Dual-Heterojunction High Electron Mobility Transistors on GaAs Substrate

The high electron mobility transistors (HEMT’s) in general and AlGaAs/GaAs/AlGaAs dualheterojunction high electron mobility transistors (DHHEMT) specifically have been studied in this paper. These devices show superior characteristics over other types of FET’s for high frequency microwave power applications. The structure of a heterojunction have been discussed followed by two and multiple-channel HEMT fabricated device examples. Several models have been reviewed for calculating the density of charge in the dual 2-dimensional electron gas (2DEG) channels present in DH-HEMT undoped GaAs layer, which leads to the device current-voltage characteristics. In the last part, An AlGaAs/GaAs/AlGaAs DH-HEMT has been designed based on the theories provided in earlier sections with describing several steps taken to optimize its performance and simulations showing the effects of various design parametrers.