Often the design of new devices and the optimization of device geometries can limit the rate of development of a new technology. Computer models for devices can help speed up this process but these are not well established for gallium arsenide. The PI will establish a research effort, directed at developing physically based computer models for GaAs devices. Such models will allow for the more efficient evaluation and design of new device structures. Our initial approach will be to refine process modeling software and adapt it to GaAs device fabrications processes. This work will form the basis for the device modeling software, initially focussed on MESFETS, which will be used to arrive at physically based closed form descriptions of the device characteristics which software such as SPICE might employ.