1. Edit and submit a transmittance or absorption spectrum data set.
    In case of an absorption spectrum (k, α), proceed to peak detection — steps 5, 6. For a transmittance spectrum (k, T), take the next steps to convert it to an absorbance spectrum (k, α) first. (Wavenumber unit, k: cm-1)
  2.  — Thickness of the film, μm
  3.  — Reflectance of the film, autodetection
  4. Convert (k, T) to (k, α).
  5. There is a default built-in reference data set of absorption peaks for Si films. If it is applicable, skip this step. To apply a different reference data set, edit it.
  6. Identify absorbance peaks.

Typically, the input data set is a transmittance spectrum, a set of wavenumber (k, cm-1) — transmittance (T, %) values. In order to match the spectrum data against a table of absorbance peak values, the original data set is converted to an absorption spectrum, a set of wavenumber (k, cm-1) — absorbance (α) values: $$\alpha = - \frac{1}{2 w \sqrt{2}} \log\left(\frac{T}{1 - r^2}\right).$$ The width of the film w is a result of direct measurement (microscopy). The reflectance r is deduced from the mean maximum transmittance level To disregarding signal oscillations (dashed line) as r = 1 - To.


The default spectrum is taken from a porous 53-micron thin silicon film previously exposed to electrochemical etching in a fluoric acid solution.