Geometric Trap Density
Use the Geometric Trap Density node to specify the density of traps within the domain. This feature enables the trap density to be entered as a function of the distance from selected boundaries. In addition to enabling a fully user-defined trap density to be entered, three preset density profiles are also available. The trap density can be used in conjunction with a Trap-Assisted Recombination feature to specify recombination via trapping sites whose density varies in space. The available options are similar to the Geometric Doping Model feature.
Continuation Settings
These settings are the same as for Analytic Doping Model.
Distribution
Select an option from the Profile away from the boundary list — Gaussian (the default), Linear, Error function (erf), or User defined.
Impurity
Select an Impurity type to give the conductivity type of the selected semiconductor material — Donor traps (the default), Acceptor traps, Neutral electron traps, or Neutral hole traps.
The Impurity type setting has no effect if a neutral level is used within the Trap-Assisted Recombination feature(s).
For Gaussian, Linear, or Error function (erf) distribution profiles, enter a Trap density at boundary Nt0 (SI unit: 1/m3). The default value is 1·1016 1/cm3.
For a User defined profile, enter a value to Define profile as a function of the distance, D, from the boundaries N(D) (SI unit 1/m3).
Profile
This section is available for Gaussian, Linear, or Error function (erf) distribution profiles. Based on the profile selection enter one of the following:
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 Decay length ld (SI unit: m, default value is 1 μm) (Gaussian profiles).
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 Gradient Ngrad (SI unit: 1/m4, default value is −1·1020 1/cm4) (Linear profiles).
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 Argument factor m (SI unit: 1/m, default value is 1 (1/μm)) to specify the factor by which the coordinate values are multiplied before being operated on by the erf() function (Error function (erf) profiles).