chapter  4
30 Pages

ELECTRICAL PROPERTIES AND RELATED MECHANISMS OF GAN HETEROSTRUCTURES USED IN HIGH ELECTRON MOBILITY TRANSISTORS

The high electron mobility transistor (HEMT) gets its name by the adoption of the conducting channel formed by a high mobility two-dimensional electron gas (2DEG). Such devices are fabricated from heterostructures whose conduction band edge forms band offsets and quantum wells at the heterointerface, and the electrons distributed in the quantum wells become the 2DEG that can move freely along the heterointerface but is confined perpendicular to the interface by the quantum wells. The source and the drain of the HEMT are to form ohmic contacts to the 2DEG for electric current to arise from the 2DEG transport along the heterointerface, while the Schottky barrier gate controls the on and off of the 2DEG channel by gate voltage. Therefore, such a device is essentially a heterojunction field effect transistor (HFET).