The finite difference method requires an orthographic grid. In the two-dimensional case the
grid points are located at horizontal and vertical lines. The points must provide a good
resolution of the regions of the device where a strong variation of the quantities is
expected. Fig. 3.1 shows an example of such a grid. The grid lines are more dense
in the regions of strong variation of the carrier concentration, like the channel and the
junctions of the source and drain doping.
Figure 3.1:
Schematic representation of an orthogonal mesh discretizing the active region of a
MOSFET.