- I am going to determine the refractive index of a thin slightly absorbing layer on a thick glass substrate. So I tried to use OptiChar. I load my measured reflectance data and see that theoretical reflectance of the uncoated substrate is about 4% instead of 8%. Layer characterization gives bad results. What am I doing wrong?
Please check, whether you included substrate back side into the calculations. To include it, open Characterization Options and uncheck the box “Reflectance without back side”. Learn more about calculations with back side…
- Is it possible to determine refractive index and extinction coefficient of a thin film deposited on a thick substrate just by giving as input data collected with the spectrometer (e.g. reflectance and/or transmittance) without the necessity of the measure with ellipsometric data?
Yes, it is possible to use only photometric data (R and/or T measured by a spectrophotometer), it is possible to use only ellipsometric data, or it is possible to use combined sets of data (photometeric + ellipsometeric). OptiChar allows you to use any of these approaches. It is demonstrated in our examples.
- I have a complicated post-production characterization problem. I am going to come to the next OptiLayer workshop and bring this problem with me. Will it be possible to discuss my problem confidentially during the workshop? Unfortunately, I cannot give you my measurement data.
We can look at your problem in the course of the workshop (of course, confidentially). You do not need to give the data, we could look at them at your computer.
- I have imported my experimental data to OptiChar. I load the data and in fitting window I see that the data are zero. I see the reasonable model transmittance shown by the black curve and measurement transmittance close to zero. What am I doing wrong?
Please check transmittance units. Probably, in OptiChar settings you set up % for R/T. At the same time experimental transmittance was recorded in your data file in absolute units. If so, go to General Configuration --> Units tab and change T/R units from % to 0-1. Then repeat data import. Specific data import options (Varian, PerkinElmer, X/Y files) allow to set units in the course of the data import procedure, without necessity to change global configuration settings.
- I am going to correct refractive index of my high index material in the course of reverse engineering. In the Indices Correction option, I have a choice between constant drift, linear drift and exponential drift. It is my understanding that constant drift is index offset? Is it correct?
Yes, you are right. Index drift in this context is index offset. These are two different notations of the same thing. If you choose this option, it means that in the course of your reverse engineering procedure, OptiRE will look for a model refractive index: where is refractive index offset. Learn more…
- I am performing post-production characterization of a produced multilayer sample on the basis of T/R data measured in the range from 320 nm to 1500 nm. In Fitting Window I observe that fitting in the range from 320 to 400 nm is very bad. At the same time fitting in the range 400-800 nm is normal. I have looked at Refractive index window and seen that refractive index is a constant in the range from 320 to 400 nm.
If refractive index is constant in 320-400 nm spectral range, it means that you specified refractive index starting with 400 nm only. Please check this. If refractive index dispersion is not specified in a spectral range, then OptiLayer automatically use a constant for calculations in this range. The constant is equal to the refractive index value at the boundary of the spectral range. In your case, refractive index in the range from 320 to 400 nm was taken equal to n(400nm). In order to observe fitting of your experimental data by model data, you have to know refractive index in the whole spectral range of interest. For this purpose, you can produce single layer samples and determine refractive index in the range from 320 to 850 nm using OptiChar.
- I have measurement data from a Woollam ellipsometer. I have Psi, Delta and also R/T. What is more convenient: to record all these data in the same measurement file or to import the data into different files? I am asking because I want first to process Psi, Delta and R/T separately.
I can do by any of these two ways. If you import all the data into one file, you can use Modify Measurement option and temporarily remove, for example, R/T data before your characterization process. Or, you can save the data into separate files and, in the case if you want to see all fitting simultaneously you can use Append to Loaded option and append R/T data to Psi/Delta fitting.