Insulation
The Insulation node is the default boundary condition. It specifies the zero normal flux condition at the selected boundaries, that is, setting the normal component of the electron current, hole current, and electric displacement field to zero.
Density-Gradient
This section appears only when one of the density-gradient formulation options are selected under the Discretization section.
Formulation
Zero density gradient as the name suggested.
Potential barrier adds the quantum confinement effect of an abrupt potential barrier at the boundary. Enter the carrier effective masses (SI unit: kg) the defaults are me_const. Enter the Barrier heights (SI unit: V) the defaults are 0.1[V].
The functionality of the Surface traps check box in versions prior to 5.4 has been replaced and expanded by the Trap-Assisted Surface Recombination boundary condition.