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 More Options button () and select Advanced Physics Options in the Show More Options dialog box. Enter a Reference temperature for energy levels T0 (SI unit: K). The default is 293.15 K.

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), Finite element quasi Fermi level (quadratic shape function), Finite element quasi Fermi level (linear shape function), Finite element density-gradient (quadratic shape function), or Finite element density-gradient (linear shape function).

Also specify the Value type when using splitting of complex variables — Real or Complex (the default).

To display the section: Click the Show More Options button () and select Stabilization in the Show More Options dialog box. 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 More Options 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 and the density-gradient formulation, the dependent variable for the electrons or holes is their quasi-Fermi level instead of their concentration. In addition, for the density-gradient formulation, the Slotboom variables are added to the list of dependent variables.