Help with Woollam

Arash Hazeghi ahazeghi at
Tue Jul 28 09:32:17 PDT 2009

Thanks Ed,
I have the calibrated n and k values for the layer I want to measure, can
you clarify how to generate a .mat file that contains these values?  I got
emails from several other users who also expressed interest in this so it is
useful for all of us.


-----Original Message-----
From: Ed Myers [mailto:edmyers at] 
Sent: Tuesday, July 28, 2009 7:39 AM
To: Arash Hazeghi; woollam
Subject: Re: Help with Woollam


n and k values for thin films are different from the bulk n and 
k.  This probably why you are seeing the variation from the values 
provided by Woollam.  It's not that these values are wrong, it's the 
fact you have a different film.  At film thickness below 10nm the 
optical constants have a tendency to converge and hence are difficult 
to quantify without additional measurement techniques.  For example, 
you will need to correlate your n and k values and the resulting 
thickness to an actual thickness measurement.

If you provide me the model, I can develop a VASE program for 
you.  What I will need is the measurement pattern and number of 
points and your model location and name.


At 06:26 PM 7/27/2009, Arash Hazeghi wrote:
>Greetings Woollam users,
>I am trying to measure a thin Alumina ALD layer on SiO2 and I want 
>to make a .mat file containing the correct n and k vs wavelength 
>values (the values in Al203.mat file appear to be extrapolated and 
>may not be accurate). Does anyone know how I can generate a .mat 
>file which is readable by woollam? Also I'd like to have a VASE 
>script to take several readings from an area of the sample and take 
>the average, does anyone know how to so this?
>I appreciate your help

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