I have the absorption data of LSMO thin film on STO substrate, measured by ellipsometry in reflectivity mode. The backside of the substrate is not polished, so it'd assume as a infinite substrate. I'm not sure if only the LSMO absorption is in my interest (and not LSMO+STO), how can I remove the STO effect? (I tried abstracting pure substrate absorption from the data, but the result was negative at some wavelengths)
Hi saeed,
The substrate is not polished, and I assume you mean it is roughened. It should be roughened in order to eliminate the substrate incoherent backside reflections.
Now, what Ellipsometry data did you get? Ellipsometry in reflectivity mode means obtaining Psi and Delta (in reflectivity mode). Is it Psi and Delta? or is it the absorption coefficient obtained from Ellipsometry modeling to Psi and Delta? Ellipsometry does not give the absorption coefficient unless the multilayered structure of the sample is modeled as a film on top of a substrate with an upper layer of film surface roughness. So most likely the absorption data you got is the absorption data extracted from the LSMO sub-layer only and it represent LSMO without the substrate
Hi
Thanks for your respond. I'm using J.A Woollam M2000 ellipsometer and WVASE software. Correct. After doing the measurement in different angles, the software gives me Psi and Delta alongside with dielectric constant, refractive index and also extinction coefficient. Then I convert the extinction coefficient to the absorption (alpha=4*pi*k/lambda). Isn't this a correct way to obtain the absorption coefficient of the film? what confuses me is that for very thin film (less than a couple of nm), the absorption (Obtained by the method I explained) converges to the pure STO absorption.
Hi,
The pSi and Delta is the effective response of the sample (LSMO and STO).
You should modulate the experimental measurment to extract just the LSMO optical constants (Real and imaginary dieclectric function, coefficient absorption).
I propose to read the ellipsometric part in this attached paper for more comprehension:
http://www.sciencedirect.com/science/article/pii/S0254058416301742
Best regards.
Bouzourâa M.-B.
https://doi.org/10.1016/j.matchemphys.2016.03.026
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