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Proceedings Paper

Simulation of light in-coupling through an aperture probe to investigate light propagation in a thin layer for opto-electronic application
Author(s): Markus Ermes; Stephan Lehnen; Zhao Cao; Karsten Bittkau; Reinhard Carius
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Paper Abstract

In thin optoelectronic devices, like organic light emitting diodes (OLED) or thin-film solar cells (TFSC), light propagation, which is initiated by a local point source, is of particular importance. In OLEDs, light is generated in the layer by the luminescence of single molecules, whereas in TFSCs, light is coupled into the devices by scattering at small surface features. In both applications, light propagation within the active layers has a significant impact on the optical device performance. Scanning near-field optical microscopy (SNOM) using aperture probes is a powerful tool to investigate this propagation with a high spatial resolution. Dual-probe SNOM allows simulating the local light generation by an illumination probe as well as the detection of the light propagated through the layer. In our work, we focus on the light propagation in thin silicon films as used in thin-film silicon solar cells. We investigate the light-in-coupling from an illuminating probe via rigorous solution of Maxwell's equations using a Finite-Difference Time-Domain approach, especially to gain insight into the light distribution inside a thin layer, which is not accessible in the experiment. The structures investigated include at and structured surfaces with varying illumination positions and wavelengths. From the performed simulations, we define a "spatial sensitivity" which is characteristic for the local structure and illumination position. This quantity can help to identify structures which are beneficial as well as detrimental to absorption inside the investigated layer. We find a strong dependence of the spatial sensitivity on the surface structure as well as both the absorption coefficient and the probe position. Furthermore, we investigate inhomogeneity in local light propagation resulting from different surface structures and illumination positions.

Paper Details

Date Published: 21 June 2015
PDF: 9 pages
Proc. SPIE 9526, Modeling Aspects in Optical Metrology V, 95260W (21 June 2015); doi: 10.1117/12.2184581
Show Author Affiliations
Markus Ermes, Forschungszentrum Jülich GmbH (Germany)
Stephan Lehnen, Forschungszentrum Jülich GmbH (Germany)
Zhao Cao, Forschungszentrum Jülich GmbH (Germany)
Karsten Bittkau, Forschungszentrum Jülich GmbH (Germany)
Reinhard Carius, Forschungszentrum Jülich GmbH (Germany)


Published in SPIE Proceedings Vol. 9526:
Modeling Aspects in Optical Metrology V
Bernd Bodermann; Karsten Frenner; Richard M. Silver, Editor(s)

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