High field carrier transport in semiconductors: From basic physics to submicron device simulation

The general trend of nowadays available semiconductor devices is the miniaturization of structures in order to make them able to respond to changes of bias conditions as fast as possible in such a way that cut-off frequencies be as high as possible and/or the response times be as short as possible. This is essential for microwave as well as rapid logic applications. With the recent advent of electron microlithography and new methods of crystal fabrication (MOCVD, MBF, …) the typical sizes of active layers of devices, especially in FET structures have shrunk well below the micron scale (submicron structures), making high field effects more important than ever. In modern devices studies we have thus to take into account not only the strong deviations from Ohm's law but also the possibility that over very short distances transport properties may be quite different from what they are known to be in bulk materials, allowing for instance electrons to achieve much higher velocities than those normally predicted in the bulk high field regime. In this summary, we will essentially illustrate III-V compound semiconductors and devices and compare with silicon where possible.