Traditional Modelling of Semiconductor Devices

Abstract

The study of semiconductor devices spans less than 50 years and the evolution of modelling techniques occupies an even shorter interval. Traditionally, the electrical properties of semiconductor devices have been modelled using equivalent circuit models, where the electrical behaviour of the device at the connecting terminals is represented by a circuit consisting of linear and non-linear circuit elements. However, this type of model can only give limited insight into the physical behaviour of the device and is often restricted in its application to well characterized devices. In contrast, physical models which describe the device in terms of the carrier transport properties and the material and geometrical attributes, allow both a physical and electrical description of the device. Physical models are by their nature more complex than equivalent circuit models and normally require numerical methods to obtain solutions to the set of transport equations. Physical models have generally been regarded in the past as requiring very powerful computers and are often considered to be the domain of the academic. Advances in computer technology over the past 15 years and powerful numerical methods have allowed physical models to address complex device structures using widely available computer resources. Simulation software capable of representing devices in two- and three-dimensions is now available commercially for use on workstations and is utilized increasingly in the semiconductor industry. The demand for supercomputer facilities is diminishing for these classical physical models.