The Semiconductor (semi) interface (), found under the Semiconductor branch () when adding a physics interface, solves Poisson’s equation for the electric potential and the drift-diffusion equations for electrons and holes in a semiconductor material. The default domain feature is the Semiconductor Material Model, which adds these equations to the domain, solving for the electric potential and dependent variables related to the electron and hole concentrations.

When this physics interface is added, these default nodes are also added to the Model Builder—Semiconductor Material Model, Insulation, Zero Charge, and Initial Values. Then, from the Physics toolbar, add other nodes that implement, for example, boundary conditions and Generation-Recombination models. You can also right-click Semiconductor to select physics features from the context menu.

The Label is the default physics interface name.

The Name is used primarily as a scope prefix for variables defined by the physics interface. Refer to such physics interface variables in expressions using the pattern <name>.<variable_name>. In order to distinguish between variables belonging to different physics interfaces, the name string must be unique. Only letters, numbers, and underscores (_) are permitted in the Name field. The first character must be a letter.

The default Name (for the first physics interface in the model) is semi.

Enter the Out-of-plane thickness d (SI unit: m) (2D components), or Cross-section area A (SI unit: m2) (1D components), or Vertical height d (SI unit: m) (1D axisymmetric components).

Use Model properties to set the carrier statistics and solution variables in the model.

Select an option from the Carrier statistics list — Maxwell-Boltzmann (the default) or Fermi-Dirac.

Select an option from the Solution list — Electrons and holes (the default) to solve for both, or Majority carriers only to solve the drift diffusion equations for only one of the carriers, computing the concentration of the other carrier by means of the mass action law: np=ni2. For Majority carriers only also select the Majority carriers — Electrons (the default) or Holes.

Enter the Interface continuation parameter Cp (dimensionless). The default is 1.

Select a Doping and trap density continuation — No continuation (the default), Use interface continuation parameter, or User defined. For User defined enter a value for the Doping and trap density continuation parameter Cp (dimensionless). The default is 1.

To display this section, click the Show button () and select Advanced Physics Options. Enter a Reference temperature for energy levels T0 (SI unit: K). The default is 293.15 K.

To see all settings available in this section, click the Show button () and select Advanced Physics Options. Use this section to change the discretization of the semiconductor equations.

Select a Formulation — Finite volume (constant shape function) (the default), Finite element, log formulation (linear shape function), Finite element, log formulation (quadratic shape function), Finite element (linear shape function), Finite element (quadratic shape function), or Finite element quasi Fermi level (quadratic shape function).

The Finite volume discretization is the default, and provides the best current conservation. The Finite element, log formulation uses fewer degrees of freedom (with a linear shape function) and can be more suitable for certain types of problem. The two Finite element discretization settings are provided mainly for backward compatibility and are not recommended for most purposes. The quasi-Fermi level formulation can be suitable for some systems, such as those at very low temperatures. Also specify the Value type when using splitting of complex variables — Real or Complex (the default).

To display the section: Click the Show button () and select Stabilization. Then under Discretization, select one of these options to further define this section: Finite element, log formulation (linear shape function), Finite element, log formulation (quadratic shape function), Finite element (linear), or Finite element (quadratic).

Streamline diffusion is on by default when the Discretization is set to Finite element. When Streamline diffusion is active additional contributions to the equation system are added which improve the numerical stability. This, however, can add unphysical artificial diffusion to the problem, which can perturb the carrier densities if they take very small values. While streamline diffusion is usually required for the Finite element (linear/quadratic) discretizations, the finite element, log formulation (linear/quadratic shape function) discretizations usually work without it.

To display the section click the Show button () and select Advanced Physics Options. This section is only applicable and visible for the Fermi-Dirac statistics with the Finite volume discretization. By selecting the check box, the computed current density is most consistent with the limiting case of equilibrium condition (zero current density).

The dependent variable (field variable) is for the Electric potential V, Electron concentration Ne, and/or Hole concentration Ph depending on the selected Solution (Electron and holes or Majority carrier only) under Model Properties. For the quasi-Fermi level formulation, the dependent variable for the electrons or holes is their quasi-Fermi level instead of their concentration. The name of the dependent variable can be changed but the names of fields and dependent variables must be unique within a model.