Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 58: Poster IIb

HL 58.25: Poster

Dienstag, 8. März 2005, 16:30–19:00, Poster TU F

Control of colloidal crystal growth by external fields — •E. von Rhein, O. Gudi, and S. Greulich-Weber — Universität Paderborn, Department Physik, Warburger Straße 100, 33098 Paderborn

Since the introduction of the concept of a photonic crystal much effort has been targeted at producing 3D photonic crystals working in the visible wavelength range. The most promising way is by self-assembly of monodisperse sub-micron spheres made of silica or organic materials resulting in fcc and hcp colloidal crystals. However, the large scale fabrication and thus their application in photonics suffer from the reproducible growth of defect-free extended bulk crystals. Commonly used ’natural’ sedimentation is unacceptably slow and often results in low crystal quality showing cracks and stacking faults or reveals a disordered bulk below an apparently ordered surface. In literature there are several examples, where additional external fields such as electric or acoustic fields were applied, which to a certain extent enhanced the crystal quality. However, the reproducibility of such experiments depends on many parameters like the chemical composition of the spheres, the solvent, the density ratio of spheres and solvent, and many more. To have control of all this parameters during crystal growth is one of our current projects. We will present details of our computer controlled crystal growth experiments using specific external fields.