Fletcher Mobility Model (C)
The Fletcher Mobility Model (C) subnode is available from the context menu (right-click the Semiconductor Material Model parent node) or from the Physics toolbar, Attributes menu. Use this to add carrier-carrier scattering to an existing mobility model (or to a constant input mobility). The ‘C’ in brackets indicates the model includes carrier-carrier scattering only. It accepts input mobilities of type L or LI, as well as user-defined input mobilities. The set of equations defining the Fletcher mobility model is shown in the Equation section.
Domain Selection
Usually the mobility model selection should not be changed from that of the parent Semiconductor Material Model.
Continuation Settings
The continuation settings enable the equation contributions for the feature to be gradually introduced into the model.
The Continuation type defaults to No continuation, which means that the equation contribution is added in the usual way.
The continuity feature allows the equation contribution to be weighted by an external parameter: the value should be between 0 and 1. Then you can sweep this parameter with the continuity solver.
Selecting User defined allows the parameter to be specified within the feature or select Use interface level continuation parameter to specify the parameter on the physics interface level.
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For User defined enter a Continuation parameter Cp (dimensionless) between 0 and 1 to determine the scaling of the equation contribution. Generally the parameter is ramped from 0 to 1 in a continuation study.
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For Use interface continuation parameter, the continuation parameter is linked to the value of the continuation parameter specified in the Continuation Settings section for The Semiconductor Interface. This enables several features to be introduced simultaneously into the equation system with a single setting controlling it all.
Solving
Input Mobilities
The Electron input mobility μn,in (SI unit: m2/(V⋅s)) parameter is used to define an input mobility to which carrier-carrier scattering is added. The default value is User defined and is a room temperature mobility for silicon, that is, 1448 cm2/(V⋅s).
The Hole input mobility μp,in (SI unit: m2/(V⋅s)) parameter is used to define an input mobility to which carrier-carrier scattering is added. The default value is User defined, and is for silicon at equilibrium, that is, 473 cm2/(V⋅s).
Other mobility models of type L (Power Law Mobility Model (L)) or LI (Arora Mobility Model (LI) as well as User-Defined Mobility Model input mobilities can be used as the Electron input mobility and Hole input mobility.
General Parameters
For each of the following properties the default takes values From material or for User defined enter a different value or expression in the text field.
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Reference temperature Tref (SI unit: K). The default is 300 K.
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Fletcher mobility coefficient1 F1 (SI unit: 1/(m.V⋅s)). The default is for silicon (1.04e21 1/(cm-V⋅s)).
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Fletcher mobility coefficient2 F2 (SI unit: 1/(m2)). The default is for silicon (7.45e12 1/cm-2).
Mobility Models and Theory for the Fletcher Mobility Model (C)