav
Holy 1,2 , Rainer T. Lechner 1 , Tomas Roch 1 , Mojmir Meduna 1 ,
Zhenyang Zhong 1 , and Günther Bauer 1 — 1 Instut für Halbleiterund
Festkörperphysik, Johannes Kepler Universität Linz, Altenbergerstr.
69, A-4040 Linz, Austria — 2 Department of Condensed Matter Physics,
Faculty of Science, Masaryk University, Kotláˇrská 2, 611 37 Brno, Czech
Republic
New device concepts and the possibility to realize simple quantum
mechanical systems drive the interest in semiconductor nanostructures.
In structures smaller than the DeBroglie wavelength of carriers, typi-
HL 8 Photonische Kristalle II
cally several nm, quantum confinement strongly influences the electronic
properties. The latter depend on size, shape, chemical composition and
strain distribution, which again vary with growth conditions. In order to
understand and control nanostructure growth, their structural properties
have to be determined. X-ray diffraction allows for the non-destructive
investigation of uncapped and buried structures, which are needed for
application.
The talk will present different scattering techniques sensitive to shape,
composition and strain of nanostructures. Results will be presented on
the shape and positional correlation of SiGe islands in superlattices, and
on the composition and strain profile in self-assembled SiGe islands. The
effect of capping on has been studied as well.
Zeit: Montag 15:15–16:30 Raum: H15
HL 8.1 Mo 15:15 H15
Microwave resonators for the optical detection of magnetic resonance
on the basis of photonic crystals — •M. Wanjek, E.
Waldmueller, and S. Greulich-Weber — University of Paderborn,
Fakulty of Science, Physics Department, D-33098 Paderbron, Germany
Electron paramagnetic resonance (EPR) is an important tool for the
study of the microscopic and electronic structure of defects in solids. Via
the optical detection of magnetic resonance(ODMR) the optical properties
of a defect can be related to its microscopic structure. Since today
often only small samples are available (e.g. epi layers) the sensitivity of
EPR has to be increased. In this regard efforts have been made to use high
frequencies, e.g. measuring EPR at 95 GHz instead of 9.5 GHz. Usually
EPR is measured using a microwave bridge with a microwave resonator
containing the sample. At low frequencies cylindrical or rectangular resonators
are used providing also sufficient space for field modulation coils.
At high frequencies the resonator becomes considerably smaller supplying
no space for field coils. External field coils would be shielded by the
metallic resonator itself. Furthermore for ODMR optical access to the
sample is needed, which can not be realized with usual resonators. High
frequency microwave resonator designs fitting to all requirements will be
presented on the basis of photonic crystals.
HL 8.2 Mo 15:30 H15
Doping of colloidal photonic crystals — Bettina Friedel 1 ,
Siegmund Greulich-Weber 1 , Carsten Blum 2 , Heinrich
Marsmann 2 , •Bettina Friedel 1 , Siegmund Greulich-Weber 1 ,
Carsten B lum 2 , and Heinrich Marsmann 2 — 1 Fakultaet fuer
Naturwissenschaften, Department Physik, Universitaet Paderborn,
Warburger Str. 100, DE-33098 Paderborn — 2 Fakultaet fuer Naturwissenschaften,
Department Chemie, Universitaet Paderborn, Warburger
Str. 100, DE-33098 Paderborn
Photonic crystals based on colloidal crystals grown from monodisperse
spherical silica particles have received considerable attention in the recent
years. To increase the relatively low refraction index contrast concerning
to air, many different techniques were proposed: for example coating the
silica spheres with dyes or doping with II-VI compound semiconductors.
For the implementation of photonic devices, like optical waveguides
or microcavities, it is necessary to change the refractive index of single
spheres in order to create point and line defects in the colloidal crystal.
Procedures are presented which allow a local doping of photonic crystals
using established silicon technology. Basic results on doping possibilities
and change of the optical properties are given.
HL 8.3 Mo 15:45 H15
Photonic crystal templates based on holographic lithography
working in a wide spectral range — •C. Enkrich 1,2 , A. Blanco 1,3 ,
K. Busch 4,2 , and M. Wegener 1,3,2 — 1 Institut für Angewandte Physik,
Universität Karlsruhe (TH), 76128 Karlsruhe — 2 DFG-Center for Functional
Nanostructures, Universität Karlsruhe (TH), 76131 Karlsruhe
— 3 Institut für Nanotechnologie, Forschungszentrum Karlsruhe in der
Helmholtz-Gemeinschaft, 76021 Karlsruhe — 4 Institut für Theorie der
Kondensierten Materie, Universität Karlsruhe (TH), 76128 Karlsruhe
The fabrication of three-dimensional photonic crystals is a major challenge
in materials science, especially when the periodicity lies in the optical
region [1]. Here we present a flexible method based on holographic
lithography [2] to fabricate photonic crystal templates. By interference
of four laser beams it is possible to create 3D microporous structures in
a photosensitive resin (SU-8) arranged in an fcc lattice with the periodicity
in the submicron region [3]. By changing experimental parameters
it is possible to tune their photonic properties. We show that the polymer
filling fraction can be varied from around 20% to 80% producing
photonic gaps covering a wide spectral range from the visible to the near
infrared. Comparison with theoretical calculations allows to optimize the
design and therefore the photonic properties. These structures can be
used as templates in which materials with a high dielectric constant can
be infiltrated to produce full photonic band gap crystals.
[1] For a recent review see C. Lopez, Adv. Mater. 15, 1679 (2003).
[2] M. Campbell et al., Nature 404, 53 (2000).
[3] Yu. V. Miklyaev et al., Appl. Phys. Lett. 82, 1284 (2003).
HL 8.4 Mo 16:00 H15
Nahfeldtransmissionsspektroskopie an 1-D metallischen Photonischen
Kristallen — •N. Rau 1 , U. Neuberth 1 , S. Linden 1 , M.
Wegener 1 , A. Christ 2 , J. Kuhl 2 , S. Pereira 3 und K. Busch 3
— 1 Institut für Angewandte Physik, Universität Karlsruhe (TH), 76128
Karlsruhe — 2 Max-Planck-Institut für Festkörperforschung, 70569 Stuttgart
— 3 Institut für Theorie der Kondensierten Materie, Universität
Karlsruhe (TH), 76128 Karlsruhe
Wir stellen Nahfeldtransmissionsexperimente an periodischen 1D-
Gold-Nanodrahtstrukturen auf einem dielektrischen Wellenleiter vor. Die
Probe wird über eine Linse mit linear polarisiertem Weißlicht beleuchtet.
Das transmittierte Licht wird über eine Apertursonde aufgesammelt
und anschließend mit einem Monochromator und einer CCD-Kamera
spektral aufgelöst. Als Sonde werden geätzte Al-bedampte Glasfasern
mit ca. 75nm kleinen Aperturen verwendet, die eine Ortsauflösung von
ca. 100nm ermöglichen. In den orts- und spektral aufgelösten Transmissionsdaten
können perioden- und polarisationsabhängige Effekte mit
feinskaligen Strukturen und hohem Kontrast beobachtet werden. Diese
lassen sich abhängig von der Polarisationsrichtung auf die Anregung von
Wellenleitermoden bzw. des Partikelplasmon-Wellenleiter-Polaritons[1]
zurückführen. Die Ergebnisse werden mit numerischen Simulationen