The Schottky-gated hall-effect transistor and its application to carrier concentration and mobility profiling in GaAs MESFET´s

A special four-terminal MESFET (HFET) is employed in a unique way to characterize carrier concentration and mobility profiles of channel implants into GaAs. This device allows measurement of carrier concentration and mobility under forward gate bias so that the near surface region within the zero bias depletion width can be profiled. From the carrier concentration and mobility profiles, surface and bulk effects can be distinguished. This characterization method allows test devices to be built on production wafers and therefore can serve as a process monitor in the fabrication of GaAs IC´s.