March 2014
Intermediate to advanced
624 pages
26h 33m
English
The depletion of the channel discussed above for a JFET can be accomplished by the use of a reverse-biased Schottky barrier instead of a p-n junction. The resulting device is called a MESFET, indicating that a metal–semiconductor junction is used. This device is useful in high-speed digital or microwave circuits, where the simplicity of Schottky barriers allows fabrication to close geometrical tolerances. There are particular speed advantages for MESFET devices in III–V compounds such as GaAs or InP, which have higher mobilities and carrier drift velocities than Si.
Figure 6–7 shows schematically a simple MESFET in GaAs. The substrate is undoped or doped with chromium, which has an energy ...