Following the discovery of the bipolar transistor and the development of
the MOS transistor the need for numerical models to simulate the
physical behaviour of semi-conductors grew considerably. The tasks
involved are complex and many models and discretization methods have
been proposed. The drift-diffusion model is one of the simplest but is
nevertheless of great importance. Conventional discretization methods
are unsuitable for
obtaining a solution and in addition the computing time required to
produce results of acceptable accuracy is too great.
