Quantities are defined by the basic semiconductor equations and are
normally , n, p, Tn, Tp, and TL. They are continuous
functions in space. When discretizing these quantities on the simulation grid
one obtains the variables on the grid points. Geometrical regions within
the device employing a distinct set of models are called segments.
Contact segments are special segments which handle the contact models.
Segments are connected to other segments by interfaces
and to contact segments by boundaries.