A microwave power double-heterojunction high electron mobility transistor

A microwave power high electron mobility transistor (HEMT) has been developed and tested in the K-band frequency range. The HEMT has a unique configuration of a selectively low-doped (AlGa)As/GaAs/AlGa)As double heterojunction resulting in both capability of high-current density and high gate breakdown voltage. The structure showed electron mobility of 6800 sq cm/V s and two-dimensional (2-D) electron density as high as 1.2 x 10 to the 12th/sq cm at room temperature. An output power of 660 mW (550 mW/mm) with 3.2 dB gain and 19.3-percent power added efficiency was achieved at 20 GHz with 1-micron gate length and 1.2-mm gate periphery. A similar device with 2.4-mm gate width produced an output power of 1 W with 3-dB gain and 15.5-percent efficiency. These results offer microwave high power capability in a double-heterojunction HEMT (DH-HEMT).