Tag Archives: master model

Master model

The list of materials offers the object type ‘Master model’. What’s that?

Master models are based on the object type ‘Dielectric function model’, i.e. they are used to compute optical constants using a user-defined set of susceptibility terms. In addition, master models have built-in so-called master parameters (you can use up to 6 of them) which can be used to compute selected parameters of the optical constant model as ‘slave parameters’.

A typical application of a master model is this: Suppose you are producing an oxide by a deposition process which can end up in various oxygen concentrations in a layer. If you describe the optical constants with an OJL model, the OJL parameters like bandgap or strength will then depend on the oxygen content of your material. In such a case you can define a master parameter ‘Oxygen content’ and compute the values for the bandgap and strength based on the oxygen content of a particular sample. In order to do this you must know the relations, of course. You can apply user-defined formulas (bandgap vs. oxygen content, for example) or lookup tables which you can generate after a batch analysis of several samples with different oxygen content.
Sometimes it is convenient to apply master parameters just to re-scale parameters. For example, if you do not like to enter bandgaps in wavenumbers, you can define a master parameter that gives the bandgap in eV, and then re-compute the OJL bandgap (which must be specified in wavenumbers for historical reasons) as a slave parameter (like OJL_bandgap = bandgap_eV* 8065).

The SCOUT and CODE software contain a list of global master parameters in their treeview which are used to connect and control any parameter of the optical model in these programs. Please try not to mix up global master parameters and the individual master parameters of master models.