Field Effect Transistors and Applications

Summary

This chapter discusses types of field effect transistors (FETs) and equivalent circuits. One can find p‐channel junction FETs (JFETs) mostly on silicon transistor and metal semiconductor FET (MESFET) on GaAs and InP, which include a Schottky gate‐channel diode instead of a pn diode. In metal oxide semiconductor FETs (MOSFETs), the gate is made up of a metallically conductive material and separated from the channel by an insulator. In JFETs, MESFETs or MOSFETs, one of the major limitations for the speed of carriers in the channel arises from the collisions between these carriers and the charged centers composed of the doping atoms. In order to eliminate this effect, it is necessary to deport these doping atoms into the gate insulator, which is then made up of another semiconductor, with a larger forbidden bandgap than that of the semiconductor channel, giving rise to a heterojunction.