Geometric Doping Model

Use the to define a dopant distribution in terms of the distance from selected boundaries. This is convenient when specifying distributions which are not easily expressed in terms of the coordinate system. For example, if a profile is defined in terms of the distance from a surface then it may not need to have its expression modified if the geometry is altered. This feature also allows any user defined decay profile away from the selected boundaries, which is suitable for cases where none of the preset decay functions available in the Analytic Doping Model are appropriate.

A default Boundary Selection for Doping Profile is added where the boundaries from which the distance is calculated can be specified.

These settings are the same as for Analytic Doping Model.

Select an option from the list — (the default), , , or .

For , , or profiles, select the — (the default) or . Then specify the maximum doping concentration of the distribution; this is the concentration of the dopants at the selected boundaries.

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For specify the NA0 (SI unit: 1/m3) of the electron acceptor impurities. The default value is 1·1016 1/cm3.

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For specify the ND0 (SI unit: 1/m3) of the electron donor impurities. The default value is 1·1016 1/cm3.

For profiles select the — (the default) or . Then enter an expression for N(D) (SI unit 1/m3). The distance from the selected boundaries is available as variable semi.gdm#.D, which can be used in an expression to define the doping profile. The default expression gives an example of a Gaussian profile defined using this variable.

For the , , and profiles it is necessary to specify the length scale of the profile decay. The section allows the length scale of the profile to be controlled. As with the Analytic Doping Model, the length scale can be controlled either by entering a junction depth or via a profile-specific length scale parameter. See Analytic Doping Model, under for the settings for more details.