The Solid node defines the properties and the model formulation of a solid domain.

By default, the Temperature model input is set to User defined and T can be manually prescribed. You can also select Common model input, and then the temperature is controlled from Default Model Inputs under Global Definitions or by a locally defined Model Input. If a heat transfer interface is included in the component, it controls the temperature Common model input. Alternatively, the temperature field can be selected from another physics interface. All physics interfaces have their own tags (Name). For example, if a Heat Transfer in Fluids interface is included in the component, the Temperature (ht) option is available for T.

In this section, select either Insulator, Conductor, or Charge transport from the Material model list. The Insulator option is equivalent to the Charge Conservation feature in the Electrostatics interface and it only adds Poisson’s equation for the selected domain. The Conductor option is equivalent to the Current Conversation feature in the Electric Currents interface. The Charge transport option is used when you want to model and solve charge carriers explicitly. The Electrons and holes, mobile and trapped model is available.

If using the Charge transport material model, the checkbox Include background ionization and an input field for specifying the background ionization rate will appear. The checkbox is selected by default, see Background Ionization for more details.

If using the Charge transport material model, the checkbox Enable custom space charge density in addition to the predefined values will appear. The checkbox is unselected by default since the space charge density of the predefined charge transport model has already been considered by the physics interface. Select this option if there are additional contributions to the charge density. You can specify these contributions by adding the Space Charge Density or Surface Charge Density features.

Select a Dielectric model to describe the macroscopic properties of the medium (relating the electric displacement D with the electric field E) and the applicable material properties, such as the relative permittivity. Two options, Relative permittivity and Polarization, are available:

This section is shown only when the Material model is Conductor. By default, the Electric conductivity σ (SI unit: S/m) for the media is defined From material. Or select User defined:

For User defined select Isotropic, Diagonal, Symmetric, or Full depending on the characteristics of the electric conductivity, and then enter values or expressions for the electric conductivity σ in the field or matrix. The default is 1 S/m. You can also enter an expression for the conductivity as a function of temperature or other variables.

This section is shown only when the Material model is Charge transport.

The electron and hole mobility is computed from the band mobility and the depth of shallow traps. By default, electron and hole band mobilities are set to From material.

By default, the diffusion coefficient is computed from the mobility with the Einstein relation. For User defined, select Isotropic, Diagonal, Symmetric, or Full and enter values or expressions in the field or matrix. The default is 10−5 m2/s.

This section is only shown when the Charge transport model is selected.