Optical Characterization of Anisotropic Thiophene-PhenyleneCooligomer Micro Crystals by Spectroscopic Imaging Ellipsometry

Christian Röling, Peter H. Thiesen, Matthias Duwe, Elena Y. Poimanova, and Vladimir V. Bruevich

Thiophene-Phenylene Co-oligomer

Dhex-TTPTT

semiconducting thiophene-phenylene co-oligomer 1,4-bis(5'-hexyl-[2,2'- bithiophen]-5-yl)benzene (dHexTTPTT) crystals were grown by solvent based self-assembly technique on silicon substrate with 300 nm thermally silicon dioxide.

Instrumentation

Nanofilm_EP4 + MM-Upgrade

Image Stitching

- The surface of the complete sample was recorded in a stitched image with an enhanced ellipsometric contrast (AOI = 60°, Lambda = 510 nm).

- Even Monolayers of the semi conductive material were observed.

Microscopic Mueller-Matrix Ellipsometry

Microscopic Mueller Matrix: 11 elements of normalized (m₁₁) Microscopic MM

Variable Theta, Angle and wavelength spectra: Change of MM-values for anisotropic regions upon rotation of the sample illustrated by MM-element m13 (AOI = 50°, λ = 650 nm)

MM-theta scans for several wavelengths

Isotropic/anisotropic: Off-diagonal blocks of the MM offer contrast between isotropic and anisotropic regions: isotropic: pixels with MM-value = 0 anisotropic: MM-values non-zero

Multilayer 

Monolayer